test 1: lecture 7 Flashcards
where does spinal cord end?
conus medullaris
lumbar and sacral nerves that travel past the conus medullaris are ___
cauda equina
dorsal root has what kind of nerves?
sensory (afferent)
ventral root have what kind of nerves?
motor (efferent)
___ is made of nerve cell bodies, dendrites and axons
gray matter
H shaped
another name for tracts?
fasciculi (pathways)
three funiculus of white matter in the spinal cord
dorsal funiculus
lateral funiculus
ventral funiculus
cervical spinal cord
Thoracic spinal cord
lumbar spinal cord
what part of the spinal cord has more grey matter then white matter?
lumbar
dorsal horn
intermediate gray
ventral horn
___ part of the spinal cord contains mainly neurons responding to sensory input
dorsal horn
___ part of the spinal cord contains some sensory neurons, some motor neurons, interneurons
intermediate gray
__ part of the spinal cord has mainly motor neurons whose axons exit the spinal cord
ventral horn
(blue)
3 divisions of the spinal gray matter
dorsal horn
intermediate gray
ventral horn
where is lateral horn found?
T1-L2
lateral horn
(T1-L2)
- cell bodies of preganglionic sympathetic neurons
- send axons out ventral root to innervate smooth muscle, cardiac muscle and glands
lower motor neurons are ___
alpha and gamma motor neurons that leave the ventral horn to innervate skeletal muscle
___ is one alpha motor neuron and all the muscle fibers it innervates
motor unit
___ is the collection of alpha motor neurons that innervates a single muscle, e.g., biceps brachii
motor neuron pool
Motor neuron pool – the collection of alpha motor neurons that innervates ____
a single muscle, e.g., biceps brachii
where do you find preganglionic sympathetic neurons?
lateral horn (T1-L2)
where are preganglionic parasympathetics found?
sacral level
on lateral edge of the intermediate grey
what type of muscle does each part of the ventral horn innervate?
pathway for motor innervation of skeletal muscle
upper motor neuron → lower (alpha) motor neuron → muscle
(2 neurons)
lower motor neuron leaves through the ventral horn and travels through spinal nerves
___ controls voluntary muscle contraction of the distal extremities
corticospinal tract (pyramidal tract)
corticospinal tract
upper motor neuron in cerebral cortex
switched sides in the brain stem at the pyramidal decussation
travels down spinal cord in lateral funiculus
synapses with lower motor neuron in ventral horn
lower motor neuron (alpha) leaves spinal cord through ventral root
travels to skeletal muscle
gamma motor neurons travel from muscle spindles (reflex contraction) through dorsal root synapses on LMN and cause reflex
is the UMN contralateral or ipsilateral to the LMN for the corticospinal tract
voluntary muscle control
(contralateral - switches sides at the pyramidal decussation)
the corticospinal tract will travel down the ___ part of the spinal cord
lateral funiculus
corticospinal tract
(descending pathway from motor cortex→ cross sides in pyramid → down through the lateral funiculus →voluntary muscle control)
lateral pathways in the spinal cord usually control ___ and is under direct ___ control.
voluntary movement of the distal musculature
cortical
(corticospinal tract and rubrospinal tract)
what are some ventromedial pathways of the spinal cord?
pontine and medullary reticulospinal tracts for posture and locomotion
what pathways control posture, locomotion and balance
ventromedial pathway
general sensory pathway
3 neurons
sensory afferent enter spinal cord by dorsal root
synapse on second order neuron
second order changes sides
2nd order synapses on 3rd order in the thalamus
3rd order travels to the somato-sensory cortex
in sensory pathway which neuron will change sides?
second neuron
the 1st neuron for the dorsal column medial lemniscal system goes where?
touch and proprioception
heavily myelinated
comes from body through dorsal root and some will trigger reflexes axon collateral will travel up spinal cord through the dorsal column will synapse on 2nd order neuron in the medulla
pathway for vibration, touch and proprioception
dorsal column- medial lemniscal tract
sensory from body through dorsal root into dorsal columns
will synapse on 2nd neuron at the medulla at the dorsal column nuclei
2nd neuron crosses sides (now called medial lemnicus)
2nd will synapse with 3rd in the thalamus (ventropostero-lateral nucleus VPL)
3rd will travel into the cerebral cortex
what is this pathway called
dorsal column-medial lemniscal tract
parts of the dorsal column
Fasiculus gracilis – hindlimb (sacal, lumbar)
Fasiculus cuneatus – forelimb (thoracic, cervical)
(organized from medial to lateral from bottom of spinal cord to top: sacral→ cervical)
___ is a body map
somatotopy
areas are divided based on where from the body they came from
dorsal column (organized from medial to lateral from bottom of spinal cord to top: sacral→ cervical)
two parts of the dorsal column
Fasiculus gracilis – hindlimb (sacral and lumbar)
Fasiculus cuneatus – forelimb (throacic and cervical)
what pathway
Dorsal Column – Medial Lemniscal Tract
Vibration, Light touch, Pressure, Proprioception
(3 neurons- dorsal root to dorsal column → medulla, change sides → 3rd at thalamus → primary somatosensory cortex
for the spinothalamic tract the first neurons are small diameter axons of dorsal roots that carry pain and temperature modalities into the cord. They all synapse with sensory neurons in the ___
dorsal horn!
(black and grey)
spinothalamic tract
pain and temperature
unmyelinated or lightly myelinated
1st from body through dorsal root will synapse in dorsal horn
2nd from dorsal horn crosses sides goes up through the anteriolateral tract
2nd synapses at 3rd in the thalamus (ventroposterolateral nucleus VPL)
up to cerebral cortex
spinothalamic tract
(pain and temperature)
1st → 2nd at dorsal horn
2 crosses
2→3 at thalamus up to the cerebral cortex
spinothalamic tract
compare the dorsal column-medial leminiscal pathway and the spinothalamic pathway
___ convey unconscious proprioception to IPSILATERAL cerebellum.
spinocerebellar system
dorsal spinocerebellar
cuneocerebellar
what controls lower limb unconscious proprioception to the cerebellum?
dorsal spinocerebellar tract
what controls upper limb unconscious proprioception to the cerebellum?
cuneocerebellar tract
dorsal spinocerebellar tract
lower limb unconscious proprioception to ipsilateral cerebellum
2 nerve pathway
sensory from muscle spindles through dorsal root ganglion
synapses on 2nd neurons at clark’s nucleus
2nd neuron up through the inferior cerebellar peduncle to the cerebellar cortex
cuneocerebellar tract
upper limb unconscious proprioception to ipsilateral cerebellum
2 nerve pathway
sensory from muscle spindles through dorsal root ganglion
synapses on 2nd neurons at accessory cuneate nucleus in the brain stem
2nd neuron up through the inferior cerebellar peduncle to the cerebellar cortex
two ascending pathways for conscious proprioception
•Dorsal Column - Medial Lemniscal Tract (proprioception/touch/vibration/ pressure)
•Spinothalamic Tract (pain/temperature)
two ascending tracts for unconscious proprioception
- Dorsal Spinocerebellar Tract (lower limb)
- Cuneocerebellar Tract (upper limb)
what tract goes through here?
dorsal spinocerebellar tract
(unconscious proprioception of the lower limb to the cerebellum)
what tract goes through here?
•Dorsal Column - Medial Lemniscal Tract (proprioception/touch/vibration/ pressure)
what tract goes through here?
spinothalamic tract
ascending pain and temperature to the cortex
these are showing ___ tracts
ascending
these are ___ tracts
descending
what tract
corticospinal tract (voluntary control of distal muscles ex. finger movement)
