Neuroanatomy Flashcards
Left hemifield projects to…?
Right hemifield projects to…?
RIght occipital lobe
Left occipital lobe
What part of visual feild does nasal retina see? waht about temporal retina?
Temporal half of visual field
nasal feild
Central scotoma. Location of leision?
macula degeneration / retina
Compete monocular vission loss. Location of leision?
optic nerve
bitemporal hemianopia. Location of leision?
optic chiasm
Contralateral homonomous hemianopia. Location of leision?
- Optic tract (from chiasm to lateral geniculate nucleus)
- Optic radiations
- Upper AND lower bank of the calcarine fissure (occipital lobe)
contralateral superior quadrantanopia? Location of leision?
Inferior meyers loops (optic raditasions) OR the lower bank of the calcarine fissure (occipital lobe)
contralateral inferior quadrantanopia? Location of leision?
superior meyers loops (optic raditasions) OR the upper bank of the calcerine fissure
Contralateral homonomous hemianopia with macular sparing. Location of leision?
PICA occlusion affecting both upper and lower banks of the calcerine fissure
Where is the lateral geniculate nucleus found?
Thalamus which is in the forebrain (superior to teh mid brain and hind brain)
Where do the inferior meyers loops / optic radiations travel? What about superior loops?
temporal lobe
parietal lobe
What does the MCA supply? superior and inferior division of MCA
MCA supplies the parietal lobe, frontal lobe and temporal lobe
- SUperior divisions mainly supply the frontal lobe (ioncluding Broccas area), inferior divisions mainly supply the temporal lobe, including wernikes area
What are the three sulci that define the temporal lobe?
Lateral sulvus seperates parietal lobe from temporal
-> superior temporal gyrus
superior temporal sulcus
-> middle temporal gyrus
inferior temporal sulcus
-> inferior temporal gyrus
What does the PCA supply?
The posteriomedial temporal lobe / inferior gyrus is supplied by the PCA
- The occipital lobe
- The midbrain
- splenium or corpus collosum (most posterior thickest part)
What does the ACA supply?
Mainly the parasagital regions of teh parietal and frontal lobes
- anterior corpus calosum
Describe the circle of willis? From bottom to top (in typical image representation)
Right and left vertebral arteries
- posterior inferior cerebelar arteries branch from vertebral arteries
Anterior spinal artery joint vertebral arteries just distal to vertebral artery union point into basilar artery
Bassilar artery has several branches
- anterior inferior cerebelar artery bilaterally
- then lots of pontine artery branches bilaterally
Basilar artery then splits like a palm tree into superior cerebellar artery bilaterally and PCA bilaterally.
the posterior communicating artery branches off from the PCA just distal to the origin of teh PCA from the bassilar. Posterior communicating and teh anterior communicating arteries froma circle with the PCA branching bilaterally from the middle of teh circle, and the ACA comiung from teh top of teh circle
What are the sections of the ACA?
A1 - precommunicating ACA
A2 - post communicating (between ACOM and callosocommunicating artery)
A3 - pre calossal
A4 - Supra callossal
A5 - post callosal
Describe the course of the PCA and the sections of the PCA?
basilar artery runs cranially in the central groove of the pons twards the midbrain
the PCA divides then wraps around the midbrain heading posteriorly towards the occipital lobe
P1 pre communicating - between origin and PCOM
P2 - from the PCOM around teh midbrain
P3
P4
P5 - terminal branches
Crossed signs in face and limbs = …?
Brain stem stroke
What are the parts of the brain stem?
Inferior to superior:
- Medulla oblongata
- Pons
- Midbrain
Thal is generally not considered part of the brain stem
What is part of the hindbrain?
Hinddbrain
- medulla oblongata
- Pons
- cerebellum
Midbrain
- midbrain
Forebrain
- everything else (inc cerebruim, thal, hypothal)
What is teh primary blood supply of the pons?
Basilar artery (pontine branches)
What is does the posterior inferior cerebellar artery supply?
Lateral medulla of brain stem
poterior inferior section of cerebellum
Blood supply of the medulla oblongata?
Lateral medulla - PICA
medial medulla - anterior spinal artery
- area between teh medial and lateral aspects supplied by direct branches from teh distal vertebral arteries
Lateral medullary syndrome features? Why are each of these features found?
- vertigo - vestibular mucleus found in lateral medulla
- Ipsilateral ataxia - inferior cerebellar peduncle
- Dysphagia / dysphonia - Nucleus solitaris (Vagal nerve nucleus)
- Ipsilateral facial numbness - spinal nuc of trigeminal nerve
- Horners syndrome - descending sympathetic fibres
- Contralateral limb weakness - anterior spinothalamic tract
Why does a pt with lateral medullary syndrome get contra-lateral limb numbness to pain and temperature?
Pain and temp carried in anterior spinothalamic tract
1st order sensory neuro from peripheries synapse in the spinal cord. then the second order neurons cross over AT THAT LEVEL, before ascending up the synapse in the thalamus
What is alexia without agraphia? what causes?
Why does this occur (ie what infarcted structure is repsonsible for this higher order loss)?
Alexia without agraphia is when you can recognize indivdual words (alexia), but can write sentances to dictation (without agraphia)
Due to LEFT occipital infarct due to PCA stroke
The splenium of the corpus callosum allows the occipital lobe (responsible for seeing things) to connect the angular gyrus (attributing meaning to them)
Describe cerebellar anatomy?
Vermis (midline section)
cerebellar hemispheres
Truncal ataxia. location of cerebellar leision?
Apendicular (hands and arms) or limb ataxia. Location of cerebellar leision?
cerebellar vermis
Cerebellar hemispheres
Right cerebellar leision will cause ataxia on which side of body?
Why does this occur on this side?
Right
- double crossing of cerebellar fibres
Left eye amarosis fugax. WHich artery affected?
Left carotid, left opthalmic, RO left retinal
- can involve into contralateral stroke -> need to investigate the left carotid
Retina blood supply?
Outer retina - avascular, relies on blood from choroidal arteries
Inner retina - ceentral retinal artery and vein
- further divided into superior and inferior branches of retinal artery
How to tell difference between arteries and veins on retinal examination?
arteries often cross veins because more superficial
Veins are thicker and darker
Blood supply of the optic nerve? If have retinal artery occlusion, how will the optic disc appear on examiantion?
Posterior cilliary artery (branch of the opthalmic artery
Normal, because retinal artery does no supply CN2 therefore will not see optic head swelling / pappiloedema
Weakness of which muscle differntiates stroke from bells palsy? Why?
frontalis
- frontalis has bilateral invervation. therefore stroke in one hemisphere will not affect it because still has supply from other hemi
Inervation of levator palpebrae superioris? Invervation of superior tarsal muscles?
Clinical significance?
Occulormotor (CN3)
Post ganglionci sympathetic axinon from cervical chain
Horners syndrom can result in ptosis
CN3 plasy results in ptosis too
Predominate site of cerbrospinal fluid production? Where is it?
CHoroid plexus
- lateral ventricles
Describe the flow of CSF?
Choroid plexus
Lateral ventricles
third ventricles
cerebral aqueduct
fourth ventricle
Exits via foramen of Luschka / median apeture are circulates in the subarachnoid space, before being absorped by teh arachnoid greanulkations
Features of horners syndrome? Best initial test?
unilateral ptosis, meiosis (constriction), facial anhydrosis (loss of facial sweating)
CT carotid angiogram ? life threatening vascular pathology such as dissection or aneurysm
Describe the order of neurons in the SNS and their path?
1st, 2nd, 3rd order neurons in SNS
- 1st order - thalamus to thorasic spinal cord (descend via medulla hence the lateral medullary syndrome horners)
- 2nd order - synapse with first order in thorasic spine T1,2 and travel superiorly via the sympathetic chain to the cervical ganlion (level of bifurcation of carotid artery)
- 3rd order - synapse in the cervical SNS ganglion. Fibres that inervate the sweat glands in face travel with external carotid, fibres that inerate the lid and eye travel with internal carotid
Caverous ICA aneurysm. Clinical manifestations?
Many potential findings:
- Horners syndrome
- CN3 (occulormotor) palsy
- CN6 (abducens) palsy
- ETC
Horners. How to accentuate the miosis findings?
Darkness (normal pupil will dilate, other one wont)
Corneal reflex arc?
CNV (nasocilliary branches of opthalmic division (v1) of CN5)
- trigeminal sensory nucleus (pons)
- facial motor nucleus (pons)
CV7 - activates obicularis oris
Which are parasympathetic cranial nerves?
3,7,9,10 (SBS,7,9,10 channels)
- these nerves carry PNS fibres along with their other fibres
3 - pupiliary reflex
7 - lacrimal glands, submandibulkat/sublingual salivary glands
9 - parotid gland
10 - bronchopconstriction/ feeding/digesation
Rule of 4 brain stem?
4 CN per section of brain stem (midbrain, pons, medulla)
- Medulla 9-12
- pons - 5-8
- Midbrain 3, 4
Mass at cerebellar pontine angle, which CN affected?
V, VII, VIII
Pons has CN 5,6,7,8
-6 6 is much more anterior than the rest, cerebellar pontine angle is lateral hence will affect these nerves
Cavernous sinus syndrome, which CN affected?
CN 3, 4 6 (EOM muscles)
CN 5 also runs through here but further away from cavernous ICA
Jugular foramen syndrome. Which CN affected?
9,10,11
COmpression of these nerves in tehe jugular foramen
Severe clawing of 4th and 5th fingers. Leision?
Ulna nerve neuropathy at the wrist
- ulna nerve problems at teh wrist can appear clinically much worse than at the elbow
Inervation of the deltoid muscle?
Axiliary nerve
Peripheral nerve responsible for elbow flexion?
Musculocutaneous nerve
What is responsible for majority of elbow, wrist and finger extension? What are the exceptions to this?
Radial nerve
- Exceptions
Anterior forearm compartment (wrist and finger flexors) innervation and the two exceptions?
Median nerve inervation
- 2 muscle exceptions - FDP (flexor digitorum profundus) of the 4th and fifth finger, and FCU (flexor carpi ulnaris)
FDP (ulna nerve)
FCU - (Ulnar nerve)
Innervation of the intrinsic muscles of the hand?
All muscles inervated by Ulna nerve EXCEPT LOAF muscles
L - lateral 2x lumbricles (median)
O - opponena policis (OK sign) (median)
A - Abductor policis brevis (Median)
F - Flexor policis brevis (median)
How is ulna claw test performed?
“Please open your fist”
- pt wont be able to extend 4ht and 5th digit, leading to a claw hand
Explain claw hand?
4th and 5th finger lumbricles are inervated by ulna nerve
These are responsible for extension of the 4th and 5th fingers at the DIP and PIP
therefore loss of these muscles will lead to unoposed flexion of the fingers and DIP and PIP
- also will have unopposed extension at MCP
If have leision at elbow, then FDP is also lost. THis is the muscle that is primarily responsible for the unopposed flexion above. therefore we will also lose this unopposed flexion leading to the loss of the claw hand
what are the two branches of teh median nerve (splits proximal the the wrist)? what is the clinical implication?
palmar cutraneous branch (travels outside of the carpel tunnel)
Digital cutaneous branch (travels in teh carpel tunnel)
therefore in carpel tunnel will have sparing of palmar sensation
Severe carpel tunnel will also involve which muscles of the hand?
LOAF muscles
Compression of radial nerve at spiral grove. what sings and why?
Spiral grove is posterior humerus
- therefore if fracture humerous can get radial damage at spiral grove
- Loss of wrist finger extensors - leision proximal to posterior interoseus nerve
- Loss of forearm elbow extensors - lesision proximal to posterior antebrachial cutaneous nerve
- Preservation of arm elbow extensors (Triceps) - lesion distal to bronchial cutaneous nerves
Compression of radial nerve at elbow. what sings and why?
- Loss of wrist finger extensors - leision proximal to posterior interoseus nerve
- preserved forearm elbow extensors - lesision distal to posterior antebrachial cutaneous nerve
- Preservation of arm elbow extensors (Triceps) - lesion distal to bronchial cutaneous nerves
Sensation of dorsum of hand will be effected because the superficial branch of teh radial nerves originates distally to the elbow
Man has wrist and finger drop. Sensation normal. Which nerve affected?
posterior interoseus nerve
- sensation intact therefor not common radial nerve (which includes the superficial branch of radial nerve)
Winging of scapula caused by which nerve? Why is this muscle relevant?
Long thorasic
- inervates the seratus anterior
Long thorasic directly comes off teh C5,6 roots proximal to the plexus
- therefore can be used to distignuis plexus injuries from more proximal leisions
Compartments of the upper leg and role and inervation?
Anterior
- Knee extension (excepts rectus femorus also does hip flexion)
- Femoral inervation
Medial
- Hip adduction (except gracilis that also does knee flexion)
- Obturator nerve (Except abductor magnus which has sciatic inervation)
Posterior
- Knee flexion
- sciatic
- medial (adductors)
- posterior
Branches of the sciatic nerve?
Common perineal nerve
Tibial nerve
Compartments of lower leg, muscle / function and innervation (nerve and root)?
Anterior compartment
- Muscle: tibialis anterior, extensor halicus longus
- Function: dorsiflexion ankle and toe
- Nerve: deep peroneal nerve
- Root: L4/5
Lateral compartment
- Muscles: peroneus longus/tirtius
- FUnction: eversion
- Nerve: superficial peroneal
- Root: L5/S1
Posterior compartment (superfical component)
- Muscle: gastrocnemius
- Function plantar flexion
- Nerve: tibial
- Root S1/2
Posterior compatment (deep component)
- Muscle: Tibialis posterior
- Function: inversion
- nerve: tibial
- root L4/5
all foot movements + Ankle jerk + knee flexion weakness indicates sciatic nerve proximal leision
Proxmial sciatic leision. Presentation?
all foot movements + Ankle jerk + knee flexion weakness indicates sciatic nerve proximal leision
L5 radiculopathy. presentation
Inversion and eversion affected
Norm,al ankle reflex
Hip abduction weakness (due to tensor facia lata and gluteus minimus affected)
