Anatomy and relations of the infraspinatus and the teres minor muscles: a fresh cadaver dissection study.
OBJECTIVE
Despite their functional importance, the infraspinatus (ISP) and teres minor (TM) muscles have been little investigated. This study aimed to describe the macroscopic morphology, innervation, and inter-relations of the ISP and TM muscles.


METHODS
Forty fresh cadaver dissections and histologic analysis were performed. Three groups of specimens were distinguished according to the rotator cuff tendon status: (1) intact rotator cuff; (2) supraspinatus tendon tears with intact ISP tendon; and (3) both supraspinatus and ISP tendons torn. Muscle fiber organization and muscle and tendon length were recorded. ISP and TM innervation and fiber structure were studied.


RESULTS
ISP muscles were composed of three groups of fiber organized in two planes: two superficial groups, with mean pennation angles of, respectively, 27° ± 4° and 23° ± 3° with respect to the axis of the central tendon of the underlying group. TMs were thick fusiform muscles showing a parallel organization; 26 specimens (67 %) had aponeuroses isolating the TM, with a mean length of 5.2 ± 2.7 cm. Rotator cuff lesions were associated with relatively greater ISP tendon than muscle length. Innervation of the ISP muscle comprised 2-4 main branches from the suprascapular nerve and that of the TM 1 branch from the axillary nerve.


CONCLUSIONS
ISP muscle body morphology derives from three groups of fibers in two planes. The TM has a parallel organization. Several nerve branches innervate the ISP muscle, whereas only one supplies the TM. The limits between the two muscles bodies consist of an aponeurotic fascia in two-thirds of cases.
Department of Orthopaedic Surgery, Hôpital Universitaire Trousseau, Tours, France. bacle.guillaume@wanadoo.fr.|Unité Mixte de Recherche Imagerie et Cerveau, Inserm U930, Université François-Rabelais, Tours, France. bacle.guillaume@wanadoo.fr.
Guillaume
http://orcid.org/0000-0001-8899-2638
G
Bacle
Unité Mixte de Recherche Imagerie et Cerveau, Inserm U930, Université François-Rabelais, Tours, France.
Jean-Marc
JM
Gregoire
Unité Mixte de Recherche Imagerie et Cerveau, Inserm U930, Université François-Rabelais, Tours, France.|Inserm CIC-IT 1415, Tours, France.
Frédéric
F
Patat
Faculty of Medicine, Institut of Normal Anatomy, FMTS, Strasbourg, France.
Philippe
P
Clavert
Department of Pathology, Hôpital Universitaire Trousseau, Tours, France.
Gonzague
G
de Pinieux
Department of Orthopaedic Surgery, Hôpital Universitaire Trousseau, Tours, France.
Jacky
J
Laulan
Department of Orthopaedic Surgery, Hôpital Universitaire Trousseau, Tours, France.|Unité Mixte de Recherche Imagerie et Cerveau, Inserm U930, Université François-Rabelais, Tours, France.
Walid
W
Lakhal
Department of Orthopaedic Surgery, Hôpital Universitaire Trousseau, Tours, France.|Unité Mixte de Recherche Imagerie et Cerveau, Inserm U930, Université François-Rabelais, Tours, France.
Luc
L
Favard
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D004210:Dissection; D005260:Female; D006801:Humans; D008297:Male; D017006:Rotator Cuff / Q000033:anatomy & histology* / Q000294:innervation*; D000070636:Rotator Cuff Injuries / Q000473:pathology*; D013708:Tendon Injuries / Q000473:pathology*; D013710:Tendons / Q000033:anatomy & histology*
Anatomy; Infraspinatus; Morphology; Rotator cuff; Teres minor