Anatomy thorax

Overview of the Thorax
• It is the superior part of
the body b/n the neck &
abdomen
• Is an irregularly shaped
cylinder like region having
I. A narrow superior
thoracic aperture (inlet)
 The superior thoracic
aperture is open, allowing
continuity with the neck
II. A relatively large inferior
thoracic aperture (outlet)
 The inferior thoracic
aperture is closed (not
completely) by the
diaphragm
Introduction
2

Functions
1. Protection of vital organs - provides a
protective cage around
• To the heart, lungs, and great vessels of the
thorax
• To some important abdominal viscera
2. Provides the necessary breathing machineries
• The diaphragm, thoracic wall (eg. the ribs, IC muscles)
3. Acts as a conduit for
• The esophagus, trachea, thoracic duct, vagus nerves, phrenic nerves,
thoracic aorta and superior vena cava
4. Providing attachment for
• Muscles of the upper limbs, neck, abdomen and back, and the muscles of
respiration
5. Supporting the weight of the upper limbs
• By providing skeletal attachment through the clavicle 3

Parts
Thoracic wall Thoracic cavity
1. Skin
2. Fascia
3. Muscles
4. Neurovascular bundles
5. Bones
1. Left and right pleural cavities
 Each surrounds a lung
2. Mediastinum
 Contains the heart, esophagus,
trachea, major nerves, and
major blood vessels
Parts/divisions
4

• Thoracic wall
• Thoracic cavity
 Pleural cavities
 Mediastinum
wall
5

Relationship to other regions
• Neck
 The root of the neck communicates with
the superior thoracic aperture
• Upper limb
 Axillary inlets (gateways to the upper
limbs) and the superior thoracic aperture
communicate via the root of the neck
• Abdomen
 Either through openings of the diaphragm
or gaps posteriorly
• Breast
 Through perforations of anterior chest
wall on each side of the sternum
6

Regional anatomy
 Thoracic wall
 Thoracic cavity
7

• The thoracic wall consists of skin,
fascia, muscles, nerves, vessels and
bones
Skeleton of the thoracic wall
• The skeletal wall of the thorax is
made up of
 12 thoracic vertebrae and their
intervertebral discs …. posteriorly
 12 pairs of ribs and their costal
cartilage … laterally
 The sternum, which consists of
the manubrium, body and xiphoid
process … anteriorly
 The wall opens superiorly and closed
by the diaphragm inferiorly
The thoracic wall
8

The skeletal wall of the thorax
9

 Ribs (L. costae) are curved, flat bones that form most of the thoracic
cage
 There are twelve pairs of ribs
• All ribs articulate with the vertebral column … posteriorly
• All ribs terminate in a costal cartilage … anteriorly
… but not all connected with the sternum … anteriorly
• They are classified according to their sternal connection into;
1. True ribs - articulate directly with the sternum through their own
costal cartilages … the upper seven ribs /vertebro-sternal ribs/
2. False ribs - the remaining five pairs
 The costal cartilages of ribs 8th - 10th articulate anteriorly
with the costal cartilages of the ribs immediately above
/vertebro-chondral ribs/
 The 11th and 12th ribs have no anterior connection with the
sternum or with other ribs, floating ribs or vertebral ribs
Ribs
10

Ribs …
• Ribs are also classified by their
relation to the vertebrae or by
their shape in to;
Typical : 3rd, 4th, 5th, 6th,7th, 8th &
9th ribs
Non- typical : the first two and
the last three
• Consist of a curved shaft with
2 ends (anterior and posterior)
 The anterior end is continuous
with its costal cartilage
 The posterior end articulates
with the vertebral column and
is characterized by a head,
neck, and tubercle
Typical ribs
shaft
Typical ribs
12

Typical ribs…
The head
• Is somewhat expanded
and presents two
articular facets /superior
& inferior/ separated by
a crest
 The superior articulates with
the inferior costal facet of the
body of the vertebra above
 The inferior articulates with
the superior costal facet of its
own vertebra
 The crest is attached to the
intervening intervertebral
disk
13

The neck
• A short flat region that
separates the head from
the tubercle
The tubercle
• Projects from the junction
of the neck with the shaft,
has two regions
1) The articular part, is
medial and has an oval
facet for articulation with
the transverse process of
the associated vertebra
2) The raised non-articular
part, is rough & for
ligament attachment
Tubercle
Typical ribs…
14

Typical ribs …
The shaft
• Is generally thin, flat with 2
surfaces & 2 boarders/margins
Surfaces …. 2
 A smooth convex external surface
 A smooth internal surface
marked by costal groove at its
lower part
 The costal groove contains vein,
artery and nerve /VAN/
Boarders/margins …. 2
 A smooth, thick and rounded
superior margin
 A sharp inferior margin
.
• The shaft has a gentle twist around its longitudinal axis
• It bends forward laterally to the tubercle at the angle of the ribs 15

• These are the 1st, 2nd,
10th, 11th and 12th ribs
Rib I
• Is the shortest,
broadest, most curved
and flat in horizontal
plane
• Has upper and lower
surfaces, and inner and
outer boarders
Non typical ribs
• From its articulation with vertebra TI, it slopes inferiorly to its
attachment to the manubrium of sternum
• The head articulates only with the body of vertebra TI and
therefore has only one articular surface
• Is poorly angled and has no costal groove 16

• Like other ribs, the
tubercle of rib I has
a facet for
articulation with
the transverse
process
• The superior
surface of the rib is
characterized by -
Rib I …
 A tubercle, the scalene tubercle, which separates two
smooth grooves that cross the shaft of the rib along midway
1) The anterior groove - caused by the subclavian vein
2) The posterior groove - caused by the subclavian artery
 Anterior and posterior to these grooves, the shaft is
roughened by muscle and ligament attachments
17

Ribs …
Ribs XI and XII
• Both articulate only with the bodies of their own vertebrae and
have no tubercles, necks or angles
• Both are short, have little curve, and are pointed anteriorly
Rib II
• Like rib I, is flat but twice in
length
• Has poorly marked costal groove
• External surface of the shaft
shows a rough tubercular
Ribs XI and XII
impression for muscle attachment
• Articulates with the vertebral column in a typical way
Rib X
• The head of rib X has a
single facet by which articulates with its own vertebra
18

Costal cartilages
• Are bars of hyaline
cartilages that extend from
the anterior end of the ribs
• They are responsible for
the mobility & elasticity of
the thoracic wall
 1st to 7th ribs have their
own costal cartilages
 8th to 10th blended with
the 7th and articulate with
the sternum
 The last two are pointed
& remain in the muscular
wall of the abdomen
19

The sternum
• An elongated flat bone
• Looks like a ‟sword’’
• It forms the middle portion of the anterior
thoracic wall
• Its upper end margins support the clavicles
• Inferior to the clavicular attachment, it
articulates with the cartilages of the upper
seven pairs of ribs
• The adult sternum has 3 bones
 Manubrium:- the upper broad part
 Widest part/handle like …. 5cm
 Body:- the longitudinally oriented middle
part
 Longest part/blade like … 10cm
 Xiphoid process:- the small and inferior part
 Tapering part/tip … 2cm 20

The sternum
The relationship of the sternum to the
vertebral column
The features of the sternum
21

Manubrium of sternum
• Forms part of the bony
framework of the neck & the
thorax
• Has anterior and posterior
surfaces, two lateral boarders,
and superior and inferior
borders
The superior border is expanded and bears palpable notch in the
mid line, the jugular (suprasternal) notch
 On either side of this notch, a large oval fossa for articulation
with the clavicle
Inferior to the claviclar fossa, on each supero lateral angle of the
manubrium, there’s a facet for the 1st costal cartilage
22

Manubrium …
• At the lower end of the lateral
border, there’s a demifacet
 For articulation with the
upper half of the 2nd costal
cartilage
• Its lower border articulate
with the body of the sternum
by a fibro cartilaginous joint,
manubrio-sternal joint
 The line of fusion form an angle which felt as a transverse
ridge, the sternal /Lewis angle
 It marks the site of junction of the 2nd costal cartilage
to the sternum
23

The body of sternum
• Is flat and longer, narrower, thinner
than the manubrium
• Attains its greatest breadth close to
the lower end
• Its superior border articulates with
the manubrium, the junction forms
a projection called the sternal angle
 It lies opposite 2nd costal cartilage:
guides to count ribs
• Its lateral margins have articular facets for costal cartilages
 Superio laterally, a demifacet for articulation with the inferior demifacet
of the 2nd costal cartilage
 Inferior to the above demifacet, four facets for articulation with the
costal cartilages of rib III to VI
 At the inferior end of this margin, there’s a demifacet which receive the
upper demifacet of the 7th costal cartilage 24

Xiphoid process
• The smallest part of the
sternum
• Its shape is variable
 It may be wide, thin, pointed,
bifid, curved, or perforated
• It begins as a cartilaginous
structure in youth but ossified
in adult
• Its superior border articulate with the body at the xiphi-sternal joint
• On its upper lateral margin, bears a demifacet for the lower
demifacet of the 7th costal cartilage
25

The sternal angle
 lies at the level of the T4-T5 IV disc & the space b/n the 3rd &
4th thoracic spinouse processes ;
1. marks the level of the position of the articulation of the 2nd
pair of costal cartilages with the sternum;
2. separates the superior mediastinum from the inferior
mediastinum;
3. marks the position of the superior limit of the pericardium;
4. marks where the arch of the aorta begins & ends;
5. Lies at the level where the superior vena cava penetrates
the pericardium to enter the heart;
6. Is the level at which the trachea bifurcates into right & left
main bronchi;
7. marks the superior limit of the pulmonary trunk.
26

28
Skeleton of thorax: thoracic apertures
 Superior thoracic aperture
/thoracic inlet
 It is the site of entrance of
the viscera & vessels from
the head, neck and upper
limbs into the thorax
 kidney shaped
 Inferior thoracic aperture
/thoracic outlet
 Closed by the diaphragm,
pierced by the inferior vena
cava (T8), aorta (T12) and
esophagus (T10)

Superior thoracic aperture
• It is completely surrounded by skeletal
elements
 The body of TI vertebra (inner upper border) … posteriorly
 The medial margin of rib I … on each side
 The superior margin of the manubrium of the sternum …
anteriorly
◊ The superior margin of the manubrium is in the same
horizontal plane to that of the intervertebral disc between
vertebrae TII and TIII
◊ The first ribs slope inferiorly from their posterior
articulation with vertebra TI to their anterior attachment to
the manubrium
 Consequently, the plane of the superior thoracic
aperture is at an oblique angle, facing somewhat
anteriorly 29

The superior thoracic apperture
30

Inferior thoracic aperture
• Skeletal elements of the inferior
thoracic aperture are
 The body of vertebra TXII …
posteriorly
 Rib XII and distal end of rib XI …
posterolaterally
 The distal cartilaginous ends of
ribs VII to X, which unite to form
the costal margin …
anterolaterally
 The xiphoid process … anteriorly
• The inferior thoracic aperture is large and expandable
• It is closed by the diaphragm
 Structures passing between the abdomen and thorax pierce or
pass posterior to the diaphragm 31

Flexible wall and inferior thoracic aperture
• The thoracic wall is expandable & allow
movement, b/c
I. Most ribs articulate with other
components of the wall by joints
II. The shape and orientation of the ribs
make it easier
 Posterior attachment of the ribs is
superior to its anterior attachment
 When a rib is elevated, it moves the
anterior thoracic wall forward relative
to the posterior wall, which is fixed
 The middle part of each rib is inferior to its two ends
 When this region of the rib is elevated, it expands the thoracic wall
laterally
III. The diaphragm changes the volume of the thorax vertically
 These changes in the anterior, lateral, and vertical dimensions of the
thoracic cavity are important for breathing
Note the arrows

Joints of the Thoracic Wall
1) Vertebral column Articulations --- b/n vertebrae
2) Costovertebral Articulations -- b/n vertebrae and ribs
3) Costochondral – b/n anterior end of ribs and their costal cartilage
4) Interchondral joints – b/n costal cartilages of adjacent ribs
5) Sternocostal – b/n sternum and costal cartilages
6) Intersternal – between sternal parts
 Manubriosternal – b/n manubrium & body
 Xiphisternal – b/n body & xiphoid process
7) Sternoclavicular joints - b/n sternum and clavicle
33

Surface Anatomy of the Thoracic Wall Skeleton
34

Intercostal spaces /ICSs
• Intercostal spaces lie between adjacent ribs and are
filled by intercostal muscles
• Intercostal nerves and associated major arteries and
veins lie in the costal groove
 Along the inferior margin of the ribs, they pass in the plane
between the inner two layers of muscles in a VAN
arrangement from above down
• Muscles of Thoracic Wall
* All innervated by IC n
The 3 layers of muscles in IC spaces:
1. Ext layer – Ext IC m
2. Middle layer – Internal IC
3. Internal layer – Innermost IC, subcostal,Transverse
thoracis.
35

Intercostal spaces & their contents
A. Anterolateral view. B. Details of an
intercostal space and relationships
36

Intercostal spaces & their contents
C. Transverse section
37

• Are three flat muscles in each
intercostal space that pass
between adjacent ribs
• Individual muscles are named
according to their positions
 External intercostal muscles
are the most superficial
 Internal intercostal muscles
are sandwiched between the
external and innermost
intercostal muscles
 Innermost intercostal muscles
Intercostal muscles
 Innervated by the related intercostal nerve of their own space
 As a group, they provide structural support for the intercostal spaces
during breathing
 They can also move the ribs during breathing 38

• Forms the most superf. layer
• Origin – inf. border of rib above
• Insertion – sup. border of rib
below
• Direction of muscle fibers -
project obliquely in a posterior to
anterior direction
External intercostal muscles
 Anteriorly, these muscles are replaced by
an aponeurosis, the external intercostal
membrane which extends to the sternum
• Action - pulls ribs upward and are
active in inspiration
Anterior
Posterior
 The muscles occupy intercostal
spaces from the regions of the
tubercles behind to costochondral
junction in front
39

• It forms the intermediate layer
• They pass between
 The most inferior lateral edge
of the costal grooves of the
ribs above to the superior
border of the ribs below deep
to the externals
 They extend from parasternal
regions, to the angle of the ribs
posteriorly
 This layer continues toward the
vertebral column replaced by an
aponeurosis, the internal
intercostal membrane
 The aponeurosis continues
with the sup. costotransverse
ligament
Internal intercostal muscles
• The fibers pass in the opposite
direction to those of the
external intercostal muscles,
obliquely posteroinferiorly
• These muscles are most active
during expiration
Internal
Posterior
Anterior
40

• These are the deepest
layer and correspond
to the transversus
abdomens
• They can be divided
in to three portions
1) The sternocostalis
muscle … in front
2) The proper
innermost
intercostal muscle
… laterally
3) The subcostalis
muscle … behind
•
Innermost intercostals muscles
41

Diaphragm
• Is a musculotendinous partition
that fills the inferior thoracic
aperture and separates the
thoracic from the abdominal cavity
• Has two parts
 Peripheral muscular part
 Central tendenous part Arcuate lig
X
C
XI
XII
• The muscular fibers may be grouped
based their origins into 3 parts
 Sternal part- arises by two fleshy slips from xiphoid process
 Costal part on either side arises
 From the costal margin of the lower six ribs
 From the ends of the XI and XII ribs
 Lumbar part - on either side arises by
 Two ligamentus arches (a medial and a lateral arcuate ligamentsl)
 Two pillars or crura to the lumbar vertebrae 45

The Diaphragm …
Inferior view
Structures passing through or around the diaphragm
Anterior view
Lateral view from left 46

• They (openings, hiatuses) permit structures (vessels, nerves &
lymphatics) to pass between the thorax and the abdomen
• There are three large apertures for the IVC, esophagus, and aorta
and a number of small ones
 The inferior vena cava passes through the central tendon at
approximately vertebral level TVIII
 Some branches of the right phrenic nerve pass with the vena cava
 The esophagus passes through the muscular part of the diaphragm,
just to the left of midline at vertebral level TX
 The vagus nerves pass through the diaphragm with the esophagus
 The aorta passes behind the posterior attachment of the diaphragm
at vertebral level TXII
 The thoracic duct passes behind the diaphragm with the aorta
.
Diaphragmatic Apertures
47

• Small apertures in the
diaphragm
 Lateral to the aortic
hiatus the
sympathetic trunks
pass deep to the
medial arcuate
ligament
 There are small
apertures in each
crus of the
diaphragm for the
greater , lesser and
least splanchnic
nerves penetrate the
crura
Diaphragmatic Apertures …
48

• Each typical intercostal space
contains three arteries
 One posterior and two
anterior intercostal arteries
 The posterior artery
originates from the aorta
(thoracic part)
 The anterior arteries from
the internal thoracic arteries
which inturn arise from the
subclavian arteries in the
root of the neck
Arterial supply of the
thoracic wall
• Together, the intercostal arteries form a
basket-like pattern of vascular supply
around the thoracic wall 50

• Are 11 pairs
• The upper two posterior intercostal arteries on each side
are derived from
 The supreme (superior )intercostal artery, which descends
into the thorax as a branch of the costocervical trunk in the
neck.
 Costocervical trunk is a posterior branch of subclavian artery
• The remaining 9 pairs of posterior intercostal arteries arise
from the posterior surface of the thoracic aorta
 Since the aorta is on the left side of the vertebral column,
posterior intercostal vessels of the right side are longer than
the corresponding vessels on the left
• The sub costal arteries
 The last pair arising from the thoracic aorta run below the
lower border of the 12th ribs
Posterior intercostal arteries
52

Branches posterior intercostal arteries
• Mammary branch – arise from
2nd to 4th arteries.
• Right bronchial br. – from 3rd
right posterior intercostal artery
to R. bronchus
• Dorsal branch – supplies
spinal cord, vertebrae,
muscles & skin of the back
• Muscular br – to all
intercostal & some fibers to
the pec. Major
• Parietal & pericardial br
• Collateral br. – arise at the
angle of ribs → passes to
upper boarder of the rib
below & anastomoses with
lower anterior intercostal a.
• Lateral cutaneous br. – to
skin of lateral
thoracoabdomenal wall
54

Anterior intercostal arteries
• Originate directly or indirectly as lateral
branches from the internal thoracic
arteries
 Each internal thoracic artery arises as
a major branch of subclavian artery in
the neck
 Each passes anteriorly over the
cervical dome of pleura and descends
vertically
 On each side, the internal thoracic artery lies posterior to the costal
cartilages of the upper six ribs and about 1 cm lateral to the sternum
 At the level of the sixth intercostal space, it divides into two terminal
branches:
• The superior epigastric artery, which continues inferiorly into the
anterior abdominal wall
• The musculophrenic artery, which passes along the costal margin, goes
through the diaphragm 55

Anterior intercostal arteries
56

cont’d
• Anterior intercostal arteries for the upper six intercostal
spaces arise from the internal thoracic artery
• While those supplying the lower spaces from the
musculophrenic artery
• In each intercostal space, there are usually two anterior
intercostal arteries
 One passes below the margin of the upper rib
 The other passes above the margin of the lower rib and
meets a collateral branch of the posterior intercostal artery
• Anterior intercostal aa. give rise to perforating branches to
supply structures external to the thoracic wall
• The anterior intercostal arteries are generally smaller than
the posterior vessels
57

Anterior intercostal arteries summary
Subclavian artery
 Int thoracic a – 1st branch, thoracic part
o Gives off pericardiophrenic a
o Ant IC 1-6 a
o Ant perforating br– med. Mammary br (2-4spaces)
o Sup epigastric a –> runs in rectus sheath, and anatomoses w/ inf
epigastric a
o Musculophrenic a
• Gives off IC a 7-9 a
NOTE – IC spaces b/w 10/11th rib, and 11/12 ribs do not
have ant IC a (10th and 11th/last 2 icspaces don’t
have ant. Ic arteries)
58

Venous drainage
• Venous drainage parallels pattern of arterial supply
• Centrally, the intercostal veins ultimately drain into
 Azygos system of veins
 Brachiocephalic veins
 Internal thoracic veins --- anteriorly
--- posteriorly
Posteriorly
• The 1st intercostal space drain by the
1st posterior intercostal veins on both
sides and join the brachiocephalic
veins
• The 2nd,3rd , 4th left intercostal spaces
drain by the superior intercostal veins
 On the left side, they form the left superior intercostal vein, which
empties into the left brachiocephalic vein
 On the right side, they form the right superior intercostal vein, but
empties into the azygos vein 59

• From the 5th & below, posterior intercostal veins
 On the right side, drain into the azygos vein directly
 On the left side, the middle & lower four posterior intercostal veins
form the superior hemiazygos vein & inferior hemiazygos vein
respectively
 Both hemiazygos flow into azygos by crossing the midline @ T8 & T9 level
respectively
Venous drainage ….
Anteriorly
• The anterior intercostal veins
drain into
 Internal thoracic veins ---
directly from the first six
intercostal spaces
 Musculophrenic veins ---
from 7-9 spaces
 The musculophrenic veins finally joins the internal thoracic veins 60

Lymphatic drainage
• Lymphatic vessels of the thoracic wall drain mainly into lymph
nodes associated with
 The internal thoracic arteries - parasternal nodes
 With the heads and necks of ribs - intercostal nodes
 With the diaphragm - diaphragmatic nodes
 Diaphragmatic nodes are posterior to the xiphoid and at sites where
the phrenic nerves penetrate the diaphragm.
 They also occur in regions where the diaphragm is attached to the
vertebral column
 Parasternal nodes, diaphragmatic nodes & intercostal nodes in the
upper thorax drain into the bronchomediastinal trunks
 Intercostal nodes in the lower thorax drain into the thoracic duct
 Superficial regions of the thoracic wall drain mainly into axillary
lymph nodes in the axilla or parasternal nodes
62

Lymphatic drainage
Major lymphatic vessels and nodes of the thoracic wall.Nodes 63

Innervation
• Innervation of the thoracic
wall is mainly by the
intercostal nerves, which are
 The anterior rami of spinal
nerves T1 to T11
 The anterior ramus of spinal
nerve T12 (the subcostal
nerve) is inferior to rib XII
 Therefore, 11 pairs of IC
nerves + subcostal n
Intercostal nerves
• ICn 1 & 2 = atypical nerve and give Intercostobrachial nn
• ICn 3-6 = Thoracic nn (typical intercostal nerve)
• ICn 7-12 = Thoracoabdominal nn
• Typical intercostal nerve passes laterally around the thoracic wall
in an intercostal space 65

Intercostal nerves
ICn 1 & 2
Intercostobronchi
al nn
66

• A small collateral branches found in the IC space running along the
superior border of the lower rib
• Parietal branches to the pleura & pericardium
• The intercostal nerves end as anterior cutaneous branches, which
emerge either parasternally or laterally to the midline on the anterior
abdominal wall to supply the skin
• Musc br --- to IC m
• Lateral cutaneous br /the
largest/ - pierces the lateral wall
and divided into anterior and
posterior branches (innervate the
oververlying skin
Branches of Intercostal
nerves
67

Atypical Intercostal Nerves
. The anterior ramus of the 1st thoracic (T1) spinal nerve
first divides into a large superior & a small inferior part.
. The superior part joins the brachial plexus & the inferior
part becomes the 1st intercostal nerve.
. The 1st & 2nd intercostal nerves course on the internal
surface of the 1st & 2nd ribs, instead of along the costal
grooves.
. The 1st intercostal nerve has no anterior cutaneous branch
& often no lateral cutaneous branch.
68

Anterior and Lateral view of thoracic dermatomes
Sensory innervation from the skin overlying the upper thoracic wall is supplied by
cutaneous branches (supraclavicular nerves), which descend from the cervical plexus
in the neck.

Arterial supply
• The arterial supply to the
diaphragm is from vessels that
arise superiorly and inferiorly
to it
 From above supplied by
o Pericardiacophrenic and
Musculophrenic arteries
 These are branches of the
internal thoracic arteries
o Superior phrenic arteries
 Directly from lower parts of
the thoracic aorta
 From below supplied by
o Inferior phrenic arteries
 The largest artery
supplying the diaphragm
(arise from abdominal
aorta)
Blood supply and innervation of the diaphragm
70

Neurovascular supply of the diaphragm
71

Venous drainage
• Venous drainage of the diaphragm is by veins that generally parallel
the arteries. The veins drain
 Superior surface into
o Internal thoracic veins --- by pericardiophrenic & musculophrenic veins
o Azygos system of veins --- by superior phrenic vein
 Inferior surface into
o The inferior vena cava --- by right inferior phrenic vein
o The left suprarenal vein --- by the left inferior phrenic vein
Lymphatic drainage
• Thoracic surface - to
phrenic nodes→ parasternal
nodes
• Abdominal surface - to
Superior lumbar lymph nodes
 Both communicate freely
72

Innervation
• The diaphragm is
innervated by
Motor
 Phrenic nerve (C3,4,5)
Sensory
 Peripheral part by
lower six intercostal
and subcostal nerves
 Central part by
phrenic nerve
• The phrenic nerves pass vertically through the neck, the superior
thoracic aperture, and the mediastinum to supply diaphragm
• Contraction of the domes of the diaphragm flattens the diaphragm,
so increasing thoracic volume
• Movements of the diaphragm are essential for normal breathing
 Spinal cord injuries below the level of
the origin of the phrenic nerve do not
affect movement of the diaphragm
73

Innervation of diaphram
Left phrenic nerveRight phrenic nerve
74

Thoracic cavity
 Plumonary cavities
• Pleura
• Lungs
 Mediastinum
• Superior mediastinum
• Inferior mediastinum
 Anterior mediastinum
 Middle mediastinum
 Posterior mediastinum
75

Thoracic cavity
• The thoracic cavity Is
bounded by the thoracic
wall
 It extends upward into the
root of the neck about 3-4 cm
above the first costal cartilage
 The diaphragm separates the
thoracic cavity from the
abdominal viscera
• The thoracic cavity can be
divided into
 The laterally placed two
Plumonary cavities and lungs
 A median partition, called the
mediastinum 77

Thoracic cavity …
• Two pleural cavities, one
on either side of the
mediastinum, surround
the lungs
 Superiorly, they extend
above rib I into the root of
the neck
 Inferiorly, extend to a
level just above the costal
margin
 Their medial wall is the
mediastinum
Pleural/Plumonary cavities
• Each pleural cavity lined by a single layer of flat cells,
mesothelium called, pleura 78

The pleura Nature - serous
Layers - two
Parts - four
Pleura• The pleura is double layer
structure.
 Pleura associated with the
walls of thoracic cavity is
parietal pleura
 Pleura that reflects from the
medial wall and onto the
surface of the lungs is visceral
pleura which adheres to &
covers the lungs
• The pleura covers the lungs
except at the hilum (door)
of the lungs
79

The pleural cavity
• Between the visceral and parietal pleurae, there is a
potential space known as pleural cavity
 This cavity contains a very thin layer of serous fluid
 This fluid reduces friction b/n the two layers. therefore,
• At the level of vertebrae TV to TVII, the mediastinal pleura
reflects off as a tubular, sleeve-like covering
 It serves as a passage way of structures that pass between the
lung and mediastinum (i.e. airway, vessels, nerves, lymphatics)
• This sleeve-like covering, and the structures it contains,
forms the root of the lung
• The root joins the medial surface of the lung at an area
referred to as the hilum of lung
 Here, the parietal pleura is continuous with the visceral pleura
80

Parietal pleura
• The names of the parietal
pleura corresponds to the
wall they are directed. Thus,
parietal pleura;
 Related to the ribs and
intercostal spaces is termed as
the costal part
 Directed to & covering the
diaphragm is the
diaphragmatic part
 Related to & covering the
mediastinum is the
mediastinal part
 The dome-shaped layer of
parietal pleura lining the
cervical extension of the
pleural cavity is cervical pleura
(dome of pleura or pleural
cupola) 82

Pleural reflections
. The relatively abrupt lines along which the parietal pleura
changes direction as it passes (reflects) from one wall of
the pleural cavity to another are the lines of pleural
reflection.
. The sternal line of pleural reflection occurs where the
costal pleura becomes continuous with the mediastinal
pleura anteriorly.
. The costal line of pleural reflection occurs where the costal
pleura becomes continuous with diaphragmatic pleura
inferiorly above the costal margin .
. The vertebral line of pleural reflection occurs where the
costal pleura becomes continuous with the mediastinal
pleura posteriorly.

• Adheres to and covers the lungs & lines the fissures.
• Visceral pleura is contniuous with parietal pleura at the
hilum(door) of each lung, where structures enter & leave
• The lung does not completely fill the potential space of
the pleural cavity, resulting in recesses
 Recesses do not contain lung and are important for
accommodating changes in lung volume during breathing
 The recesses also provide potential spaces in which fluids
can collect and from which fluids can be aspirated
 Costo-diaphragmatic recess – b/w costal & diaphragmatic
pleura (The largest and clinically most important)
 Costo-mediastinal recesses – vertical in direction, costal &
mediastinal pleura meet
Visceral pleura
84

Pleural reflections & recesses
Costodiaphragmatic
recess
Pleural reflections Pleural recesses
85

Blood supply and drainage of the pleura
• Arterial supply - the two layers from different sources
 Parietal pleural --- from arteries that supply the wall
 Visceral pleura --- from arteries that supply the lungs &
bronchi, bronchial arteries ---
• Venous drainage,Lymphatic drainage and nerve supply
- follow the pattern of arteries
86

The Lungs
Position
• Inside the thoracic cavity, surrounded by pleural cavities, on both
sides of the mediastinum and above the diaphragm
Characteristics
• Shape
 Half-cone shape/pyramidal
• Size
 The right lung is larger than the left one because of the heart
 Are heavier in the male than in the female
• Substance nature
 Light, porous, soft
 Spongy texture and highly elastic
87

Characteristics…
Features
 Apex --- up
 Base --- down
 Surfaces --- three
 Borders --- three
 Root and hilum --- towards the mediastinum
 Fissures/clefts --- one in the left, two in the right
 lobes --- three in the right, two in the left
88

Anatomical features …
• The apex projects above rib I
into the root of the neck
• The base sits on the diaphragm
• Three surfaces -
 The costal surface lies
immediately adjacent to
the ribs and intercostal
spaces
 The mediastinal surface
lies against the
mediastinum contains the
hilum through which
structures enter and leave
 The diaphragmatic surface
rests on the dome of
diaphragm 90

Features …
• The posterior border is smooth and rounded separate the
costal surface from the mediastinal surface posteriorly
• The anterior
separate the costal
surface from the
mediastinal surface
anteriorly
• The inferior border
separates the base
from the costal and
mediastinal
surface
Three borders- anterior, posterior & inferior
91

• The root is a short tubular structures that attach the lung to
structures in the mediastinum covered by a sleeve of mediastinal
pleura
 A thin fold of pleura projects inferiorly from the root which
extends from the hilum to the mediastinum pulmonary
ligament
• Structures within each root and located in the hilum are:
- Pulmonary artery - Pulmonary plexuses of nerves
- Two pulmonary veins - Lymphatic vessels
- Bronchus (two on the right) - Bronchial lymph nodes
- Bronchial vessels - Areolar tissue
Root and hilum
92

 Infront --- phrenic nerves
and anterior pulmonary
plexus
 Behind --- vagus nerves
and posterior pulmonary
plexus
 Above --- the vena azygos
arch (over the right root),
the aortic arch (over the
left root)
 Below --- pulmonary
ligament
Relations to the root
94

• Is divided into three lobes by two interlobular fissures
Lobes – the right lung has three lobes
• Superior, middle & inferior lobes
Fissures
1) The oblique fissure
o Separates the inferior lobe, from the superior lobe and
the middle lobe of the right lung
2) The horizontal fissure
o Separates the superior lobe (upper lobe) from the
middle lobe
o It follows the fourth intercostal space from the sternum
until it meets the oblique fissure as it crosses rib v.
Right lung
95

Fissure and lobes of the right lung
96

The right lung…
Behind the root
• A groove for esophagus
• A groove for azygos vein immediately behind the esophagus
• Impressions are made by the
adjacent/mediastinal structures on the
medial surface of the right lung
At the center
• Root of the lung and plumonary ligament
Infront of the root
• Concave area, cardiac impression, for the
right atrium
• A groove for superior venacava descends
down to join the cardiac impression
• A groove for inferior venacava ascends
infront of plumonary ligament to join the
cardiac impression from below
97

Impressions on the medial surface of the right lung
Above the root
• A groove for upper part of
superior venacava which is
continuous above with the
right innominate vein's
groove
• An arched furrow of
azygos vein which joins the
groove for sup. vena cava
• A groove for trachea
behind sup. vena cava’s
groove
• A groove for the esophagus
which lies behind the
tracheal groove
 The right subclavian artery and vein arch over and are related to
the superior lobe as they pass over the dome of cervical pleura98

Left lung
• The lingula of left lung projects
over the heart bulge
Fissure and lobes of the left lung• The left lung is smaller than
the right lung
• Is divided into upper/superior
and a lower/inferior lobes by,
interlobular fissure, an
oblique fissure
 The oblique fissure extends
from the costal to the
mediastinal surface of the
lung both above and below
the hilus
 This fissure is slightly more
oblique than the
corresponding fissure of the
right lung
99

The left lung …
• Impressions are made by the mediastinal
structures on medial surface of the left lung
Near the center
 Root of the lung and pulmonary lig.
In front of the root
 A deep concave area, cardiac impression, for the left ventricle
Behind the root
 A deep vertical groove for the descending aorta which
descends behind the root and pulmonary ligament
Above the root
 A deep groove for the Aortic arch
 Above the Aortic arch groove, two grooves which join it
• One for the left common carotid artery anteriorly
• One for the left subclavian artery posteriorly
 The left brachiocephalic vein arches over and is related to the superior
lobe of the left lung as it pass over the dome of cervical pleura 100

Impressions on the medial surface of the left lung
Left common
carotid artery
Left
subclavian
arteryLeft
brachiocephalic
vein
101

Bronchial tree & bronchopulmonary segments
• The lung has a spongy parenchyma containing the bronchial tree
Bronchial tree
• A highly branched system of air tubes extending from the
primary bronchus to about 65,000 terminal bronchioles
• The trachea is a flexible tube that extends from vertebral level
CVI in the lower neck to vertebral level TIV/V in the mediastinum
 It bifurcates into a right and a left main bronchus
 The trachea is held open by 'C-shaped' transverse cartilage rings
 The posterior wall of the trachea is smooth muscle
 Each main bronchus enters the root of a lung through the hilum
 The right main bronchus is wider and takes a more
vertical course than the left main bronchus
102

Bronchial tree …
 Within each bronchopulmonary
segment, the segmental bronchi →
bronchioles, which further subdivide
and supply the respiratory surfaces.
 The walls of the bronchi are held open
by discontinuous plates of cartilage,
but not present in bronchioles
• The main bronchus divides within the
lung into lobar bronchi (secondary
bronchi), each of which supplies a lobe
 On the right side, the lobar bronchus
to the superior lobe originates within
the root of the lung
 Further divide into segmental bronchi
(tertiary bronchi), which supply
bronchopulmonary segments
103

Bronchial tree & bronchopulmonary segments
104

cont’d
• A bronchopulmonary segment is smallest irregular cone
shape area of the lung with the apex and base
 The apex at the origin of the segmental bronchus and the base
projected peripherally
• The segment is the smallest and functionally
independent region of a lung
 Supplied by a segmental bronchus and its accompanying
pulmonary artery branch
 Tributaries of the pulmonary vein pass intersegmentally between
and around the margins of segments
• They can be isolated and removed without affecting
adjacent regions
• There are ten bronchopulmonary segments in each lung
;some of them fuse in the left lung may become eight
Bronchopulmonary segment
105

Bronchopulmonary segments
Superior (upper) lobe:
 Apical
 Posterior
 Anterior
Middle lobe
 Lateral
 Medial
Inferior (lower) lobe:
 Superior (apical)
 Medial basal
 Anterior basal
 Lateral basal
 Posterior basal
Right Lung
107

Left Lung
Superior (upper) lobe:
 Apical
 Posterior
 Anterior
 Superior lingular
 Inferior lingular
Inferior (lower) lobe:
 Superior (apical)
 Anterior basal
 Medial basal
 Lateral basal
 Posterior basal
Anteromedial basal
Bronchopulmonary segments
Apicoposterior
108

Bronchioles
Bronchial tree …
• Are continuations of the airway that are
1 mm or less in diameter and lack
cartilage
• A well developed layer of smooth
muscle in their walls enables them to
dilate or constrict
• The portion of the lung ventilated by one bronchiole is called a
pulmonary lobule
• Each bronchiole divides into 50 to 80 terminal bronchioles, the final
branches of the conducting division
 They measure 0.5 mm or less in diameter and have no mucous
glands or goblet cells
 They do have cilia so that mucus draining into them can be
driven back by the mucociliary escalator
 Thus preventing congestion of the terminal bronchioles and alveoli 109

Bronchial tree …
 Each divides into 2-10 elongated, thin-walled passages called
alveolar ducts that end in alveolar sacs, which are grapelike
clusters of alveoli
 Alveoli also bud from the walls of the respiratory bronchioles and
alveolar ducts
• Each terminal bronchiole gives
off two or more smaller
respiratory bronchioles
 They mark the beginning
of the respiratory division
• All branches of the respiratory
division are defined by the
presence of alveoli
• The respiratory bronchioles
have scanty smooth muscle,
and the smallest of them are
no ciliated
110

Alveoli
• Each human lung is a spongy
mass composed of 250 million
little sacs, the alveoli, which
provide about 70 m2 of
surface area for gas exchange
• An alveolus is a pouch about
0.2 to 0.5 mm in diameter
• Each alveolus is surrounded by a basket of blood capillaries supplied
by the pulmonary artery
 The barrier between the alveolar air and blood, called the
respiratory membrane, consists of
 The squamous type I alveolar cell
 The squamous endothelial cell of the capillary
 Their fused basement membranes.
 These have a total thickness of only 0.5 μm
 Consists predominantly of squamous (type I) alveolar cells,
allow rapid gas diffusion between the alveolus and blood
111

Alveoli …
• About 5% of the alveolar cells are round to cuboidal great
(type II) alveolar cells
 They secrete a detergent-like lipoprotein called pulmonary
surfactant, which forms a thin film on the insides of the
alveoli and bronchioles
112

Pulmonary arteries
• They originate from the
pulmonary trunk
• Carry deoxygenated blood
to the lungs from the right
ventricle of the heart
Blood Vessels and Nerves of the Lung
Right pulmonary artery
• The right pulmonary artery is longer than the left and passes
horizontally across the mediastinum). It passes:
 Anterior and slightly inferior to the tracheal bifurcation and anterior to
the right main bronchus
 Posterior to the ascending aorta, superior vena cava, and upper right
pulmonary vein
• The bifurcation of the
pulmonary trunk occurs to
the left of the midline at vertebral level TIV/V
113

• The right pulmonary artery
enters the root of the lung
and gives off a large branch to
the superior lobe of the lung
• Continues through the hilum,
gives off a second (recurrent)
branch to the superior lobe,
and then divides to supply the
middle and inferior
Pulmonary arteries …
Left pulmonary artery
• Is shorter than the right
• Lies anterior to the descending aorta and posterior to the superior
pulmonary vein
• It passes through the root and hilum and branches within the lung
114

• On each side a superior and an inferior pulmonary vein
carry oxygenated blood from the lungs back to the heart
• The veins begin at the hilum, pass through the root, and
immediately drain into the left atrium
Bronchial arteries and veins
• The bronchial arteries supply blood for nutrition of the
structures making up the root of the lungs, the supporting
tissues of the lungs, & the visceral pleura
• They interconnect within the lung with branches of the
pulmonary arteries and veins
• The bronchial arteries originate from the thoracic aorta or
one of its branches:
Pulmonary veins
116

• A single right bronchial artery normally arises from the
third posterior intercostal artery
• Two left bronchial arteries arise directly from the
anterior surface of the thoracic aorta-
The bronchial veins
• They drain into
 Into the azygos vein on the right or into the superior
intercostal vein or accessary hemiazygos vein on the left
Bronchial arteries and veins …
117

• The visceral pleura and other structures of the lung are
supplied by
 Visceral afferents and efferents through the anterior and
posterior pulmonary plexus
o These plexuses lie anteriorly and posteriorly to the
tracheal bifurcation and main bronchi
 The anterior plexus is much smaller than the posterior
plexus
o Branches of these plexuses originate from the sympathetic
trunks and vagus nerves, are distributed along branches of
the airway and vessels
 Visceral efferents from
 The vagus nerves constrict the bronchioles
 The sympathetic system dilate the bronchioles
Innervation of the Lung
118

• Superficial, or
subpleural, and
deep lymphatics of
the lung drain into
tracheobronchial
nodes around the
roots
Lymphatic drainage
120

. The superficial (subpleural) lymphatic plexus lies deep to the
visceral pleura & drains the lung parenchyma (tissue) &
visceral pleura.
. These drain into the bronchopulmonary lymph nodes (hilar
lymph nodes) in the hilum of the lung.
. The deep lymphatic plexus is located in the submucosa of the
bronchi & in the peribronchial connective tissue.
. It drains the structures that form the root of the lung.
. Lymphatic vessels from this deep plexus drain initially into the
pulmonary lymph nodes, located along the lobar bronchi
bronchopulmonary (hilar) lymph nodes superior &
inferior tracheobronchial lymph nodes, superior & inferior to
the bifurcation of the trachea & main bronchi, respectively.

 The right lung drains primarily thru the respective sets of
nodes on the right side,
. The superior lobe of the left lung drains primarily thru
respective nodes of the left side.
 Most of the lymphatics from the lower lobe of the left
lung drain to the right superior tracheobronchial nodes.
. Lymph from the tracheobronchial lymph nodes passes to
the right & left bronchomediastinal lymph trunks.
. These trunks usually terminate on each side at the venous
angles (junctions of the subclavian & internal jugular
veins).

 however, the right bronchomediastinal trunk may first
merge with other lymphatic trunks, converging here to
form the short right lymphatic duct.
. The left bronchomediastinal trunk may terminate in the
thoracic duct.

Mediastinum
• The mediastinum is a broad central partition that
separates the two laterally placed pleural cavities
• Contains all the thoracic viscera, except the lungs
• It extends:
 From the thoracic inlet superiorly to the
diaphragm inferiorly
 From the posterior aspect of the sternum
anteriorly to the thoracic vertebrae posteriorly
• Contains the thymus gland, the pericardial sac,
the heart, the trachea, and the major arteries
and veins
• Serves as a passageway for the esophagus,
thoracic duct, and nerves as they traverse the
thorax on their way to the abdomen
124

• A plane extending from the
sternal angle to the intervertebral
disc between vertebrae T4 and T5
divide the mediastinum into:
• Superior mediastinum
• Inferior mediastinum
 The inferior mediastinum
further divided by the
pericardial sac into
 Anterior mediastinum
 Middle mediastinum
 Posterior mediastinum
Divisions of the mediastinum
125

Anterior mediastinum
• The area anterior to the
pericardial sac and posterior to
the body of the sternum
Posterior mediastinum
• The region posterior to the
pericardial sac and the diaphragm
and anterior to the bodies of the
vertebrae
Middle mediastinum
• The area in the middle, which
includes the pericardial sac and its
contents
Subdivisions of the inferior mediastinum
126

The superior mediastinum
• Is the upper part of the Mediastinum
bounded by:
 Anteriorly – manubrium sterni
 Posteriorly – upper four thoracic vertebrae
 Superiorly – thoracic inlet
 Inferiorly – plane extending from the
sternal angle to the intervertebral disc
between vertebrae T4 and T5
127

The Superior mediastinum …
• You can visualize the contents in planes from anterior
to posterior
1) Glandular plane
2) Venous plane
3) Neuro – arterial plane
4) Visceral plane
5) Lymphatic plane
128

Thymus
• Is the most anterior component, lying
immediately posterior to the manubrium of
the sternum
• The upper extent of the thymus can reach
into the neck as high as the thyroid gland
The first plane - glandular
• Large in children, begins to atrophy
after puberty
• Mainly fat in the adult with small
islets of active thymic cells scattered
• A lower portion typically extends
into the anterior mediastinum over
the pericardial sac
• It is a bilobed structure
129

The second plane - venous plane
• Consists of
 Left and right
brachiocephalic vein
 Left superior
intercostal vein
 Arch of the azygos vein
 Superior vena cava
130

The left brachiocephalic vein
• Is formed by the left internal
jugular and left subclavian
veins, posterior to the left
sternoclavicular joint
• Passes anterior and superior to
the branches of the aortic arch
• Joins with the right
brachiocephalic vein and form
the superior vena cava at the
level of the 1st right intercostal
space close to the right sternal
border
Superior vena cava
R. brachiocephalic vein
131

• Is formed by the union of
the right internal jugular
and right subclavian veins
posterior to the right
sternoclavicular joint
 The vertebral vein
 The 1st right posterior intercostal vein
 Internal thoracic veins
The right brachiocephalic vein
Tributaries of
right brachiocephalic
132

The superior vena cava
• Enters the right atrium
at the level of the 3rd
right costal cartilage
• It receives the arch of
the azygos system on its
posterior surface
• The right phrenic nerve
runs with it
Arch of the azygos
• Drain the posterior thoracic wall from the 2nd intercostal space to
the subcostal veins
 The azygos vein ascends on the right side of the vertebral
column
 Arches over the right bronchus to enter the posterior aspect of
the superior vena cava at the level of the costal cartilage of rib II133

• The third plane is the artero-nervous plane and consists of
the intermediate structures
1) Aortic arch and its branches
• Brachiocephalic artery
• Left common carotid artery
• Left subclavian artery
2) Nerves include
• Left and right vagus nerves
• Left and right phrenic nerves & cardiac plexus
Aortic arch and its branches
• The aortic arch begins at the level of a line from the sternal
angle through the T4/5 intervertebral disc behind the sternum
 The ascending aorta is posterior to the right margin of the
sternum
Neuro - arterial plane
134

Plane of arteries and nerves
135

• Extending as high as the
midlevel of the manubrium of
sternum
 It is initially anterior and
finally lateral to the trachea
 It arches over the right
pulmonary artery and left
bronchus
 It then curves to the left
and becomes the
descending aorta to the left
of the T5 vertebral body
• It lies anterior to the end of the
trachea, left recurrent laryngeal,
superior portion of the
esophagus and the thoracic duct
Aortic arch
• The left vagus, left phrenic nerves,
and left superior intercostal vein
cross it anteriorly
136

Aortic arch …
• The inferior aspect of
the aortic arch contains
the ligamentum
arteriosum, vestige of
the ductus arteriosus
 The ductus arteriosus
shunted blood from the
pulmonary system in
prenatal life
 With expansion of the
lungs and a decrease in
resistance in the
pulmonary arterial
system postnatally, it
closes
 The ligamentum arteriosum is
intimately associated with the course
of the left recurrent laryngeal nerve.
137

Branches of the arch of aorta
• All the branches arise from the
superior aspect of the aortic arch.
They are
 Brachiocephalic trunk
 Left common carotid
 Left subclavian arteries
 All three are crossed anteriorly by
the left brachiocephalic vein
138

• It descend in the neck
• On the post. aspect of
the common carotid
arteries in the carotid
sheath
• Enter the thoracic
inlet posterior to the
medial end of rib 1
• Pass anterior to the
arterial system
(subclavian artery on
the right side and
aortic arch on the left
side
• The two vagi then course posterior to the roots of the lung giving
out branches to the cardiac and pulmonary plexuses
The vagus nerves
139

The left recurrent laryngeal nerve
• Branches from the left vagus
• Passes below the ligamentum arteriosum and the arch of the aorta
• Ascends between the trachea and the esophagus into the root of
the neck
The right recurrent laryngeal nerve
• Arises from the right vagus anterior to the right subclavian
artery
• Courses around the artery
• Ascends in the neck
• Both recurrent nerves provide vagal innervation to the
trachea and esophagus before innervating the larynx
140

• Arise from anterior rami
of C3,4, 5
• Enter the thoracic inlet,
coursing medially
 The left phrenic nerve crosses
the left vagus anteriorly
• Descend anterior to the
root of the lungs, between
the lateral wall of the
fibrous pericardium and
the mediastinal pleura
 The right phrenic nerve is associated with the superior vena
cava in its upper course and pierces the diaphragm with the
inferior vena cava
 The left phrenic nerve pierces the diaphragm at the margin of
the fibrous pericardial attachment to the central tendon
Phrenic nerves
141

The cardiac plexus
• Contains sympathetic ,
vagal (parasympathetic)
fibers and visceral
afferents
• Are superficial & deep
Superficial
• Inferior to the aortic
arch and between it
and the pulmonary
trunk
Deep
• Located anterior to the
bifurcation of the
trachea 144

 The fourth plane is
the visceral plane and
includes the
Prevertebral
structures
 Trachea
 Esophagus
 Left recurrent
laryngeal nerve
The visceral plane
 The esophagus lies posterior to the trachea & the left
recurrent laryngeal nerves between laterally
145

The trachea
• Begins below the larynx
(below the cricoid cartilage)
at the level of C6
• Half is in the neck and half is
in the superior mediastinum
• Bifurcates at the level of
T4/5, at the carina
• Wall contains
 16-20 “C” shaped rings of
hyaline cartilage
 Trachealis muscle
(smooth muscle)
 Soft CT
146

Esophagus
• Pharynx to Stomach
• Passes thru diaphragm
at esophageal hiatus
• Anterior to vertebrae,
Posterior to trachea
147

• Consists of the thoracic duct & its tributaries
Thoracic duct
• Begins at the cisterna chyli, posterior to the abdominal aorta, inferior to
the diaphragm
• Enters the thorax posterior to the descending aorta
• ascends through the posterior mediastinum to the right of midline
between the thoracic aorta and the azygos vein, posterior to the
esophagus and anterior to the bodies of the vertebra to T5
 It then crosses the vertebral column and enters the root of the neck on the
left side
 Terminating at the junction between the left subclavian and left internal
jugular veins
• It drains all the lymph of the body except for the right thorax, right upper
limb and right side of the head and neck
 These remaining areas drain into the right lymphatic duct which joins
the junction of the right internal jugular and right subclavian veins
Lymphatic plane
148

• Is the narrow part of the
Mediastinum b/n sternum
& fibrous pericardium
Boundaries
 Anteriorly – body of the
sternum
 Posteriorly – fibrous
pericardium
 Superiorly - an imaginary
plane passing from the
sternal angle to the
intervertebral disc between
vert. T4 and T5
 Inferiorly - upper surface
of diaphragm
 On each side – mediastinal
pleura
Contents
 Sternopericardial ligaments
 Lymph nodes & areolar tissues (most of the
space)
 Some mediastinal branches of internal
thoracic aa
The anterior mediastinum
150

• Is the widest part of the
Mediastinum occupied by the
pericardium & its contents
Contents
 Heart & its cover (pericardium)
 Ascending aorta, pulmonary
trunk & its branches
 Four pulmonary veins, lower
part of sup. Venacava, &
azygus vein (terminal part)
 Pericardiacophrenic vessels
 Phrenic & deep cardiac plexus
 Tracheobronchial lymph
nodes.
 Bifurcation of trachea into
right & left bronchi
The middle mediastinum
151

Thoracic Viscera, Pericardial Sac
152

Pericardium and Heart
Pericardium
• Is a fibroserous sac invaginated by the heart
and great vessels during development
• Has two parts
• Outer fibrous & inner serous double layers
(outer parietal & inner visceral)
1) Fibrous pericardium- a cone shaped bag
with blunt apex upward continuous with the
tunica adventitia of great vessels
 Attachment
 Infront – with the sternum by sterno
pericardial ligaments
 Above – with pre-tracheal layer of deep
cervical fascia
 Below - adherent with central tendon of the
diaphragm
 Function
 Anchorage of heart
 Prevent overdistension
153

Pericardium …
2) Serous pericardium - a closed serous sac within fibrous
pericardium enclosing the heart
Consists of two layers
A) Visceral pericardium - lines the surface of the heart – becomes the
outer layer of the heart (epicardium)
B) Parietal pericardium - lines inner surface of fibrous sac
 Pericardial cavity is a potential space between the above two layers
contains a fluid called pericardial fluid (lubricant serous fld)

Pericardium cont’d
Pericardial sinuses
• The parietal layer of serous pericardium is continuous with
the visceral layers of serous pericardium around the roots
of the great vessels
• These reflections of serous pericardium occur in two
locations:
1. Transverse sinus
 Lye posterior to the ascending aorta and pulmonary trunk,
anterior to the SVC, and superior to the left atrium and the
pulmonary veins
 Is of great importance to the cardiac surgeon while performing
surgery on the aorta or pulmonary artery
2. Oblique sinus
 surrounded by the reflection of the serous pericardium around
the right and left pulmonary veins and the inferior vena cava
(IVC).
155

. The pericardium is supplied by branches from the internal
thoracic, pericardiacophrenic,musculophrenic, & superior
phrenic arteries, & the thoracic aorta.
. Veins from the pericardium enter the azygos system of
veins & the internal thoracic & inferior phrenic veins.
. Nerves supplying the pericardium arise from the vagus
nerve [X], the sympathetic trunks, & the phrenic nerves.
Blood supply,drainage and innervation of
pericardium

The heart
• It is a hollow, more or less conical muscular organ
Location
• It lies in the middle mediastinum (enclosed in the pericardium)
between the lungs, behind the body of the sternum along with
adjoining parts of the rib cartilage and above the diaphragm
Situation
• It is placed obliquely and about 1/3rd of it is
situated on the right and 2/3rd on the left of the median plane
• It has the following features
 Base (superoposterior surface)
 Apex (inferolaterally)
 Surfaces - three
 Grooves - three
 Borders - four
 Wall - three layers
 Chambers - four
Major valves - four 159

The base of the heart
 Faces posteriorly toward the bodies of
vertebrae T6-T9 & is separated from them by
the pericardium, oblique pericardial sinus,
esophagus, & aorta
 Formed by mainly the left atrium & the 4
pulmonary veins and partly by right
atrium(2/3 :1/3 ratio)
 The visceral pericardium is continuous
with the parietal pericardium at this point
and forms the oblique pericardial sinus
The apex of the heart
 Is the most moveable part
 Located in the left 5th intercostal space
9cm from mid sternal line
 Formed by tip of left ventricle 160

base of the heart
the heart art
The base and apex
of the heart
161

Surfaces of the heart
• Three surfaces
 Anterior (sternocostal)
 Left (plumonary)
 Inferior (diaphragmatic)
1) Anterior (sternocostal) surface
o related anteriorly to the sternum, costal
cartilages, & anterior ends of the 3rd-5th
ribs on the left side.
o Formed by anterior surface of
 Right auricle & atrium
 Right ventricle ( 2/3rd )
 Left ventricle ( 1/3rd )
o It presents the following features
 Anterior part of atrioventricular
groove
 Anterior interventricular groove 162

Anterior (sternocostal) surface
163

2) Left surface
 Sometimes called the
pulmonary surface b/c it
lies in the cardiac notch of
the left lung
 It presents the left part of
atrioventricular groove
 Formed by left auricle &
left ventricle(mainly)
3) Inferior (diaphragmatic) surface
 Is the flat surface directed down
ward & backward
 Formed 2/3rd by the left ventricle
& 1/3rd by the right ventricle
 It presents the Posterior
interventricular groove 164

Inferior (diaphragmatic) surface
165

Heart cont’d
Grooves/sulci
 Are shallow depressions on the surface of the heart
 Externally three important grooves demarcate junctions
(septum) of chambers of the heart
1) Interatrial groove – demarcates the right & left atrium
o Posteriorly – not well visible
o Anteriorly – hidden by Aorta & pulmonary trunk
2) Atrioventricular groove – demarcates the two atria above
& the two ventricles below
3. Interventricular groove
• Demarcates the right & left ventricles
166

Boarders
• Four --- Right, inferior, left & superior boarders
1) Right boarder
 Rounded convex extending from right end of opening
of superior vena cava to inferior vena cava
 Formed by right atrium
 It separates sternocostal surface from base of the heart
2) Inferior boarder
 A sharp boarder separating sternocostal from
diaphragmatic surface
 Extends from opening of inferior vena cava to the apex
 Marginal branch of right coronary & corresponding
veins run along this boarder
167

Heart cont’d
3) Left boarder
 defined convex boarder separating sternocostal from left
surface
 Formed by left auricle & left ventricle
 Extends from left auricle to apex of the heart
 Marginal branch of left coronary artery runs along this
boarder
4) Superior boarder
 Is the upper boarder where the great vessels enter &
leave the heart
 Formed by the right & left auricles with the conical
portion of right ventricle (infundibulum)
169

Wall of the heart
• Structurally it is composed of three
layers
Epicardium – the outer wall derived from
visceral serous pericardium
Myocardium – is the middle muscular layer
responsible for pumping action
Endocardium – is the inner epithelial layer
continuous with the epithelium of the
great vessels
Chambers of the heart
• Its interior has four Chambers separated
by septum
 Two atria & two ventricles
Wall and chambers of the Heart
170

Chambers of the heart
2 receiving chambers
Right atrium
Left atrium
2 pumping chambers
Right ventricle
Left ventricle
171

Heart cont’d
Right atrium /RA
• Forms the right margin of the heart with the right auricle
projecting superiorly and anteriorly
• The interior of the right atrium is divided by the crista terminalis
into anterior & posterior parts
 The anterior part has a ridge area with musculi pectinati
(pectinate muscles) capable of contraction
 The posterior is smooth where great vessels open into the RA &
has openings of the;
1. Superior vena cava – from its upper part
2. Inferior vena cava – from its lower part
3. Coronary sinus – from its postero-medial part
4. Right atrioventricular opening – b/n the two right
chambers
• The tricuspid valve guards this opening
172

The left atrium
• Forms 2/3 of base of heart
 The auricle is visible anteriorly from the left side of the pulmonary
trunk.
• The interior of the left atrium presents the following
features
 Smooth posterior part
 Has 4 openings of pulmonary veins & one left atrioventricular
opening (guarded with valves)
 Rough anterior part
 Has musculi pectinati (pectinate muscles) capable of contraction
• The left atrioventricular (bicuspid or mitral valve) is located
anteriorly
 It is an opening of communication b/n left atrium & left ventricle
174

The ventricles
• Right and left ventricles lie anteroinferior to the right and left atria
The right ventricle / RV
 Forms most of the anterior (sternocostal) & small inferior surface of the
heart and the inferior margin
 The interior of the right ventricle consists of two parts
1) Rough or inflowing part – is the ventricle proper continuous with right
atrium & receive blood from RA
• It is lined with trabeculae carnae (contractile tissue)
 Some form papillary muscles arising from the anterior and posterior
walls (2)
 The right ventricle also has septal papillary muscles (3rd)
 The apex of the above papillary muscles are attached to the cusp of
right atrioventricular (tricuspid) valve by the chordae tendinae
(thread like tendinous cord)
 The three papillary muscle groups attached to the three cusps
pull the cusps down to the L.ventricle before ventricular systole176

• The portion of out flow
continuous with the pulmonary
trunk
 The pulmonary orifies located at
the apex of the infundibulum is
guarded by a valve which has
three cusps (right, left &
anterior)
 A thick muscular ridge, the
supraventricular crest,
separates the ridged muscular
wall of the inflow part of the
chamber from the smooth wall
of the conus arteriosus.
2) Infundibulum( conus arteriosus) or smooth
part
178

• It forms
 The apex
 1/3rd of the sternocostal surface
 Most of the left boarder & surface
 2/3rd of the diaphragmatic surface
• The interior of the left ventricle
has two parts
The left ventricle
Aortic vestibule
1) Rough or inflowing part
• Is lined with trabeculae carnae (ridges) from which the papillary
muscles arising from the anterior and posterior walls
 Two papillary muscles are present - are anterior & posterior
 Attached to both cusps of the mitral (bicuspid) valve by cordae
tendinae
 The apex of a papillary muscle is attached to the apex of
cusps where they guard the opening b/n left ventricle & left
atrium
Inflowing
part
179

The left ventricle …
2) The smooth/ out flow part
• The out flow part known as
aortic vestibule
• Is just below & continuous
with the aortic orifice
 The aortic orifice is at the
beginning of the ascending
aorta guarded by aortic
valve which has three cusps
(right, left & posterior)
 Three dilatations/sinuses
(aortic) are present
above the cusps which give
origin to coronary arteries
(they supply the heart)
Aortic vestibule
180

The interventricular septum (IVS) is a strong, obliquely placed
partition b/n the right & left ventricles
. composed of membranous & muscular parts, the latter forming
the majority of the septum.
. Superiorly & posteriorly, a thin membrane, part of the fibrous
skeleton of the heart, forms the much smaller membranous
part of the IVS.
. On the right side, the septal cusp of the tricuspid valve is
attached to the middle of this membranous part of the fibrous
skeleton.

• The four valves inside the heart wall are located
• Pulmonary valve … left 3rd costal cartilage
 Aortic valve … left 3rd intercostal space /behind the left half
of the sternum/
 Mitral valve … left 4th costal cartilage
 Tricuspid valve … right 4th intercostal space
* The closing of the valves can be heard
 Over the right 2nd intercostal space for the aorta /Aortic valve
 Over the left 2nd intercostal space for the pulmonary trunk /
pulmonary valve
 Over the left 5th intercostal space for Tricuspid (immediately
lateral to the sternum) & Mitral (over the apex, 9cm from
midsternum) valves
Surface markings of valves
183

Cardiac skeleton
• The four rings of the
cardiac skeleton surround
 The two atrioventricular
orifices
 The aortic orifice
 The opening of the
pulmonary trunks
• A collection of dense,
fibrous connective
tissue in the form of
four rings
184

• Arteries
 Ascending aorta, pulmonary trunk & its arteries (at
their bifurcation level)
• Veins
 Four pulmonary veins, lower part of sup. Venacava, &
azygus vein (terminal part)
• Nerves
 Phrenic & deep cardiac plexus
• Lymph nodes
 Tracheobronchial lymph nodes
• Bifurcation of trachea into right & left bronchi
Other structures in the middle Mediastinum
185

• The terms referring
the vessels of the
heart
 Coronary refers to
arterial vessels
 Cardiac refers to
venous vessels
• The heart is supplied
by two arteries
 Right and left
coronary arteries
arise from right and
left coronary sinuses
of the aortic valve
Blood supply of the heart
186

• Runs in the coronary
sulcus between the right
atrium and right ventricle
 It gives off a nodal
artery which passes
onto the posterior
aspect of the right
atrium and supplies
 The area of the
sinoatrial (SA) node
Coronary arteries …
 Then gives off a marginal branch (smaller than the left) supply
 The right ventricle
 Terminates in the posterior interventricular sulcus as the posterior
interventricular artery, supplying mainly
 The posterior aspect of the right and left ventricles as well as the
posterior 1/2 of the interventricular septum
The right coronary artery
187

The left coronary artery
• Passes anteriorly between
the pulmonary trunk and
the tip of the auricle of
the left atrium.
• It divides on the anterior
aspect of the heart into
 Anterior
interventricular
branch
 Circumflex branch
Coronary arteries …
189

Cont’d
(1) Anterior interventricular branch
• Descends in the anterior interventricular sulcus to the inferior
margin of the heart
• Continues into the posterior interventricular sulcus on the
diaphragmatic surface
 It supplies anterior aspects of the right and left ventricles, and
anterior 1/2 of the interventricular septum
(2) Circumflex branch
• Runs to the left in the atrioventricular sulcus between the left
atrium and ventricle
 It gives off a marginal branch for the lateral margin of the left
ventricle and continues onto the posterior aspect of the heart
 It forms an anastomosis with the arteries (derived from the right
coronary artery) in the posterior interventricular sulcus
190

Cont’dThe cardiac veins
• Accompany coronary arteries and their branches
• Lie superficial to the arteries in the sulci
• Most of the veins drain into the coronary sinus
The coronary sinus
• Is derived from the sinus venosus (the primitive receiving chamber
of the developing heart)
• Lies in the coronary sulcus between the left margin of the heart and
the posterior interventricular sulcus
• It drains into the right atrium by an opening to the left of the
entrance of the inferior vena cava
 The heart is drained by
 Three major veins through the coronary sinus
(60%)
 Other small veins (40%) 193

A) Great cardiac vein
• Formed in the anterior interventricular sulcus
 Left marginal vein is a tributary of the great cardiac vein
• Joins the coronary sinus near the left margin of the heart
• Drains the area of the heart supplied by left coronary a
B) Middle cardiac vein
• It occupies the posterior interventricular sulcus
• Enters coronary sinus near the entrance to the right atrium
C) Small cardiac vein
• Follows the right marginal branch of the right coronary a
• Joins the coronary sinus near the junction with the middle
cardiac vein at the left of the right atrium posterorly
 The middle & small cardiac veins drains the area of the
heart supplied by right coronary a
The three major veins
194

The oblique vein
• Drains from the left atrium into
the coronary sinus along with
posterior ventricular veins
The posterior ventricular veins
• Drain the diaphragmatic surface
of the left ventricle
The anterior cardiac veins
• Drain the anterior surface of
the right ventricle
• Open directly into the right
atrium
Venae cordis minimae or
Thebesian veins
Other small veins
• Are tiny veins draining the heart wall specially myocardium
• Open directly into the chambers 196

Conducting System of the Heart
■ Is composed of modified, specialized cardiac muscle cells
that lie immediately beneath the endocardium and carry
impulses throughout the cardiac muscle, signaling the
heart chambers to contract in the proper sequence.
197

1. Sinoatrial Node
■ Is a small mass of specialized cardiac muscle fi bers that
lies in the myocardium at the upper end of the crista
terminalis near the opening of the SVC in the right
atrium.
■ Is known as the pacemaker of the heart and initiates the
heartbeat, which can be altered by autonomic nervous
stimulation (sympathetic stimulation speeds it up, and
vagal stimulation slows it down). Impulses spread in a wave
along the cardiac muscle fi bers of the atria and also travel
along an internodal pathway to the AV node.
■ Is supplied by the sinus node artery, which is a branch of
the right coronary artery.
199

2. AV Node
■ Lies in the interatrial septum, superior and medial to
the opening of the coronary sinus in the right atrium,
receives the impulse from the sinoatrial (SA) node and
passes it to the AV bundle.
■ Is supplied by the AV nodal artery, which usually arises
from the right coronary artery opposite the origin of
the posterior interventricular artery.
■ Is innervated by autonomic nerve fibers, although the
cardiac muscle fibers lack motor endings
200

3. AV Bundle (Bundle of His)
■ Begins at the AV node and runs along the membranous
part of the interventricular septum.
■ Splits into right and left branches, which descend into the
muscular part of the interventricular septum, and breaks
up into terminal conducting fibers (Purkinje fibers) to
spread out into the ventricular walls.
201

• By superficial & deep
cardiac plexuses that are
located
 A superficial part is inferior
to the aortic arch and
between it and the
pulmonary trunk
 A deep part is between the
aortic arch and the tracheal
bifurcation
• The components are
1) Sympathetic
2) Parasympathetic
3) Visceral afferent (sensory)
fibers
Innervations of the heart
202

Innervations …
1) Sympathetic - is via
• Cervical cardiac branches from the superior and middle
cervical ganglia ( C1-6 ) – sup. and middle cardiac nerves
• Cervicothoracic branches from the stellate (cervicothoracic)
ganglion (C7-T1)– inferior cardiac nerve
• Thoracic branches from ( T2-4 )
 They are cardioaccelerators & coronary dilator
2) Parasympathetic - is via Vagus
• Is cardioinhibitory & coronary constrictor
 Saving energy between periods of increased demand
 All the branches fuse into
• A cardiac plexus which courses around the right pulmonary
artery to the posterior aspect of the atria
 They distribute to the SA node, AV node and to the
coronary plexuses 203

Sympathetic and Parasympathetic
components
204

Parasympathetic innervation
. Stimulation of the parasympathetic system:
. decreases heart rate;
. reduces force of contraction;
. constricts the coronary arteries, saving energy b/n periods
of increased demand.

Sympathetic innervation
. Stimulation of the sympathetic system:
. increases heart rate;
. increases the force of contraction.
. increases impulse conduction;
. increases blood flow thru the coronary vessels to support
the increased activity

Mediastinum cont’d
• Is the longest part of the mediastinum
• Boundaries
 Superiorly - an imaginary plane passing from the sternal
angle to the intervertebral disc between vert. T4 and
T5
 Inferiorly - diaphragm
 Anteriorly – from above → down:
 Bifurcation of trachea
 Pulmonary vessels
 Fibrous pericardium
 Posterior sloping of upper surface of the diaphragm
 Posteriorly – lower eight vertebrae & intervertebral discs
 On each side – mediastinal pleura
The posterior mediastinum
207

Structures in the posterior mediastinum
 Tube – Esophagus with its associated nerve plexus
 Arteries – Descending thoracic aorta & its branches
 Veins – Azygos,hemiazygos & accessory hemiazygos
veins & posterior intercostal veins
 Nerves – Vagus & Sympathetic trunks and the
splanchnic nerves
 Lymph vessels & nodes – Posterior mediastinal lymph
node & thoracic duct
208

Cont’d
Descending aorta
 From the left side of the body of T5, descends on the left of the
vertebral column posterior to the root of the left lung
 Passes through the aortic hiatus at T12
1.The visceral branches of the descending aorta are
 Bronchial arteries
 Esophageal arteries
 Branches to pericardium and diaphragm
2.The parietal (thoracic) branches
• The right and left posterior intercostal arteries
from the 3rd intercostal space to the subcostal
arteries
210

Cont’dEsophagus
 Extends from the posterior
aspect of the pharynx at the
level of C6 to the stomach,
below the left dome of the
diaphragm.
 Pierces the diaphragm at the
level of the rib 7/8 costal
cartilage at the level of T10.
 It is constricted in 4 regions:
 C6 (upper esophageal
sphincter-voluntary),
 T2/3 (crossing of aortic arch),
 T4/5 (crossing of left primary
bronchus),
 T10 (diaphragm).
211

The sympathetic trunks
• The symathetic trunk and their associated ganglia form a
major portion of the ANS
• The thoracic sympathetic trunks are in continuity with the
cervical and lumbar sympathetic trunks
• The thoracic sympathetic trunks lie against
 The heads of the ribs in the superior part of the thorax
 The costovertebral joints in the midthoracic level
 The sides of vertebral bodies in the lower part of the thorax
• This sympathetic trunks consists of two parallel cords
punctuated by 11 or 12 ganglia
 Two types of medial branches are given off by the ganglia
 The first type includes branches from the upper four/five ganglia
 The second type includes branches from the lower eight /seven
ganglia
212

Sympathetic trunks and the splanchnic nerves
213

Sympathetic …
• The first type, from the upper four/five ganglia
• Consists mainly of postganglionic sympathetic fibers, which
supply the various thoracic viscera
• These branches are relatively small, and also contain visceral
afferent fibers
• The second type, from the lower eight/seven ganglia
• Consists mainly of preganglionic sympathetic fibers, which
supply the various abdominal and pelvic viscera.
• These branches are large, also carry visceral afferent fibers,
and form the three thoracic splanchnic nerves referred to as
the greater, lesser, and least splanchnic nerves
214

• Solid lines indicate pre-
ganglionic axons while
broken lines indicate post-
ganglionic axons
Sympathetic …
215

The splanchnic nerves
• The lower thoracic splanchnic nerves, also known as greater,
lesser, and least splanchnic nerves, are part of the
abdominopelvic splanchnic nerves because they supply viscera
inferior to the diaphragm
• They consist of presynaptic fibers from the 5/6th to 12th
sympathetic ganglia, which pass through the diaphragm and
synapse in prevertebral ganglia in the abdomen
The greater splanchnic nerve
• On each side usually arises from the fifth to ninth or tenth
thoracic ganglia.
• It descends across the vertebral bodies moving in a medial
direction, passes into the abdomen through the crus of the
diaphragm, and ends in the celiac ganglion
216

The splanchnic nerves …
• usually arises from the ninth and tenth, or tenth and
eleventh thoracic ganglia
• It descends across the vertebral bodies moving in a medial
direction, and passes into the abdomen through the crus of
the diaphragm to end in the aorticorenal ganglion
• Usually arises from the twelfth thoracic ganglion.
• It descends and passes into the abdomen through the crus
of the diaphragm to end in the renal plexus
The lesser splanchnic nerve
The least splanchnic nerve (lowest splanchnic
nerve)
217

Anatomy thorax

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Anatomy thorax

Ähnlich wie Anatomy thorax (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Anatomy thorax