Tendons of the Hand
Within the structure of the hand there are many specialized units that allow extensive articulation and movement. Some of the more prominent features of a dissected hand include tendons. The hand is composed of a tight network of tendons that include examples such as flexor digitorum superficialis (FDS) tendon and the flexor digitorum profundus (FDP) tendon. Tendons such as these within the hand are encased in sheaths (e.g. FDS & FDP are encased in the common flexor sheath). The common flexor sheath is deep to the flexor retinaculum, and the tendons (FDS & FDP) enter the central part of the hand. An important aspect of the sheath is the various types that enable various movements of the hand. For example, the digital synovial sheaths allows for the tendons to move when the fingers flex.
This topic allows a segue to a pathology associated with these sheaths within the hand. A common occurrence is when a tendon within the hand becomes inflamed and prevents movement within the sheath, this is known as Tenosynovitis or "Trigger Finger". This most often occurs in either digit #1 or #2 and usually only occurs singularly. However, if the patient has certain comorbid disorders, such as arthritis or diabetes, multiplicity (either more than one digit involved or repeat of occurrence) may occur. In general, 95% of all trigger finger patient cases can be solved by non-operative procedures. However, repeat offenses may find surgery as an unavoidable consequence.
Innervation of the Hand
Another aspect of the hand that is worth mentioning is of the hand's expanse of innervation. Very few places in the human body present as much branching and complexity as the nerves in the hand. Three main nerves constitute the primary composition of innervation of the hand. These three nerves include the Radian, Ulnar, and Median nerves. Each of the these nerves have several branches each, but in general these nerve are localized to certain aspects of the posterior and anterior views of the hand. These innervations, as mentioned, contain branches of nerve plexuses, and contain fibers from more than one spinal cord segment.
Interestingly, a pathology that is associated with Radial nerve injury is the "wrist drop". This is interesting because the Radial nerve doesn't supply any muscles in the hand, but Radial nerve injury in the arm can cause serious hand instability. This is because the damage to the Radial nerve can cause paralysis of the extensor muscles of the forearm. However, despite how debilitating this sounds, usually the restriction of movement is minimal, even in serious injuries.
Lymphatics of the Upper Limb