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The Skull
The Bones of the Skull
--8 Paired bones (bilateral)
a. parietal
b. temporal
c. zygomatic
d. nasal
e. lacrimal
f. inferior concha
g. palatine
h. maxilla
--6 Unpaired bones
a. frontal
b. ethmoid
c. occipital
d. sphenoid
e. vomer
f. mandible
Sutures of the Skull (where bones of skull are joined by fibrous types of joints
syncondroses)
--sagittal suture: b/w parietal bones
--coronal suture: b/w frontal and parietal bones
--lambdoid suture: separates occipital bone from parietal and temporal bones
Superior Aspect of the Skull
--Surface Landmarks
a. vertex: highest point of the skull
b. bregma: at junction of the sagittal and coronal sutures
Anterior Aspect of the Skull
--Surface Landmarks
a. glabella: median elevation b/w the eyebrows (superciliary arches)
--Bones
a. frontal bone
*superciliary arches: extend laterally from glabella
*supraorbital notch: in upper margin of orbit
b. nasal bones
c. maxillary bone
d. zygomatic bone
e. mandible
*Body: landmarks (external/internal)
--mental protuberance
--mental foramen (below 2nd molar)
--oblique line (runs upward and backward)
--alveolar process (contains the lower teeth)
--submandibular fossa (below myelohyoid line, for
submandibuar gland)
*Ramus: landmarks (external/internal)
--mandibular notch (upper border of ramus)
--coronoid process (anterior to notch)
--mandibular foramen (middle of ramus, for vessels and nerves)
--lingula (spine at mandibular foramen for sphenomandibular
ligament)
*Condylar process: landmarks (posterior to notch)
--head/condyle (articulates in mandibular fossa of temporal
bone)
--neck (just below the head)
*Angle: junction of the posterior and inferior borders of the mandible
Lateral Aspect of the Skull
--Surface Landmarks
a. pterion: circular area formed by the junction of the frontal, sphenoid,
parietal, and squamous part of temporal bones
--Bones
a. mandible bone: with condylar process, coronoid process, ramus, and angle
--Structures
c. zygomatic arch
d. temporal line
e. external auditory meatus
--Infratemporal Fossa: inferior to the temporal fossa
a. Fissures
*inferior orbital fissure
*pterygomaxillary fissure to the pterygopalatine fossa
--Pterygopalatine fossa: located below the apex of the orbit
a. Sphenopalatine foramen: to the nasal cavity, medialy
Posterior Aspect of the Skull
--Surface Landmarks
a. lambda: at junction of lambdoid and sagittal sutures
b. inion: center of the external occipital protuberance
c. external occipital protuberance: diamond shaped structure at the inion
d. superior nuchal line: extends laterally from EOP to provide attachment for
several muscles
e. inferior nuchal line: provides attachment for rectus capitis posterior major
and minor muscles
Orbit
--Margins
*supraorbital notch/foramen: at medial 1/3
*medial margin
*fossa/groove for lacrimal sac
*nasolacrimal canal: downward continuation of lacrimal fossa
--Walls
*superior wall/roof: fossa for the lacrimal gland (anterolaterally)
*apex: the optic foramen
*lateral wall: superior orbital fissure (b/w lesser and greater wings of
sphenoid) and inferior orbital fissure (b/w greater wing of sphenoid above
and maxillary and palatine bones below)
*Inferior wall/floor: infraorbital groove and canal
*Medial wall: thinnest wall of the orbit; orbital plate of ethmoid (lamina
papyracea)
Inferior Aspect of the Skull
--Bones
a. occipital bone
*foramen magnum
*occipital condyles: 2 large protuberances lateral to foramen magnum
*hypoglossal canal: above and ant. to each of the occipital condyles
*basilar part: ant. to foramen magnum, joins body of sphenoid bone
--pharyngeal tubercle: at center of basilar part of occiput
b. temporal bone
*Squamous Part:
 mandibular fossa: articulates with head of condylar process
 articular tubercle: at ant. part of mandibular fossa
*Styloid Part:
 styloid process
*Mastoid Part:
 mastoid process
 stylomastoid foramen: b/w styloid process and mastoid
process (TRANSMITS CN VII)
*Petrous part:
 jugular foramen (TRANSMITS CN IX, X, XI)
 carotid canal (TRANSMITS internal carotid artery, and
sympathetic nerve plexus)
 foramen lacerum
c. sphenoid bone: consists of a body, greater wings, lesser wings, and
pterygoid process
*Greater wings:
 lateral to lateral pterygoid plates
 foramen ovale: posterior to lateral pterygoid plate
(TRANSMITS mandibular n.)
 foramen spinosum: posterolateral to foramen ovale
*Pterygoid Process:
 extend downward from juction of body and greater wing of
sphenoid bone
 each pterygoid process separates into 2 plates (lateral
pterygoid plate and medial pterygoid plate whose inf.
extremity forms the pterygoid hamulus for tendon of tensor
veli palatini muscle)
d. Posterior nasal aperture/choana: posterior opening of the nasal cavity
e. vomer: forms the posterior inferior part of the nasal septum
f. Palatine Bone
*Perpendicular plate/vertical part
 pterygopalatine canal: TRANSMITS greater palatine nerves
and vessels
*Horizontal plate
pyramidal process
g. Maxilla
*Incisive fossa/foramen: in midline behind the incisors
 in the foramen are 2 incisive canals (for terminal branch of
the sphenopalatine artery and nasopalatine nerve)
Cranial Cavity
--Anterior cranial fossa
a. Frontal bone
*orbital plates: form the roof of the orbits
b. Ethmoid bone
*cribiform plate: the superior surface of the ethmoid bone that
appears in the anterior cranial fossa (has perforations for the
transmission of olfactory nerves)
*crista galli: triangular process projecting superiorly from the mdiline
of the cribiform plate, the posterior border serves as attachment for
the falx cerebri
c. Sphenoid bone
*lesser wings of sphenoid: behind the orbital plates of the frontal bone
--Middle Cranial fossa
a. sphenoid bone: body of sphenoid
*optic/chiasmatic groove: for optic chiasm
*optic canals/foramen: transmit the optic nerves
*anterior clinoid processes
*tuberculum sellae: posterior to the chiasmatic groove
*sella turcica (Turkish saddle): deep depression behind the
tuberculum sellae
--hypophyseal fossa: deepest part (lodges pituitary)
--dorsum sellae: posterior boundary of sella turcica
--posterior clinoid processes
b. greater wings of sphenoid and squamous and petrous parts of temporal
*superior orbital fissure: between greater and lesser wings of
sphenoid (TRANSMITS CN III, CN IV, CN V1, CN VI, and superior
ophthalmic vein)
*foramen rotundum: immediately below the medial end of the
superior orbital fissure (TRANSMITS CN V2)
*foramen ovale: posterior to foramen rotundum (TRANSMITS CN V3,
and accessory meningeal artery)
*foramen spinosum: posterior and lateral to foramen ovale
(TRANSMITS middle meningeal artery)
*foramen lacerum
c. temporal bone
*arcuate eminence: rounded elevation caused by the projection of the
superior/anterior semicircular canal
*hiatus and canal for the greater petrosal nerve: branch of the nervus
intermedius (in association with CN VII) carrying PREganglionic
PARAsympathetic nerve fibers to the pterygoid/Vidian canal
*hiatus and canal for the lesser petrosal nerve: carrying
PREganglionic PARAsympathetic nerve fibers (association w/ CN IX)
--Posterior Cranial Fossa
a. Sphenoid bone
*dorsum sellae
*clivus: slopes down and posteriorly
b. Petrous temporal
*internal auditory meatus: TRANSMITS CN VII, VIII, and nervus
intermedius
c. Occipital bone
*foramen magnum
*hypoglossal canals
*internal occipital protuberance
--transverse grooves
--groove for sigmoid sinusees