Interior of The Skull Flashcards
A midline ridge, frontal crest, on the frontal bone serves for the attachment of the ____ ____
falx cerebri
Frontal crest terminates at the beginning of what groove?
groove for the superior saggital sinus
Parietal bones have grooves from the ___ ____ artery
middle meningeal
Granular foveae are small pits and depressions in the calvaria that host the ____ ____
arachnoid granulations
The floor of the cranial cavity has three depressions, anterior, middle, and posterior. The ____ cranial fossa is the shallowest and most superior of the three
anterior
In regards to the anterior cranial fossa, this bone forms a cribriform plate and a median cost, crista galli, for the attachment of falx cerebri.
ethmoid
In regards to the anterior cranial fossa, the body and lesser wings of the sphenoid are located ____
posteriorly
The foramen cecum is located in the anterior cranial fossa. It allows passage of what?
nasal emissary veins
The cribiform foramina is located in the anterior cranial fossa. It allows passage of what?
axons of olfactory nerves
The anterior and posterior ethmoidal foramina, in the anterior cranial fossa, allow passage of what?
ethmoid artery and vein
The middle cranial fossa is posterior and inferior to the anterior cranial fossa. It is separated from the anterior fossa by ____ crests, anterior cloned processes and ___ of sphenoid bone, and from the posterior cranial fossa by superior border of ____ part of temporal bone
sphenoidal; sphenoid; petrous
The ___ bone forms most of the middle cranial fossa with its bilaterally placed ____ wings and the centrally located upper part of the body termed ___ ____
sphenoid; greater; sella tucica
The ___ of the sphenoid forms the anterior boundary of the chiasmatic sulcus, which is formed as the continuation of the optic canals where the optic nerves cross
limbus
The sella turcica is formed by what three things?
tuberculum sellae (posterior elevation) hypophysial fossa (depression housing pituitary gland) dorsum sellae (bony ridge superior with posterior cloned processes as lateral edges)
In regards to the middle cranial fossa, this foramen goes through the lesser wing of the sphenoid and opens into the orbit
optic
What passes through the optic canal?
CN II (optic nerve) and ophthalmic artery
In regards to the middle cranial fossa, this foramen is located between the greater and lesser wings of the sphenoid and opens into the orbit.
superior orbital fissure
What passes through the superior orbital fissure
CN III (occulomotor), CN IV (trochlear), CN V1 (ophthalmic nerve - trigeminal), CN VI (abducens), ophthalmic veins
In regards to the middle cranial fossa, this foramen is large, opens inferiorly into the infratemporal fossa
foramen ovale
What passes through foramen ovale?
CN V3 (mandibular nerve), lesser petrosal nerve, accessory meningeal artery
In regards to the middle cranial fossa, This foramen is located posterior to the medical end of the superior orbital fissure and opens externally into the pterygopalatine fossa
foramen rotundum
What passes through foramen rotundum?
CN V2 (maxillary nerve)
In regards to the middle cranial fossa, this foramen is located posterolateral to f. ovale and opens into the infratemporal fossa
Foramen spinosum
What passes through foramen spinosum?
MMA
In regards to the middle cranial fossa, this foramen opens into the cranium posteromedial to f. ovale.
Carotid canal
What passes through the carotid canal?
ICA and nerve plexus
In regards to the middle cranial fossa, this foramen lies posterolateral to the hypophyseal fossa and is partially filled with cartilage during life
foramen lacerum
The posterior cranial fossa is limited anteriorly on the midline by the ____ ____, laterally by the superior border of the ___ part of the temporal bone, and inferiorly and posteriorly by the ____ bone
dorsum sellae; petrous; occipital
In regards to the posterior cranial fossa, the sphenoid body and the basilar part of the occipital bone form the _____, a shallow depression behind the dorsum sellae that slopes posteriorly
clivus
In regards to the posterior cranial fossa, the ____ ____ crest runs along the midline from the foramen magnum posteriorly to the internal occipital protuberance and divides the posterior cranial fossa into two bilateral depressions, the deep ____ ____
internal occipital; cerebellar fossae
In regards to the posterior cranial fossa, this foramen is the largest in the skull within the occipital bone
foramen magnum
What passes through the foramen magnum?
brain stem/spinal cord with meninges, vertebral arteries, and CN XI (spinal accessory nerve)
In regards to the posterior cranial fossa, this foramen is at the base of the petrous ridge of the temporal bone.
jugular foramen
What passes through the jugular foramen?
CN IX (glossopharyngeal), CN X (vagus), CN XI (accessory), sigmoid sinus as it becomes the superior bulb of the IJV
In regards to the posterior cranial fossa, this foramen is located anteriosuperior to the jugular foramen within the petrous portion
internal acoustic meatus
What passes through the internal acoustic meatus?
CN VII (facial), CN VIII (vestibulocochlear), and labyrinthine artery
In regards to the posterior cranial fossa, this foramen is located anterolaterally within the foramen magnum
hypoglossal canal
What passes through the hypoglossal canal
CN XII (hypoglossal)
Several sinuses converge towards the jugular foramen to from the ___ ___ vein
internal jugular
The groove for ____ ____ sinus is lateral to the clivus
inferior petrosal
The ___ sinus is between temporal and occipital bones running towards the jugular foramen
sigmoid
The ____ sinuses extend laterally from the internal occipital protuberance to join the sigmoid sinuses
transverse
What is the difference between cranial meninges and spinal meninges?
cranial dura mater has two layers - periosteal and membranous
At the foramen magnum, all layers except ____ dural layer are continuous with the spinal meninges
periosteal
The subarachnoid space contains ____ produced by chord plexuses in brain ventricles and resorbed though arachnoid granulations into the superior sagittal sinus
CSF
____ ____ is a large, sickle-shaped dural infolding that passes between two cerebral hemispheres and attaches anteriorly to crista galli and the frontal crest
falx cerebri
note: ends posteriorly at internal occipital protuberance
_____ _____ separates cerebellum from inferior portion of the cerebrum and is raised up “like a tent” by its superior attachment to falx cerebri
tentorium cerebelli
The tantorium cerebelli has a central opening, the ___ ____, through which the brainstem passes
tentorial notch
This is a small, vertical projection from inferior surface of tentorium cerebelli between the two cerebellar hemispheres. It attaches to the internal occipital crest.
falx cerebelli
This is a small, horizontal sheet of dura that roofs the hypophyseal fossa, which has an opening in the middle for the passage of infundibulum of pituitary gland
diaphragm sellae
____ ___ sinuses are endothelium-lined spaces between the two dural layers. Venous blood enters these from cerebral veins, diploic veins, and through emissary veins.
Dural venous
Where is the confluence of sinuses located?
dilated region near the internal occipital protuberance where several dural sinuses meet
This sinus lies in superior region of the falx cerebri from foramen cecum to end in the confluence of sinuses. It connects with laterally placed venous lacunae into which arachnoid granulations project for return of CSF to venous circulation.
superior sagittal sinus
This sinus is found in the free, inferior border of falx cerebri and ends in the straight sinus
inferior sagittal sinus
This sinus lies at junction of falx cerebri with tentorium cerebelli; formed by the merging of inferior sagittal sinus and great cerebral vein; terminates in the confluence of sinuses
straight sinus
This sinus is found in falx cerebelli, where it attaches to the occipital bone; communicates with internal vertebral venous plexus and terminates into confluence of sinuses
occipital sinus
This sinus courses laterally from the confluence of sinuses along attached border of tentorium cerebelli to drain into the sigmoid sinus
transverse sinus
This sinus is the continuation of the transverse sinus as it curves inferiorly to pass through the jugular foramen forming the IJV
sigmoid sinus
This sinus is located bilaterally, lateral to sella turcica. Fibrous extensions between meningeal and periosteal dura layers give it trabeculated form. It connects with structures outside cranial cavity via ophthalmic veins and emissary veins from the pterygoid plexus
cavernous sinus
What passes through the cavernous sinus?
ICA, CN VI (abducens)
Which nerves lie in the lateral wall of the cavernous sinus?
CN III (occulomotor), CN IV (trochlear), CN V1 (ophthalmic-trigeminal), and CN V2 (maxillary-trigeminal)
These sinuses are small, receive blood from diploic and meningeal veins, and drain into the anterior part of the cavernous sinus
sphenoparietal sinuses
This sinus runs within tentorium cerebelli, where it is attached to the superior border of the petrous part of the temporal bone. It connects posterior part of cavernous sinus to transverse sinus, becoming the sigmoid sinus
superior petrosal sinus
This sinus connects the posterior part of the cavernous sinus to the junction of sigmoid sinus and IJV at the jugular foramen
inferior petrosal sinus
This sinus interconnects the two inferior petrosal and cavernous sinuses with internal vertebral plexus
basilar
This artery is the largest of the meningeal arteries and supplies about 80% of the dura.
MMA
note: arises from maxillary artery
The trigeminal nerve supplies the dura. What does CN V1 (ophthalmic) supply?
anterior cranial fossa and falx cerebri
The trigeminal nerve supplies the dura. What does CN V2 (maxillary) supply?
tentorium crebelli
The trigeminal nerve supplies the dura. What does CN V3 (mandibular) supply?
middle cranial fossa
What is the posterior cranial fossa innervated by?
upper cervical nerves and vagus nerve
_____ hemorrhage occurs when blood collects between calvaria and periosteal layer of dura.
extradural
note: usually due to rupture of MMA caused by skull fracture; yield a lens-shaped hematoma
____ hemorrhage occurs when blood collects between the meningeal layer of the dura and the arachnoid layer.
Subdural
note: usually due to rupture of veins draining into dural venous sinuses; yield a crescent shaped
____ hemorrhage occurs when blood collects in subarachnoid space mixing with the CSF. The most common non-traumatic cause is the rupture of a cerebral aneurysm
subarachnoid
CN I begins from the _____
telencephalon
CN II begins form the _____
diencephalon
CN III/IV begin from the ____
midbrain
CN V-VIII begin from the ____
pons
CN IX-XII begin from the ____
medulla
This nerve is sensory only, gives the sense of smell.
olfactory nerve (CN I)
The olfactory nerve projects to the limbic system (emotions, memory, visceral reflexes). What is the significance?
smells can trigger memories, emotions, etc.
This nerve is motor and supplies extraocular muscles that move the eyeball
occulomotor nerve (CN III)
This nerve is motor and is the second CN involved in innervation of the extraocular eye muscles. It passes through the superior orbital fissure and innervates the superior oblique muscle of the eye
trochlear nerve (CN IV)
This nerve is motor and sensory. It passes over the medial aspect of petrous part of temporal bone. It has three subdivisions which interface with nuclei in the brainstem
trigeminal nerve (CN V)
This subdivision of the trigeminal nerve is sensory. It passes through the superior orbital fissure and innervates the orbital contents, parts of face, scalp, nasal cavity, sinuses, and dura
ophthalmic nerve (CN V1)
This subdivision of the trigeminal nerve is motor and sensory. It passes through foramen ovale and provides sensory innervation to parts of face, TMJ, mandibular test, tongue (anterior 2/3), mouth, and dura. It proves motor innervation to muscles of mastication and several other muscles form the first pharyngeal arch
mandibular nerve (CN V3)
This subdivision of the tirgeminal nerve is sensory. It passes through the foramen rotundum and provides sensory innervation to parts of face, nasal cavities, maxillary teeth, maxillary sinus, and dura.
maxillary nerve (CN V2)
What is the mnemonic for the trigeminal nerve?
standing room only
V1: Superior orbital fissure
V2: foramen Rotundum
V3: foramen Ovale
This nerve is motor. It is the third CN involved in the innervation of extra ocular eye muscles. It passes through dura covering clivus, cavernous sinus, an superior orbital fissure to innervate the lateral rectus muscles.
Abducent nerve (CN VI)
This nerve is mixed, parasympathetic. It provides sensory and motor innervation to the face. After giving off branches within the petrous part of temporal bone, it exits the skull through the sylomastoid foramen.
facial nerve (CN VII)
This nerve is sensory (hearing and balance). It provides sensory innervation through the vestibular nerve for balance and cochlear nerve for hearing. It projects to 4 vestibular nuclei and 2 auditory nuclei in the pons.
vestibulocochlear nerve (CN VIII)
This nerve is mixed, parasympathetic. It passes through the jugular foramen and provides motor to stylopharyngeus, parasympathetics to parotid gland, sensory for taste on posterior 1/3 of tongue and oral cavity and middle ear, sensory in carotid body and sinus.
glossopharyngeal (CN IX)
This nerve is mixed, parasympathetic and passes through the jugular foramen and provides motor innervation to muscles form 4th and 6th pharyngeal arches (laryngeal, tongue, palate); parasympathetics to smooth muscle and glands in the pharynx, larynx, thoracic, and abdominal viscera; sensory innervation for taste from epiglottis
vagus nerve (CN X)
The axons of the olfactory receptor neurons coalesce into 20 fibers called the ___ ____, which pass through the foramina of the cribriform plate - technically the olfactory nerve
filia olfactoria
On the superior surface of the cribriform plate, is the olfactory bulb which contains a group of cells termed the ____ cells
mitral
note: the axons of the mitral cells extend to the brain as the olfactory tract
At the base of the forebrain, the olfactory tract divides into three branches. This sensory pathway is unusual, why?
bypasses thalamus and lacks a clear topographic representation
Loss of smell most commonly arises from what?
nasal infection and ethmoidal fractures
Bilateral anosmia can be psychologically debilitating due to the associated loss of ____
taste
Photoreceptor neurons from the optic nerve are located within the ___ of the eye
retina
The most superficial neuronal cells making up the optic nerve are the ____ cells
ganglion
Immediately postero-medial to the inner opening of the optic canal, the medial fibers of the optic tract cross (decussate) at the ____ ____
optic chiasm
From the optic chiasm, the two optic tracts diverge to lateral geniculate bodies of the ____
thalamus
