Flexor Retinaculum and Palmar Aponeurosis

When you first examine the wrist and hand you should examine the skin of the hand to identify any unusual marks. When the skin is removed, there are two dense connective tissue structures identifiable. The first crosses over the carpal bones, forming a bony tunnel and the second crosses over the long tendons of the fingers coming into the hand from the forearm.
flexor retinaculum (FR)
  • 1 scaphoid
  • 2 trapezium
  • 3 pisiform
  • 4 hamate
live hand flexor retinaculum flexor retinaculum
  • median nerve
  • tendons of flexor digitorum superficialis
  • tendons of flexor digitorum profundus
  • tendon of flexor pollicis longus
  • tendon of flexor carpi radialis
contents of carpal tunnel

The flexor retinaculum forms a space between it and the unerlying carpal bones called the carpal tunnel. I am sure most of you have heard of or have had the carpal tunnel syndrome. In this syndrome, the structures under the retinaculum are compressed by swelling caused by irritation and inflammation and the median nerve is weakened. If left untreated, major paralysis to the small muscles of the hand can occur.

The second connective tissue structure in the palm of the hand is the palmar aponeurosis. This sheet of tissue is under the skin of the palm and helps to form the ridges in the palm. The ridges, in turn, help increase friction so that we can grasp objects firmly. The tendon of the palmaris longus inserts into the aponeurosis and can be accentuated by grasping an object such as a ball.
The tendon is superficial to the flexor retinaculum.
palmar aponeurosis

Bones of the Hand Muscles & Tendons of the Hand

Table of Contents for Upper Limb & Back