Neuroanatomy Flashcards
What constitutes the brainstem?
The midbrain, pons, and medulla
Name and describe the types of glial cell.
Astrocytes - maintains BBB
Oligodendrocytes (CNS) and Schwann cells (PNS) - produces myelin
Microglia - similar to macrophages, immune function and antigen presentation
Ependymal cells - ‘neuroepithelium’ lines ventricles
What is grey and white matter?
Grey - neurones, cell processes, synapses, support cells
White - axons and their support cells
Where are the motor and somatosensory cortices located?
Motor - precentral gyrus
S’sensory - postcentral gyrus
Describe the blood supply of the brain.
ICA: gives MCA and ACA, as well as anterior choroidal arteries
Vertebral: combines to give basilar artery, which gives PCAs
Name the layers from skin to spinal cord.
Skin and subcut fat Supraspinous ligament Interspinous ligament Ligamentum flavuum Dura & arachnoid
What are the two primary anatomical concerns associated with LP?
Raised ICP - may cause herniation
Epidural fat contains venous plexuses - rupture can cause epidural haematoma
Describe the formation of a spinal nerve.
Anterior root (motor) + posterior root (sensory; has ganglia). Gives off anterior and posterior rami (mixed) and grey and white rami.
Describe the dorsal column pathway.
- Lower limb (fasciculus gracilis) central; upper limb (fasciculus cuneatus) ‘added on’
- synapses in medulla as nucleus gracilis / cuneatus
- decussates via internal arcuate fibres to VPL nucleus of thalamus
FG/FC -> medulla (nuclei) -> VPL -> X internal arcuate -> cortex
Describe the spinothalamic tract.
- nociceptors to dorsal horn
- decussates via Lissauer’s tract
- travels via medulla to VPL nucleus of thalamus
Describe the corticospinal tract.
Motor tract
- motor cortex, to posterior limb of internal capsule, cerebral peduncles, and basis pontis
- decussates in medullary pyramids
Name the lobes and features of cerebellum.
Anterior, posterior and flocculonodular lobes
Vermis (‘worm’) splits into lateral hemispheres, which supply lateral body.
Vermis supplies midline
Name the inputs to the cerebellum.
- spinal cord (proprioceptors)
- cerebral cortex (pons)
- vestibular apparatus
- inferior peduncle: vestibulocerebellar, spinocerebellar, olivocerebellar
- middle peduncle: corticopontocerebellar fibres, motor neurons via anterior pons
Name the outputs of the cerebellum.
Solely from PURKINJE cell layer to
- inferior peduncle (to vestibular system)
- superior peduncle (contralateral to origin to red/VLN of thalamus)
Name and describe the 3 functional divisions of the cerebellum.
- vestibulocerebellum (flocculonodular node - vestibular and eye movement)
- spinocerebellum (central, midline)
- pontocerebellum (lateral, communicates with pons)
Name the components of the basal ganglia, and their collective names.
- caudate nucleus
- putamen [striatum]
- globus pallidus [+ putamen = lenticular nucleus]
- [corpus striatum]
- subthalamic nucleus
- substantia nigra
Describe the function of the basal ganglia.
Facilitates purposeful movement, prevents unwanted movement, has a role in muscle tone and posture.
Lesions affect the contralateral side (‘talks’ to ipsilateral cerebellum).
Describe CN I’s course through the brain.
Directly to olfactory area (anteromedial temporal, posteroinferior frontal), bypassing the thalamus
Name the modalities of CN V.
- somatosensation (discriminative touch, vibration, pain, temp)
- proprioception (TMJ, mastication)
- motor (mastication, tensor tympani, mylohyoid, ant belly of digastric, tensor veli palatini)
Describe the sensory pathways associated with CN V.
- V1 ophthalmic: upper eyelid, cornea, conjunctiva, skin of root, bridge, and tip of nose
- V2 maxillary: lower eyelid, maxilla, ala of nose, upper lip
- V3 mandibular: skin over mandible/TMJ
Then travels to nuclei:
- mesencephalic (proprioception)
- pontine/principal (discriminative touch, vibration)
- spinal (/spinothalamic; pain and temperature)
Then travels to thalamus via the ventral trigeminothalamic tract; most fibres cross. Lower spinal pathology = perioral sparing
Name and describe the nuclei of CN VII.
Salivatory nucleus - parasympathetic (to submandibular and pterygopalatine ganglion)
Solitary - taste from anterior 2/3 of tongue; conveyed by chorda tympani
Spinal trigeminal - somatosensation associated with pinna/EAM
Geniculate nucleus - sensory nerve cell bodeis
Describe the motor supply of CN VII.
To Zanzibar By Motor Car:
- temporal [frontalis, orbicularis oculi]
- zygomatic [orbicularis oculi]
- buccal [buccinator, zygomaticus]
- mandibular [orbicularis oculi]
- cervical [platysma]
Name and describe the nuclei of CN IX.
- solitary [gustatory/posterior 1/3 taste tongue; commissural/baro- and chemoreceptors]
- spinal trigeminal [pinna/EAM]
- inferior salivatory [parasympathetic to parotid gland]
- nucleus ambiguus [stylopharyngeus]
Name and describe the nuclei of CN X.
- dorsal (motor) [parasympathetic except to heart]
- solitary [gustatory, commissural]
- spinal trigeminal [pain from dura, pinna/EAM]
- nucleus ambiguus [motor to pharynx / larynx, para to heart]
Describe the auditory pathway.
- spiral ganglion to ventral/dorsal cochlear nucleus / superior
olivary complex - to lateral lemniscus
- to inferior coliculus then the medial geniculate body of the thalamus
- primary auditory cortex and secondary (Herschel’s) gyrus
Describe the vestibular pathway.
- NB: no agreed primary cortex
- vestibular ganglion to vestibular nuclei (dorsolateral medulla)
then 3 main pathways
- to cerebellum (via inferior peduncle)
- to vestibulospinal tract and nuclei of CN III, IV, and IV (via medial longitudinal fasciculus, superior / inferiorly)
- to thalamus [and then cortex] by VPM nucleus (following medial lemniscus)
What and where are Broca’s and Wernicke’s areas?
- Broca’s area: dominant frontal lobe; concerned with production of speech
- Wernicke’s area|: superior temporal gyrus, concerned with understanding speech`
Describe the differences in Broca’s, Wernicke’s, and global aphasias.
[Broca - production; Wernicke - understanding]
- Broca’s aphasia: can understand speech, but has trouble producing/repeating it
- Wernicke’s aphasia: can produce speech, but cannot understand/repeat it
- Global aphasia: cannot produce, understand or repeat language
Describe transcortical motor, transcortical sensory, and mixed transcortical aphasias.
- TC motor: cannot produce, but can understand and repeat
- TC sensory - cannot comprehend, but can produce and repeat
- mixed TC - can repeat, but cannot understand/ produce
Describe the visual pathway.
- optic nerves
- optic chiasm, where nerves cross
- LGN
- optic tracts
- primary visual cortex, via Meyer’s loops
Describe the pupillary light reflex.
- pretectal nuclei (project bilaterally,
- Edinger-Westphal nucleus (CN III)
- parasympathetic fibres to ciliary ganglia
- short ciliary nerves constrict the pupils
Draw out the optic nerve/tracts and describe the visual defects seen in pathology in each area.
- optic nerve (1st part): monocular blindness
- optic chiasm: bitemporal hemianopia
- tract/LGN: homonymous hemianopia
Name the boundaries and landmarks of the back.
- neck (superior)
- gluteal region (inferior)
- upper and lower limbs (peripherally)
- T1 process, scapular spine, iliac crests, sacrum, coccyx
Name the main muscles of the back, and their position relative to the spinal cord.
- lateral (psoas major)
- immediately posterior (transversospinalis)
- posterior (erector spinae)
- posterolateral (quadratus lumborum, then latissimus dorsi most dorsal)
Name the components of the typical vertebrae.
- vertebral body
- vertebral arch (consisting of pedicles, then laminae)
- transverse processes
- superior and inferior articular processes
- spinous process
Describe the ligaments seen in the spinal cord.
- ligamentum flavuum: short ligaments, posterior to spinal cord, connects adjacent laminae
- posterior longitudinal ligament: anterior to spinal cord; narrow and weak, prevents over-flexion
- anterior longitudinal ligament: broad and strong, helps prevent over-extension
- supraspinous ligament: connects tips of the spinous processes
- interspinous ligament: runs inbetween the spinous processes themselves.
Describe the transduction of sense from dermatomes.
- AP produced in axons of stimulated receptors
- synapse within dorsal root ganglion then travel via dorsal root to spinal cord
- nerves that have >1 spinal nerve root (and therefore cross >1 dermatome) are given names
Describe the transduction of motor impulses to myotomes.
- AP generated in primary somatocortex, then conducted via UMN axons of the CST
- impulse reaches anterior horn
- stimulates LMN at level of necessary vertebrae
- passes through anterior/posterior rami to arrive at NMJ
Describe the reflex arc (e.g., with the patellar reflex).
- patellar ligament tapped
- quadriceps fibres stretched, initiates AP
- conducted via femoral nerve to dorsal horn of L4
- axons pass into dorsal horn, synapses on LMNs
- AP conducted via femoral nerve to reach quadriceps NMJ
- muscle contracts
Name the layers of the scalp.
Skin Connective tissue Aponeurosis Loose connective tissue Pericranium
What is the name of the meeting of sutures in the skull? What are the names of the regions superior and inferior to this?
Pterion - thinnest part of the skull, middle meningeal artery runs directly deep (‘God’s little joke’)
- superior: calvaria (skull cap)
- inferior: skull base
Name the main infoldings of the dura.
- falx cerebri (separates cerebral lobes in midline)
- tentorium cerebelli (separates cerebellum in midline)
- diaphragma sellae (forms roof of pituitary fossa)
Name the main herniation types in the brain, from superior to inferior.
- transcalvarial (through skull)
- cingulate [subfalcine] (under falx cerebri)
- central [transtentorial] (across tentorum cerebelli)
- upward cerebellar [transtentorial]
- uncal
- downward cerebellar [tonsillar]
Why may tonsillar herniation be particularly dangerous?
Compresses on vital centres in the medulla/pons (e.g., respiratory, cardiac)
