Intro to Nervous - Sensory & Motor Flashcards
What is the name of the connective tissue layer surrounding the axon?
Endoneurism
What is the Endoneurism?
A connective tissue layer that surrounds the axon of an individual neurone
What is the name of the connective tissue layer surrounding a fascicle?
Perineurisum
What is the Perineurium?
A connective tissue layer that surrounds a fascicle (a collection of neurons)
What is the name of the connective tissue layer surrounding a fascicle?
Perineurium
What is the Epineurium?
Surrounds the entire nerve; it’s formed by a collection of fascicles. Contains small blood vessels supplying the nerve fibres and is created by arachnoid and pia mater.
What is a fascicle?
A bundle of neurons.
What are Group A nerves?
The largest myelinated fibres that are somatic afferent and efferent fibres. Split into alpha, beta and delta.
Alpha are for efferent motor fibres
Beta are for touch sensation
Delta are for pain and temperature
What are Group B nerves?
Myelinated autonomic and pre-ganglionic fibres
What are Group C nerves?
They’re thin, unmyelinated fibres that are visceral and somatic afferent.
In the frontal lobe what gyri does the central sulcus separate?
The precentral gyrus and postcentral gyrus
What is the precentral gyrus?
Primary motor cortex for voluntary movement. Works by the homunculus.
What is the postcentral gyrus?
Where integration is done, where info is processed and passes on to the pre-central gyrus to provide a response to the info. Sensory processing/integration.
What is the sensory tracts for?
Pain, touch/pressure, temperature and 2-point discrimination that all follow specific pathways through the CNS
Where do the somatosensory stimuli from below the neck pass along?
The sensory pathways of the spinal cord
Where do the somatosensory stimuli from the head and neck travel?
Through the cranial nerves through the trigeminal system
What are the two major pathways that bring sensory info to the brain?
Dorsal Column System & the Spinothalamic Tract
How many neurons do the dorsal column system and spinothalamic tract have?
Three
Where do the dorsal column system neurons cross?
At the medulla it reaches the 4 dorsal column nuclei
Which of the 4 dorsal column nuclei do the peripheral and central sensations come in at?
Peripheral = outside nuclei
Central = the 2 inside/middle nuclei
Where do the the 3rd order neurons travel up to?
The thalamus and then up the primary somatosensory cortex to the post-central gyrus
What is the spinothalamic tract?
Part of the dorsal root ganglion
What’s the tract of the spinothalamic tract?
Axons extend from the dorsal root within the spinal cord and synapse with the 2nd order neuron in their respective pathway
Where do the axons in the spinothalamic tract decussate?
In the spinal cord at the level that they come in
What does the dorsal column system deal with?
Touch and proprioception
What does the spinothalamic tract deal with?
Pain and temperature
Where is the postcentral gyrus?
In the somatosensory cortex
What are neurons in the primary motor cortex called?
Betz cells
What are Betz cells?
Neurons in the primary motor cortex that synapse with lower motor neurons in the spinal cord/brain stem
Where do Betz cells travel?
The corticospinal tract (rest of body that’s not head or neck)
Or the Corticobulbar tract (cranial nerves from the cortex to brainstem - efferent)
They’re named after original or their targets (either spinal or brainstem).
What does the corticobulbar tract do?
Tells the cranial nerves (the motor ones) what to do & don’t cross and thus are ipsilateral so the motor cortex are to the same side of the nervous system.
What does the corticospinal tract do?
It’s the major neuronal pathway providing voluntary motor function starting in the pre-central gyrus. It generates all motor info that passes through the midbrain and once in the medulla split.
What is the lateral corticospinal tract?
It’s part of the corticospinal tract where 80-90% cross at the spinal cord and tell the arms and legs what to do (appendicular appendages). Decussate in the medulla and thus are contralateral.
What is the anterior corticospinal tract?
Part of the corticospinal tract that deals with the axial muscles (trunk). Some collateral branches of the tract project to ipsilateral ventral horn. Ipsilateral.
