An anatomical study of the subcoracoid space.
OBJECTIVE
To evaluate the amplitude of the subcoracoid space under maximum internal and external rotations of the humeral head and measure the distance between the apex of the coracoid process and the following anatomical structures: (a) point of entry of the musculocutaneous nerve and its branches into the coracobrachial muscles and into the short head of the biceps brachii muscle; (b) acromial artery; (c) lesser tubercle of the humerus.


METHODS
Thirty shoulders of fresh cadavers, without any kind of shoulder pathology, (9 males and 6 females) were dissected, and the distances (in mm) were measured between the anatomical structures defined above and the apex of the coracoid process.


RESULTS
The mean distance between the apex of the coracoid process and the musculocutaneous nerve was 49.2 mm (in all specimens a proximal branch of the nerve was identified 34.2 mm away from the apex of the coracoid process), which was not significantly different between the sexes or body sides; the mean distance between the apex of the coracoid process and the acromial artery was 12.4 mm, which was not significantly different between the sexes or body sides; the mean distance between the apex of the coracoid process and the lesser tubercle of the humerus, with the humeral head under internal rotation, was 10.6 mm in men and 8.6 mm in women, values that were significantly different between the sexes.


CONCLUSIONS
In women, the smaller distance between the apex of the coracoid process and the lesser tubercle of the humerus in the arm internal rotation suggests a higher chance of impingement between those bone structures among the female sex.
Ferreira Neto
Arnaldo Amado
AA
Shoulder and Elbow Group and Arthroscopy, Laboratory of Department of Orthopedics, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil. aafneto@terra.com.br
Almeida
Adriano Marques de
AM
Maiorino
Renzo
R
Zoppi Filho
Américo
A
Benegas
Eduardo
E
D000174:Acromion / Q000098:blood supply / Q000294:innervation; D002102:Cadaver; D005260:Female; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology* / Q000294:innervation; D008297:Male; D009138:Musculocutaneous Nerve / Q000033:anatomy & histology*; D016059:Range of Motion, Articular; D012399:Rotation; D012540:Scapula / Q000033:anatomy & histology* / Q000294:innervation; D017678:Sex Distribution; D012737:Sex Factors; D019534:Shoulder Impingement Syndrome / Q000473:pathology; D012785:Shoulder Joint / Q000033:anatomy & histology* / Q000294:innervation