The skeleton provides structure and protection for the body. It is divided into the axial skeleton, which includes the skull, vertebral column, ribs, and sternum, and the appendicular skeleton, which includes the bones of the upper and lower limbs. The skull has 22 bones that form the cranium and face. The vertebral column consists of 33 vertebrae including 7 cervical, 12 thoracic, 5 lumbar vertebrae, the sacrum, and coccyx. The rib cage is formed by 12 pairs of ribs and the sternum. The appendicular skeleton includes the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

1. 1-The skeleton constitutes the bony framework
of body.
2-It is inner structure of body and provides
main support and protection.
3-General shape and posture of body is
because of skeleton.

2. Classification
• Axial skeleton
-Consists of bones that lie
around axis of body
-skull bones.
-Hyoid bones
-Thoracic cage
(Ribs and sternum)
-Vertebrae
• Appendicular skeleton
-Consists of bones of upper
and lower extremities
Pectoral girdle & upper limb
Pelvic girdle & lower limb

3. I-SKULL
Total number of bones-22
Skull rests on superior end of the
vertebral column.
Skull-made of 2 types-
a)Cranial bones(8)
b)Facial bones(14)

4. A)The cranial bones
i)Frontal bone(1)
-Forms anterior part of forehead.
-Roof of orbit
Most of anterior part of cranial floor
ii)Parietal bones(2)
-Forms the middle part of skull cap.
iii)Occipetal bone(1)
-Forms posterior part of skull.
-Base of the skull.
iv)Temporal bone(2)
-Forms lacteal part----ear region of skull.
-Part of cranial floor.
v)Ethmoid bone(1)
Forms base of skull,part of orbits.
vi)Sphenoid bone-(1)
-Lies in middle part of base of skull.
-articulates withn all other skeletal bones holding them together

6. B)Facial bones(14)-That forms the face
i)Nasal bones(2)
-Forms the lateral wall of the nos.
-Inferior nasal concha(2)-Forming the lateral wall of nose.
-vomerbone(1) which forms the septum of nose.
-Lacrimal bones(2),forms the medial wall of the orbit.
-Zygomatic bones(2),also referred as the cheek bones.
-Maxillae(2)----Forms upper jaw bone
-Mandible(1)----Forms lower jaw bone
--It is largest and strongest facial bone and only the moving skull bone
Palantine bones(2)
-L shaped and form posterior part of hard palate.
-part of lfoor
-small portion of floor of orbit
-lateral wall of nasal cavity

8. Sutures
Joints between various skull bones are known as
sutures.
They are immovable and fibrous in nature
i)Suture between frontal and 2 parietal bones-
coronal suture.
ii)Suture between 2 parietal bones –
sagittal suture
iii)Suture in between 3to8% of two halves of
frontal bones-metopic suture

9. Paranasal Sinuses
 Hollow portions of bones surrounding
the nasal cavity

10. BONES OF NECK
-Overall eight bones are loacted in neck region
1 hyoid bone
7 cervical vertebrae
 The only bone that
does not articulate with
another bone
 Serves as a moveable
base for the tongue,
and other muscle
attachments

11. VERTEBRAL COLUMN
1-Consists of 24 separate,movale.irregular bones called
vertebrae which are divided into 3 groups—
1-Cervical(7),thoracic(12),lumbar(5),sacrum,coccyx
Consists of 2 basic parts-
• 1-A body
• 2-neural arch
A neural arch of a typical vertebrae possessesfollowingparts
2 pedicle or root
2 lamina
2 transverse process
1 spinous process or spine
4 Articular processes

12. ∙ Vertebrae
separated by
intervertebral discs
made of cartilage
∙ The spine has a
normal S curvature
∙ Each vertebrae is
given a name
according to its
location

14. 1-Body-
Solid,box shaped structure.
Situated anteriorly and possesses slightly concave upper and
lower surfaces.
The intervertebral disc made of fibrocartilage separates body
of the vertebra from upper and lower one.
2-Pedicles-
Each vertebra has two cylinder-shaped projections (pedicles)
of hard bone that stick out from the back part of the vertebral
body, providing side protection for the spinal cord and nerves.
The pedicles also serve as a bridge, joining the front and back
parts of the vertebra.
3-Laminae-
Plates of bone that form the posterior walls of each vertebra,
enclosing the spinal cord

15. 4-The transverse process-
Transverse process is a small bony projection off the
right and left side of each vertebrae.
5-The spine or spinous process-
It is formed at the union of laminae,and project
backwards,but in few parts,downwards.
6-The articular processes-
These are 2 in number and are situated on the upper
and lower surface of each vertebra at the junction of
pedicles and laminae,near the origin of transverse
processes

17. 1-Cervical vertebrae
-They are smallest separate vertebrae with large opening.
-They run down the neck forming a slightly forward curve.
-They have special features-
a)Each transverse process carries an opening through which vertebral artery
passes upwards to the brain.
b)The spinous process gives attachment to muscles and ligaments.

18. Atlas
• First cervical vertebrae is
known as atlas.
• It is large ring with anterior
and posterior arch.Does not
possess body or spine.
-Anterior part-occupied by
odontoid process of axis
which is held in position by
transverse ligament.
-Posterior part-is vertebral
foramen and is occupied by
spinal cord.On its superior
surface,it has 2 facets that
form joints with condyles of
occipetal bone.The nodding
movements of head takes
place at these joints
Axis
• In axis body is absent.
• Contains up-projecting
process called dens,which
articulates with atlas to
form pivot joint.
• Helps in rotating head side-
to-side.

19. Superior view of axis
Superior view of atlas

20. 2-Thoracic vertebrae
• These are larger and stronger as compared to cervical vertebrae.
• 12 in number.
• Articulates with ribs,at surface called facets.
Special featrues-
-Pointed spinous processes are pointed downwards.
-Possess types of articular facets for ribs
i) 2 facets-1 above,1 below
ii) Small facet at tips of transverse process articulate with tubercles of ribs.

21. 3-Lumbar vertebrae
• The largest vertebrae in vertebral column.
• 5 in number.
• Body-is nearly kidney shaped.
• Do not have articulating facets for ribs.
• Aspinous processes-broad,flat and stout,directed backwards.
• Well adapted for attachment of large back muscles.

22. 4-Sacrum/Sacral vertebrae
• These are fused together to form one bone known as sacrum.
• This runs down the back of pelvis forming a backward curve and
upper projecting curve forming the promontory of the sacrum.
• Upper aprt of bas of bone articulates with 5th lumbar vertebrae.
• On each side it articulates with the ilium to form sacroiliac joint.Its
inferior tip,articulates with coccyx.

23. 5-Coccyx
• It is also referred as tail and is triangular.
• On the upper side it articulates with tip of sacrum.

24. The thoracic cage/Bones of thorax
• The skeletal framework of the thorax is
formed by the thoracic vertabrae in the back
side and sternum,costal cartilage and ribs in
front.
• True ribs are directly attached to the sternum
• (first seven pairs)
• Three false ribs are joined to the 7th rib
• Two pairs of floating ribs

25. The sternum
-Also known as breast bone.
-Flat, possess anterior and posterior surface.
-Coastal cartilage of ribs are attached to sternum.
-Composed of 2 plates of compact bone with a layer of
spongy bone in between containing red bone marrow.
PARTS:
a. Manubrium
b. Corpus or body
c. Xiphoid process

26. 1-The manubrium
• Is upper part of sternum.
• Articulates with clavicle at the sternoclavicular joint.
• Intraclavicular notch is located between 2 sternoclavicular
joints.
• The cartilage of first rib joins the sternum ust below the
sternoclavicular joints.
2-The body-
It is the middle portion and known as gladiolus.
It presesnts facets on lateral borders for the attachment of the
ribs.
3-The xiphoid process-
Lower part of sternumCartilage of 7th rib joins at the union of
xiphoid and body.

27. The Ribs
• Ribs forms the thoracic cage which protects delicate organs –lungs
and heart.
• 12 pairs of ribs
• Each rib is flat curved bone having head,neck,tubercle,angle,sternal
end,anterior and posterior surface and superior and inferior border.
• The head articulates with thoracic vertebrae.
• The neck portion is between head and shaft.
• The neck region possess a tubercle and a facet which articulates with
transverse process of vertebrae.
• The shaft is flat and curved.Slightly twisted.
• The maximum curvature part is called angle of rib.
• The anterior end of shaft is attached to costal cartilage.
• The borders of ribs are attached to intercoastal muscle.

28. Classification of ribs:
a. Sternal or true ribs (1st to 7th)
-The upper 7 pairs
- ribs whose costal cartilages are directly
attached to sternum
b. Asternal or false ribs (8th to 12th)
- ribs whose costal cartilages are not
attached directly to the sternum.
-costal cartilage of 8,9,10th rib fuse with the
cartilage immediately above the 11th and 12th
ribs only have one small costal cartilage and
known as floating ribs.

30. Image of sternum Image or Rib

31. II)The appendicular skeleton

32. Classification of bones
• Upper Extremities
(Pectoral girdle/upper limb)
Clavicle -2
Scapula- 2
Humerus -2
Radius- 2
Ulna- 2
Carpals -10
Metacarpals- 10
Phalanges- 20
• Lower exetrimities
(Pelvic girdle/lower limb)
Hip bone-2
Femur-2
Patela-2
Tibia-2
Fibula-2
Tarsals-14
Meattarsals-10
Phalanges-20

33. The Clavicle
• Also known as collar bone.
• Roughly S shaped bone.
• On one end articulates with manubrium of
sternum and on other end forms joint with
‘acromion process’ of scapula.
• This clavicle is the only bony link between the
upper extremity and the axial skeleton.
• It lies close under the skin and is easily felt.
• It keeps the scapula in position

35. The scapula
• Also known as shoulder blade.
• Flat,triangular bone lying on posterior chest wall lying superficial to
the ribs.
• Held in place by muscles which attach it to ribs and vertebral
column.
• Three borders-medial(vertebral),superior(upper),lateral(axillary)
• Three angles-superior,inferior,lateral.
• With meeting of these 3 borders 3 angles are formed
1-The superior angle-formed due to meeting of superior border and
vertebral border.
2-The inferior angle-formed due to meeting of vertebral border and
axillary border
The glenoid cavity is placed at junction of superior border and
axillary border,articulates with head of humerus

36. • The anterior surface of scapula is slightly hollowed or concave
and is referred as subscapular fossa.The subscapularis muscles
are attached here.
• The spine of scapula which is large ridge divides the posterior
slightly convex side of scapula in 2 unequal parts i.e
-the upper and smaller part is called the supraspinous fossa.
-the lower and larger part is called the infraspinous fossa.
-The expanded broad free end of the spine of scapula is called
acromion process and outward process projecting forward from
the superior border is known as coracoid process.

38. 3-Humerus
• Longest and largest bone of upper limb.Also known as Arm bone.
• It extends from shoulder to the elbows.
• The humerus consists of an elongated cylindrical shaft,which possesses
upper and lower extremities.
• The upper extremity of humerus contains head,greater tuberosity and lesser
tuberosity.
• Head-smooth
- structure-hemispherical
- Articulates with-glenoid cavity of scapula forming ball and socket joint.
• The tubercles are divided by a deep groove which is occupied by one of the
tendons of the bicep muscles.
• At the proximal end the shaft is cylindrical in shape but is flattened at its
anterior and posterior surface towards the distal end.
• The distal end of the bone presents two articular surfaces,the capitulum and
trochlea

40. The Radius
• It is the lateral bone of forearm lying on thumb
side.
• It is also a long bone with shaft and upper and
lower extremities.
• The upper extremity is smaller than the lower
and consists of head.
• The head possesses a depression on the top for
articulation with capitulum of the humerus and
circumference of head articulate with radial
notch of ulna.