Upper Limb Musculature and Brachial Plexus

In this chapter we describe the upper limb musculature musculature of the bonobos dissected by us and by other previous authors, and compare it with that of common chimpanzees. The three major differences between the two chimpanzee species are: (1) the intermetacarpales and flexores breves profundi muscles in the hand of bonobos usually fuse to form dorsal interossei, a shared feature with modern humans; (2) bonobos usually have a stout tendon of the flexor digitorum profundus attaching to digit 1 (in modern humans the homologous tendon of the flexor pollicis longus to digit 1 is usually also stout; and (3) bonobos usually have an attachment between the pectoralis minor and the coracoid process of the scapula, as modern humans usually do.