Topographical anatomy of the pronator teres muscle and median nerve: a study using histological sections of human fetuses

Abstract

Summary: The median nerve passes through the humeral and ulnar heads of the pronator teres muscle (PT), although variations such as absence of the ulnar head may exist. We observed histological sections of the upper extremity from 24 embryos and fetuses. In the early stage, the PT extended between the radius and the medial epicondyle of the humerus, but no candidate for the ulnar head was found. In mid-term fetuses, the ulnar margin of the PT was attached to the elbow joint capsule. Moreover, in late-stage fetuses, a small deep part of the PT arose from the thick joint capsule of the humero-ulnar joint near the coronoid process of the ulna. This joint capsule also provided the most proximal origin of the flexor digitorum profundus muscle. Therefore, we considered fetal PT origin from the capsule as a likely candidate for the ulnar head. Consequently, the PT seemed to develop from a single anlage through which the median nerve passed, but laterpossibly after birth -a small PT origin from the joint capsule appeared to obtain an aponeurosis connecting the muscle fiber to the ulna. This secondary change in PT morphology might explain the muscle variation seen in adults.

Absence of Median Nerve in Cubital Fossa - A Rare Anatomical Variation

“…In pattern C, the nerve will pass between two anlagen of muscles in early developmental stage, then muscle will fuse and finally nerve will pass piercing the muscle fibres. The course of MN in the present case follows the pattern C. 12…”

“…Shinichi Abe et al 12 have studied the topographical relation between the PT muscle and MN. They have hypothesized three patterns (Pattern A, B and C) of morphological development in which the MN adopts its course between the two heads of PT muscle.…”

Median Nerve Passing below the Ulnar Head of Pronator Teres in Cadavers of a Medical College in Western Nepal: A Descriptive Cross-sectional Study

“…This secondary change in PT morphology might explain the muscle variation seen in adults. 12 In our study out of 8 (14.82%) upper limb were from female cadavers where all median nerve (100%) pass between two heads of pronator teres muscle and out of 46 (85.28%) specimens of upper limb from male cadaver 42 (91.30%) passes between two heads of pronator teres and 4 (7.40%) Median Nerve pass below ulnar head of pronator teres muscle. These results signal our attention towards gender differences in the course of the median nerve.…”

Thoracoscopic bilateral sympathectomy for the treatment of hyperhidrosis: A complication of patient positioning

“…Since the median nerve is located in an area over the operation region, hypoesthesia was not associated with the thermal effect of cautery. [1,7] Patient positioning is another cause of operative nerve damage. The stretch sourced from hyper-abducted arm or any compression may have caused temporary hypoesthesia.…”