Palmar aponeurosis is a thick triangular fascia anchoring palmar skin to the underlying connective tissues.
The palmar aponeurosis is a thick, triangular-shaped fibrous tissue layer located in the center of the palm. It serves as a continuation of the tendon of the palmaris longus (when present) and functions to protect the underlying structures of the palm, provide attachment for muscles, and stabilize the skin for gripping. It is especially important in maintaining the integrity of the hand during movement and pressure.
The palmar aponeurosis lies just deep to the skin and superficial fascia of the palm. It occupies the central part of the palm and extends distally from the flexor retinaculum toward the bases of the fingers, splitting into digital slips for each finger.
The palmar aponeurosis is a dense connective tissue sheet with the following features:
The palmar aponeurosis serves several key functions:
Deep to the palmar aponeurosis lie the flexor tendons (from the flexor digitorum superficialis and profundus), the lumbrical muscles, and the digital branches of the median and ulnar nerves, as well as the superficial palmar arch. Superficially, it is related to subcutaneous fat and skin.
The palmar aponeurosis forms the firmness and slight elevation of the central palm. The longitudinal cords beneath the skin can be felt in individuals with well-developed grip strength or seen prominently in certain contracture conditions.
The palmar aponeurosis develops from the palmar deep fascia of the hand during embryonic mesenchymal condensation. It becomes well-defined in late fetal development and is fully formed postnatally.
In other primates and mammals, a similar palmar fascia exists but is less robust. In humans, it has evolved to provide enhanced support for intricate thumb and finger movements, reflecting advanced manual dexterity and tool use.