The peripheral nervous system: from anatomy to surgical indication

Surgery of the peripheral nerves is microsurgery and requires sound knowledge of the microscopic anatomy of the nerves and associated vasculature but also knowledge of the organisation of the nervous system and its general anatomy.

The lecture will therefore define the anatomy of the ‘lower motor neuron’ from the spinal cord to the muscle: this includes the motor nerve cell body, the axon (rootlets, ventral root, plexus, spinal nerves, peripheral nerves) and neuromuscular endplates. The sensory components of the peripheral nervous system will also be presented, such as the dorsal root ganglion but the emphasis will be on the definition of a dermatome and overlap and autonomous zones (table 1) some being innervated by a single nerve and others by fused spinal nerves. Testing autonomous zones is of particular importance for correct neuroanatomical localisation of peripheral nerve diseases / injuries but also to choose a source of nerve grafts.

Then, the complex structure of the nerves will be described to emphasise the various features of special relevance to injury and regeneration. In particular, peripheral nerves have three kinds of connective tissue: (i) the endoneurium; (ii) the perineurium; and (iii) the fascicular and epineurial tissue surrounding the axons in the nerve trunks. The amount of fascicular and epineurial tissue contributing to the cross sectional area of the nerve varies along the course of a nerve, from the spinal level to the target muscle, and this is important to consider for example with foraminal compressions. [...]