Lecture 5 Flashcards
ventricles filled with ____
cerebrospinal fluid
on either side of third ventricle
Thalamus
Lateral ventricles connected to third ventricle via ____
foramen of monro
Third ventricle narrows into ____
cerebral aqueduct
openings at base of fouth ventricle
laterally- foramen of luscka
Medially- foramen of magendie
Two larger opening with CSF
cersterna magna, lumbar cystern
Rootlets out of anterior horn of spinal cord form ____
ventrol root
When spinal roots becomes mixed spinal nerve
when exit interventrical foraman
Dorsal root ganglion contains
cell bodies of afferent fibers
Spinal cord grey mater separted into _____
10 regions called rexed laminae
Laminae IX of spinal cord grey matter contains
cell bodies for motor nuclei
Where Rexed laminae IX (9) found and what it forms
collections of nuclei found in medial and lateral aspects of anterior horn of spinal cord, form parts of ventral roots
Identify this rexed laminae
Laminae IX
spinal nerves project out and innervate…
multiple muscles (myotomes)
Myotome
Multiple muscles innervated by a spinal cord segment
Muscles innervated my portions of spinal cord with nuclei in the midline
proximal muscles
Muscles innervated by portions of spinal cord with nuclei sitting laterally
distal muscles
Identify this
Lateral motor system
Identify this
Medial motor systems
Identify this
Anterior horn cells for proximal muscles
Identify this
Anterior horn cells for lateral muscles
Number of spinal segments
31
length of spinal cord realtive to spine
Spinal cord shorter than the spine
Where spinal cord terminates
L1-L2
Name of end of spinal cord
conum medularis
What exists below L1-L2 vertebra
below L2 only nerve roots= cauda equina
Filum terminali
thread of pia mater that extends from tip of spinal cord to coccys, stabilises, holds cord in place
Number of cervical segments
8 (T1-T8)
Number of thoracic segments
12 (T1-T12)
Number of lumbar segments
5 (L1-L5)
Number of sacral segments
5 (S1-S5)
Number of coccygeal segments
1 (Co1)
Identify this structure
Cervical cord
Identify this structure
Thoracic cord
Identify this structure
Lumbar cord
Identify this structure
Sacral cord
Identify this structure
conus medullaris
Identify this structure
cauda equina
Where cervical nerve roots exit spinal cord vertebra and exeption to this
C1-C7 cervical nerves enter above C1-7 spinal vertebra, C8 nerve exits below C7 and above T1
Number of cervical vertebra
7
Where thoracic and lumbar nerves exit
thoracic and lumbar nerve roots exit spine below associated vertebrae
Distance travels by cervical vs lumbar/sacral nerve roots
cerical dont have to travel as far as lumbar/sacral roots
cervical enlargements
(C5-T1) Give rise to nerve roots for the arms
Lumbosacral enlargments
(L1-S3) give rise to nerve roots for the legs
Reasons for cervical and lumbosacral enlargments
contains motor motor nuclei- finer control for these regions, thoracic mostly innervates axial muscles, needs less control
Proportions of white to grey mater higher up in spinal cord (at cervical levels)
Larger proportion of white mater, many segements below it
Proportions of white to grey mater higher up in at lumbosacral levels
Greater proportion of grey mater, not much going below it
myotomes of cervical levels
cervical levels innervates muscles of the head, neck, diaphragm, arms and hands
myotomes of thoracic level
thoracic nerves innervates muscles of the thorax, chest, abdomen, back
Mytomes of lumbar level
lumbar nerves innervate muscles of the legs
Myotomes of the sacral levels
higher levels innervate the lower leg, muscles and feet and other nerves bladder muscules for sexual function
Identify the nerve root that innervates this
C5
Identify the nerve root that innervates this
C5-C6
Identify the nerve root that innervates this
C7
Identify the nerve root that innervates this
C6
C5 nerve root innervates/mediates
muscles of shoulder, mediates arm adbductiom at the shoulder
C5-C6 nerve roots innervates/mediates
innervates muscles of the bicep, mediates flexion of the elbow and the biceps reflex
C7 nerve root innervates/mediates
Muscles of the triceps, mediates elbow extension and the triceps reflex
C6 nerve root innervates/mediates
innervates the wrist, mediates wrist extension
Identify the clinically relevant nerve roots of the arm
C5, C6, C7
Identify the nerve roots that innervate this
L4
Identify the nerve roots that innervate this
L5
Identify the nerve roots that innervate this
S1
L4 nerve root innervates/mediates
quadriceps, mediates leg extension at the knee and the patellar tendon reflex
L7 nerve root innervates/mediates
ankle dorsiflexors, e.g. tib anterior mediates dorsiflexion at the ankle
S1 nerve root innervates/mediates
innervates ankle plantarflexors e.g. soleus, gastroc, mediates plantar fkexion at the ankle and the achilles tendon reflex
Location of cell bodies for motor neurons
anterior horn of spinal cord
Describe lower motor neurons
Cell bodies in any layer of the spinal cord (including cervical levels), axons extend out to innervate muscles. Final common pathway, no other synapses for these neurons
Idnentify this neuron
Lower motor neuron
Identify this neuron
Upper motor neuron
Identify this
Precental gyrus (primary motor cortex)
Identify this
Pyramidal decussation
Describe upper motor neurons
Cell body in primary motor cortex and synapse on lower motor neurons in spinal cord
Identify the 5 specific symptoms of lower motor neuron lesions
- Muscle weakness- loss of strength
- Fasciculations- uncontrolled muscle twitch
- Atrophy- Loss of muscle mass
- Reflexes decreased- Hyporeflexia
- Tone decreased- hypotonia, lack of passive resistance
Where can damage to a lower motor neuron occur
cell bodies, axon or as they travel in mixed nerve
define paresis and example
weakness (partial paralysis) e.g. hemiparesis weakness in one side of the body (face, arm, leg)
define -plegia and example
no movement e.g. hemiplegia no movement in one side of the body (face, arm, leg)
Define paralysis and example
no movement (synonymous with plegia), e.g. leg paralysis, no movement of the leg
Define palsy and example
imprecise term for weakness or no movement e.g. facial palsy, weakness or paralysis of the face muscles
define hemi- and example
one side of the body e.g. hemiplegia, no movement on one side of the body (face, arm, leg)
define para- and example
both legs, e.g. paraparesis, weakness in both legs
Define mono- and example
one limb e.g. monoparesis, weakness on one limb (arm or leg)
Define di- and example
both sides of body equally affected e.g. facial diplegia, symmetrical facial weakness
Define quadri- or tetra-
all four limbs e.g. quadraplegia (tetraplegia), paralysis of all four limbs
Identify way of testing for abnormal strength loss
isolate muscle groups identify myotomes involved, which level of SC segments involved, test bilaterally, have individual move joint through resistance
0 on muscle strength scale
no movement
1 on muscle strength scale
slight contraction, no movement
2 on muscle strength scale
movement possible, without gravity
3 on muscle strength scale
movement possible with gravity
4 on muscle strength scale
movement possible, some resistance
5 on muscle strength scale
movement possible, full resistance
Describe fasciculations
uncontrolled muscle twitching, happens for long durations of time/ episodes
Cause of fasciculations
caused by degenerative hypersensitivity e.g. damaged lower motor neurons, signals the muscles are recieving are reduced/stopped. Muscle becomes hypersensitive at the synapse, starts becoming activated by other stimuli e.g. metabolites even though individual is at rest
