Skeletal System-Axial Skeleton
Skull and Face
Axial Skeleton
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Forms longitudinal axis of body
Face and skull
Bony Thorax (chest)
Skull
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Cranium bones
Facial Bones
Cranium
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Composed of eight flat bones
All are single except for two:
and
Frontal
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Forehead bone
Supraorbital margin
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Supraorbital foramen
Glabella
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External auditory meatus
Styloid process
Parietal
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Forms top sides of cranial cavity
Temporal
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Forms lower sides of cranial cavity
Mastoid process
Occipital
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Forms posterior part of cranium
Foramen magnum- where spinal cord enters skull
Sphenoid
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Butterfly shaped bone
Spans width of skull and forms floor of cranial cavity
Contains sella turcica, aka Turks saddle which holds pituitary gland in place
Ethmoid
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Lies anterior to sphenoid
Forms roof of nasal cavity and medial walls of orbits
Contains crista galli- process
Fontanels
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Skull is unfinished at birth
Fontanels are areas where hyaline cartilage hasn’t undergone ossification in skull
These are called “soft spots” at birth
Anterior fontanel (largest), closes at 18 months
 Posterior fontanel (2nd largest), 2 months
Mastoid fontanel, begins closure at 1 month
after birth, not complete until age 1
 Sphenoid- closes by 3 months
Sutures
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Interlocking, immovable joints that hold all but one of facial bones together
Saggital suture- separates parietal bones
 Squamous- temporal and parietal
Lamboidal suture- occipital and parietal
 Coronal-parietal and frontal
Bones of the face
 14 bones
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All but 2 are paired
Inferior Nasal Conchae
 Bone that forms shelf along inner surface of sidewall of nasal cavity
 Serves to filter air and then bring it to body temp
Palantine
 L shaped
Nasal
 Forms bridge of nose
Maxilla
 Articulates with every bone of face
except mandible
Zygomatic
 Cheek bone
Mandible
 Largest and strongest bone of face
 Only moveable bone of face
Lacrimal
 Smallest bone of face
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Forms posterior part of hard palate
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If palantine process and maxilla don’t
unit before birth, cleft palate will result
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Mental foramen- site of anesthetic
administered by dentist
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Resembles shape and size of fingernail,
helps form sidewall of nasal cavity
Vomer
 Dagger like bone that forms the interior and posterior parts of nasal septum
Bones of the ear
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Two sets of 3 bones (one set/ear)
Malleus (hammer)
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Incus (anvil)
Stapes (stirrup)
In summary
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Total # of bones of skull
 8 cranial bones
 14 facial bones
 6 ear bones
Bones that form the orbit
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Ethmoid
Lacrimal
Maxillary
Frontal
Sphenoid
Zygomatic
Palentine