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Lecture 7

ANAT 1010 Lecture Notes - Lecture 7: External Occipital Protuberance, Sphenoidal Sinus, Mandibular FossaPremium

14 pages26 viewsFall 2018

Department
Anatomy
Course Code
ANAT 1010
Professor
A. Jaffar
Lecture
7

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Lecture 7: Skeletal System Axial Skeleton
Axial Skeleton:
- Composed of 80 bones
- Lies along the longitudinal axis of the body an imaginary vertical line that runs
through the body’s center of gravity from the head to the space between the feet:
the skull bones, auditory ossicles (ear bones), the hyoid bone, ribs, sternum
(breastbone) and the bones of vertebral column.
Appendicular Skeleton:
- Composed of 126 bones
- Upper and lower limbs [“appendages”] + pelvic/pectoral girdles.
o Skull: (22 bones)
The bony framework of the head; rests on the superior end of the vertebral column and
contains two sets of bones:
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Cranial Bones: “cranial cavity – encloses and protects the brain” (8)
- Protects the brain and houses the ear ossicles.
- Muscle attachment for jaw, neck, and facial muscles.
Frontal bone:
- Anterior portion of the cranium, the roofs of orbits (eye sockets), and most of the
anterior part of the cranial floor + frontal sinus.
- In most individuals, the frontal bone is UNPAIRED.
- After birth, the left and right sides of the frontal bone are united by the metopic
suture, which disappears between 6 and 8.
2 Parietal bones:
- The sides and the roof of the cranial cavity.
- Quadrilateral (4-sided) bones
- Each bone articulates with five other bones.
2 Temporal bones:
- Zygomatic process that projects anteriorly from the inferior portion of the temporal
squama forms part of the arch, articulating (forming a joint) with the temporal
process of the zygomatic (cheek) bone.
- External auditory meatus ear canal; directs sound waves into the ear.
- Mastoid Process a rounded projection of the mastoid portion of the temporal
bone posterior and inferior to the external auditory meatus that serves as a point of
attachment for several neck muscles.
- Mandibular fossa (TMJ) the mandibular fossa and the articular tubercle articulate
with the mandible to form TMJ (temporomandibular joint).
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Occipital bone:
- Forming the posterior part and most of the cranium base, it appears as a plate like
bone with somewhat of a triangular shape.
- The foramen magnum (large hole) is in the inferior part of the bone, and within this
foramen, the medulla oblongata (inferior brain part) connects with the spinal cord.
- The occipital condyles (two oval processes with convex surfaces one on either side
of the foramen magnum) articulate with depressions on the first cervical vertebra to
form the atlanto-occipital joints.
- The ligamentum nuchae (large fibrous, elastic ligament) helps support the head,
extends from the external occipital protuberance to the 7th cervical vertebra.
Sphenoid bone:
- The middle portion at the base of the skull; the “keystone” of the cranial floor, as it
articulates with all the other cranial bones, holding them together.
- The shape of the bone (wedge-shaped) resembles a butterfly with outstretched
wings, and the body is the hollowed, cube-like medial portion between the ethmoid
and the occipital bones.
- Includes the sphenoidal sinuses (the hollow of the body of the sphenoid bone),
which drains via a narrow opening into the superior portion of the nasal cavity.
- Sella turcica (bony, saddle-shaped structure on the superior surface of the sphenoid
body) holds the pituitary gland.
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