2C. Motor System - General Somatic Efferent (GSE) Lower Motor Division Flashcards
The process of ________________ is going to determine the net effect of all of the impulses that are synapsing on the LMN to determine if it’s going to generate that action potential or not
Summation
Where is LMN located in the spinal cord?
Ventral Horn of the Spinal Cord
GSE neurons to extrafusal fiber: Regular Skeletal muscle fiber
Alpha motor neurons
GSE neurons to INTRAfusal fiber: Modified skeletal muscle fiber
Gamma motor neurons
providing motor innervation to the extrafusal, we call this:
Alpha motor neuron
If it innervates the muscle spindle or the intrafusal fiber, it would be a schematic example of a:
Gamma motor neuron
Relatively rare, Myotatic reflex
Monosynaptic arc
Lesion sites: Can occur anywhere along the extent of the LMN
1- Neuromuscular Junctions = Toxins
2- __________nerve = inflammation or trauma
3- Spinal nerve proper = trauma, fracture, neoplasia
4- _______________ = trauma, fracture, neoplasia
5- Cell body - pressure, ischemia
2- Peripheral
4- Ventral Root
List the LMN signs
- Hyporeflexia
- Hypotonia
- Flaccid (soft) Paralysis
- Relatively QUICK muscular atrophy
relating to the body, especially as distinct from the mind
Somatic
Neurons that carry motor information away from the central nervous system to the muscles and glands of the body in order to initiate an action
Efferent
Spinal GSE neurons are located in the ___________________ and then sent fiber out to reach a target, usually the skeletal muscle, either extrafusal or intrafusal fibers
Ventral gray matter
Cranial LMN neurons
- Voluntary skeletal muscle
GSE: General Somatic Efferent
Cranial LMN neurons
- Skeletal muscle of branchial arch origin
SVE: Special Visceral Efferent
Cranial LMN neurons
- cardiac muscle, smooth muscle, glands
GVE: General Visceral Efferent
The skeletal muscle that is developing in the area of the neck from the embryo
Branchial Arches
If it is an “S” it is only in ______________ nerve
cranial
Means that the cell body wants to be close to the target that it innervates
Neurobiotaxis
Nuclear Column Concept and Cranial Nerve LMN Nuclei
- Neurobiotaxis and columnar fragmentation: produces ______________________ nuclei
cranial nerve
GSE Nuclei and Cranial Nerves
- Nucleus Location - Rostral Colliculus
- Target - Extraocular muscles
(ex. might not be able to open eye)
Oculomotor nerve CN III
GSE Nuclei and Cranial Nerves
- Nucleus Location - Caudal Colliculus
- Target - Extraocular muscles
Trochlear nerve CN IV
GSE Nuclei and Cranial Nerves
- Nucleus Location - just caudal to caudal cerebellar peduncle
- Target - Extraocular Muscles
Abducens Nerve CN VI
GSE Nuclei and Cranial Nerves
- Nucleus Location - Obex
- Target - Muscles of the Tongue
Hypoglossal nerve CN XII
For which nerves is the target the extraocular muscles?
What do they do?
III, IV, VI
They cause CONTRACTION of them, if there is a lesion we lose the contractibility of the muscle
is misalignment of the eyes, causing one eye to deviate inward (esotropia) toward the nose, or outward (exotropia), while the other eye remains focused
Strabismus
If you see atrophy of the tongue, that would indicate a problem with nerve __________
XII
The “final common pathway” of the nervous system refers to the:
LMNs in the Spinal Cord and Brainstem
a reflex arc where the sensory neuron synapses directly on a motor neuron is classified as:
monosynaptic
innervation of the extraocular muscles is provided by cranial nerves fibers that are functionally classified as:
GSE
The motor component of spinal nerves is functionally classified as:
GSE
