Gross Anatomy U4 L30 Skull

cranium is what

the skeleton of the head

what are the two parts of the skull

viscerocranium and neurocranium

what is the viscerocranium

anterior part of skull

facial skeleton

what are the parts of the viscerocranium

orbits, nasal cavity and septum, zygomatic arches, maxilla and hard palate, mandible

what is the neurocranium

brain case

houses the brain, it’s associated vasculature, meninges, and proximal cranial nerves

what are the paired bones of the neurocranium

parietal and temporal

what are the unpaired bones of the neurocranium

frontal, occipital, sphenoid, ethmoid

what are the two parts of the neurocranium

calvaria/cranial vault and the cranial base

calvaria/cranial vault

domed roof

protects the superior aspect of the brain

formed by the union of the frontal bone, paired parietal bones, and occipital bone

cranial base

three tiered platform for brain to sit on (anterior, middle, posterior)

contains openings that transmit neurovascular structures

superior cranial sutures

fibrous joints between cranial bones

coronal, sagittal, bregma

coronal suture

unites frontal bone with parietal bones

bregma

convergence of the coronal and sagittal sutures

former site of anterior fontanelle

posterior cranial sutures

sagittal

lambdoid

occipitomastoid

lambda

lateral cranial sutures

squamous

sphenosquamous

sphenofrontal

sphenoparietal

parietomastoid

pterion

asterion

what is the pterion the convergence of

sphenofrontal

sphenoparietal

sphenosquamous

coronal

squamous sutures

pterion suture

weakest point of the skull, landmark for middle miningeal artery

former site of sphenoid fontanelle

fontanelles

flexible, cartilage-filled joints found in neonates/infants

• supports birth

  • bones can move closer together

• support brain growth

  • bones can spread further apart

anterior cranial fossa

shallowest

supports frontal lobes of the brain

connects cranial and nasal cavities

3 bones of the anterior cranial fossa

frontal bone

ethmoid bone

sphenoid bone

what is the frontal bone

orbital plate, roof of orbit

ethmoid bone features

cribiform plate

crista galli

what is the cribiform plate

multiple foramina that transmit olfactory nerve filaments from the nasal cavity

crista galli

broad, perpendicular plate that projects upward, central to cribiform plate

attachment for anteroinferior part of the falx cerebri dural fold

sphenoid bone

body and lesser wings

form a ledge overlooking the middle cranial fossa

middle cranial fossa

butterfly shaped fossa that supports temporal lobes of the brain and the pituitary gland

connects cranial cavity to orbit and face

three bones of the middle cranial fossa

sphenoid bone

temporal bones

parietal bones

what does the middle cranial fossa do

supports temporal lobes of the brain and the pituitary gland

connects cranial cavity to orbit and face

what runs in optic canal

optic nerve II

ophthalmic artery

what runs in superior orbital fissure

ophthalmic nerve III

trochlear nerve IV

ophthalmic nerve V1

abducens nerve VI

what runs in foramen rotundum

maxillary nerve V2

what runs in foramen ovale

mandibular nerve V3

what runs in foramen spinosum

middle meningeal artery

what runs in carotid canal

internal carotid artery

what is within the trigeminal impression

trigeminal ganglion

what does the posterior cranial fossa do

supports cerebellum, pons, medulla oblongata

connects cranial cavity with the auditory system and face

bones of the posterior cranial fossa

temporal, occipital, sphenoid, parietal

what passes through the foramen magnum

spinal cord

vertebral arteries

accessory nerve (CN XI)

spinal root

what passes through the jugular foramen

glossopharyngeal (IX)

vagus nerve (X)

accessory nerve (XI)

internal jugular vein

what passes through the hypoglossal canal

hypoglossal nerve (CN XII)

what passes through the internal acoustic meatus

facial nerve (VII)

vestibulocochlear nerve (VIII)

paranasal air sinuses

hollow spaces within pneumatized bones that are continuous with the nasal cavity

lined with respiratory mucosa

warms and humidifies inhaled air before it reaches lungs

bones that contain paranasal sinuses

frontal bone - frontal sinuses

sphenoid bone - sphenoid sinus

ethmoid bone - ethmoidal air cells

maxillary bones - maxillary sinuses

layers of the meninges from outer to inner

cranial bone

dura mater

arachnoid mater

arachnoid trabeculae

pia mater

cerebral cortex

two layers of the cranial dura

outer endosteal layer adheres to internal surface of braincase and is continuous with periosteum

inner meningeal layer forms a sack continuous between brain and spinal cord

cranial epidural space

potential space between endosteal dura and boney braincase

arises when dura is peeled away from bone by physical forces

how does epidural hematoma arise

fractured pterion = ruptured middle meningeal artery that sits within the dura mater

subdural space

space between dura and the arachnoid, contains CSF, projects arachnoid granulations into dural sinuses to facilitate CSF drainage

encloses brain and vasculature

how do subdural hematomas arise

bridging veins pass through subdural space

can rupture following trauma = subdural hematoma

venous blood from cerebral cortex into superior sagittal sinus

subarachnoid hemorrhage

aneurysms occur where multiple vessels unite

rupture of aneurysm causes subarachnoid hemorrhage

pia mater

innermost wall of subarachnoid space

adheres tightly to brain and spinal cord

dural infoldings

four folds of meningeal dura that project inward and partition the cranial cavity

contain endothelial spaces that act like veins

receive blood from vessels in the scalp and surface of the brain (empty into internal jugular vein)

falx cerebri

separates two cerebral hemispheres

superior sagittal sinus receives…

receives venous blood via superior cerebral veins

receives CSF via arachnoid granulations

inferior sagittal sinus

unites with great cerebral vein to form straight sinus

tentorium cereblli

separates posterior aspect of cerebrum from cerebellum

falx cerebelli

separates cerebellar hemispheres

diaphragma sellae

keeps pituitary gland compartmentalized in hypophyseal fossa

dural venous sinuses

epithelial lined space within dural infoldings

receives blood from surface of the brain and scalp

empty into internal jugular vein

four unpaired dural venous sinuses

superior sagittal sinus

inferior sagittal sinus

straight sinus

occipital sinus

five bilateral sinus pairs

transverse sinuses

sigmoid signuses

superior petrosal sinuses

inferior petrosal sinuses

cavernous sinuses

special sensory only cranial nerves

I: olfactory

II: optic

VIII: vestibulocochlear

optic nerve arises from

optic canals

fibers interconnect as the optic chiasm which distributes fibers through optic tracts

vestibulocochlear nerve pathway

vestibular nerve and cochlear nerve united in IAM

vestibular n: controls equilibrium via vestibular ganglion

cochlear n: controls hearing via spiral ganglia

motor only cranial nerves

III: oculomotor (also carries visceral motor)

IV: trochlear

VI: abducens

XI: accessory

XII: hypoglossal

oculomotor nerve pathway

passes through cavernous sinus and superior orbital fissure

innervates all but two extraocular muscles

ciliary ganglion

trochlear nerve pathway

passes through superior orbital fissure, innervates superior oblique muscle

abducens nerve pathway

innervates lateral rectus muscle

passes through cavernous sinus and superior orbital fissure

spinal accessory nerve pathway

exits skull via jugular foramen, passes upward through foramen magnum

innervates sternocleidomastoid and trapezius

hypoglossal nerve pathway

exits posterior cranial fossa via hypoglossal canal

joined by ansa cervicalis

innervates most tongue muscles

mixed cranial nerves (both sensory and motor)

V: trigeminal

VII: facial

IX: glossopharyngeal

X: vagus

3 divisions of trigeminal

1: ophthalmic

2: maxillary

3: mandibular

ophthalmic nerve pathway

superior orbital fissure

1: nasociliary

2: frontal

3: lacrimal

facial nerve pathway

passes through internal auditory meatus, facial canal, stylomastoid foramen

glossopharyngeal and vagus pathway

exits via jugular foramen