MUSCLES OF HEAD AND NECK BASIC ANATOMY AND APPLIED ASPECTS

1. Presented by
Dr. Aaby Abraham
1st year Post Graduate
Dept. of Oral and
Maxillofacial Surgery
VS Dental College

2.  Introduction
 Classification
 Embryology of muscle
 Anatomy of muscle
 Physiology of muscle
 Muscles of –
 Scalp
 Face
 Eyelid
 Extraocular
 Nose
 Mouth
 Mastication

3.  Suprahyoid
 Infrahyoid
 Lateral Cervical muscles
 Lateral Vertebral muscles
 Tongue
 Palate
 Pharynx
 Triangles of the neck
 Conclusion
 References

4.  Muscles are formed from Myoblasts of the Mesenchyme
which forms the bulk of the mesoderm
 There are more than 600 muscles in our body
 Muscle cells can be excited chemically, electrically and
mechanically to produce an action potential that is
transmitted along their cell membranes.
 In man, muscle tissue constitutes 40–50% of the body
mass.
 These muscles have their full complement of cells during
development and increase in size only by increasing the
volume of individual myocytes, rather than by increasing
the number of cells.

7.  Both striated and smooth muscles arise from Mesoderm with
an exception for a few which originate from the Ectoderm.
 The intrinsic muscles of the trunk are derived from the
myotomes while the muscles of head and limbs differentiate
directly from the mesoderm.
 Intraembryonic mesoderm formed from epiblast during
gastrulation is divided into three components
 Somites: segmentally arranged, paired structures located lateral to
the notochord and spinal cord and runs along the embryonic axis
from head to tail.
 Intermediate mesoderm: forms lateral to the somites
 Lateral plate mesoderm: forms lateral to the intermediate
mesoderm.

9.  General principles of muscle differentiation applies
equally well to smooth and cardiac muscle.
 MYOBLASTS, the precursors of muscle cells develop
from mesenchymal cells.
 They have a prominent nucleus and an enlarged
nucleolus, many free ribosomes and polysomes in
their cytoplasm, a few uniformly distributed globular
mitochondria and sparse endoplasmic reticulum.

10.  *to add pic here*

11.  MUSCLE FIBRE
 ENDOMYSIUM
 FASCICULI
 PERIMYSIUM
 EPIMYSIUM
 FASCIA
 ATTACHMENTS
 FLESHY
 TENDON
 APONEUROSIS
 SEPTA

13. TYPE 1
• Small
• Slow-firing
• Relatively fatigue
resistant
• Oxidative fibres
TYPE 2
• Large
• Fast-firing
• Fatigable fibres
• Type 2a – fast, oxidative,
glycolytic fibres
• Type 2b – fast, glycolytic,
fibres
• The distribution of these muscle fibre types in
specific muscles seems correlated to the muscle
functions.
• In the Oral apparatus: the ratio of TYPE1: TYPE2
shifts towards Type 1 in edentulous jaws.

16. CONTRACTION
• Action potential reaches the axon of motor nerve
• The action potential activates voltage gated Ca2+
channels and Ca2+ rushes in.
• Acetylcholine vesicles fuse with membrane and
release Acetylcholine into the cleft between axon
and motor end plate.
• Acetylcholine binds to nicotinic receptors on the
motor end plate.

18.  Sodium rushes in and Potassium rushes out but
 Action potential causes release of Calcium
ions.
 Calcium binds to troponin which modulates
tropomyosin (allosterically)
 Troponin forces tropomyosin to move out of
way to expose the binding sites to which
myosin heads bind and pull the actin filaments
causing overlapping of the two myofibrils
(actin and myosin)

21. RIGOR MORTIS
The absence of ATP results in the inability of
myosin heads to be released. The actin-myosin
complex becomes stable leading to muscular
rigidity
 After the impulse is over, the SR actively pumps back
Calcium ions back into the sacs.
 Calcium ions are stripped from troponin molecules
and tropomyosin returns to its position, blocking
actin’s active sites.
 Myosin cross bridges are prevented from binding to
actin and thus can no longer sustain contraction.
 Since the myofibrils are not connected to each other
the muscle returns to its longer, resting state.

22. OCCIPITOFRONTALIS
 Origin & Insertion:
 Has 4 bellies- 2 occipital and
2 frontal which are connected
by an aponeurosis (galea
aponeurotica)
 Occipital bellies arise from
the highest nuchal line and
passes forward to attach to the
aponeurosis. The 2 muscle
bellies are separated in the
midline.
 Frontal belly arises from the
aponeurosis and passes
forwards to become attached
to the upper part of
orbicularis oculi and the skin
of the eyebrow.

23.  NERVE SUPPLY:
 Facial nerve
 Post auricular branch to occipitalis
 Temporal branches to frontalis
 BLOOD SUPPLY: Branches of the superficial temporal,
ophthalmic, posterior auricular and occipital arteries.
 ACTION:
 Frontalis: Raise the eyebrows and the skin over the root of the
nose, and at the same time draw the scalp forward forming
transverse wrinkles of the forehead.
 Occipitalis: in some individuals occipitalis can pull the scalp
backwards, but otherwise it merely anchors the aponeurosis
when frontalis elevates the eyebrows.

24.  APPLIED ANATOMY:
 Frontalis muscle is one among the many
muscles examined to check the functioning
of facial nerve. Transverse wrinkles on the
forehead are absent when the patient is
asked to look upwards without moving his
head in cases of infranuclear lesions of the
facial nerves

25.  Also known as muscles of
facial expression are
subcutaneous muscles.
 These muscles are regulators
(sphincter or dilators) of the
three opening on the face
namely; the palpebral
fissures, nostrils and oral
fissure.
 Facial expressions produced
are secondary functions of
these muscles. Some
anatomists think that facial
expressions are merely side
effects of the action of the
muscles of face.

26. OPENING SPHINCTER DILATORS
PALPEBRAL FISSURE ORBICULARIS
OCULI
• LEVATOR
PALPEBRAE
SUPERIORIS
• FRONTALIS
NOSTRILS COMPRESSOR
NARIS
• DILATOR NARIS
• DEPRESSOR SEPTI
• MEDIAL SLIP OF
LEVATOR LABII
SUPERIORIS
ALAEQUE NASI
ORAL FISSURE ORBICULARIS ORIS ALL MUSCLES
AROUND THE
MOUTH EXCEPT
ORBICULARIS ORIS
AND MENTALIS

27. Levator palpebrae
superioris
Orbicularis oculi
Corrugator
supercilli

28.  Origin and Insertion:
 From nasal part of the
frontal bone and from
the frontal process of
the maxilla in front of
the lacrimal groove,
and from the anterior
surface and borders of
a short fibrous band,
the medial palpebral
ligament.
 the muscle has three
parts:- the palpebral
portion, the orbital
portion and the
lacrimal portion.

29.  Palpebral portion:
 Thin and pale muscle which arises from the bifurcation of
the medial palpebral ligament
 Forms a series of concentric curves and gets inserted into
the lateral palpebral raphe.
 Orbital portion:
 Reddish colour
 Fibres form complete ellipse without interruption at the
lateral palpebral commisure.
 The upper portion of the muscle blends with Frontalis and
Corrugator
 Lacrimal portion:
 Situated behind the medial palpebral ligament and lacrimal
sac.
 Divides into two; upper and lower parts which are inserted
into the superior and inferior tarsi medial to puncta
lacrimalia.

30.  Origin and Insertion:
 Arises from medial
end of the
supercilliary arch
and its fibres pass
upwards and lateral
between the
palpebral and orbital
portions of the
Orbicularis oculi.
 Inserted into deep
surface of skin,
above the middle of
the orbital arch.

31.  Both Orbicularis oculi and Corrugator supercilli are
supplied by the facial nerve.
• ORBICULARIS OCULI: Branches of the facial,
superficial temporal, maxillary and ophthalmic
arteries
• CORRUGATOR: Branches from adjacent arteries,
mainly from the superficial temporal and
ophthalmic arteries.

32.  Orbicularis oculi: It acts a sphincter muscle.
 Palpebral portion is involuntary - closes the lid during
sleeping/blinking.
 Orbital portion is voluntary – firm closure of the eyelids. During
closure the medial palpebral ligament is tightened and the wall
of the lacrimal sac is drawn lateral and forwards forming a
vacuum and tears are sucked through the lacrimal canals.
 The lacrimal part draws the eyelids and the ends of the lacrimal
canals medially and compresses them against the globe of the
eye placing them in the most favourable situation for receiving
the tears.
 Levator palpebrae superioris – direct antagonist of orbicularis
oculi. It raises the upper eyelid and exposes the bulb of the eye.
 Corrugator supercilli: draws the eyebrow downwards and medially
producing vertical wrinkles of the forehead.

33. APPLIED ASPECTS
 Paralysis from of orbicularis oculi prevents eye from being
closed and exposes cornea leaving it to become dry.
 Lower eyelid falls away from the eyeball forming a pond in
which the tears pool and spill over the face. It also causes
conjunctival sac to get accumulated with grit causing
infections.

34. Voluntary
Muscles
Levator
palpebrae
superioris
Rectus
superior
Rectus
inferior
Rectus
medialis
Rectus
lateralis
Obliquus
superior
Obliquus
inferior

35. Origin and insertion:
 Origin
 Arises from the under surface of
the small wing of the sphenoid
anterosuperior to the optic
foramen. The narrow tendinous
muscle becomes broad and fleshy
and end in the wide aponeurosis
which splits into three lamellae.
 Insertion:
 Superficial lamella: blends with
the orbital septum and inserts
into the anterior surface of the
superior tarsus.
 Middle lamellae: inserted into the
upper margin of the superior
tarsus
 Deep lamellae: blends with the
sheath of rectus superior and
attached to the superior fornix of
the conjunctiva.

36. Origin and insertion:
 Arises from a fibrous ring (common annular tendon or tendinous
ring) which surrounds the upper, medial, and lower margins of
the optic foramen and encircles the optic nerve. It also encloses
the lower and medial part of the superior orbital fissure.
 Two specialised parts of the fibrous ring
 A lower, LIGAMENT/TENDON OF ZINN: gives origin to inferior
rectus and lower head of lateral rectus.
 An upper, SUPERIOR TENDON OF LOCKWOOD: gives origin to
superior rectus, medial rectus and upper head of lateral rectus.
 Each muscle passes forward and is inserted into the sclera by a
tendinous expansion 6mm above the margin of the cornea.

37. Superior oblique muscle
Origin and insertion:
 Arises: above the margin of the
optic foramen, above and
medial to the origin of superior
rectus. The fibres become a
rounded tendon and pass
through fibrocartilaginous ring
or pulley attached to the
trochlear fovea of frontal bone.
The tendon passes backwards
laterally and downwards below
the superior rectus
 Insertion: sclera of the lateral
part of the bulb of the eye
between insertions of superior
rectus and lateral rectus.

38. Origin and insertion:
 Arises from the
orbital surface of the
maxilla, lateral to the
lacrimal groove. The
fibres pass laterally
backward and
upwards between
inferior rectus and the
floor of the orbit
 Insertion: sclera of
the lateral part of the
eye between superior
rectus and lateral
rectus behind the
insertion of superior
oblique

39.  NERVE SUPPLY:
 Lateral Rectus: abducent nerve (VI)
 Superior Oblique: trochlear nerve (IV)
 Rest of the muscles: occulomotor nerve (III)
 BLOOD SUPPLY
 All extraocular muscles are supplied by Ophthalmic
artery.

40.  ACTIONS
 Levator palpebrae superioris: antagonist of orbicular
oculi as it raises the eyelid
 Other extraocular muscles

41.  In Thyroid orbitopathy: MR and IR thicken. especially near
the orbital apex causing compression of the optic nerve as
it enters the optic canal adjacent to the body of the
sphenoid bone.
 Fascial sheath of the SR muscle closely adheres in its
anterior external surface to the undersurface of the sheath
of LPS of upper lid. The fusion of SR and LPS accounts for
the cooperation of upper lid and globe in elevation of the
eye, a fact that must be kept in mind during surgical
procedures on the superior rectus muscle

45.  Procerus (pyramidalis nasi):
 fascia covering the lower part of the nasal bone and upper part of
the lateral nasal cartilage.
 inserted into the skin over the lower part of the forehead between
two eyebrows. Its fibres decussate with that of frontalis.
 Nasalis: two parts: transverse and alar.
 Transverse part: from maxilla, superior and lateral to incisive fossa.
Fibres expand into a thin aponeurosis which is continuous on the
bridge of the nose.
 Alar part is attached by one end to the greater alar cartilage, and by
the other to the integument at the point of the nose.
 The Depressor septi (Depressor aloe nasi)
 arises from the incisive fossa of the maxilla
 inserted into the septum and back part of the ala of the nose. It lies
between the mucous membrane and muscular structure of the lip.

46.  The Dilatator naris posterior is placed partly beneath the
Quadratus labii superioris.
 arises from the margin of the nasal notch of the maxilla, and
from the lesser alar cartilages.
 inserted into the skin near the margin of the nostril.
 The Dilatator naris anterior is a delicate fasciculus, passing
from the greater alar cartilage to the integument near the margin
of the nostril.
 Levator labii superioris alaequae nasi:
 Arises from the upper part of the frontal process of the maxilla and
divides into medial and lateral slips.
 Insertion:
 Medial slip blends into the perichondrium of the lateral crus of the major
alar cartilage of the nose and the skin over it.
 Lateral slip is prolonged into the lateral part of the upper lip, where it
blends with levator labii superioris and orbicuris oris. The fibres curve
across the front of levator labii superioris and attach along the floor of
the dermis at the upper part of the nasolabial furrow and ridge.

47.  Nerve supply
 Facial nerve
 Blood supply
 Procerus is supplied mainly by branches from the facial
artery
 Nasalis is supplied by branches from the facial artery
and from the infraorbital branch of the maxillary artery
 Depressor septi is supplied by the superior labial branch
of the facial artery
 Levator labii superioris alaequae nasi is supplied by the
facial artery and the infraorbital branch of the maxillary
artery

48.  Procerus:
 draws down the medial
angle of the eyebrows and
produces transverse
wrinkles over the bridge of
the nose.
 The two Dilators (Anterior and
Posterior)
 enlarges the aperture of the
nares.
 resist the collapse of the
nostrils due to atmospheric
pressure.
 strongly contract during the
expression of some
emotions such as Anger.
 Depressor septi:
 antagonist to other muscles
of nose.
 Draws the ala of nose
downwards and constricts
the nares.
 Nasalis:
 depresses the cartilaginous
part of the nose
 draws the ala towards the
septum.

49.  Lateral slip raises and
everts the upper lip,
deepens and increases
the curvature of the top
of the nasolabial furrow.
 Medial slip pulls the
lateral crus superiorly,
displaces the circumalar
furrow laterally and
modifies its curvature.
 Secondary dilator of
naris

50.  Buccinator
 Orbicuaris oris
 Risorius
 Platysma
• Levator labii superioris
• Caninus
• Zygomaticus
• Mentalis
• Levator labii inferioris
• Triangularis

51. Origin and Insertion
 Has three heads
 Angular head
 Intermediate
head/infraorbital
head
 Zygomatic head

52.  Angular head:
 arises from the frontal process of the maxilla
 passes obliquely downwards and splits into two;
 one inserts into the greater alar cartilage
 the other into the lateral part of the upper lip, blending
with infraorbital head and orbicularis oris.
 Intermediate head/infraorbital head:
 Arises from the lower margin of the orbit above the infra-
orbital foramen.
 Inserted into the muscular substance of the upper lip
between the angular head and the Caninus.
 Zygomatic head:
 arises from the malar surface of the zygomatic bone
behind the zygomaticomaxillary suture
 Inserts into medial aspect of the upper lip.

53. Origin and insertion
 Arises from the the
canine fossa
immediately below
the infraorbital
foramen
 Inserted into the
angle of the mouth
intermingling with
those of the
Zygomaticus,
Triangularis and
Orbicularis oris.

54. Origin and insertion:
 It arises from the anterior
aspect of lateral surface
of zygomatic bone
 Inserts into the upper lip
medial to the angle of the
mouth.
Origin and insertion:
 Arises from the zygomatic
bone, in front of the
zygomaticotemporal suture.
 Inserted into the angle of the
mouth, where it blends with
the fibres of the Caninus,
Orbicularis oris and
Triangularis.

55.  NERVE SUPPLY:
 FACIAL NERVE.
 BLOOD SUPPLY:
 Levator labii superioris is supplied by the facial artery and the
infraorbital branch of the maxillary artery.
 Caninus is supplied by the superior labial branch of the facial artery
and the infraorbital branch of the maxillary artery.
 Zygomaticus is supplied by the superior labial branch of the facial
artery.
 ACTIONS:
 Levator labii superioris: elevator of upper lip.
 Angular head: dilator of naris
 Infraorbital and zygomatic head assist in forming the nasolabial furrow.
 When the whole muscle contracts it gives the expression of contempt and
disdain
 Caninus: helps in producing the nasolabial furrow.
 Zygomaticus: helps in smiling.
 Zygomaticus major: pulls the angle of the mouth upwards and lateral
 Zygomaticus minor: elevates the upper lip

56. Origin and insertion
 arises from the
oblique line of
mandible, between
symphysis and
mental foramen.
 Inserts into the
integument of the
lower lip. Its fibres
blend with that of
orbicularis oris and
with those from the
opposite side.

57. ORIGIN AND
INSERTION
 Arises from the incisive
fossa of the mandible
 Inserts into the
integument of the chin.

58. ORIGIN AND
INSERTION
 Arises from the oblique
line of the mandible.
 Inserts into the angle of
the mouth.
At the origin its fibres are
continuous with platysma
and at the insertion it is
continuous with that of
orbicularis oris
TRIANGULARIS

59.  NERVE SUPPLY:
 Facial nerve
 BLOOD SUPPLY:
 Mentalis is supplied by the inferior labial branch of the facial artery
and the mental branch of the maxillary artery.
 Depressor labii inferioris is supplied by the inferior labial branch of
the facial artery and the mental branch of the maxillary artery.
 Triangularis: supplied by the inferior labial branch of the facial
artery and the mental branch of the maxillary artery
 ACTIONS:
 MENTALIS: Raises and protrudes the lower lip and at
the same time wrinkles the skin of the chin, expressing
doubt or disdain.
 DEPRESSOR LABII INFERIORIS: draws the lower lip
downwards and laterally, as in expression of Irony
 TRIANGULARIS: depresses angle of mouth medially
along with Platysma

60. ORIGIN AND INSERTION
 Arises from the outer
surface of the alveolar
process of the maxilla and
mandible, corresponding
to the molars anteriorly
and from the anterior
border of
pterygomandibular raphe
posteriorly.
 Insertion: the fibres
converge towards the angle
of the mouth. The central
fibres intersect with each
other, those from below
continuous with upper
segment of Orbicularis oris
and those from above with
the lower segment.

61.  Previously considered as a sphincter muscle but
recent studies have shown that the muscle
consists of 4 independent quadrants (viz. upper,
lower, left and right)
 Each quadrant contains large Pars peripheralis
and small Pars marginalis.
 Both peripheralis and marginalis originate from
the modiolus. Pars peripheralis decussate at the
midline and insert into the contralateral philtrum
edge where as pars marginalis is a continuous
band from modiolus to modiolus.

62. ORIGIN AND INSERTION
 It arises from
 Anterior surface of maxilla
 Anterior surface of mandible
 Modiolus
 Insertion: peripheral part decussate
with opposite fibres crossing the
midline to insert into the skin near
the opposite midline from the
nasolabial sulcus to the margin of the
red lip superiorly and from the
mentolabial sulcus to the margin of
the red lip inferiorly. Similarly the
marginal part interdigitates and
crosses the midline to insert into the
dermis just opposite the midline in
both superior and inferior lips.

63.  In cases of cleft lip the pars
peripheralis runs all the way
the columella while the pars
marginalis end at the
margin of the defect
 In correction of cleft lip
 Orbicularis muscle is
everted with vertical
mattress sutures
 The muscle can be divided
into horizontal strips that
are interdigitated and
sutured to the undersurface
of the dermis (Furlow et.al)
 The muscle can be split in
coronal planes and
overlapping the four muscle
flaps (Cho et.al)

64. ORIGIN AND
INSERTION
 Arises in the fascia
over Masseter and
passes
horizontally
forward above the
platysma.
 Insertion: into the
skin of the angle
of the mouth.

65.  Nerve supply:
 Facial nerve
 Blood supply:
 Orbicularis oris: supplied mainly by the superior
and inferior labial branches of the facial artery,
the mental and infraorbital branches of the
maxillary artery and the transverse facial branch
of the superficial temporal artery
 Buccinator is supplied by branches from the
facial artery and the buccal branch of the
maxillary artery.
 Risorius is supplied mainly by the superior labial
branch of the facial artery

66.  Orbicularis oris:
 Pursing of lips and pouting.
 Buccinator:
 compresses the cheeks so that during
mastication the food is kept under immediate
pressure of the teeth.
 whistling
 Risorius: retracts the angle of the mouth and
helps in producing unpleasant grinning
expression

67. Origin and insertion
 Origin: upper parts of pectoral and
deltoid fasciae and fibres run upwards
and medially
 Insertion:
 Anterior fibres to the base of the
mandible
 Posterior fibres to the skin of the
lower face and lip and maybe
continuous with the Risorius.
 Nerve supply: Facial nerve
 Blood supply: By the submental branch
of the facial artery and by the
suprascapular artery
 Actions:
 Releases pressure of skin on the
subjacent veins
 Depresses mandible
 Pulls the angle of the mouth
downwards as in horror or surprise

68.  It is defined as a lateral point to the corner of the angle of
the mouth where the muscles of facial expression converge.
(Jablonski 1982; Manhold and Balbo 1985; Harry and
Ogston 1987).
 The muscles which form the modiolus are:
 Orbicularis oris
 Buccinator
 Caninus
 Triangularis
 Zygomaticus major
 Risorius
 Platysma
 Levator labii superioris

69. Shimada and Gasser (1989) have reported
variations in the location of Modiolus.
Type A: modiolus lateral to
the angle of the mouth
Type B: modiolus above the
angle
Type C: modiolus below the
angle*Clinical anatomy 2:29-134(1989); Variations in the facial
muscles at the angle of the mouth – Kazuyuki Shimada and
Raymond F. Gasser

72.  The platysma muscle has to be sutured separately so
that skin does not adhere to deeper neck muscles
otherwise the skin will get an ugly scar.
 Chemodenervation of procerus and corrugator
supercilii to alleviate frown lines is one of the most
common aesthetic indications for botulinum toxins.
 Procerus is sometimes debulked during endoscopic
brow lift procedures to reduce the horizontal frown
crease.

73.  Charles Bell in 1821 first described Bell’s Palsy.
 It is Common, acute, benign neurological disorder,
characterized by sudden, isolated peripheral facial
nerve paralysis
 Bell’s Palsy- Lower Motor Neuron Disorder.
 Various and unknown etiology
 However infectious, genetic, metabolic, autoimmune,
vascular condition, and nerve entrapment, viral
etiology

74.  Tetanus is a clinical diagnosis
characterized by a triad of muscle
rigidity, muscle spasms and autonomic
instability.
 Clostridium tetani spores enter into the
body through any abrasions on the skin.
 Release tetanospasmin (potent
neurotoxin)
C/F:
 Early symptoms of tetanus include
 neck stiffness,
 sore throat
 dysphagia
 trismus.
 Spasm extending to the facial muscles
causes the typical facial expression,
‘risus sardonicus’.
 Truncal spasm causes opisthotonus.

75.  Parkinson’s disease (PD) is a
chronic, progressive,
neurodegenerative disorder .
 Characterized by resting tremors,
cogwheel rigidity, bradykinesia.
 PD results from idiopathic
degeneration of dopaminergic cells
in the pars compacta of substantia
nigra
 Depletion of neurotransmitter
dopamine in the basal ganglia
 The four cardinal signs of PD are
resting tremor, rigidity or stiffness,
bradykinesia and postural
instability.

76. MOBIUS SYNDROME
 It is an extremely rare
congenital neurological
disorder
 Characterized by facial
paralysis and the inability to
move the eyes from side to
side.
 Born with complete facial
paralysis and cannot close
their eyes or form facial
expressions.
 Limb and chest wall
abnormalities sometimes
occur with the syndrome.

77. MELKERSONS-ROSENTHAL
SYNDROME
It is a rare neurological characterized by recurring facial
paralysis, swelling of the face and lips (usually the upper lip), and
the development of folds and furrows

78.  Ramsay Hunt Syndrome:
Peripheral facial nerve palsy
May be unilateral or bilateral
Vesicular rash on ear
Ear pain, tingling, tearing, loss of
sensation and nystagmus.
 Ramsay Hunt Syndrome Type II:
Reactivation of latent Herpes
zoster virus within the dorsal root
ganglion of facial nerve is
associated with vesicles affecting
ear canal.
84

80. Origin and insertion:
 It is divided into three layers:
 Superificial part:
 originates from the anterior 2/3rd
of lower border of ZM arch and
zygomatic process of maxilla.
 Inserts into lower part of lateral
surface of ramus
 Middle layer:
 originates from the anterior2/3rd
of the deep surface and
posterior1/3rd of the lower
border of ZM arch.
 Inserts into middle part of
ramus
 Deep layer:
 originates from the deep surface
of ZM arch.
 Inserts into the upper part of
ramus and lateral surface of the
coronoid process of the
mandible

81.  Nerve supply: masseteric nerve which is branch of
anterior division of mandibular nerve.
 Blood supply: Supplied by the masseteric branch of
the maxillary artery, the facial artery and the
transverse facial branch of the superficial temporal
artery.
 Action: elevates the mandible to close the mouth

82. Origin and insertion:
 Originates from Temporal fossa
excluding the zygomatic bone, and
the temporal fascia.
 The fibres converge and passes deep
to the ZM arch and inserts into the
margins and deep portions of the
Coronoid process and anterior border
of the ramus.
 Nerve supply: two deep temporal
branches from the anterior division of
the mandibular nerve.
 Blood supply: Supplied by the deep
temporal branches from the second
part of the maxillary artery
 Actions:
 elevates the mandible to close the
mouth.
 Posterior fibres retract the protruded
mandible.
 Side to side grinding movement

83. ORIGIN AND INSERTION
 It has two heads
 Upper head: originates
from the infratemporal
surface and crest of the
greater wing of sphenoid.
 Lower head: from the
lateral surface of the lateral
pterygoid plate.
 Its fibres insert into
 Pterygoid fovea on the
anterior surface of the neck
of the condyle mandible
 Anterior margin of the
articular disc and capsule
of TMJ

84.  Nerve supply: a branch of anterior division of
mandibular nerve.
 Blood supply: Lateral pterygoid is supplied by
pterygoid branches from the maxillary artery
 Actions:
 Depresses mandible to open the mouth along with
suprahyoid muscle.
 Lateral and medial pterygoids protrude the mandible.
 Left lateral pterygoid and right medial pterygoid turn
the chin to the left side and vice versa.

85. Origin and insertion:
 It has two heads
 Superficial head: originates
from the tuberosity of the
maxilla and adjoining bone.
 Deep head: originates form
the medial surface of lateral
pterygoid plate and
adjoining process of
palatine bone.
 Inserts into the roughened
area on the medial surface of
angle and adjoining ramus
of mandible, below and
behind the mandibular
foramen and mylohyoid
groove.

86.  Nerve supply: nerve to medial pterygoid, a
branch of the main trunk of mandibular nerve.
 Blood supply: Medial pterygoid derives its main
arterial supply from the pterygoid branches of
the maxillary artery
 Actions:
 elevates mandible
 Protrusion of mandible
 Side to side grinding movements

87.  Masseteric hypertrophy
 Temporalis Muscle Flap
 Antero-medial displacement of condyle during
subcondylar fractures due to the Spasm of Lateral
Pterygoid
 Medial Pterygoid Spasm rendering trismus due to
improper technique of IAN block.
 Traversing of facial artery along the antero-inferior
border of masseter over the body of mandible
 Favourability of fracture displacement.

88. Digastric
Stylohyoid
Mylohyoid
Geniohyoid
Hyoglossus

89. ORIGIN AND INSERTION
 It has two bellies united by
an intermediate tendon.
 Origin:
 Anterior belly: originates
from the digastric fossa of
mandible.
 Posterior belly: originates
from mastoid notch of
temporal bone.
 Insertion: Both these bellies
meet at the intermediate
tendon which perforates the
Stylohyoid and is held by a
fibrous pulley to the hyoid
bone.

90.  Nerve supply:
 Anterior belly: nerve to mylohyoid
 Posterior belly: facial nerve
 Blood supply: The posterior belly is supplied by the
posterior auricular and occipital arteries. The anterior
belly of digastric receives its blood supply chiefly from
the submental branch of the facial artery
 Action:
 Depresses mandible while opening mouth or against resistance.
 Elevates hyoid bone

91.  The facial artery is divided and
ligated just above the posterior belly of
digastric muscle.

92. ORIGIN AND INSERTION
 Originates from Posterior
surface of styloid process.
 Insertion into the
junction of body and
greater cornua of hyoid
bone.
 Nerve supply: facial nerve
 Blood supply: Stylohyoid
receives its blood supply
from branches of the
facial, posterior auricular
and occipital arteries
 Actions:
 pulls hyoid bone
upwards and backwards
 Fixes the hyoid along
with other muscles

93.  Origin and insertion:
 Origin from mylohyoid line of the
mandible
 Insertion:
 Posterior fibres: body of hyoid bone.
 Middle and anterior fibres: median
raphae between mandible and hyoid
bone.
 Nerve supply: Nerve to mylohyoid
 Blood supply: Receives its arterial
supply from the sublingual branch of
the lingual artery, the maxillary artery,
via the mylohyoid branch of the
inferior alveolar artery, and the
submental branch of the facial artery
 Action:
 Elevates floor of the mouth during
deglutition
 Helps in depression of mandible and
elevation of hyoid bone.

94.  Origin and insertion:
 Originates from inferior
mental spine (genial
tubercles)
 Insertion: anterior surface
of hyoid bone.
 Nerve supply:
 Branches of first and
second cervical nerves
which reaches the muscle
through hypoglossal nerve
 Blood supply:
 Derived from the lingual
artery (sublingual branch)
 Action:
 Elevates the hyoid bone
 Depresses the mandible
when hyoid is fixed.

95.  Origin and insertion:
 Origin: whole length of
greater cornua and lateral
part of body of hyoid bone.
 Insertion: side of the tongue
between styloglossus and
inferior longitudinal muscle
of the tongue.
 Nerve supply:
 hypoglossal nerve
 Blood supply:
 supplied by the sublingual
branch of the lingual artery
and the submental branch
of the facial artery
 Action:
 Depresses tongue
 Makes dorsum convex and
retracts protruded tongue

96. Sternohyoid
Sternothyroid
Thyrohyoid
Omohyoid

97.  Origin and insertion:
 Origin:
 posterior surface of
manubrium sterni.
 Adjoining parts of the
clavicle and posterior
sternoclavicular ligament.
 Insertion into medial part
of lower border of hyoid
bone
 Nerve supply:
 Ansa cervicalis (C1, C2, C3)
 Blood Supply:
 supplied by branches from
the superior thyroid artery
 Actions:
 Depresses the hyoid bone
following elevation during
swallowing and vocal
movements

98. Origin and insertion:
 Origin:
 posterior surface of manubrium
sterni.
 Adjoining part of first costal
cartilage.
 Insertion:
 Into oblique lamina of the
thyroid cartilage
 Nerve supply:
 First cervical nerve through
hypoglossal nerve.
 Blood supply:
 supplied by branches from the
superior thyroid and lingual
arteries
 Actions:
 Depresses hyoid bone
 Elevates the larynx when the
hyoid is fixed by the suprahyoid
muscle

99.  Has two bellies – inferior
and superior and a common
tendon. It arises by the
inferior belly and is inserted
through the superior belly.
 Origin and insertion:
 Origin:
 from upper border of scapula
near suprascapular notch.
 Adjoining part of
suprascapular ligament.
 Insertion:
 lower border of hyoid bone
lateral to sternohyoid.
 The central tendon lies on
the internal jugular vein at
the level of the cricoid
cartilage and is bound to
the clavicle by fascial pulley

100.  Nerve supply:
 Superior belly by superior root of the ansa
cervicalis.
 Inferior belly by ansa cervicalis
 Blood supply: supplied by branches from
the superior thyroid and lingual arteries
 Actions:
 Depresses the hyoid bone following its
elevation during swallowing or in vocal
movements.

101. TRAPEZIUS
STERNOCLEIDOMASTOID

102.  ORIGIN AND INSERTION
 Origin: spinous process of vertebrae
C7-T12 and nuchal ligament
 Insertion: external occipital
protruberance, nuchal ligament and
medial superior nuchal ligament,
posterior border of the lateral third of
the clavicle, acromion process and
spine of scapula
 Nerve supply: accessory nerve and cervical
nerves C3 and C4.
 Blood supply:
 Upper third: tansverse muscular
branch from occipital artery
 Middle third: superficial cervical
artery
 Lower third: muscular branch from
dorsal scapular arterry
 Actions: rotation, retraction, elevation
and depression of scapula.

103.  ORIGIN AND INSERTION
 Arises from the sternum and
clavicle by two heads
(medial/sternal head and
lateral/clavicular head)
 Medial head arises from the
upper part of the anterior
surface of the manubrium
sterni.
 Lateral head arises from the
superior border and anterior
surface of the medial third of
clavicle.
 Two head are separated from one
another at their origins by a
triangular interval but gradually
blend to form a thick rounded
muscle below the middle of the
neck
 It inserts into the lateral surface of
the mastoid process through a
strong tendon and through a thin
aponeurosis into the lateral half of
the superior nuchal line.

104.  Nerve supply: spinal part of the accessory nerve
 Blood supply:
 branches of the occipital and posterior auricular arteries
(upper part of muscle), the superior thyroid artery
(middle part of muscle), and the suprascapular artery
 Actions:
 Acting alone, each sternocleidomastoid muscle
will tilt the head towards the opposite side and
flexes laterally to the same side.
 Acting together it flexes the neck and extends
the head
 Accessory muscles of respiration, along with
scalene muscles

105.  TORTICOLLIS: aka crick in the neck, wry
neck or LOXIA
 It is a dystonic condition defined by an
abnormal, assymeterical head or neck
position due to a variety of causes being
muscular fibrosis, congenital spine
abnormalities or toxic or traumatic brain
injury.
 There is shortening of the SCM
(congenital) or it could be due spasms
 Causes:
 Congenital
 Acquired
 Spasmodic
 Trochlear
 Types:
 Laterocollis: head tipped towards shoulder
 Rotational: head rotates along the long axis
 Anterocollis: forward flexion of the head and
neck
 Retrocollis: hyperextension of head and neck
backwards
 Patient experiences neck pain, occasional
formation of a mass, tenderness of cervial
spine etc.

106.  BRANCHIAL CYSTS usually present in the upper neck in early
adulthood as fluctuant swellings at the junction of the upper and
middle thirds of the anterior border of sternocleidomastoid.
 ERB’S POINT: (Wilhelm Heinrich Erb)
 It is a point about 2-3 cm above the clavicle at the junction of
upper and middle thirds near the posterior border of SCM
immediately in front of the transverse process of C6.
 Nason et.al reported that Erb’s point is located at midway
between the mastoid process and the clavicle along the
posterior border of SCM
 The point can also be located by dropping a vertical line 6 cm
long, from the midpoint of the line joining the mastoid
process and the angle of mandible (Landers and Kimberly)
 The spinal accessory nerve can often be found 1-2 cm above
this Point.

107. • Injury to Erb’s point is
commonly sustained at
birth or from a fall onto
the shoulder. The nerve
roots normally involved
are C5 and partly C6.
• Symptoms include
paralyisis of biceps
brachialis,
coracobrachialis,
brachioradialis.
• The arm hangs at the
side with the hand
rotated medially, like a
porter waiting for tip
hence called Porter’s Tip
Hand

108. Scalene muscle are group of three pairs of
muscles in the lateral neck
• SCALENUS ANTERIOR
• SCALENUS MEDIUS
• SCALENUS POSTERIOR
Innervation: 4th, 5th and 6th cervical spinal nerves
Blood supply:Supplied by the ascending cervical
branch of the inferior thyroid artery.
• Scalenus posterior receives an additional supply from the
superficial cervical artery.

110.  ORIGIN AND
INSERTION
 Origin: anterior
tubercles of the
transverse
processes of 3rd,
4th,5th and 6th
cervical
vertebrae
 Insertion:
scalene tubercle
on the inner
border of the 1st
rib and into the
ridge of the
upper surface of
the 2nd rib.
 ORIGIN AND
INSERTION
 Origin: arises
from the
posterior
tubercles of the
transverse
processes of the
lower six
cervical
vertebrae.
 Insertion: upper
surface of the 1st
rib between the
tubercle and the
subclavian
groove.
 ORIGIN AND
INSERTION
 Origin: arises by
two or three
separate tendon,
from posterior
tubercles of the
transverse
processes of the
lower two or three
cervical vertebrae.
 Insertion: inserted
by tendon into the
outer surface of
2nd rib, behind the
attachment of the
anterior scalene

111.  Anterior and middle scalene muscles:
 Elevates the first rib and laterally flex the neck to the
same side.
 Posterior scalene muscle: elevates the 2nd rib and tilt
the neck to the same side.
 Accessory muscles of respiration along with
sternocleiomastoid.

112.  Brachial plexus pass through the space between the
anterior and middle scalene muscles hence this area is
targeted for regional anesthesia
 Anterior and middle scalene muscles can be involved
in certain forms of thoracic outlet syndrome and
MPDS.

113. EXTRINSIC
MUSCLES
• Genioglossus
• Hyoglossus
• Palatoglossus
• Styloglossus
• Chondroglossus
INTRINSIC
MUSCLES
• Superior
longitudinal
• Inferior
longitudinal
• Verticalis
• Transverse

114. ORIGIN AND INSERTION
 It arises from a short tendon
attached to the superior genial
tubercle behind the
mandibular symphysis, above
the origin of geniohyoid.
 Insertion:
 The inferior fibres of
genioglossus are attached by a
thin aponeurosis to the upper
anterior surface of the hyoid
body near the midline
 Intermediate fibres pass
backwards into the posterior
part of the tongue
 Superior fibres ascend
forwards to enter the whole
length of the ventral surface of
the tongue from root to apex,
intermingling with the
intrinsic muscles.

115.  Nerve supply:
 hypoglossal nerve
 Blood supply:
 Genioglossus is supplied by the sublingual branch of the
lingual artery and the submental branch of the facial
artery
 Action:
 Protrusion of tongue apex from the mouth.
 Acting bilaterally, the two muscles depress the central
part of the tongue, making it concave from side to side.
 Acting unilaterally, the tongue diverges to the opposite
side.

116. Origin and insertion:
 Arises from the whole length
of the greater cornu and the
front of the body of the hyoid
bone.
 Insertion:
 It passes vertically up to
enter the side of the tongue
between styloglossus
laterally and the inferior
longitudinal muscle
medially.
 Fibres arising from the body
of the hyoid overlap those
from the greater cornu.
 Nerve supply:
 hypoglossal nerve
 Blood supply:
 Hyoglossus is supplied by
the sublingual branch of the
lingual artery and the
submental branch of the
facial artery
 Action:
 Depresses the tongue

117.  Origin and insertion:
 It arises from the anterolateral
aspect of the styloid process near its
apex, and from the styloid end of
the stylomandibular ligament.
 Insertion: Passing downwards and
forwards, it divides at the side of the
tongue into a longitudinal part,
which enters the tongue
dorsolaterally to blend with the
inferior longitudinal muscle in front
of hyoglossus, and an oblique part,
overlapping hyoglossus and
decussating with it.
 Nerve supply:
 Hypoglossal nerve
 Blood supply:
 Styloglossus is supplied by the
sublingual branch of the lingual
artery
 Action: Styloglossus draws the tongue
up and backwards.

118.  The Chondroglossus is
sometimes described as a part
of the Hyoglossus, but is
separated from it by fibers of
the Genioglossus, which pass
to the side of the pharynx. It is
about 2 cm. long, and
 Arises from the medial side
and base of the lesser cornu
and contiguous portion of
the body of the hyoid bone.
 Insertion: passes directly
upward to blend with the
intrinsic muscular fibers of
the tongue, between the
Hyoglossus and
Genioglossus.
 Vascular supply, innervation
and action these are similar to
those described for
hyoglossus.

121.  Origin and insertion:
 The superior longitudinal muscle constitutes a thin
stratum of oblique and longitudinal fibres lying beneath
the mucosa of the dorsum of the tongue.
 It extends forwards from the submucous fibrous tissue
near the epiglottis and from the median lingual septum
to the lingual margins.
 Some fibres are inserted into the mucous membrane

122.  Origin and insertion:
 The inferior longitudinal muscle is a narrow band of
muscle close to the inferior lingual surface between
genioglossus and hyoglossus.
 It extends from the root of the tongue to the apex.
 Some of its posterior fibres are connected to the body of
the hyoid bone.
 Anteriorly it blends with styloglossus.

123.  The transverse muscles pass laterally from the median
fibrous septum to the submucous fibrous tissue at the
lingual margin, blending with palatopharyngeus
• The vertical muscles extend from the dorsal to the
ventral aspects of the tongue in the anterior
borders

124.  Nerve supply:
 All intrinsic lingual muscles are innervated by the
hypoglossal nerve.
 Blood supply:
 The intrinsic muscles are supplied by the lingual artery
 Actions:
 Contraction of the superior and inferior longitudinal
muscles tend to shorten the tongue, but the former also
turns the apex and sides upwards to make the dorsum
concave, while the latter pulls the apex down to make
the dorsum convex.
 The transverse muscle narrows and elongates the
tongue, while the vertical muscle makes it flatter and
wider.

125.  Genioglossus is the only muscle of tongue which
protrudes it forwards. It is used for testing the
intergrity of hypoglossal nerve. If the hypoglossal
nerve is paralysed, the tongue on protrusion will
deviate to the right side.
 Genioglossus is also known as the safety muscle as it
prevents the tongue from falling back which would
obstruct the airways. Genioglossus is more active in
people with Obstructive Sleep Apnea.

127. ORIGIN AND INSERTION
 Arises from the under surface
of the apex of the petrous part
of temporal bone and from
the medial lamina of the
cartilage of the auditory tube.
 The fibres passes above the
concave margin of superior
constrictor muscle and
spreads out in the palatine
velum and extends obliquely
downward and medially
where they blend with the
fibres of the opposite side.

128. ORIGIN AND INSERTION
 Arises by a flat lamella from the
scaphoid fossa at the base of the
medial pterygoid plate, from
the spina angularis of the
sphenoid and from the lateral
wall of the cartilage of the
auditory tube. It descends
vertically into a tendon and
hooks around the pterygoid
hamulus and passes medially.
 Inserted into the palatine
aponeurosis and into the
surface behind the transverse
ridge on the horizontal part of
the palatine bone.

129.  Origin and insertion:
 Arises from the
posterior nasal
spine of the
palatine bone and
from the palatine
aponeurosis.
 Inserted into the
Uvula.

130.  ORIGIN AND INSERTION
 Arises form the anterior
surface of the soft palate
where it is continuous with
the muscle of the opposite
side.
 Fibres pass downwards,
forwards and laterally in
front of the palatine tonsil
and is inserted into the side
of the tongue.

131. ORIGIN AND
INSERTION
 Arises from the soft palate where
it is divided into two fasciculi
(posterior and anterior) by
Levator veli palatini and Musculus
uvulae.
 Posterior fasciculus lies in contact
with mucous membrane and joins
with that of the opposite muscle
in the middle.
 Anterior fasciculi lies in the soft
palate between the levator and
tensor and joins with the
corresponding part of the
opposite muscle in the middle.
 The fibres pass laterally and
downwards behind the palatine
tonsil and along with the
Stylopharyngeus is inserted into
the posterior border of thyroid
cartilage.

132.  Nerve supply:
 Tensor veli palatini is supplied by branch of mandibular
nerve through nerve of medial pterygoid.
 All other muscle are supplied by the accessory nerve
through the pharyngeal plexus.
 Blood supply:
 Levator veli palatini:
 ascending palatine branch of the facial artery
 greater palatine branch of the maxillary artery
 Tensor veli palatini:
 ascending palatine branch of the facial artery
 greater palatine branch of the maxillary artery
 Palatoglossus:
 ascending palatine branch of the facial artery
 ascending pharyngeal artery

133.  Palatopharyngeus:
 ascending palatine branch of the facial artery
 the greater palatine branch of the maxillary artery
 pharyngeal branch of the ascending pharyngeal artery
 Musculus uvulae:
 ascending palatine branch of the facial artery
 descending palatine branch of the maxillary artery.
 Salpingopharyngeus:
 ascending palatine branch of the facial artery
 greater palatine branch of the maxillary artery
 pharyngeal branch of the ascending pharyngeal artery

134.  Levator veli palatini:
 elevate the posterior part of the soft palate and
pull it slightly backwards causing the soft palate
to touch the posterior wall of pharynx
separating nasopharynx and oropharynx during
swallowing.
 Tensor veli palatini:
 primary role is to open the pharyngotympanic
tube. The muscles tauten the soft palate
 On acting unilaterally, the muscle pulls the soft
palate to one side. Contraction of both muscles
will slightly depress the anterior part of the soft
palate.

135.  PALATOGLOSSUS: elevates the root of the tongue
and approximates the palataglossal arch to its
contralateral fellow, thus shutting off the oral cavity
from the oropharynx.
 PALATOPHARYNGEUS: Acting together the
palatopharyngei pull the pharynx up, forwards and
medially and thus shorten it during swallowing. They
also approximate the palatopharyngeal arches and
draw them forwards.

136.  Retracts the uvular mass and thickening
the middle third of the soft palate, this
muscle aids levator veli palatini in
palatopharyngeal closure.

137.  Uvulopalatopharyngoplasty
 Paralysis of soft palate due
to lesions of Vagus
produces:
 Nasal regurgitation of
liquids
 Nasal twang in voice
 Flattening of the palatal
arch
 Deviation of Uvula to
normal side.

138. Superior constrictor
Middle constrictor
Inferior constrictor
Stylopharyngeus
Salpingopharyngeus
Pharyngopalatinus

139. ORIGIN AND INSERTION:
 Arises from sides of the cricoid
and thyroid cartilage.
 From the cricoid cartilage it arises
in the interval between the
Cricothyreoideus in front, and the
articular facet for the inferior
cornu of the thyroid cartilage
behind.
 On the thyroid cartilage it arises
from the oblique line on the side
of the lamina, from the surface
behind this nearly as far as the
posterior border and from the
inferior cornu
 Inserted with the muscle of the
opposite side into the fibrous
raphe in the posterior median line
of the pharynx and also overlap
the middle constrictor.

140. ORIGIN AND INSERTION:
 arises from the whole
length of the upper border
of the greater cornu of the
hyoid bone, from the lesser
cornu, and from the
stylohyoid ligament.
 inserted into the posterior
median fibrous raphé,
blending in the middle line
with the muscle of the
opposite side.

141. ORIGIN AND INSERTION:
 Arises
 lower third of the posterior margin
of the medial pterygoid plate
 hamulus,
 pterygomandibular raphé, from the
alveolar process of the mandible
above the posterior end of the
mylohyoid line, and by a few fibers
from the side of the tongue.
 Insertion:
 median raphé, being also prolonged
by means of an aponeurosis to the
pharyngeal spine on the basilar part
of the occipital bone.
 The interval between the upper
border of the muscle and the base
of the skull is closed by the
pharyngeal aponeurosis, and is
known as the sinus of Morgagni.

142.  Origin and insertion:
 Arises from the medial side
of the base of the styloid
process, passes downward
along the side of the
pharynx between the
superior constrictor and
middle constrictor, and
spreads out beneath the
mucous membrane.
 Insertion: Some fibres
mingle with the constrictor
muscles, others along with
pharyngopalatinus are
inserted into the posterior
border of the thyroid
cartilage.
 Glossopharyngeal muscles
runs lateral to the muscle
and crosses over it to reach
the tongue.

143. ORIGIN AND
INSERTION
 Arises from the inferior
part of the auditory tube
near its orifice.
 Insertion: it passes
downward and blends
with the posterior
fasciculus of the
Pharyngopalatinus,
upper border of thyroid
cartilage blending with
the constrictors.

144.  The Constrictors and Salpingopharyngeus are supplied
by branches from the pharyngeal plexus,
 The Constrictor inferior by additional branches from
the external laryngeal and recurrent nerves, and the
 Stylopharyngeus by the glossopharyngeal nerve.

145.  Superior constrictor: pharyngeal branch of the
ascending pharyngeal artery and the tonsillar
branch of the facial artery.
 Middle constrictor: pharyngeal branch of the
ascending pharyngeal artery and the tonsillar
branch of the facial artery
 Inferior constrictor: Pharyngeal branch of the
ascending pharyngeal artery and the muscular
branches of the inferior thyroid artery.

146.  Stylopharyngeus: Pharyngeal branch of the
ascending pharyngeal artery.
 Salpingopharyngeus: Ascending palatine branch of
the facial artery, the greater palatine branch of the
maxillary artery and the pharyngeal branch of the
ascending pharyngeal artery
 Palatopharyngeus : Ascending palatine branch of
the facial artery, the greater palatine branch of the
maxillary artery and the pharyngeal branch of the
ascending pharyngeal artery

147.  When deglutition is about to be performed, the pharynx is
drawn upward and dilated in different directions, to receive
the food propelled into it from the mouth.
 The Stylopharyngei draw the sides of the pharynx upward
and lateralward, which increases its transverse diameter;
its breadth in the antero-posterior direction is increased by
the larynx and tongue being carried forward in their
ascent.
 As soon as the bolus of food is received in the pharynx, the
elevator muscles relax, the pharynx descends, and the
Constrictors contract upon the bolus, and convey it
downward into the esophagus.

148.  Pharyngeal diverticulum aka ZENKER’s
diverticulum
 Seen inferior to Inferior constrictor and
above Cricopharyngeus muscle due to
uncoordinated swallowing and impaired
relaxation. This leads to building up of
pressure within the distal pharynx so
that the wall herniates through the point
of least resistance, the Killians’s triangle
(between inferior constrictor and
cricopharyngeus) forming a pouch in the
posterior pharyngeal wall

150.  STERNOCLEIDOMASTOIDEUS divides this space
into two traingles. The triangular space in front of this
muscle is called the ANTERIOR TRIANGLE; and that
behind it, the POSTERIOR TRIANGLE.

151.  Anteriorly:
 by the median line of the neck and posteriorly by the anterior
margin of sternocleidomastoid.
 Base:
 inferior border of the mandible and its projection to the mastoid
process.
 Apex:
 manubrium sterni.
It can be subdivided into suprahyoid and infrahyoid areas
above and below the hyoid bone by the passage of digastric
and omohyoid across the anterior triangle into
 Digastric
 Submental
 Muscular
 Carotid triangles

154.  Boundaries:
 On each side by the anterior belly of digastric muscles.
 Base: body of hyoid
 Apex: lies at the chin.
 Floor: right and left mylohyoid and median raphe
uniting them.
 Contents:
 2-4 submental nodes between the two anterior bellies of
digastric muscles.
 Submental veins that join to form the anterior jugular
vein.

155.  Boundaries:
 Antero-inferiorly – Anterior belly of digastric
 Postero-inferiorly – Posterior belly of digastric
 Superiorly (base) – base of the mandible and line joining
the angle of the mandible and mastoid process
 Roof:
 Skin
 Superficial fascia ( platysma, cervical branch of facial
nerve and ascending branch of transverse or anterior
cutaneous nerve.
 Deep fascia (splits to enclose the submandibular gland
 Floor: Mylohyoid muscle (anteriorly) and hyoglossus
posteriorly. A small part of the middle constrictor
muscle of the pharynx also appears on the floor

156.  Anterior part:
 Structures superficial to mylohyoid - Superficial part of the
Submandibular gland, facial vein and submandibular lymph
nodes and facial artery, submental artery, mylohyoid nerve
and vessels.
 Structures superficial to the hyoglossus – submandibular
gland, intermediate tendon of digastric and stylohyoid and
hypoglossal nerve.
 Posterior part:
 Superficial structures – lower part of parotid,external carotid
artery before it enters the parotid.
 Deep structures between ICA and ECA – styloglossus,
stylopharygeus, glossopharyngeal nerve, pharyngeal branch
of vagus nerve, styloid process and a part of parotid gland.
 Deeper structures include ICA, IJV and Vagus nerve.

157.  Boundaries:
 Antero-superiorly – posterior belly of digastric and
stylohyoid
 Antero-inferiorly – superior belly of omohyoid
 Posteriorly – anterior border of sternocleidomastoid.
 Roof:
 Skin
 Superficial fascia ( platysma, cervical branch of facial
nerve, transverse cutaneous nerve of neck
 Investing layer of deep cervical fascia.
 Floor: thyrohyoid, hyoglossus, middle and inferior
constrictor muscles.

158.  Arteries: CCA, with carotid sinus and the carotid body at its
termination, ICA, ECA and branches (superior thyroid,
lingual, facil, ascending pharyngeal and occipital branches.
 Veins: IJV, common facial vein draining into IJV,
pharyngeal vein, lingual vein
 Nerves: Vagus, Superior laryngeal branch of vagus nerve,
spinal accessory nerves, hypoglossal nerve, sympathetic
chain
 Carotid sheath with contents
 Lymph nodes: deep cervical lymph nodes situated along
internal jugular vein, the jugulo-digastric node, jugulo-
omohyoid node

159.  Boundaries:
 Anteriorly: anterior median line of the neck from the
hyoid bone to the sternum.
 Postero-superiorly: superior belly of omohyoid
 Postero-inferiorly: anterior border of the
sternocleidomastoid.
 Contents: infra-hyoid muscles – sternohyoid,
sternothyroid, thyrohyoid, omohyoid.

160.  BOUNDARIES
 Anteriorly by the posterior edge of
sternocleidomastoid
 Posteriorly by the anterior edge of trapezius
 Inferiorly by the middle third of the clavicle
 Apex is between the attachments of
sternocleidomastoid and trapezius
 Roof of the posterior triangle is formed by the
investing layer of the deep cervical fascia.
 Floor of the triangle is formed by the prevertebral
fascia overlying splenius capitis, levator scapulae and
the scalene muscles.

161.  The posterior triangle is divided into two by
the omohyoid muscle (Inferior Belly)
 Occipital triangle
 Subclavian triangle.

163.  Boundaries:
 Anteriorly – SCM
 Posteriorly – Trapezius
 Inferiorly – lower belly of Omohyoid
 Floor: splenius capitis, levator scapuale and Scaleni
medius and posterior.
 Roof: formed by cutaneous nerves of cervical plexus
and the external jugular vein and platysma muscle,
deep fascia , superficial fascia and by skin.

164.  Boundaries:
 Superiorly – Inferior belly of Omohyoid
 Inferiorly – Clavicle
 Anteriorly (base) – Posterior border of SCM
 Floor: formed by the first rib with the first digitation of
the serratus anterior.
 Roof: formed by the integument, superficial and deep
fasciae and the Platysma and crossed by
Supraclavicular nerves

166. • CONTENTS
• Fat
• Lymph nodes (level V)
• Spinal accessory nerve
• Cutaneous branches of the cervical plexus
• Inferior belly of omohyoid
• Branches of the thyrocervical trunk (transverse cervical and
suprascapular arteries)
• The third part of the subclavian artery, and the external
jugular vein.

167.  The external jugular vein lies deep to the platysma. As it
pierces the fascia ( investing layer of deep cervical fascia)
the margins of the vein gets adherent to the fascia. So if the
vein gets cut, it cannot close and air is sucked in due to
negative intra-thoracic pressure causing air embolism. To
prevent this the deep fascia has to be cut.
 External jugular vein can be marked by joining the points-
 Point below and behind the angle of the mandible
 Point on the clavicle, just lateral to the posterior border of the
SCM.
 The spinal accessory nerve emerges above the middle of the
posterior border of the SCM. It runs through a tunnel in
the fascia forming the roof of the triangle. It passes
downwards and laterally and disappears under the anterior
border of the trapezius about 5cm above the clavicle.

168.  The most common swelling in the posterior triangle is
due to enalargement of supraclavicular lymph nodes.
It could also be due to lipoma cystic hygroma or
lymphangioma, pharyngeal pouch or a cervical rib

169.  B.D Chaurasia’s Human Anatomy
 Sicher and Dubrul’s Oral Anatomy
 Anatomy of Human Body- Henry Gray’s
 Cunningham’s Manual of Practical Anatomy
 Grant’s Atlas of Anatomy
 Netters Head and Neck Anatomy
 Textbook of Head and Neck Anatomy – Hiatt Garner
 Development of musculoskeletal system - Human
developmental anatomy; Kurt E Johnson
 Human Embryology- Inderbir Singh
 Human anatomy- Kent. M Van De Graaff
 Pathology Basis of Disease – Robins and Cotran
 Last’s Anatomy

170.  Essentials of Medical Physiology- Shambuligam
 Medical Physiology – Ganong
 Anatomy of clefts - David Ross Dickinson
 Correction of skeletal defects in secondary cleft lip and
Palate deformities – Kenneth E Salyer et.al
 Clarification of Erb’s point as an anatomic landmark in
the posterior cervical triangle, Landers et.al
 Clinical anatomy 2:29-134(1989); Variations in the
facial muscles at the angle of the mouth – Kazuyuki
Shimada and Raymond F. Gasser
 Rogers c, Meara J, Mulliken J (2014) The philtrum in
cleft lip. J craniofac Surg 25(1):9-13