The skeletal system includes all of the bones and joints in the body. Each bone is a complex living organ that is made up of many cells, protein fibers, and minerals. The skeleton acts as a scaffold by providing support and protection for the soft tissues that make up the rest of the body. The skeletal system also provides attachment points for muscles to allow movements at the joints. New blood cells are produced by the red bone marrow inside of our bones.

1. SKELETAL SYSTEM
Prof. Amol B Deore
MVP’s Institute of Pharmaceutical Sciences,
Nashik (India)

2. • The framework of joined bones and cartilage that
protect internal organs and allow movements is called
as the skeleton.
• The skeletal system consists of bones and other
structures that make up the joints of the skeleton.
Bone is a strong and durable type of connective
tissue.
• It consists of mineral salts like calcium carbonate and
calcium phosphate embedded in the matrix of the
bone tissue. Almost 300 bones are to be present in
human at birth but they become 206 in adults.
Osteology is the study of bone structure and
treatment of bone disorders.

4. FUNCTIONS OF THE SKELETAL SYSTEM
1.Support: Skeletal system provides a boney framework for
the body by supporting soft tissue and providing point of
attachment for many skeletal muscles.
2.Protection: It protects vital and delicate internal organs of
the body from injury. For example cranial bones protect the
brain; thoracic cage protects the heart and lungs.
3.Assists in movement: Skeletal muscles attached to the
bones. When muscle contact, they pull on bones and
together they produce movement.

5. 4. Blood cell production: bones consist of specialized
cells called as red bone marrow, which produce RBCs,
WBCs and platelets. This process is called as
hematopoiesis.
5. Mineral reservoir: It acts as temporary reservoir for
minerals, especially phosphorous and calcium, and fats
which are important in muscle contraction and other
functions.

6. 6. Storage of energy: Fats and lipids stored in yellow
bone marrow cells which act as chemical energy reserve.
7. Criminology: Skeletal system helps in Criminology
for sex determination of victim based on shape of pelvic
girdle; it also helps to examine the cause of death if by
blunt force, stubbing, hit by objects or weapons, or by
hammering on skull.

7. BONE TISSUE
• Bone cells are called osteocytes, and the matrix of bone is made of
calcium salts and collagen. The calcium salts are calcium carbonate
and calcium phosphate, which give bone the strength required to
perform its supportive and protective functions.

8. DIVISIONS OF THE SKELETON
• The axial skeleton part consists of the bones which lie around the
axis; skull (including the cranial and facial, the hyoid bone), the
vertebrae, the ribs, and the sternum.
• The appendicular skeleton part consists of the bones of the upper
extremities or arms (including bones of the shoulder girdle) and the
bones of the lower extremities or legs (including the bones of the
pelvic girdle).

9. AXIAL SKELETON
SKULL
The skull is rest on the upper end of the vertebral column. The skull consists of
two sets of bones: cranial bones and facial bones.
The cranium is formed by number of flat and irregular shaped bones that
provide a bony protection to the brain and special sense organs like the brain,
eyes and ears. Muscles for chewing and muscles for head movement attach to
certain cranial bones. The bones of cranium are
• 1 Frontal bone
• 2 Parietal bone
• 2 Temporal bone
• 1 Occipital bone
• 1 Sphenoid bone
• 1 Ethmoid bone

11. • Frontal bone is the bone of forehead. It forms part of orbital cavities
(eye sockets) and prominent ridges above the eyes.
• Two Parietal bone these bones form the sides and roof of the skull.
They joined to each other at the sagittal suture.
• The two temporal bones help form the lower sides and base of the
cranium. Each temporal bone encloses an ear and consists of a fossa
for articulation with the lower jaw or mandible. The temporal bones
are irregular in shape. Projecting from its lower part is the zygomatic
process that forms the lateral part of the cheek bone.

12. • The occipital bone is a single bone that forms the back and base of the
cranium. The inferior portion of this bone consists of a large opening called
the foramen magnum through which the spinal cord connects with the
brain. On each lower side of the occipital bone is a process called the
occipital condyle. This occipital condyle articulates with the first cervical
vertebra (atlas), thus allowing the head to connect with and rest onthe
vertebrae.
• The single sphenoid bone forms the anterior portion of the base of the
cranium. It acts as an anchor binding all of the cranial bones together.
• The single ethmoid bone is the principle supporting structure of the nasal
cavities and helps form part of the orbits.

13. SUTURES
• Suture is an immovable (fixed) joint that found only between skull bones.
• Coronal suture: The coronal suture is found where the frontal bone joins the
two parietal bones.
• Sagittal suture: The two parietal bones form the upper sides and roof of the
cranium. They are joined at the sagittal suture in the midline.
• Lambdoid suture: The occipital bone is a single bone that forms the back and
base of the cranium and joins the parietal bones superiorly at the lambdoid
suture.
• Frontal suture: The frontal suture is a fibrous joint that divides the two halves
of the frontal bone of the skull in infants and children.
•

15. FACIAL BONES
• Like the bones of the cranium,
the facial bones are also
united by immovable sutures,
with one exception: the lower
jaw bone (or mandible).
• This bone is capable of
movement in a number of
directions. It can be elevated
and depressed as in talking
and it can protract and retract
and move from side to side as
in chewing.

16. • The two nasal bones are thin and delicate bones that join in a suture to
form the bridge of the nose.
• The two maxillary bones make up the upper jaw.The maxillary bones stand
the teeth of the upper jaw.
• The single mandible bone develops in two parts. It is the strongest and
longest bone of the face. It consists of a U-shaped body to bear the teeth of
the lower jaw. It allows the wide range of movement of the lower jaw bone.
• The two lacrimal bones make up part of the orbit at the inner angle of the
eye. These very small and thin bones lie directly behind the frontal process
of the maxilla. Their lateral surface has a lacrimal sac or tear sac.
• The two nasal bones are very thin and fragile. They help form a series of
shelves in the nasal cavity where air is moistened, warmed, and filtered.
• The single vomer bone is a flat bone that makes up the lower posterior
portion of the nasal septum.
• The hyoid bone is like a horseshoe shaped acts as a support for the tongue
and its associated muscles. It also helps elevate the larynx during swallowing
and speech.

17. TRUNK
• The sternum, ribs, and vertebral column make up the trunk (or
backbone) of the axial skeleton. The vertebral column is composed of
a series of bones called vertebrae. Its length is about 71 cm in adult
male and 61 cm in adult female.
• The vertebrae are rigid and provide support for the body but the
intervertebral discs between the vertebrae allow for a high degree of
flexibility. The discs and vertebrae protect the delicate spinal cord.
The vertebral column is formed from a series of 33 vertebrae,
separated and cushioned by the intervertebral discs.

19. Typical Vertebra
• Body is the thick, disc shape anterior portion which is the weight bearing part of a
vertebra. Superior and inferior surfaces are rough for the attachment of
intervertebral discs.
• Vertebral foramen is the space between vertebral arch and body. The spinal cord
passes through the vertebral foramen. The vertebral foramina of all vertebrae
together form the vertebral canal.
• Spinous process (spine) projects posteriorly and inferiorly from the laminae.
• Two transverse processes extend laterally on each side.
• Two superior articular processes articulate with vertebra superior to them.
• Facets are the articulating surfaces of the articular processes.

22. Types of vertebrae
Types of Vertebrae
a) Cervical vertebrae (7) neck
b) Thoracic vertebrae (12) upper back
c) Lumbar vertebrae (5) middle back Total 33 vertebrae
d) Sacral vertebrae (5) lower back
e) Coccyx vertebrae (4) tail bone

23. • Cervical vertebrae (C1-C7)
• The cervical vertebrae are the smallest vertebrae. The first two have been
given special names.
• Atlas (C1): The first is called the atlas; it supports the head by articulation
with the condyles of the occipital bone.
• Axis (C2): The second vertebra is the axis; it acts as the pivot on which
the atlas and head rotate.
• Thoracic vertebrae (T1-T12)
• The thoracic vertebrae have two distinguishing characteristics: the long
spinous process pointing downward and six facets, three on each side
forarticulation with a rib.
• Lumbar vertebrae (L1-L5)
• The lumbar vertebrae are the largest and the strongest. They are
modified for theattachment of the powerful back muscles.

24. • Sacrum (S1-S5)
• It consists of five vertebras fused
to form a triangular and slightly
curved bone. The vertebral
foramina are present for the
passage of spinal nerves.
• Coccyx (Co1-Co4, tail bone)
• The curving coccyx can move
slightly to increase the size of the
birth canal during delivery in the
female.

25. Functions of vertebral column
1)The vertebral column is a strong, flexible rod that bends anteriorly, posteriorly,
laterally and rotates.
2)It forms the axis of the trunk, giving attachments to the ribs, shoulder girdle, upper
limbs, pelvic girdle and lower limbs.
3)The vertebral foramina of vertebral column provide bony protection for the spinal
cord and support the body.
4)It supports the skull.
5)Transverse foramina on both sides of vertebras provide opening for spinal nerves
and blood vessels.
6)The intervertebral discs act as cushion and shock absorber. Thus protecting the
brain.
7)It permits number of body movements.

26. THORAX
The term thorax refers to the entire chest. The skeletal portion of the
thorax is a bony cage formed by the sternum, costal cartilage, ribs and
the bodies of thoracic vertebrae.
Functions of the Thorax
• This bony cage encloses and protects the heart and lungs.
• It also supports the bones of the shoulder girdle and the bones of the
upper extremities.
• It produces blood cells. This process is called hematopoiesis and
occurs chiefly in red bone marrow.

28. Sternum
The sternum is a flat bone just under the skin in the middle front of
chest. Sternum consists of red bone marrow which is the most
common site for withdrawal of sample in bone marrow biopsy.
It develops in three parts: the manubrium, the gladiolus, and the
xiphoid process. No ribs are attached to the xiphoid but it provides
attachment for some abdominal muscles.
The manubrium and gladiolus have notches on each side for
attachment of the first seven costal cartilages. The manubrium
articulates with the clavicle to form sternoclavicular joint.

29. THORACIC RIBS (12 PAIRS OF RIBS)
Twelve pairs of ribs make up the sides of the thoracic cavity. Each rib articulates
anteriorly with sternum and posteriorly with its corresponding thoracic
vertebra.
• True ribs (1st to 7th)
• The upper seven pairs articulate directly with the sternum by costal
fibrocartilage, they are called true ribs.
• False ribs (8, 9,10th)
• The lower three pairs are called false ribs. The costal cartilages of the eighth,
ninth, and tenth rib pairs are attached to the cartilage of the seventh rib so
they join the sternum only indirectly.
• Floating Ribs (11 and12th)
• Because the 11th and 12th pairs of ribs have no cartilage and do not attach at
all anteriorly to sternum. Hence these “false” ribs have another name, floating
ribs. Of course, all ribs attach posteriorly to the thoracic vertebrae.

30. APPENDICULAR SKELETON
BONES OF UPPER EXTREMITIES (UPPER LIMB)
The bones of the upper extremities include the bones of the shoulder
girdle (pectoral girdle), the arm, the forearm, the wrist, the hand, and
the fingers. The bones of the pectoral girdle (shoulder girdle) are the
scapula and the clavicle.

31. SCAPULA
The scapula or shoulder blade is a large,
flat, triangular shaped bone located on the
dorsal portion of the thorax, covering the
area from the second to the seventh ribs.
Acromion process of the scapula articulates
with clavicle. Two other prominent bony
projections on the scapula are the coracoids
process, which functions as an attachment
for muscles that move the arm, and the
glenoid cavity which receives the head of
the humerus and helps form the shoulder
joint.

32. Clavicle
The clavicle or collarbone is a long slim
bone located at the root of the neck just
below the skin and anterior to the first
rib. Clavicle is long ‘S’ shaped bone with
double curves, one convex and one
concave.
The medial end of the clavicle is rounded
and articulates with sternum to form
sternoclavicular joint. The lateral end
articulates with acromion cavity of
scapula called as acromioclavicular
joint.

33. Humerus
The humerus (arm bone) is the largest and longest bone of the upper arm.
The rounded head of the humerus articulates with the glenoid cavity of the
scapula to form shoulder joint (type of ball and socket joint). The head also
consists of two projections of bone, greater and lesser tubercles for
attachment of skeletal muscles.
The distal end of humerus consists of capitulum cavity which articulates with
the head of the radius. The trochlea is located medial to the capitulum
which is a pulley like surface that articulates with the ulna.
The coronoid fossa is anterior depression that receives part if ulna when the
forearm is flexed. Olecranon fossa is a posterior depression that receives the
olecranon of the ulna when the forearm is extended.

35. ULNA
The ulna is the longer, medial bone (little finger side) of the forearm
and is longer than the radius. Its shaft is triangular and the distal or
lower end is called the head. At its proximal end of the ulna is the
olecranon process (or elbow). The coronoid process is an anterior
projection that together with the olecranon receives the trochlea of
the radius. A styloid process is on the posterior side of the distal end.
Radius and ulna articulate with humerus at elbow joint.

37. RADIUS
The radius is the shorter, lateral bone (thumb side) of the forearm. The
proximal end of the radius has a head that articulates with the
capitulum of the humerus and radial notch of ulna. The styloid process
of the radius articulates with some of the bones of the wrist. Radius
and ulna articulate with carpals at wrist joint.

38. Carpals
They are also known as wrist Bones.
The carpals consist of eight small bones
joined to one another by ligaments.
They are arranged in two rows, with
four bones in each row.
In the proximal row from medial to
lateral they are the pisiform, triquetral,
scaphoid, hamate, capitates, lunate,
trapezoid, and the trapezium.

39. METACARPALS (5) & PHALANGES (14)
• The palm of the hand is made up of the five metacarpal bones. Each
metacarpal bone consists of proximal base, intermediate shaft and
distal end. The bases articulate with distal row of the carpal bones.
The head articulates with the proximal phalanges of each finger. Each
finger, except the thumb, has three phalanges but the thumb has only
two phalanges.

40. BONES OF LOWER EXTREMITIES
(LOWER LIMB)
The bones of the lower extremities include the pelvic girdle, which
supports the trunk and provides attachment for the legs. It consists of
the paired hip bones, the lower extremity include the thigh bone
(femur), the kneecap, the tibia, the fibula, the ankle bones, the foot,
and the toes.

41. PELVIC GIRDLE

42. • The pelvic girdle is actually made up of two hip bones that articulate
with one another anteriorly at the pubic symphysis. The pelvic girdle
provides a strong and stable support for the lower extremities on
which the weight of the body is carried. The hip bones are united to
form pubic symphysis. Posteriorly they articulate with the sacrum.

43. Each hip bone consists of three fused bones-
ileum, ischium and pubis.
• Ilium: The ilium is the uppermost and largest portion of a hipbone. It
forms the expanded prominence of the iliac crest. It is wider and
broader in females and smaller and narrower in males. The spines act
as point of attachment to the skeletal muscles.

44. • Pubis: The pubis is superior and slightly anterior to the ischium. The
anterior border of the pubis is called as pubic crest and its lateral end
is a projection called as pubic tubercle. Between the pubis and the
ischium is the large obturator foramen.
• This is the largest foramen in the body and allows for the passage of
nerves, blood vessels, and tendons. On the lateral side of the hip just
above the obturator foramen is the deep socket called the
acetabulum cavity.
• All three parts of the pelvic bone meet and unite in this acetabulum
cavity socket. It also receives the head of the femur to help form the
hip joint. Together with sacrum and coccyx, the two hip bones of the
pelvic girdle form the basin like structure called the pelvis.

45. • Ischium: The ischium is the strongest portion of a hipbone and is
directed slightly posteriorly. It has the rounded and thick ischial
tuberosity, which you sit on, and it bears the weight of the body in
the sitting position.

47. Differentiate between male and female pelvic girdle
Key Points Pelvic girdle
in male
Pelvic girdle
in female
1. Greater pelvis Deep Shallow
1. Pelvic brim Heart shaped Oval shaped
1. Pubic arch Less than 90° angle Greater than 90°
angle
1. Ilium More vertical Less vertical
1. Iliac crest More curved Less curved
1. Acetabulum Large Small
1. Obturator
foramen
Round Oval

48. FEMUR
The femur (or thigh bone), is the largest, longest, strongest and
heaviest bone of the body. Its upper end consists of a large head that
articulates with the acetabulum cavity of the pelvic bone to form Hip
joint.
The greater trochanter and lesser trochanter are projections that serve
as point of attachment for some of thigh and buttock muscles. Its
lower portion is widened into a large lateral condyle and medial
condyle. It articulates with the tibia. A depressed area between the
condyles on the posterior surface is called as intercondylar fossa. The
patella is located between the condyles on the anterior surface.

50. PATELLA
The patella is also known as knee cap. It is flat and triangular lying
right in front of the knee joint and is enveloped within the tendon of
the quadriceps femoris muscle. Its posterior surface contains two
articular facets, which articulates with medial condyle and lateral
condyle of the femur bone. Patella is a movable bone and it increases
the force of the muscles that straighten out the knee.

51. TIBIA
Tibia is also known as shin bone.
It is larger, medial bone of the
leg. It bears the weight of the
body. The tibia is the larger of the
two bones forming the lower leg.
The rounded condyles of the
femur articulate with the
proximal end of the tibia to form
knee joint. The tibial tuberocity
on the anterior surface is a point
of attachment for patellar
ligament. The lower end of tibia
forms the Ankle joint with tarsal.

52. FIBULA
It is the slim bone of the body. It lies
parallel with and on the lateral side
of the tibia. It is considerably smaller
than tibia.
It does not articulate with the femur
but attaches to the proximal end of
the tibia via its head. The distal end
articulates with the talus bone of the
ankle.

53. TARSAL BONES (7)

54. • The bones of the ankle are known as the tarsal bones. The seven
short tarsal bones similar to the carpal bones of the wrist but are
larger. The tarsal bones of the hindfoot are the calcaneum (heel
bone/the talus/ankle bone), the navicular and the cuboid, medial,
intermediate, and cuneiforms. Talus is the largest and the most
superior bone of the tarsal bones which articulate with tibia and
fibula. During walking, the talus bears the entire weight of the body.

55. • METATARSALS (5)
• The rest of the forefoot bones are the metatarsals and phalanges.
There are five metatarsal bones in the forefoot. Each is classified as a
long bone based on shape and each has a base, shaft, and a head.
The metatarsals articulate proximally with cuneiform and cuboid
bones, distal ends articulate with proximal row of phalanges. The first
metatarsal is thicker than the others because it bears more weight.
• PHALANGES (14)
• They have the same arrangement as the phalanges of the fingers of
hand. Each phalange consists of a proximal base, an intermediate
shaft and a distal end. There are two phalanges in the great toe, a
proximal and distal. The proximal one is large due to its weight-
bearing function when walking.

56. ARTICULATION (JOINT)
• An articulation is a point of union or junction between two or more bones,
regardless of the degree of movement allowed by this union.
Types of joints
• Fibrous Joints (Immovable Joints)
• These immovable joints have fibrous tissue between the bones. Theseare
joints or unions between bones that do not allow movement i.e. fixed joint.
• Ex. Joint between the bones of the skull (coronal suture, lamboidal
suture), joint between teeth and maxilla-mandible
• Cartilaginous joints (slightly movable joints)
• There is a pad of fibrocartilage between the ends of the bones that form
the joint which allow very slight movement.
• Ex. pubic symphysis, joint between the vertebral bodies

57. • Synovial Joints (freely movable joints)
• Synovial joint have characteristic features that allow a wide range of
movements. They are classified according to the range of movement
possible or to the shape of the articulating parts of the bone involved.
• Ball and socket joint: In this type of joint a ball-shaped head of one
bone articulates with a concave socket of another bone. It allows a
wide range of movements.
• Ex. Hip joint and shoulder joint
• Hinge joint: is structured in such a way that a convex surface
of one bone fits into a concave surface of another bone.
• Ex. Elbow joint, Ankle joint, Knee joint, joint between the atlas and the
occipital bone, interphalangeal joints of the fingers and toes

58. • Gliding joint: In this type of joint, articular surfaces
glide over each other.
• Ex. Sternoclavicular joint, acromioclavicular joint, intercarpal joints and
intertarsal joints
• Pivot joint: Pivot joint permits movement in a single plane around
one axis (rotation). The rounded end of one bone articulates with
depression in other bone. Ex. Joint between atlas vertebra and axis
vertebra, joint between radius and ulna
• Condyloid joint: Movement is possible in two planes at right angles
to each other. Movements permitted by saddle joint are side-to-side
and back and forth. Ex. Wrist joint
• Saddle joint: In a saddle joint, movement is possible in two planes
(biaxial) at right angles to each other. Movements permitted by
saddle joint are side-to-side and back and forth.
• Ex. Joint between carpals and metacarpals of the thumb

59. DISORDERS OF BONES
• Osteoarthritis
Osteoarthritis is a degenerative
disorder of weight bearing joints,
resulting from aging, irritation,
bear, rubbing and abrasion of
joints. It is characterized by
degeneration of articular cartilage
of joints. Hence the joints
become stiff, swollen and
extremely painful. Osteoarthritis
affects the larger joints (knees,
hips) and is due to wear and tear.

60. Rheumatoid arthritis
• Rheumatoid arthritis is chronic
inflammatory disease in which immune
system attacks on cartilage and synovial
membrane of the joints. Arthritis is
characterized by antigen/antibody complex
leading to inflammation of joints, swelling,
deformity, pain and loss of functioning of
bones. The joints most commonly affected
are those of the hands, feet, wrist, fingers
and knee. It is most commonly in female
than males usually develop between ages
of 35 to 55 years.

61. Osteoporosis
• Osteoporosis is a disease
characterized by bone fragility
(weakness) and decreased bone
density due to loss of bone minerals
like calcium, phosphorous and
proteins. In fact, the matrix becomes
deficient in its fiber and minerals.
Toxins such as tobacco, alcohol, soft
drinks, certain medications like
antacids, steroids may be deposited in
the bones to cause osteoporosis.

62. Gouty arthritis (gout)
• Gout is characterized by deposition
of excessive amount of uric acid
crystals in cartilages of joints and in
kidney nephrons. The base of the
large toe and other joints of the
feet and legs most commonly
affected. Sodium urate salt crystals
cause inflammation to cartilages
leading to irritation and swelling of
joint and restricted body
movements. It is more common in
men than in women.

63. • Thanking you