University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

443

Pages:

6
Author:

Mariam A. A.

Peripheral nerves ● ● ● ● ● ● ● ● ● Plexus = mixing of nerves (nerves after mixing have fibres from multiple spinal levels) ○ Bulging disc that affects one spinal nerve doesn’t cause paralysis of whole muscle group (redundancy) ○ When the fibres get to their terminal site, fibres from the same spinal nerve will terminate near each other Body is covered in dermatomes - section of skin innervated by the same spinal nerve Even though they may have been mixed with other spinal nerves - they spread out into their individual stripes across the body Most are myelinated (but there are also unmyelinated ones) 31 pairs of spinal nerves which form plexuses or peripheral nerves ○ Arms and legs = plexuses (doesn’t have the same simple horizontal lines like the green and orange) Myotomes = muscle group performs a specific action that is innervated by a specific spinal nerve ○ E.g. flexion of the elbow = C6, C5 Most have multiple spinal nerves for a movement = plexuses = redundancy if one nerve is affected, we can still perform the movement using the other spinal nerve = prevent paralysis Combination of dermatomes and myotomes (muscle nerves) = assess function and determine which spinal nerves are being affected Pathophysiology of the body - can bring it back to a specific spinal nerve that is affected ○ Loss of sensation on the skin and weakness of action in the movement can be used to diagnose a spinal nerve affect Cervical ● Phrenic nerve goes through the thorax and innervates the diaphragm (breathing) ● Controls the diaphragm ● Damage to phrenic nerve = cannot control diaphragm = cannot breathe ● Cervical plexus Upper limb ● Brachial plexus → redundancy (as shown in the example image below) ● Brachial plexus originates at C5 Lower limb ● Lumbosacral plexus → redundancy (as shown in the example image below) ● We have 8 cervical nerves on each side and 7 cervical vertebrae ● One extra spinal nerve compared to the number of vertebrae ● ● ● How do the peripheral nerves exit the vertebral cavity = superior and inferior vertebral notch at the level of the pedicel Creates the intervertebral foramen which are on the lateral sides Ligaments at the back close off the shape = makes it an oval ● ● ● ● Plexuses are larger as you go down because the target organ is further away Brachial plexus = the target muscles are further away so the plexus are thicker (cervical plexus enlargement) Lumbar enlargement Needs more cell bodies to extend throughout the body ● ● ● ● 5 spinal roots These 5 continue to join with each other and split = mixing of the spinal levels Medial nerve comes from the lateral and medial cord and this comes from C5-T1 Inputs from all 5 spinal nerves = maximum redundancy