neuro anatomy Flashcards
what separates the external and internal tables of contact bone that make up the cranium
spongy bone = diploe
what is a suture?
immobile joints of the cranium
where is the coronal suture
marks where the frontal bones (anteriorly) articulate with the parietal bones (posteriorly)
where is the saggital suture
between the right and left parietal bones
where is the lamboid suture
between the occipital bone (posteriorly) and the parietal bones (anteriorly)
in what plane is the lambdoid suture
coronal plane
what is the pterion?
the H shaped suture formation representing the immobile joint between the frontal bone, parietal bone, temporal bone and the sphenoid bone
what runs in the groove of the pterion
the middle meningial artery
explain the 2 parts of the frontal bone
has a vertical part and a horizontal part (forms the roofs of the orbits)
what is the line of demarcation between the vertical and horizontal parts of the frontal bone
the supraorbital margins
What are the parts of the temporal bones
squamous part of the temporal bone and its projections: - zygomatic process (anteriorly) - mastoid process (posteriorly) - styloid process (inferiorly) - petrous part
explain the squamous part of the temporal bone
it is the part of the temporal bone that is flat and moulded to the contour of the brain
what does the styloid process of the temporal bone give rise to
structures associated with the oral cavity and the pharynx
shape of the petrous part of the temporal bone
wedge shaped
shape of the sphenoid bone
bat with outstretched wings and legs that hang down
where does the pituitary gland sit in the skull
in the depression of the body of the sphenoid bone = sella tucica
what divides the wings of the sphenoid bone into lesser and greater parts
the superior orbital fissure
where is the ethmoid bone?
sits between your eyes
what is the crista galli
the little protrusion of the ethmoid bone that jutts up between the cribiform plate
what is the cribiform plate
part of the ethmoid bone with lots of little holes in it (pathway for olfactory neurons)
what are the 3 cranial fossa
anterior middle posterior
fossa of the anterior cranial fossa
cribiform plate
fossa of the middle cranial fossa
- hypophysial - optic canal - superior orbital fissure - foramen rotundum - foramen ovale - foramen spinosum
fossa of the posterior cranial fossa
- internal acoustic meatus - jugular foramen - hypoglossal canal - foramen magnum
what forms the anterior cranial fossa
the horizontal plates of the frontal bone with the intervening cribiform plate of the ethmoid bone and the lesser wings of sphenoid
what forms the middle cranial fossa
formed by the body and the greater wings of sphenoid anteriorly, and the petrous part of the temporal bone
the superior orbital fissure allows direct communication between…
the cranial cavity and the orbit
what are the fissures that lie along the arch made in the middle cranial fossa
superior orbital fissure foramen rotundum foramen ovale foramen spinosum
which foramen is covered by a membrane (closed off)
foramen lacerum
where is the optic canal
between the body of the sphenoid and the lesser wing
what is the arrangement of foramina in the posterior cranial fossa
vertical line of 3 foramina along with the foramen magnum
3 foramina that lie in a vertical line in the posterior cranial fossa and where are they
- internal auditory meatus - hole in the petrous part of the temporal bone - jugular foramen - hole between petrous part of the temporal bone and the occipital bone - hypoglossal canal - in the occipital bone itself
3 layers of meninges from outside to inside
dura mata arachnoid pia mata
what is the extradural/epidural space
the potential space between the dura and the skull
what is the subdural space
the potential space between the dura and the arachnoid
what is the subarachnoid space
the actual space between the arachnoid and the pia - occupied by CSF
what are layers of tissue and spaces from outside to inside
scalp, skull, potential extradural space, dura mata, potential subdural space, arachnoid, subarachnoid space, pia, brain tissue
what are the 4 dural projections into the cranial cavity
falx cerebri falx cerebelli tenorium cerebelli diaphragma sellae
what is the function of the dural projections into the cranial cavity
to prevent or restrict rotatory displacement of the brain in response to a blow to the skull
where is the falx cerebri and what are its attachments
the fold of dura that lies between the 2 cerebral hemispheres - attaches to the crista galli anteriorly and to the occipital protrubrence posteriorly - runs along the saggital suture
where is the tentorium cerebelli and what are its attachments
roofing over the posterior cranial fossa separating the cerebral hemispheres above from the cerebellum below - attaches to the posterior cranial fossa posteriorly
where is the falx cerebelli
between the two hemispheres of the cerebellum
where is the diaphragma sellae
rooves the pit in the body of the sphenoid bone
what are the dural venous sinuses
endothelial lined spaces that exist between the outer layer of the dur and the inner layer of the dura where there are collections of venous blood
from which veins do the dural venous sinuses receive blood from
the cerebral veins the diploic veins (drains the layer of spongy bone of the skull the emissary veins (connecting with the external structures of the head)
why is it easy to get meningitis from a scalp wound
because the venous sinuses receive drainage from the emissary veins from the external superficial surface of the head, and therefore if the scalp wound is infected, it is easy for the infection to drain to the sinuses and then infect the meninges
where is the superior sagittal sinus
at the top of the falx cerebri
where is the inferior sagittal sinus
at the inferior margin of the falx cerebri
where is the straight sinus
where the inferior sagittal meets the great cerebral vein of Galen - runs along the roof of the tentorium towards the occipital protrubrence
where is the confluence of sinuses
where the straight sinus meets the superior saggital sinus
where are the transverse sinuses
the run along the L and R roots of the tentorium cereblli
where is the sigmoid sinus
the transverse sinus gets to the petrous part of the temporal bone –> they leave the tentorium and snakes down to the jugular foramen to associate with the internal jugular vein
what are the 8 venous sinuses of the brain
superior sagittal inferior sagittal straight transverse sinuses sigmoid sinuses superior petrosal sinus inferior petrosal sinus cavernus sinus
where is the cavernus sinus
associated with the dura that lines either side of the body of the sphenoid
what is the importance of the cavernus sinus
important structures run through this sinus to access their foramina to exit the skull
the MMA is a branch of the…
maxillary artery
which foramina does the MMA enter the skull through
the foramen spinosum –> middle cranial fossa
what happens to the MMA once it has entered the skull
it splits into an anterior and posterior division and then both groove the internal aspect of the terion
in which layer of the head does the MMA run through
the extradural space
why is a tear of the MMA a medical emergency
because blood accumulates in the extradural space (space does not give) –> IC pressure rises as it is an artery –> brain is squished –> brainstem pushed through the foramen magnum –> cardiorespiratory arrest
why is a tear of the cerebral veins entering the superior sagittal sinus not as big of an emergency as tearing the MMA
because the collection of blood will be slower (venous)
what are the spinal roots of the upper limb dermatomes?
C4-T1 (same as brachial plexus)
what are the spinal roots for the lower limb dermatomes?
L2-S2 (nerve roots for the femoral and sciatic nerves)
what are the 3 key landmark dermatomes?
C7 = middle finger T10 = umbilicus L5 = big toe
Shoulder: myotomes involved in flexion and extension
F = C5 E = C6-7
Elbow: myotomes involved in flexion and extension
F = C5-6 (5,6 pick up sticks) E = C7-8 (7,8 lay them straight)
Wrist: myotomes involved in flexion and extension, and supination and pronation
F = C6-7 E = C6-7 S = C6 P = C7-8 (pronate, 7, 8)
Digits: myotomes involved in flexion and extension, and abduction
F = C7-8 E = C7-8 Abduction = T1 (C8)
Hip: myotomes involved in flexion and extension
F = L2-3 E = L4-5
Knee: myotomes involved in flexion and extension
F = L5 and S1 E = L3-4 (kick the door)
Ankle: myotomes involved in flexion and extension, and inversion and eversion
F = L4-5 E = S1-2 (buckle your shoe) I = L4-5 E = L5, S1
where is the 3rd ventricle located
inbetween the right and left thalamus
how is the 3rd ventricle connected to the lateral ventricles
by the interventricular foramen (above the anterior thalamus)
how is the 3rd ventricle connected to the 4th ventricle?
cereberal aqueduct caudally (in between cerebellum and pons/medulla) - connects to 4th ventricle
what is the order of CSF flow through the ventricles
lateral -> 3rd ventricle -> 4th
what is the septum pellucidum
the thin band of tissue that separates the R and L lateral ventricles
what is the importance of the calcarine sulcus and where is it
in extends back to the occipital pole - landmark for primary visual cortex
what makes up the brainstem
midbrain, pons and medulla oblongata
what are the landmarks for the hypothalamus
the mamillary bodies optic chiasm marks the anterior limit
what are the 5 layers of the scalp
S - skin C - connective tissue A - aponeuroses L - loose CT P - periosteum
where does the scalp extend to/from
from the external occipital protrubrence behind right over the head to the supraorbital margins anteriorly
what is the aponeuroses of the scalp
the aponeuroses of the occipital frontalis muscle
what does the aponeuroses of the scalp allow you to do
move the forehead muscles –> wrinkles
what does the loose CT layer of the scalp allow you to do
allows the first 3 layers of the scalp to move over the pericranium which is fused to the skull
what is the significance of the CT layer of the scalp
has very rich anastomoses between the branches of the internal and external carotid arteries
what are the 3 reasons why a scalp lacerations cause profuse bleeding?
1) rich anastomoses between internal and external carotid arteries in the CT layer of the scalp 2) if the aponeuroses is severed - the occipitalis and the frontalis bellies of the occipitofrontalis muscle will make the wound gape open 3) fibrous septa of the CT layer prevent vasoconstriction of the blood vessels required for clotting
where do the muscles of facial expression arise from and attach to
arise from the bone/fascia attach to the skin of the face
where are the muscles of facial expression
surround the orifices of the face (eyes, nose, mouth)
what are the two sets of muscles of facial expression
sphincters - orbicularis dilators - depressors/dilators/levators
what is the developmental origin of the muscles of facial expression
arise from the 2nd pharyngeal arch
what nerve supplies the muscles of facial expression
cranial nerve 7 - facial nerve
what are the nerves that supply the anterior and posterior sections of skin on the face
anterior - via cranial nerve 5 (trigeminal nerve) posterior - via dorsal rami of C2 and C3 - spinal nerves
what landmark demarcates the anterior and posterior skin of the face
the ears
what are the divisions of the anterior sensory innervation of the skin
trigeminal nerve branches and gives innervation to the: opthalmic division (V1) maxillary division (V2) mandibular division (V3)
what are the foramina associated with the divisions of the trigeminal nerve (supply the skin on the anterior face)
V1 - othalmic - superior orbital fissure V2 - maxillary - foramen rotundum V3 - mandibular - foramen ovale
2 major branches of the internal carotid artery supplying the face
supraorbital branches supratrochlear branches
4 branches of the external carotid artery supplying the face
- facial artery - superficial temporal artery - posterior auricular artery - occipital artery
what is the course of the facial artery (from the external carotid)
tortuous course over the face to the medial angle of the eye giving branches to the nose, cheeks and lips medially and laterally
course of the superficial temporal artery (branch of external carotid)
passes up to the side of the scalp on the lateral side
what are the 6 lymph nodes associated with the face
submental nodes submandibular nodes mastoid nodes occipital nodes pre-auricular nodes parotide nodes
where do the 6 lymph nodes of the face drain to
the deep cervical nodes
where is the parotid gland
- below the zygomatic process of the temporal bone - infront of the mastoid process of the temporal bone and ear - above the angle of the mandible - behind the masseter muscle - superficial to the styloid process of the temporal bone
why is mumps so painful
because the parotid gland gets swelled up - and because of the dense fibrous envelope of fascia surrounding it - not stretch - pressure =pain
how does saliva get to the mouth from the parotid gland and what is its course
through the parotid duct - emerges from the anterior border of the gland onto masseter, where in then turns inwards at the anterior edge to pierce buccinator and enter the oral cavity near the 2nd upper molar
what are the major structures within the parotid gland from superficial to deep
- cranial nerve 7 (facial nerve) (motor supply of muscles of facial expression) - retromandibular vein - external carotid artery scattered throughout - parotid lymph nodes
how does the facial nerve exit the skull
goes through internal auditory meatus –> course through the temporal bone –> through the stylomastoid foramen onto the back of the parotid gland
course of the facial nerve
- posteriorly - auricular branch –> goes back to supply the occipitalis belly of occipitofrontalis - enters the substance of the parotid gland creating a plexiform arrangement = pes anserinus - gives of terminal branches
what are the 5 terminal branches of the facial nerve
temporal zygomatic buccal mandibular cervical (Tall Zulus Bear Many Children)
how is the retromandibular vein formed
by the superficial temporal vein and the maxillary veins
within the structure of the parotid gland… what branches are given off by the external carotid artery
maxillary artery and superficial temporal artery
which part of the ventricular system does not contain choroid plexus
cerebral aqueduct
what type of haemorrhage can cause thunderclap headache?
subarachnoid haemorrhage
what percentage of cardiac output goes to the brain
10-20%
what is the advantage of the circle of willis
it anastomoses - therefore gives some leverage for continued perfusion of the brain if there is a blockage
what are the major arteries that come to supply the circle of willis and where do they branch from
internal carotid (branch of common carotid) vertebral artery (branch of subclavian)
where do the internal carotid and vertebral arteries enter the CNS
internal carotid - through carotid canal vertebral artery - through transverse foramina and through foramen magnum
where is the basilar artery
formed at the posterior end of the circle of Willis by the joining of the two vertebral arteries
what are the main branches of the circle of willis and what do they branch from
anterior cerebral artery - from internal carotid middle cerebral artery - from internal carotid posterior cerebral artery - form basilar artery
where are the anterior communicating arteries and the posterior communicating arteries
anterior - between the 2 anterior cerebral artery posterior - between the internal carotid and the posterior cerebral artery
what does the anterior cerebral artery supply
medial part of the frontal and parietal lobes
describe the course of the anterior cerebral artery
branches off the internal carotid just lateral to the optic chiasm and then projects medially into the longitudinal fissure and then hooks over the genu of the corpus callosum and then goes backwards over the top of it
what would result as a stroke of the anterior cerebral artery
contralateral sensory loss and motor loss in the lower limbs
where does the middle cerebral artery supply
most of the lateral surface of the frontal, parietal, temporal and occipital lobes
what would happen as a result of a stroke of the middle cerebral artery
contralateral sensory loss and motor loss of the upper limbs and face, and if on the left hemisphere –> aphasia
describe the course of the middle cerebral arteries
projects through the lateral fissure out towards the lateral aspect of the cerebrum
describe the course of the posterior cerebral artery
heads towards the occipital lobes
where does the posterior cerebral artery supply
most of the medial and inferior surfaces of the temporal and occipital lobes
what would happen as a result of a stroke in the posterior cerebral artery
visual problems - in particular, loss of the contralateral visual field
where do the lenticulostriate arteries branch off
the middle cerebral artery
what do the lenticulostriate arteries supply
basal ganglia and internal capsule
where do the anterior perforating branches come off and what do they supply
come off the anterior communicating artery supply part of the optic chiasm and the anterior aspect of the hypothalamus
where do the posterior perforating branches come off and what do they supply
come off the posterior communicating artery supply the ventral midbrain and the posterior part of the hypothalamus and thalamus
what supplies the blood to the pons
the pontine branches (that come off the basilar artery)
what does the anterior choroidal artery supply
the optic tract, lateral ventricles and the hippocampus
what are the 4 main branches that supply the brainstem and cerebellum
anterior spinal artery anterior inferior cerebellar artery posterior inferior cerebellar artery superior cerebellar artery
what is the route of the anterior spinal artery
follows the ventral-median fissure of the spinal cord
which arteries supply the cerebellum
posterior inferior cerebellar artery anterior inferior cerebellar artery superior cerebellar artery
explain the blood supply to the midbrain
most comes from the posterior cerebral artery - superior cerebellar artery gives a little branch to the colliculi as it goes past to the cerebellum
explain the blood supply to the medulla
3 arteries: - anterior spinal artery - supply median medulla - vertebral artery - supply around the olives (ventrolaterally) - posterior inferior cerebellar artery - does most of the posterolateral part of the medulla
what is medial medullary syndrome and what are the symptoms
the symptoms associated with blockage of the anterior spinal artery - lack of blood supply to the median strip of the medulla –> ipsilateral paralysis and atrophy of the tongue muscle (with deviation towards the side of the lesion) –> contralateral hemisensory loss (medial lemniscus) –> contralateral hemiparesis - UMN (pyramids)
explain the blood supply to the spinal cord
anteriorly - anterior spinal artery posteriorly - posterior spinal artery Anastomose around the spinal cord - giving branches inwards dorsally or ventrally (Both are reinforced all the way down by the segmental branches of the aorta)
