Special Senses Anatomy Flashcards
What is the Stria of Gennari?
Well developed layer IV of V1
Inputs from thalamus
Where are the dorsal and ventral cochlear nuclei?
Dorsolateral surface of the medulla
Where is the lateral lemniscus?
Pons
As ascend, moves dorsally to lie superficially
SO and cochlear fibres to rectum IC of midbrain
Where is the MLF?
Runs through the whole brainstem
Continues caudally into the upper cervical segments
For vestibuloocular eye movements, connects vestibular nuclei to oculogyric nuclei
For head movement, connects superior colliculus to cervical motor neurons in upper spinal cord
Dorsal medulla
Deep to aqueduct in midbrain
What are the four vestibular nuclei?
Superior inferior lateral medial
Which vestibular nucleus gives rise to the vestibulospinal tract? What does it do?
Balance
the lateral/Deiter’s nucleus
Large neurons
Which vestibular nucleus projects to the thalamus?
Superior
Where do the striate arteries enter and what is their significance?
Anterior perforated substance
Supply internal capsule and striatum
Susceptible to stroke
What is the function of the pretectal projection of the visual pathway?
Pupil response
What is the function of the superior chiasmatic nucleus projection of the visual pathway?
Circaidan rhythms
Where does the optic radiation run? What are lesions in it called?
LGN
Curls around temporal horns, atria and occipital horns of LVs
In parietal cortex: contralateral inferior quadrantanopia
In temporal cortex: contralateral superior quadrantanopia
Where is V1? What are lesions in part of it called?
Occipital lobe around the banks for the calcarine fissure
Scotoma
What do optic chiasm lesions give?
Bitemporal hemianopia
What do optic tract lesions give?
Homonymous hemianopia
Where is the oculomotor nucleus?
Upper midbrain
Midline
What can MLF damage be caused by and lead to?
MS
Nystagmus, diplopia, defects in gaze control
How do eye movements happen?
Eye fields in cerebral cortex (frontal and parietal)
Project to retinotopic map in SC
Gaze centres in reticular formation of pons translate position into appropriate motor commands to the three oculogyric nuclei, carried in MLF
What are the major thalamic nuclear groups? What do they each do?
Medial, ventral, anterior
Ventral:
- Ventroposterior ascending somatosensory relays
- Ventrolateral relays from cerebellum and basal ganglia to primary motor cortex
- Ventroanterior relays from cerebellum and basal ganglia to supplementary motor areas
Posterior to all of these LGN and MGN
Anterior:
- Projects to cingulate gyrus
- Important for perception of internal emotional state
Medial + Pulvinar:
- Cortico-thalamo-cortical relays
- Project to areas of association cortex
- Medial to prefrontal association area
- Temporal-parietal-occipital association area: input from pulvinar
What is a major input to the anterior thalamus?
Mammillary bodies of the hypothalamus, which are important for the formation of declarative memory
Which are the largest thalamic nuclei?
The medial and pulvinar
What is Brodmann’s map?
A map of the cerebral cortex
52 areas based on cytological structure
What is the Brodmann number for the primary motor cortex?
4
What is the Brodmann number for the premotor and supplementary motor areas?
6
What is the Brodmann number for the primary somatosensory cortex?
3, 2, 1
What is the Brodmann number for V1?
17
What is the Brodmann number for the primary auditory cortex?
41
How big is a brain? How much of it is primary cortex and how much association cortex?
1200cm2
Primary 65-70cm2
Association 1130cm2
Where is the uncus?
The most anterior part of the para-hippocampal gyrus in the MTL
Where is the primary cortex for taste?
Anterosuperior temporal just post to lateral fissure
Which way do the layers of cortex run?
I = superficial, VI = deep
What do the layers of the cortex do?
I molecular layer. II, III project to other cortical layers IV thalmic input V output to subcortical structures VI feedback to thalamus
What do the layers of the cortex look like?
I molecular layer. fibres parallel to cortical surface, but very few neurons, so not visible with Golgi or Nissl stain
II Outer granular layer - small rounded neurons
III Outer pyramidal layer - triangle shaped pyramidal neurons
IV inner granular layer
V inner pyramidal
VI Multiform layer - thin innermost with some scattered cells in it
What does Golgi stain stain?
Entire cells
What does Nissl stain stain?
Nucleic aicds
What does Weigart stain stain?
Myelinated axons
What does the primary motor cortex look like histologically?
Fat layer V output
Few granule cells in layer IV
What does association cortex look like?
Lacks anatomical specialisation in any particular layer - homotypic
What is 3 layered cortex and what is 4-5 layered cortex called? Where do you find it?
Allocortex - hippocampus
Juxtallocortex - parahippocampal gyrus/cingulate gyrus
What are auditory processing disorders?
Apparatus of ear is functional but CNS deficits make auditory processing difficult
Can affect different aspects of hearing e.g. sound recognition and sound localisation
What is anosmia/hyposmia/dysosmia?
Anosmia - inability to detect odours
Hyposmia - decreased ability to detect odours
Dysosmia - poor identification of odour
Give two examples of dysosmia
Phantosmia: perception of smell in the absence of an odorant
Agnosia: odours can be detected but not distinguished
What is retrosigmoid craniotomy?
Removing and replacing the bone posterior to the sigmoid sinus and inferior to the transverse sinus
Allows access to lateral cerebellum and cerebellopontine angle
Used to remove ependymoma
What is an ependymoma?
Tumour that arises from the ependymal cells that line the ventricles, esp 4th ventricle and in childhood
