Chapter 5: Internal Anatomy of the Spinal Cord Flashcards
What is located in gray matter?
cell bodies of the neurons
What is located in white matter?
ascending and descending axons
What do the propriospinal axons do?
they interconnect different segments of the spinal cord
Dorsal horn
sensory
ventral horn
motor
central canal
dividing pint between sensory and motor portions of the spinal cord
Where do peripheral sensory nerves enter?
through the dorsal root
What is nocioceptive information
noxious, painful, tissue damaging information
amount of gray matter is greatest in what region?
regions that innervate the limbs
Why do the brachial and lumbosacral enlargements have large ventral and dorsal horns?
they are large because of the extensive motor and sensory input from the limbs
As you ascend rostrally through the spinal cord the amount of white matter….
increases because ascending tracts of axons (sensory) receive more input at rostral levels
There is much less white matter in which areas?
the low sacral region of the spinal cord
Thoracic spinal cord
only has medial motor nuclei to innervate trunk muscles
has smaller and less complicated dorsal horn and intermediate gray
contains the intermediolateral cell group and Clarkes nucleus
dorsal funiculus
lies between the two dorsal horns and carries epicritic information to the brainstem
lateral funiculi
lateral to the gray matter and between the dorsal horn and the exit of the ventral roots
ventral funiculus
region of white matter between the two ventral roots
gracile fasiculus
located medially it is made up of dorsal root axons entering the cord at the mid-thoracic and more caudal levels
cuneate fasiculus
located laterally it is made up of axons that enter more rostrally (cervical and upper thoracic)
Where is the anterolateral system located?
found anteriorly and laterally in the white matter.
This system terminates mainly in the dorsal horn
Which side of the body carries protopathic information?
the axons on the OPPOSITE side carry pain and temperature information
What is the most important descending nerve tract?
the lateral corticospinal tract (a.k.a pyramidal tract)
lateral corticospinal tract is concerned with…
distal motor control
anterior corticospinal tract is concerned with…
proximal and axial muscular movement
Which tract is part of the lateral extrapyramidal pathway?
the rubrospinal tract which originates in the red nucleus of the midbrain
axons immediately cross over to the opposite side
works together with the lateral corticopsinal tract for distal arm control and movement
What tracts make up the medial extrapyramidal pathways?
reticulospinal tract which arises from the reticular formation of the pons and medulla
vestibulospinal tract arises from neurons int he vestibular nuclei
Both of these tracts work with the anterior corticospinal tract
Hypothalamo-reticulo-spinal pathway
descending hypothalamic control of teh inermediolateral cell column
damage to any of these descending axons above T1 can cause Horner’s syndrome
symptoms of Horner’s syndrome
damaged sympathetic control of the sup. cervical ganglion
small pupil
ptosis (droopy eyelid)
absence of sweating on one side
symptoms of a lower motor neuron lesion
lesion is to peripheral nerve flaccid paralysis decreased DTR hyporeflexic or areflexic fasciculatons (rippling movements)
UMN lesion
damage to the brains descending motor pathways period of spinal shock slow disuse atrophy hyperactive reflexes spasticity spastic paralysis positive babinski response
What happens during a period of spinal shock?
flaccid paraplegia is seen first
spinal reflex circuits are unresponsive but remain intact
