Skull formed by 2 sets of bones
 Cranium – encloses & protects brain.
 Facial bones – holds eyes in anterior position & allows the
facial muscles to show emotions.
 All but 1 of the bones are joined by sutures (interlocking,
immovable joints)
o Mandible attached by a freely moving joint.
Cranium – 8 large flat bones
 Frontal – forms forehead, brow bone, superior eye orbit
 Parietal (2) – form most of the superior & lateral walls of
the cranium
o Meet in midline = sagittal suture
o Meet frontal = coronal suture
 Temporal (2) – inferior to parietals & join to them at the
squamous sutures
o Important bone markings found here
 External acoustic (auditory) meatus – canal
leading to eardrum
 Styloid process – sharp needle-like projection
inferior to external auditory meatus (attachment
point for many neck muscles
 Zygomatic process – thin bridge of bone that
joins w/ the zygomatic (cheek) bone
 Mastoid process – rough projection posterior &
inferior to the external auditory meatus
 Full of air cavities (sinuses)
 Attachment for some neck muscles
 Close to middle ear & leads to ear infections
 Jugular foramen – junction of occipital &
temporal
 Allows for passage of jugular vein
 Largest vein of the head – drains the brain
 Internal auditory meatus – anterior to jugular
foramen
 Transmits cranial nerves 7 & 8 (facial &
vestibulocochlear)
 Carotid canal - anterior to jugular foramen
 Carotid artery runs through it to brain
 Occipital – most posterior bone of cranium forming back
wall & floor of the skull
o Joins parietals anteriorly at lambdoid suture
o Foramen magnum = large opening in base of the
occipitals (spinal cord connects with the brain)
 Lateral to the foramen magnum are rockerlike
occipital condyles which rest on the 1st vertebra
 Sphenoid – butterfly-shaped – spans the width of the skull
and forms part of cranial cavity floor
o Sella turcica “Turk’s saddle” = small depression on
the midline of the sphenoid, holds the pituitary gland
o Foramen ovale = large oval opening in line w/ the
posterior end of the sella turcica (allows cranial nerve
5 (trigeminal) to pass to chewing muscles of mandible
o Parts of the sphenoid form part of the eye orbits
 2 important openings:
1. Optic canal (optic nerve)
2. Superior orbital fissure (cranial nerves 3, 4
& 6 – eye movements)
o Central part of the sphenoid riddled w/ air cavities =
sphenoid sinuses
 Ethmoid – irregularly shaped, anterior to sphenoid –
forms roof of nasal cavity and medial walls of the orbits.
o Crista galli “cock’s comb” = superior ethmoid surface
projection – outermost brain covering attaches
o Cribriform plates – holey areas on sides of crista
galli= nerve fibers for smell pass through from nose
o Superior & middle nasal conchae – extensions of the
ethmoid – form part of lateral walls of nasal cavity &
increase turbulence of air flowing
Facial Bones
*14 bones
*12 paired, only the mandible and vomer are single
 Maxillae (2) / maxillary bones – fused to form upper jaw
o Upper teeth carried in the alveolar margin
o Palatine processes- extensions that form the anterior
part of the hard palate
o Paranasal Sinuses – drain the nasal passages, lighten
the skull bones, amplify sounds as we speak
 Sinusitis (infection of sinuses) – can result in
headache or upper jaw pain
 Palatine(2) – posterior to palatine processes of maxillae
– form posterior part of hard palate
o cleft palate= failure of these to fuse
 Zygomatic (2) – cheek bones – form portion of lateral
walls of orbits
 Lacrimal (2) – fingernail sized bones forming part of
medial walls of orbits
o Groove serves as passageway for tears
 Nasal (2)– small rectangular bones – form bridge of nose
– lower part of nose made of cartilage
 Vomer “plow”(1) – median line of nasal cavity – forms
most of the nasal septum
 Inferior nasal conchae (2) – thin, curve bones
projecting from lateral walls of the nasal cavity
 Mandible (lower jaw) – largest, strongest bone of the
face – joins temporal bones on each side of face, forming
the only freely movable joints in the skull (find them!)
o Horizontal part (body) forms the chin
o 2 upright bars of bone (rami) extend from the body to
connect the mandible with the temporal bone.
o Lower teeth lie in alveolar margin
Hyoid bone
 Not really part of the skull
 Horseshoe shaped w/ a body and 2 pair of horns (cornua)
 Closely related to mandible and temporal bones
 Unique b/c it’s the only bone that does not articulate w/
any other bone
 Suspended in mid–neck region 2 cm above the larynx,
anchored by ligaments to the styloid processes of the
temporal bones
 Serves as a movable base for the tongue & attachment
point for neck muscles (lower and raise larynx when we
swallow & speak)
Fetal Skull
 Face small compared to size of cranium (skull is large
compared to body length)
 Adult skull is 1/8 total body length, newborn ¼
 Fontanels – fibrous membranes connecting the cranial
bones
o Baby’s pulse can be felt in these soft spots (explains
their name “little fountain”)
o Allow fetal skull to be compressed in birth process
o Allow infants brain to grow
o Largest fontanels are diamond shaped anterior shaped
fontanel and smaller triangular shaped posterior
o No longer felt by 22 – 24 months after birth