The upper (superior) subscapular nerve is the first branch of the
posterior cord of the
brachial plexus
The brachial plexus is a network of nerves (nerve plexus) formed by the anterior rami of the lower four Spinal nerve#Cervical nerves, cervical nerves and first Spinal nerve#Thoracic nerves, thoracic nerve (cervical spinal nerve 5, C5, Cervical spi ...
. The upper subscapular nerve contains
axons
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pot ...
from the
ventral rami of the
C5 and
C6 cervical
spinal nerves
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into ...
. It innervates the superior portion of the
subscapularis muscle
The subscapularis is a large triangular muscle which fills the subscapular fossa and inserts into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint.
Structure
The subscapularis is covered by a dense fasci ...
. The inferior portion of the subscapularis is innervated by the
lower subscapular nerve.
Structure
The
axons
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pot ...
which form the upper subscapular nerve travel from the
ventral rami of
C5 and
C6.
They join at the
upper trunk and move through its
posterior division to form the
posterior cord, along with the other two posterior divisions of the middle and lower trunks.
The axons then branch from the posterior cord and form the upper subscapular nerve.
Function
The upper subscapular nerve innervates the superior portion of the
subscapularis muscle
The subscapularis is a large triangular muscle which fills the subscapular fossa and inserts into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint.
Structure
The subscapularis is covered by a dense fasci ...
.
Clinical significance
A lesion to the upper subscapular nerve can cause a reduced ability to medially rotate at the shoulder joint, however this function is supplemented by other muscles.
Additional images
File:Brachial plexus.svg, Brachial plexus
File:Gray809.png, The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.
References
Nerves of the upper limb
{{Portal bar, Anatomy