Early fetal development of the rotator interval region of the shoulder with special reference to topographical relationships among related tendons and ligaments

Abstract

Purpose There is little information on the early fetal development of the rotator interval region of the shoulder, particularly with regard to whether topographical relationships among the ligaments and tendons change during development.Methods We examined the histological sections (transverse or frontal) of right or left shoulder in 20 mid-term human fetuses (7-15 weeks of gestation). ResultsThe biceps tendon had an accompanying bursa-like cavity before the joint cavitation. The bursa for the tendon remained open to the joint cavity until 12 weeks. When reaching the glenoid, the biceps tendon involved and carried mesenchymal tissue around the coracoid process (the future coracohumeral ligament) toward the infraspinatus tendon. Until 10 weeks, the primitive glenohumeral ligament was established as simple collateral ligaments on the inner or humeral side of the rotator cuff tendons and the biceps long tendon. However, the subscapularis tendon crossed, attached to, and reformed the upper structure of the superior glenohumeral ligament.Conclusions The early development of the coracohumeral ligament suggests that it is a primitive and basic structure. However, we hypothesize that mechanical demands from the subscapularis tendon and biceps long tendon are likely to

Oblique cord (chorda obliqua) of the forearm and muscle-associated fibrous tissues at and around the elbow joint: a study of human foetal specimens

“…Therefore, the foetal elbow joint is apparently supported by muscles in a foetus-specific manner. As seen in primitive glenohumeral joints, in which simple collateral ligaments are evident rather than rotator cuff tendons [2], the foetal elbow is not a miniature version of the adult elbow. The topographical relationships between joints and muscles likely change drastically depending on foetal stage.…”

Variation of the subscapularis tendon at the fetal glenohumeral joint

“…Abe et al [8] considered that the so-called intra-articular course of the biceps tendon was formed at the late stage. In contrast to the biceps tendon, even in mid-term fetuses, the fetal subscapularis tendon often took an intra-articular course.…”

“…Previously, our group histologically examined the rotator interval region in mid-term fetuses, but we did not find such a tissue loss [8]. The rotator interval is defined as a triangular structure, in which the coracoid process forms the base, the anterior margin of the supraspinatus forms the upper border, and the superior margin of the subscapularis muscle-tendon unit forms the lower border [9].…”

“…Overall, in fetuses, there is little information to connect with adult variations of the middle and inferior glenohumeral ligaments. Abe et al [8] considered that the variations seen in adults correspond to postnatal mechanical demands from the subscapularis and biceps tendons. To provide a developmental basis for better understanding of the adult shoulder, the aim of the present study was to describe fetal morphology, especially that of the subscapularis tendon, at the glenohumeral joint.…”

Positional changes in tendon insertions from bone to fascia: development of the pes anserinus and semimembranosus muscle insertion in human foetuses

“…To date, no tendon in human foetal extremities has been reported to show a highly tortuous course near the bony insertion, as shown for the shoulder and arm [1], forearm and hand [7], and foot and ankle [21]. Conversely, foetal development of a long muscle belly may require a short or long straight tendon attached to the hard tissue.…”