Yoshikuni Ohta

An investigation of the digital nerves of the thumb.

With the use of a stereoscopic microscope, observations were made on the course of the proper digital nerve of the thumb on ten upper limbs in adult cadavers. By observation from the dorsal side after removal of the bone, it was possible to clearly see the ramification of the digital nerve from the subcutaneous tissue to the dermis. Ramification from the palm to the level of the interphalangeal joint was segmental. The digital nerve of the thumb trifurcates from the proximal site of the distal palmar thumb crease into the main, medial, and lateral branches. The main branch is thick and extends from the center of the pulp toward the fingertip. Ramification at the pulp of the thumb is of a radiating rather than segmental type, and its control can be considered as spotty or intermittent. Distribution of pacinian corpuscles is dense in the subcutaneous tissue of the distal palmar thumb crease. These observations are of clinical importance not only for avoidance of injury to the digital nerve in surgical procedures such as the incision and drainage for felon and the trigger thumb release but also for precise repair of the digital nerve in the reconstructive surgery of the thumb.

Microvasculature of the Triangular Fibrocartilage Complex of the Wrist

The microvascular anatomy of the triangular fibrocartilage complex (TFCC) of the human wrist was investigated by the acrylic plastic and India ink injection method in 16 cadaver specimens, whose ages had ranged from 24-weeks (stillborn) to 84 years. It was found that the TFCC was supplied by the branches of the ulnar artery and of the anterior interosseous artery. The microvascular supply of the articular disc was basically the same as that of the meniscus of the knee joint. In the TFCC of the adult, the articular disc was avascular, with the exception of the border to the meniscus homologue and the radioulnar ligaments. A capillary plexus originating in the meniscus homologue and the radioulnar ligaments supplied the peripheral 10%-15% of the articular disc. The prestylold recess was coverd with layers of vascular synovial tissue. In the TFCC of the fetus and the infant, capillaries were observed at the surface of the TFC and the attachment to the radius. Avascular areas of articular discs in the fetus and the infant were relatively smaller than that in the adult. Cellularity was more prominent in the fetus and the infant.