week 9 - neuro (spinal cord and embryology) Flashcards
What are the main physical features of the spinal cord?
Dorsal median sulcus, ventral median sulcus, dorsal, ventral and lateral horns, white matter, grey matter, central canal
Where are the two enlargements of the spinal cord?
Cervical (C3-T1) to upper limb and Lumbar (L1-S3) to lower limb
What is the end point of the spinal cord called?
The conus medullaris
What is the terminal strand of connective tissue at the end of the spinal cord called?
The filum terminale
Where does the spinal cord end in babies?
L3
Where does the spinal cord end in adults?
L1/2
What are the features of the dorsal roots?
Primary afferents, cell bodes in dorsal ganglia
What are the features of the ventral roots?
Efferents, cell bodies in spinal root grey matter
What happens to the two roots when they leave the spinal cord?
They fuse near the intervertebral foramen and form a mixed spinal nerve, this divides into a small dorsal and a larger ventral ramus
Where do the cell bodies of lower motor neurons usually lie?
In the ventral horn of the spinal cord, brainstem motor nuclei of the cranial nerves with motor modalities
What is the grey matter of the spinal cord made up of?
nerve cell bodies, dendrites and synapses
Where do the nerves of muscles with the same function arise from?
The same groups of motorneuron pools - grouped together (motorneurons supplying a particular muscle are in the same location)
Where do the nerves of antagonistic muscles arise from?
The same horizonal plane as their agonist
What are rexed lamina?
ten layers of grey matter to label portions of the grey columns of the spinal cord
What is contained within the white matter of the spinal cord?
The ascending and descending tracts
What are the most dorsal tracts of the spinal cord?
Faciculus gracilis, facilulus cuneatus
What are the most ventral tracts of the spinal cord?
Tectospinal, ventral corticospinal, lateral vestibulospinal and pontine reticulospinal
What are the six main descending tracts?
Corticospinal, corticobulbar, tectospinal, rubrospinal, vestibulospinal, reticulospinal
What does the corticospinal tract do?
control of voluntary muscles of the body
What does the tectospinal tract do?
head-turning in response to visual stimuli and blinking reflex
What does the rubrospinal tract do?
assists in motor functions - regulates flexor and extensor tone
What does the vestibulospinal tract do?
muscle tone and posture - body balance
What does the reticulospinal tract do?
spinal reflexes and maintains muscle tone when standing and walking
What are pyramidal and extra-pyramidal tracts?
pyramidal - originate in motor cortex, voluntary control of striated muscle
extrapyramidal - originate in brain stem, involuntary and automatic control of muscle tone, balance, posture and modulation of motor plans
What are first order/upper motor neurons?
from the cerebral cortex or brainstem to spinal cord - synapsing in the anterior gray horn
What are second order/lower motor neurons?
From spinal cord to skeletal muscles innervating them
What are the two pyramidal tracts?
corticospinal and corticobulbar
What are the four extrapyramidal tracts?
rubrospinal, vestibulospinal, reticulospinal and tectospinal
What do the corticobulbar tracts do?
From UMN in primary motor cortex terminating in the brainstem in the motor nuclei of the cranial nerves. LMN carry on as the cranial nerves and innervate the muscles of the head and neck