The document summarizes the division of the skeletal system into the axial and appendicular skeleton. The axial skeleton consists of 80 bones including the skull, vertebral column, ribs, and sternum. It forms the vertical axis of the body. The appendicular skeleton has 126 bones and includes the limbs and their attachments via girdles. The skull is made up of 28 cranial bones including the frontal, parietal, temporal, occipital, ethmoid, and sphenoid bones, as well as 14 facial bones such as the maxilla, zygomatic, and mandible.

1. Division of Skeletal System
Tanveer Saeed
Assistant Professor
AKU-SONAM

2. TANVEER SAEED
Division of Skeleton
206 BONES: These bones can be grouped
in two divisions:
1. Axial Skeleton
2. Appendicular Skeleton

3. Division of Skeleton
• The 80 bones of the axial
skeleton form the vertical
axis of the body.
They include the bones of
the:
• head
• vertebral column
• ribs
• breastbone or sternum.
• The appendicular
skeleton consists of 126
bones and includes the:
• Free appendages and
their attachments to the
axial skeleton.
• The free appendages are
the upper and lower
extremities, or limbs, and
their attachments which
are called girdles.

4. Axial Skeleton (80 bones)
• Skull (28) consists of
8 cranial and 14 facial
bones.
1. Cranium
• Frontal (1)
• Parietal (2)
• Temporal (2)
• Occipital (1)
• Ethmoid (1)
• Sphenoid (1)
2. Facial Bones 14
• (Maxilla (1) ( originated
as 2)
• Zygomatic (2)
• Mandible (1) (originated
as 2)
• Nasal (2)
• Palatine (2)
• Inferior nasal
conchae (2)
• Lacrimal (2)
• Vomer (1)

5. Axial Skeleton Cont’d
• Auditory Ossicles (6 bones)
• Malleus (2)
• Incus (2)
• Stapes (2)
• Hyoid (1)
Total skull bones = 29
Hyoid bone

6. Skull (Cranial Bones)

7. Skull

8. Frontal and Parietal Bones
• Located anteriorly, forms part of orbital
roof, and anterior portion of cranial floor.
• Supraorbital margin – Arched ridge just
below eyebrows, forms superior edge of
orbits.
• Supraorbital foramina – in supraorbital
margin slightly medial to midpoint,
transmits nerve and blood vessels.
• Parietal Bones
• Superior lateral portion of cranium.

9. Frontal Bone

10. Occipital Bone
• Forms posterior wall and
floor of cranium.
• Foramen Magnum –
large passageway for
spinal cord exit from
cranium.
• Occipital Condyles –
located lateral to
foramen magnum
articulates with atlas
(C1).
• External Occipital
Protuberance –
prominent projection on
posterior surface.

11. Occipital Bone

12. Temporal Bone
Divided into four parts:
• Zygomatic process – projection that articulates
with zygomatic bone.
• Mastoid process – protuberance inferior and
posterior to ear, muscle attachment. Styloid
process – slender spike of bone extending
inferior and anteriorly.
• Squamous part - thin fan shaped part that
articulates with the parietal bone.
• Petrous portion- forms part of the base of the
skull and contains organ of hearing.

13. Temporal Bone

14. Sphenoid Bone
• Keystone of cranial floor.
• Resembles bat wings, lies deep and slightly
superior to nose and throat, forms parts of orbital
wall floor and posterior.
• Greater wings – lateral projection from body,
forms lateral wall of orbit.
• Lesser wings – superior portion of sphenoid
body, forms posterior orbital wall.
• Sella turcica –saddle shaped depression on
superior surface of body, contains Pituitary gland
(Hypophyseal gland).

15. Sphenoid Bone

16. • Ethmoid Bone

17. Ethmoid
• Irregular bone that makes up the anterior portion
of cranial wall, medial wall of orbits, upper parts
of nasal septum, lateral nasal roof.
• Perpendicular plate – forms upper part of nasal
septum.
• Nasal Conchae – Upper and middle conchae
or turbinated processes.
• Horizontal (cribriform) plate – passage of
olfactory nerves through multiple openings.

18. Facial Bones
Zygomatics
• Cheekbone, forms part of anterior and lateral surface of orbit.
• Temporal process – articulates with zygomatic process of temporal
bone.
Lacrimals
• Posterior and lateral to nasal bones in median wall of orbits, forms
lateral of nasal cavity.
Palatines
• Posterior portion of hard palate, inferior and lateral surface of nasal
cavity, inferior surface of orbit.
Nasal bones
• Superior portion of nasal cavity.
Vomer
• Inferior and posterior nasal septum.
Inferior Nasal Conchae
• Turbinated bones forms posterior of nasal cavity.

19. Tympanic region
of temporal bone

20. Maxillae or Upper Jaw
• Upper jaw bones, part of floor of orbit,
anterior portion of roof of mouth and floor
of nose and part of lateral walls of nasal
cavity.
• Alveolar ridge or process-- carries teeth.
• Maxillary Sinus--- on each side lined with
ciliated mucous membrane.

21. Mandible or Lower Jaw
• Movable bone of the skull.
• Rami (ramus)
• Condyloid process – part of
each ramus that articulates
with mandibular fossa of
temporal bone forming
temporomandibular joint.
• Coronoid process--- gives
attachment to muscles and
ligaments.

23. Paranasal Sinuses
• Spaces or cavities in bone those
associated with nasal cavity called
paranasal sinuses and includes:
• frontal, sphenoidal, ethmoidal, and
maxillary.
• Function – Humidify, warm and filter
inspired air through nasal cavity.

24. Paranasal Sinuses

25. Fontanels
• “Soft spots” where ossification is incomplete at
birth, allows some compression of cranium at
birth to pass through the birth canal.
• Frontal (anterior) –intersection of sagittal and
coronal sutures, diamond shaped largest
fontanel.
• When does it closes?
• Occipital (posterior) – intersection of sagittal
and lambdoidal sutures.
• When does it closes?

26. Fontanelles

27. Sutures
• Sutures are immovable joints between cranial
bones.
• Sagittal – between parietal bones.
• Squamous – between temporal and parietal
bones.
• Coronal (frontal) – between frontal and parietal
bones.
• Lambdoidal – between parietal and occipital.

29. Thank You
Practice