Cervical enlargement

The cervical enlargement of the spinal cord is the source of the spinal nerves that contribute to the brachial plexus and supply the upper limbs.

Gross anatomy

It is one of two symmetrical enlargements which occupy the segments of the limb plexuses, the other being the lumbosacral enlargement for the lumbar and sacral plexuses. Hence it occupies, in the spinal cord, the segmental levels C5 to T1. As the spinal cord is shorter in length than the vertebral column, it extends from the C3 to T1/T2 vertebral levels, its greatest circumference (approximately 38 mm) at the C6 level.

The cervical enlargement is a result of the increased volume of motor cells in the ventral horns of the grey matter. Here, motor neurons which innervate muscles of the upper limb are sited posteriorly in the anterior grey column, and those which supply the most distal muscles (i.e. intrinsic muscles of the hand) are situated further posteriorly.