neurologic anatomy of the skull/cranial cavity Flashcards
rhinorrhea
CSF leaking through nose
two parts of the skull
neurocranium - vault around the brain and viscerocranium - forms the skeleton of the face
the viscerocranium is formed mainly from the embryonic _______
pharyngeal arches
At birth, why is the viscerocranium especially small compared to the neurocranium?
Virtual absence of paranasal sinuses (maxillary sinus) Teeth have not erupted Small size of the mandible
the nasal cavity and forms the floor of the orbit
MAXILLA
forms the forehead and superior aspects of the orbit
frontal bone
form the check bones and also contributes to the orbit
zygomatic bones
the lower jaw bone
mandible
the foramina in the anterior aspect of the skull are necessary for the passage of nerve branches including ____
trigeminal nerve
the area where the 4 flat bones of the skull articulate together
Pterion
paired parietal bones are joined by the midline
sagittal suture
parietal bones articulate with the occipital bone via the ____ suture
lambdoid
a prominent osseous protrusion posteriorly
external occipital protuberance EOP
what is this structure
Pterion
______ is formed by the paired parietal bones, frontal bone, and the occipital bone
skull cap
Internal aspect of the skull cap reveals numerous grooves which mark the location of the _________
middle meningeal blood vessels
tufts of arachnoid mater that serve as sites for reabsorption of CSF into the venous system
arachnoid granulations
3 layers of skull bone
dense outer layer
middle diploe
thin inner table
the small recesses or “pits” called ______ produced by the arachnoidgranulations
foveolae
this artery runs just beneath the pterion
middle meningeal artery (branch of maxillary)
The middle meningeal artery can be lacerated following trauma to the pterion resulting in an _______ and subsequent herniation of the brain
epidural hematoma
Ossification of the skull is _______ at birth to allow for continued brain growth and facilitate passage through the birth canal
incomplete
_____ and _____ in the infant skull are areas of membrane not yet replaced by bone
sutures
fontanelles
anterior fontanelle closes
18-24 months
in an infant, the anterior fontanelle is _____ if severely dehydrated
sunken
in an infant, the anterior fontanelle is ______ if increased intracranial pressure (hydrocephaly, encephalitis)
Bulging
If there is premature closure (fusion) at one of the sutures ________ occurs along other suture lines to compensate for the growing brain
… …compensatory growth
Enlargement/growth of the neurocranium occurs by bony deposition via __________ at these sutures and fontanelles
(intramembranous bone formation)
premature closure of the sagittal suture which prevents normal growth in the width of the skull
scaphocephaly
premature closure of coronal suture which prevents normal growth in the length of the skull…
brachycephaly
scaphocephaly results in a ___(shape)___ neurocranium
long and narrow
brachycephaly results in a _____ neurocranium
short - wide
coverings that surround and protect the brain
cranial meninges
layers of cranial meninges
- dura mater - thick dense external fibrous membrane
- arachnoid mater - delicate intermediate membrane with fine trabeculuae
- pia mater - a delicate inner membrane closely adhered to surface of brain and its contours
Collectively, the arachnoid and pia are referred to as the ______
leptomeninges
what is between the arachnoid and pia mater?
subarachnoid space
Subarachnoid space contains the ____________ and is continuous with the space around the spinal cord
cerebrospinal fluid (CSF)
_________ protrude through the dura into the venous sinus
arachnoid granulations
The arachnoid granulations serve to ____ the circulating CSF into the ____
transfer
venous system
Excess CSF is reabsorbed into the venous circulation via the _______
arachnoid granulations
areas where the subarachnoid space enlarges are called
cisterns
name the 4 cisterns
Cerebellomedullary cistern (aka..cisterna magna)- largest
Quadrigeminal cistern
Pontomedullary cistern
Interpeduncular cistern
label the cisterns
how many layers in the dura mater
2
- outer periosteal
- inner periosteal
the outer periosteal dura and inner meningeal dura diverge to form _______ which collect and drain venous blood from the brain and surrounding areas
dural venous sinus
the inner meningeal layer converges to form septa or _______ which serve to separate and support parts of the brain
dural partitions
a vertical sickle-shaped septa that separates the cerebral hemispheres
falx cerebri
horizontal septa which separates the occipital lobe from the cerebellum
tentorium cerebelli
common site of brain herniations
tentorial notch
Large veins from the surface of the brain empty into these sinuses and venous blood eventually drains into the ______
internal jugular veins (IJV)
dural venous sinus that lies on both sides of the pituitary gland
cavernous sinus
these nerves traverse the cavernous sinus
- Oculomotor (CN III)
- Trochlear (CN IV)
- Trigeminal divisions V1 and V2
- Abducens nerve (CN VI)
what artery traverses the cavernous sinus
internal carotid
a life threatening infection in the cavernous sinus
cavernous sinus thrombosis
life threatening facial infection results when facial veins drain blood into the cavernous sinus and into the _______
danger triangle
infections in the oral cavity (dental abscess) as well as sinus infections, can spread into the ________ via venous tributaries
cavernous sinus
symptoms of cavernous sinus thrombosis
Eye/orbital swelling (venous congestion)
Facial pain or numbness (along V1 & V2)
Dysfunctional eye movements (CN III, IV, & VI)
Meningitis
a ‘potential’ space between the dura and the skull
Epidural Space-
a ‘potential space’ between the dura and the arachnoid
Subdural Space-
real space between the arachnoid and pia and contains the cerebrospinal fluid (CSF) and large cerebral vessels
Subarachnoid Space
_________ are due to rupture of a meningeal artery
Epidural hematomas
epidural hematoma on imaging studies
Classic biconvex “lens-like” appearance
___________ are due to rupture of a cerebral veins or “bridging veins”
Subdural hematomas
subdural hematomas on imaginge
Classic “crescent shaped” appearance on imaging studies
onset of subdural hematomas
days to weeks, since venous system is less pressure
Subarachnoid hemorrhage are often from ruptured aneurysms of_______
cerebral arteries
onset of subarachnoid headache
sudden - described as worst headache of life, “thunderclap” headache
presence of blood in the tympanic cavity of the middle ear
Hemotympanum or hematotympanum
battle sign
bruising over the mastoid process as a result of extravasation of blood - post auricular/mastoid ecchymosis
“Raccoon Eyes”
Bilateral periorbital ecchymosis
nAnterior fossa houses the
frontal lobes
Middle fossa houses the
temporal lobes
Posterior fossa houses the
pons/medulla & cerebellum
______ houses and protects the pituitary gland
sella turcica
Foramina in the cranial cavity are for the passage of specific_______ and ____
cranial nerves and blood vessels
cribriform plate of foramen houses
olfactory nerve CN I
the optic canal foramen houses
Optic nerve (CN II) & ophthalmic artery
the superior orbital fissure foramen houses
CNs III, IV, V1, VI & ophthalmic veins
foramen rotundum houses
Maxillary division of Trigeminal V2
foramen ovale houses
Mandibular division of Trigeminal V3
Carotid canal houses
Internal carotid artery
foramen spinosum foramen houses
Middle meningeal artery
internal acoustic meatus houses
Facial (CN VII) & vestibulocochlear (CN VIII)
jugular foramen houses
Glossopharyngeal (IX), vagus (X), & accessory (XI)
hypoglossal canal houses
Hypoglossal nerve (CN XII)
The cranial dura mater is _____ and receives sensory innervation from several sources
highly innervated
provides the majority of the sensory branches (called meningeal nerves) into the cranial cavity to innervate the dura mater
Trigeminal nerve (V1, V2 and V3)
signs of skull base fractures
Raccoon Eyes, Hemotympanum, and Battle sign (post auricular/mastoid ecchymosis), and oto/rhinnorrhea
