What is the distal attachment of the palmaris longus?

The distal attachment of the palmaris longus is indeed the flexor retinaculum and palmar aponeurosis. This tendon plays an essential role in the function of the wrist and hand by contributing to the structure of the palm and assisting with gripping actions. The palmar aponeurosis acts as a protective layer for the underlying structures of the palm and aids in the transmission of force when gripping or holding objects.

While other options reference anatomical features relevant to the upper limb, they do not represent the specific distal attachment of the palmaris longus. Recognizing the specific anatomical relationships helps in understanding the muscle's function and its importance in hand movements and grip strength.