open access

Vol 75, No 4 (2016)
ORIGINAL ARTICLES
Published online: 2016-04-08
Submitted: 2016-01-11
Accepted: 2016-02-13
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Oblique cord (chorda obliqua) of the forearm and muscle-associated fibrous tissues at and around the elbow joint: a study of human foetal specimens

Z. W. Jin, Y. Jin, M. Yamamoto, H. Abe, G. Murakami, T. F, Yan
DOI: 10.5603/FM.a2016.0019
·
Pubmed: 27830875
·
Folia Morphol 2016;75(4):493-502.

open access

Vol 75, No 4 (2016)
ORIGINAL ARTICLES
Published online: 2016-04-08
Submitted: 2016-01-11
Accepted: 2016-02-13

Abstract

In adults, the oblique cord or chorda obliqua separates the origins of the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) muscles from the supinator muscle and elbow joint. This study examined the topographic anatomy of the oblique cord and related muscles in foetuses. Semiserial sections of five mid-term foetuses of gestational age (GA) 14–16 weeks and 12 late-stage foetuses of GA 28–30 weeks were histologically examined and three forearms at GA 30 weeks were macroscopically evaluated. Late-stage foetuses showed a fascial structure between the supinator and FDP muscles. The latter extended proximally to the elbow joint and the muscle origin thickened the distal, ulnar part of the capsule. The FPL origin also extended proximally but did not reach the joint capsule. These morphologies were consistent with macroscopic examinations. The brachialis muscle was widely inserted into the proximal, anterior part of the capsule. In addition, the medial collateral ligament was not covered by the pronator-flexor muscles but by the triceps brachii muscle. The oblique cord apparently did not form prenatally. After birth, the proximal parts of the FDP and FPL muscles were likely replaced by collagenous tissues, providing a specific type of intermuscular septum i.e., the oblique cord. This type of muscle-ligament transition was observed in the annular ligament of the radius. The foetal elbow joint was characterised by strong support by the FDP, brachialis and triceps brachii muscles. Therefore, the foetal elbow is not a miniature version of the adult elbow.  

Abstract

In adults, the oblique cord or chorda obliqua separates the origins of the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) muscles from the supinator muscle and elbow joint. This study examined the topographic anatomy of the oblique cord and related muscles in foetuses. Semiserial sections of five mid-term foetuses of gestational age (GA) 14–16 weeks and 12 late-stage foetuses of GA 28–30 weeks were histologically examined and three forearms at GA 30 weeks were macroscopically evaluated. Late-stage foetuses showed a fascial structure between the supinator and FDP muscles. The latter extended proximally to the elbow joint and the muscle origin thickened the distal, ulnar part of the capsule. The FPL origin also extended proximally but did not reach the joint capsule. These morphologies were consistent with macroscopic examinations. The brachialis muscle was widely inserted into the proximal, anterior part of the capsule. In addition, the medial collateral ligament was not covered by the pronator-flexor muscles but by the triceps brachii muscle. The oblique cord apparently did not form prenatally. After birth, the proximal parts of the FDP and FPL muscles were likely replaced by collagenous tissues, providing a specific type of intermuscular septum i.e., the oblique cord. This type of muscle-ligament transition was observed in the annular ligament of the radius. The foetal elbow joint was characterised by strong support by the FDP, brachialis and triceps brachii muscles. Therefore, the foetal elbow is not a miniature version of the adult elbow.  

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Keywords

oblique cord, elbow joint capsule, flexor digitorum profundus muscle, brachialis muscle, collateral ligament, human foetuses

About this article
Title

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

Journal

Folia Morphologica

Issue

Vol 75, No 4 (2016)

Pages

493-502

Published online

2016-04-08

DOI

10.5603/FM.a2016.0019

Pubmed

27830875

Bibliographic record

Folia Morphol 2016;75(4):493-502.

Keywords

oblique cord
elbow joint capsule
flexor digitorum profundus muscle
brachialis muscle
collateral ligament
human foetuses

Authors

Z. W. Jin
Y. Jin
M. Yamamoto
H. Abe
G. Murakami
T. F, Yan

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