ANATOMY - Head part 2 Flashcards
embryological origin pons
embryonic metencephalon
what structure separates the pons and the cerebellum posteriorly
4th ventricle
what structure is inferior to the pons
medulla oblongata
what structure is superior to the pons
midbrain
what is the pontomedullary junction
angle between the lower border of the pons and the superior border of the medulla
which 4 cranial nerves originate from the ventral pons surface
V
VI
VII
VIII
draw circle of Willis
where are the lateral ventricles of the brain
located within the hemispheres of the cerebrum
where do the horns of the lateral ventricles project into
frontal, occipital and temporal lobes
what happens to the volume of the lateral ventricles with age
increases
lateral ventricles drain into the 3rd ventricles via
Foramen of monroe
where are the 3rd ventricles
between the R+L thalamus
what are the 3 protrusions on the anterior surface of the 3rd ventricle
supra-optic recess (above optic chiasm)
infundibular recess (above optic stalk)
what connects the 3rd and 4th ventricles
cerebral aqueducts
where is the 4th ventricles?
within brainstem at jct pons of medulla
names of the lateral and medial foramen connecting the 4th ventricle to the subarachnoid space
foramen of Magendie (medial)
foramen of Lushka (lateral)
what 2 spaces does the 4th ventricle drain into
central spinal canal (bathes SC)
sub-arachnoid cisterns (baths brain between arachnoid + pia)
where is CSF reabsorbed back into the circulation?
at the subarachnoid cisterns (then via the dural venous sinuses)
what is CSF produced. by
choroid plexus
what is the choroid plexus
capillaries + loose CT, surrounded by cuboid epithelial cells
what 2 paired arteries make up the circle of Willis
vertebral and ICA
what spinal level does the ICA originate from
C4
what structure does the ICA move upwards in to entry the brain ?
carotid sheath
where is the carotid canal
in the temporal bone of the middle crfanial fossa
before giving rise to its branches in the cranial cavity, through which area does the ICA pass anteriorly through?
cavernous sinus
4 branches of the ICA in the cranium
ophthlamic aa
post communicating aa
ant choroidal aa
ant cerebral aa
post communicating aa supplies
connects vessels in circle of willis
ant choroidal aa supplies
brain structures important for vision + motor control
what aa does the ICA continue as
middle cerebral aa
origin of the vertebral aa
SCA, medial to the anterior scalene
how does the vertebral aa travel up the spine
through foramen strasversarium of the transverse processes of the C spine
via which foramen do the vertebral aa enter the cranium
foramen magnum
after the foramen magnum, what 3 branches does the vertebral aa give rise to
meningeal branch (falx cerebelli)
ant/post spinal aa
post infer cerebellar aa
after giving off its branches in the brain, what do the vertebral aa converge to become
basillar aa
anterior cerebral aa supplies
anteromedial part of the cerebellum
middle cerebral aa supplies
lateral part of the brain
posterior cerebral aa supplies
medial/lateral post parts of the brain
where do the posterior spinal aa anastomose with eachother
pia mater
aa supplying the spinal cord
ant + post spinal aa (^ vertebral aa)
also support via the segmental + radicular aa
where does the dural vv drainage of the brain lie?
between the periosteal + meningeal layers of the duramater
does the dural venous system have valves?
no
how many veins make up the dural venous system?
11
drainage of dural venous system to the IJV
straight, sup saggital + inf saggital converge at the confluence
–> transverse –> sigmoid –> IJV
journey of venous blood from the cerebrum to the dural venous sinuses
superficial and deep systems –> exit parenchyma –> SA space –> pierce meninges –> dural sinuses
what are the 5 main vv in the superficial cerebrum system
sup cerebral vv
sup middle cerebral vv
inf cerebral cc
sup anastomotic vv of Trolard
Inf anastomotic vv of Labbe
what does the sup anastomotic vv of Trolard connect?
sup middle cerebral vv to sup saggital sinus
what does the inf anastomotic vv of Labbe connect
connects sup middle cerebral vv to transverse sinus
what are the deep vv system of the cerebrum (2)
subependymal vv + medullary vv
vv drainage of the cerebellum
sup + inf cerebellar vv –> sup petrosal, transverse + straight sinuses
vv drainage spinal cord
3 x ant + 3 x post spinal vv –> form anastomotic network along spinal cord –> vertebral plexus –> systemic segmental vv
name of glands which secrete ear wax
ceruminous glads
blood supply to the ext auditory canal
auricotemporal branch of the sup temporal aa
post auricular branch of eca
sensory inn ext auditory canal
auricotemporal branch of CN X
which bone is the middle ear within>
temporal
inn of the tympanic membrane
auricotemporal + auricular branch of CN X
what is the name of the weakest point of the tympanic membrane
pars flaccida
what pathology can occur in the pars flaccida of the ear?
cholesteatoma
what is the largest ossicle of the ear
malleus
what part of the malleus is attached to the tympanic membrane?
lateral process
what part of the incus is associated with the malleus
body
what part of the stapes is associated with the incus
head
which 2 muscles are attached to the ossicles?
tensor tympani
stapedius
which 2 nerves run through the middle ear
chorda tympani
facial nn
what bone is the inner ear in?
petrous part temporal bone
base of cochlear transmits..
low frequency sounds
apex of cochlear transmis …
high frequency sounds
where is the pterygopalatine fossa?
from infratemporal fossa to nasal cavity
betewen the maxilla, phenoid + palatine bone
borders pterygopalatine fossa
ant - post wall maxillary sinus
post - pterygoid process sphenoid bone
inf - palatine bone, palatine canals
sup - inf orbital fissure
med - perpendicular plate palatine bone
lat - pteryogmaxillary process
nn contents ptergopalatine fossa
CN V2 + here it branches:
infraorbital nn
zygomatic nn
nasopalatine nn
sup alveolar nn
pharyngeal nn
greater/lesser palatine nn
through which foramen for CN V2 enter into the ptergopalatine fossa?
foramen rotundum
what is the predominant innervation of the pterygopalatine ganglion
greater petrosal branch of CN VII
name the 7 foramina of the ptergopalatine fossa
pterogmaxillary fissure
foramen rotundum
2 x pterygoid + pharyngeal arches
infra orbital fissure
greater palatine canal
sphenopalatine foramen
contents pterygomaxillary fissur e(2)
post sup alveolar nn
maxillary aa
pterygoid canal transmits aa/vv/nn from the pterygopalatine fossa to the
nasopharynx
pharyngeal canal transmits the pharyngel branch of CN V2 to the
nasopharynx
contents of infraorbital fissure (3)
zygomatic branch CN V2
infra orbital aa/vv
to the orbit, lacrimal gland + eye mm
greater palatine canal tranmits aa/vv/nn from the ptergopalatine fossa to the
oral cavity - hard and soft palate
contents of the greater palatine canal (4)
descending palatine aa
descending palatine vv
greater palatine nn
lesser palatine nn
sphenopalatine formaen transmits aa/vv/nn from the pterygopalatine fossa to the
nasal cavity
contents sphenopalatine foramen (3)
sphenopalatine aa
sphenopalatine vv
nasopalatine nn
where is the infratemporal fossa
at the base of the skull, deep to the masseter muscle and zygomatic arch
shape of infratemporal fossa
wedge shaped
boundaries of the infratemporal fossa
lateral: condylar process + ramus mandible
medial: lat pterygoid plate, TVP, TLP, sup constrictor mm
anterior: post border maxillary sinus
post: carotid sheath
roof: greater wing sphenoid - prov passageways to the foramen ovale + spinosum
floor: medial pterygoid
contents infratemporal foramen (8)
mm mastication specifically the pterygoids
CN V3 + branches - auricotemporal, buccal, lingual, inf anveolar
chorda tympani (follows lingual nn)
otic ganglion (hitchhikes along auricotemporal to parotid)
maxillary aa
pteerygoid vv plexus
maxillary vv
middle mengingeal vv
what does the maxillary aa branch into in the infratemporal fossa?
MMA (then goes through foramen spinosum)
where is the mastoid fossa?
triangular shape depression in the external surface of the temporal bone
borders of the mastoid fossa
sup: supramastoid crest (extension of the zygomatic process)
ant: suprameatal spine of henle
post: hypothetical vertical line at the midpoint of the post border of the ext auditory canal
contents mastoid fossa
NOTHING except mastoid air cells
importance mastoid fossa
safe zone in mastoidectomy to start drilling
where is the cavernous sinus?
within the middle cranial fossa, eitherside of the sella turcica of the sphenoid
borders of the cavernous sinus
roof: meningeal layer attaching to ant + middle clinoid process sphenoid
ant - sup orbital fissure
post - petrous part temporal bone
medial - body sphenoid
lateral - meningeal layer dura mater of middle cranial fossa
floor - endosteal layer dura mater overlying greater wing sphenoid
structures travelling through the cavernous sinus (3)
CN VI
carotid plexus
ICA
structures travelling through lateral wall cavernous sinus (4)
CN III
CN IV
CN V1
CN V2
what is cavernous sinus thrombosis
clot within cavernous sinus
what is cavernous sinus thrombosis usually due to
infection
Sx cavernous sinus thrombosis
periorbital oedema
CN VI palsy
Tx cavernous sinus thrombosis
ABx
which vv does each dural venous sinus receive blood form (5)
ophthalmic vv
central vv retina
spenparietal sinus
superficial middle cerberal vv
pterygoid plexus
route of cavernous vv sinus to IJV
cavernous sinus –> sup + inf petrosal sinus –> IJV
