Anatomical specificities as the basis of focal neuropathies of the upper extremity

Peripheral nerves of the upper and lower extremities have a specific position and often close relationships with osseous and articular structures. They are frequently compressed in narrow tunnels, canals, and grooves formed by soft tissue structures. For these reasons, as well as the length of the nerves themselves and their frequent superficial position, they are susceptible to injuries, both of the nerves themselves and from surrounding structures with which they are in relation. Due to their specific structure and myelin sheath, they may be affected by systemic diseases, not only of the peripheral nerves themselves but also by numerous endocrinological, metabolic, inflammatory, immunological, and infectious disorders. Knowledge of the anatomy of peripheral nerves becomes very important, not only to recognize peripheral nerve disease but also to guide diagnostic methods and thus pave the way for adequate and timely therapy. It is important to know the innervation field of each nerve so that, based on symptomatology—motor, sensory, or autonomic nervous system symptoms—we can recognize that it is a peripheral nerve. If we know the innervation field, we will also know at what level changes occur in the nerve, allowing us to select and direct the appropriate diagnostic method. Anatomy is also important for recognizing possible influences of surrounding structures on the peripheral nerve and for raising suspicion of an attack from structures with which the nerve is in relation. Potential variations must also be considered. What we learn in basic anatomy are merely descriptions of structures and relationships in the majority of cases, but there are numerous variations that must be taken into account. These are particularly important in the field of surgery, so that the surgeon is prepared for possible challenges when performing an operative procedure. Knowledge of anatomy and relationships is especially important in focal neuropathies.