Subclavian nerve
Nervus subclavius
A slender nerve from the superior trunk of the brachial plexus that runs down in front of the plexus to supply subclavius.
At a glance
- English
- Subclavian nerve
- Latin (TA2)
- Nervus subclavius
- System
- Nerve
- Region
- Upper limb
- Side
- Paired, left and right
About the subclavian nerve
The subclavian nerve, more often called the nerve to subclavius, is one of the slender branches of the brachial plexus given off above the clavicle. It leaves the upper trunk, formed by the ventral rami of C5 and C6, and carries fibres from those two segments, mainly C5. It is the first branch of the trunk, arising close to the point where the two roots unite.
From its origin the nerve descends almost vertically in front of the lower part of the plexus and the third part of the subclavian artery, and behind the clavicle. It passes over the subclavian vein to reach the small subclavius muscle, which lies under the clavicle and runs from the first costal cartilage to the groove on the clavicle's undersurface. The nerve enters the deep surface of the muscle.
Subclavius helps to steady the clavicle and draws it down and forward towards the first rib, protecting the sternoclavicular joint during shoulder movement. The muscle and its nerve are small, so damage to the nerve on its own causes no clear disability. Its fibres are lost together with those of the rest of the upper trunk in traction injuries of the shoulder. The small muscle also sits between the clavicle and the subclavian vessels and plexus, cushioning them when the collarbone is broken.
The nerve's main interest is a common variant. It often gives off an accessory phrenic nerve, a twig that runs down to join the phrenic nerve in the root of the neck or in the thorax and so adds C5 fibres to the supply of the diaphragm. In some people the accessory phrenic nerve comes instead from the ansa cervicalis or the nerve to sternohyoid. Its presence explains why the diaphragm on one side may still move after the main phrenic nerve has been cut or blocked in the neck, and why surgery near the clavicle can occasionally weaken that half of the diaphragm.
Course and supply
- Arises from
- Upper trunk of the plexus (C5, C6), near the union of the two roots.
- Ends in
- Enters the deep surface of the subclavius muscle.
- Supplies
- Motor to subclavius; often gives an accessory phrenic nerve to the diaphragm.
Anthromica
See the subclavian nerve where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
