Neuro Module exam 3 Flashcards
Peripheral nerve region
Which spinal nerves contribute to the cervical plexus?
C1-C4
What is the phrenic nerve?
The phrenic nerve is formed by the anterior rami of cervical spinal nerves C3-C5 and is the only motor nerve supply to the diaphragm.
Which spinal nerves contribute to the brachial plexus?
C5-C8, T1
What are the distinguishing differences between spinal nerve lesions and peripheral nerve lesions?
Peripheral nerve lesions show a peripheral nerve distribution, while spinal nerve lesions show a myotomal and/or dermatomal distribution.
What type of information is typically carried by somatic peripheral nerves?
Mixed (sensory and motor)
What is a motor unit?
A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals.
What do mechanoreceptors respond to?
Mechanoreceptors respond to mechanical deformation such as touch, pressure, stretch, or vibration.
What do chemoreceptors respond to?
Chemoreceptors respond to substances released by cells, such as histamine from damaged cells.
What do thermoreceptors respond to?
Thermoreceptors respond to heating or cooling.
What are nociceptors?
Nociceptors are a subset of each type of receptor that preferentially respond to stimuli that damage or threaten damage to tissue, causing pain.
What is a receptive field?
A receptive field is the area of skin innervated by a single afferent neuron, with smaller fields distally and larger fields proximally.
How do receptive fields contribute to 2-point discrimination?
If two points are within the receptive field of a single neuron, they are perceived as one point; if they are in different receptive fields, they are perceived as two points.
How are peripheral axons classified?
Peripheral axons are classified by type (Aα, Aβ, Aδ, B, and C fibers) based on size and level of myelination.
Why is movement important for nerve health?
Movement promotes blood flow throughout the nerves and the flow of axoplasm through the axons, supplying nutrients and oxygen.
What are possible sensory changes due to peripheral nerve damage?
Decreased or lost sensation and abnormal sensations.
What are possible motor changes due to peripheral nerve damage?
Paresis or paralysis, with rapid muscle atrophy and fibrillation.
What is denervation?
Denervation is the loss of nerve supply.
What are trophic changes?
Trophic changes occur when nerve supply is interrupted, leading to muscle atrophy, shiny skin, brittle nails, and thickened subcutaneous tissues.
What is neuropathy?
Neuropathy is a general term for pathology involving one or more peripheral nerves, with symptoms like loss of feeling and sharp pain.
What is traumatic myelinopathy?
Traumatic myelinopathy refers to the loss of myelin limited to the site of injury, primarily affecting large-diameter axons.
What is the sequence of sensory loss with nerve compression?
Sensory loss proceeds in the order: conscious proprioception and discriminative touch, cold, fast pain, heat, and slow pain.
Focal nerve compression redults in lose of proprioception and discriminative touch. Name an example:
Nereve entrapment, carpal tunnel syndrome
What two fibers remain intact and why?
Pain and temperature remain intact because the compression f the nerve affects the LARGE, myelinated fibers first.
- Initial relative sparing of small carrying pain and temperature.
What occurs with complete severance of a nerve?
Complete severance results in loss of sensation, motor control, and reflexes in structures innervated by that nerve.
