One of the more complex structures, the hand has a high concentration of nerves and vessels. There are also many small intrinsic muscles which allow fine motor function.
Tendons, blood vessels and nerves originating in the arm cross the wrist to enter the hand; the intrinsic muscles are solely within the hand.
The structures crossing the double row of wrist bones are held in place by the flexor retinaculum on the volar (palmar) side (“carpal tunnel”), and by the extensor retinaculum on the dorsal side. The flexor retinaculum can sometimes thicken or scar, causing compression of the median nerve, or carpal tunnel syndrome.