Download Axial Skeleton

Organization of the
Skeleton
The Human Skeleton
206 bones
 Divided into two portions.
Axial Skeleton- Contains the bones
which are in the mid-vertical axis of the
body.
Appendicular Skeleton- Bones which
are outside the mid-vertical axis,
associated with the appendages.

Axial Skeleton

Skull
 Contains
22 bones.
 Bones of the skull include; (8) cranial, (13) facial
and the (1) mandible.
 Sutures- Connection between the bones of the
skull.
 Sinus-Chamber- Located in the skull, are lined with
mucous membranes, and filled with air.
 Connect with the nasal cavity to drain fluids and
reduce the weight of the skull.
Axial Skeleton

Cranium (8) bones

1.Frontal Bone- Large bone forming
the anterior part of the skull
(forehead).
 Orbits: Eye sockets, partially
formed by the frontal bone.
 Supraorbital Foramen: Hole above
each orbital where blood vessels
pass.
Axial Skeleton

Cranium
 2.Parietial Bone(s)-Two bones which
form most of the superior/lateral
cranium.
 Meet at the top of the skull at the
sagittal suture.
 Meet the frontal bone at the coronal
suture.
Axial Skeleton

Cranium
 3.Occipital Bone- Thick bone which forms the
posterior wall and floor of the cranium.
 Meets the parietal bone at the lambdoid
suture.
 Foramen Magnum- Opening for the spinal
cord.
 Occipital Condyles- Processes that
articulate with the first vertebrae, to allow
head movement.
Axial Skeleton

Cranium
4.Temporal Bone(s)- Two bones on
either side of the cranium, below the
parietal bones.
 Meet the parietal bones at the
squamous suture.
 Styloid Process- Serves as an anchor
for muscles of the tongue and
pharynx.
Axial Skeleton

Cranium
 5. Sphenoid Bone- Butterfly shaped bone
that forms the lower lateral walls and floor of
the cranium, also the posterior walls of the
orbits.
 Optic foramen- Location of the optic nerve
passage.
 6.Ethmoid Bone- Small bone anterior to the
sphenoid bone.
 Forms sections of the cranial floor, orbital
walls, and nasal cavity.
Axial Skeleton
Facial Bones
 Contains 13 immovable bones and a
movable mandible.
1.Maxillary Bone(s)- Two bones on each
side of the face that form the upper jaw.
2.Palatine Bone(s)- Two L-shaped
bones that are posterior to the maxillary
bones.
 Forms posterior roof of mouth and
floor of the nasal cavity.

Axial Skeleton

Facial Bones
3.Zygomatic Bone(s)- Two bones on the
side of the face that form the cheeks.
4.Nasal Bone(s)- Two small rectangular
bones that meet to form the bridge of
the nose.
5.Lacrimal Bone(s)- Two fingernail
shaped bones, form part of the orbits
medial walls.
Axial Skeleton

Facial Bones
 6.Vomer- Single bone along the midline
within the nasal cavity.
 Meets with the ethmoid bone to form the
nasal septum, which divides the nasal
cavity in half.
 7.Inferior Nasal Concha- Two thin scrolllike bones attached to the lateral walls of
the nasal cavity.
 Forms shelves which air is channeled
into the nasal cavity.
Axial Skeleton

Facial bones
8.Mandible-Single lower jaw bone,
articulates with the temporal bones.
 Only movable bone of the skull.
 Forms TMJ (temporal-mandibular
joint)
Lock
Jaw
Dislocated Jaw
Axial Skeleton

Hyoid Bone
Single bone that doesn’t articulate with
any other bones.
Located in the upper neck region.
Horse-shoe shaped
supports the tongue and provides
attachments for muscles.
Axial Skeleton

Vertebral Column
 Strong
flexible rod that supports the trunk,
while allowing for movement.
 Extends from the base of the skull to the
pelvis.
 Comprised of a series of irregular bones
known as vertebrae.
 Between each vertebrae is an intervertebral
disc.
 The adult vertebral column contains 26
vertebrae (after fusion).
Axial Skeleton

Structure of typical vertebra:
 Body:
Thick, disc-shaped front portion,
designed for supporting weight.
 Vertebral Arch: Forms a ring to hold the spinal
cord called the Vertebral Foramen.
 Seven processes arise from this vertebral
arch and serve for either joint formation or
muscle attachment.
Axial Skeleton

Types of Vertebrae and their Structures.
Cervical- (7) Vertebrae of the neck
region, the support the head.
 The lightest of the vertebrae
 Transverse foramen- small hole that
permits the passage of arteries to the
brain.
Axial Skeleton

Types of Vertebrae and their Structures.
 Cervical- (7) Vertebrae of the neck region, the
support the head.
 Atlas- First vertebrae that connects with the
occipital condyles of the cranium.
 Contains no body
 Allows for the up and down movement of the
head
 Axis- Second vertebrae that contains a tooth like
projection called the:
 Odontoid process- It projects up through the
rings of the atlas and allows for twisting of the
head.
Axial Skeleton

Types of Vertebrae and their Structures.
Thoracic- (12) Only vertebrae that
articulate with the ribs. (upper and
middle of the back)
Lumbar- (5) Vertebrae that are larger
and thicker, this is due to the increase in
the body weight stress they support.
(lower back)
Axial Skeleton

Types of Vertebrae and their Structures.
 Sacrum- Large triangular bone that forms the
posterior part of the pelvis.
 (5) vertebrae fused together.
 Sacral Canal: contains the spinal cord.
 Coccyx- A series of 3-5 fused bones that is
attached to the sacrum by ligaments. (tail
bone)
Axial Skeleton

Thoracic Cage
Formed by thoracic vertebrae, sternum,
and the ribs.
Conical, basket-shaped structure
(cone shaped).
Partially encloses the internal structures
of the chest.
Supports the upper limbs.
Axial Skeleton

Thoracic Cage
Sternum- AKA breast bone, It’s a flat,
narrow bone at the center of the chest.
 Articulates
with the clavicles on one end.
 Articulates with the ribs via the costal
cartilage.
 Consists of three (3) parts:
 Manubrium-
Superior part
 Body- Large middle part
 Xiphoid Process- Small pointy inferior end.
Axial Skeleton

Thoracic Cage
 Ribs
(12) sets in every individual.
 Attach to the thoracic vertebrae in the back and the
sternum in the front.
 True Ribs- First seven (7) pair, connects directly to
the sternum via the costal cartilage.
 False Ribs- Remaining five (5) pair, have an
indirect connection or no connection at all to the
sternum.


Floating Ribs- Last two (2) or sometimes three (3) pairs
of ribs, have no connection at all to the sternum.