Palmaris Longus Muscle, Absence Of

Clinical Features

At the wrist the tendon of the palmaris longus muscle is located in the middle of the ventral surface. It is flanked by the tendons of the flexor carpi ulnaris and flexor carpi radialis. Schaeffer (1953) recorded that the muscle was absent from 12.6% of the 310 limbs of 155 subjects and was bilaterally absent in 7.7% of subjects. The muscle is said to be absent more often in females and on the left side. For example, Thompson et al. (1921) found the muscle missing in about 16% of males and 24% of females, these figures being based on studies of cadavers.

Inheritance

From their study of 81 families with a total of 188 children, Thompson et al. (1921) concluded that absence of the palmaris longus muscle is dominant with incomplete penetrance and lateral variability.