EEPORT ON THE SPHENISCID^. 87 



Nerve sup2:)ly. — A twig from the nerve to the latissimus dorsi. It turns round 

 the axillary margin of the scapula, and enters the lower border of the muscle. 



Remarhs. — In Pygosceles tceniatus the absence of the dorsal portion of the cutaneous 

 muscle occasions a corresponding difference in the relations of the infra-spinatus muscle. 



9. Latissimus dorsi. 



Grand dorsal, Vicq d'Azyr, 1772, p. 631, No. 4. 



Grand dorsal, Cuvier, vol. i. p. 270. 



Der hintcre anziehende Armmuskel, Merrem, p. 153, Nos. 7 and 8. 



Der Riiclcgratsoherarvumislcel, Wiedemann, pp. 84 and 85. 



Latissimus dorsi, Tiedemann, p. 308, No. 4. 



Der breite Riicliemniiskd, Heusinger, p. 183, No. 4. 



Muscle large du dos, Meckel, vol. vi. p. 31, No. 7. 



Der breite Miickenrmiskel, Schoepss, p. 103, No. 12. 



Latissimus dorsi and another, Eeid, p. 141. 



Latissimus dorsi, Selenka, vol. vL p. 1 20, No. 45. 



Grand dorsal, Gervais and Alix, p. 21. 



Attachments. — The latissimus dorsi con.sists of two distinct portions, which for the 

 sake of clearness we may distinguish as A. and B. 



Portion A. arises by means of a broad flattened tendon from the spines of the second, 

 third, fourth, fifth, and sixth dorsal vertebrae. The fibres converge as they pass forwards 

 and outwards, and terminate on a narrow tendon, which, after passing through a fibrous 

 pulley, attached to the axillary margin of the scapula, is inserted into the posterior border 

 of the shaft of the humerus, close to the lower margin of the tricipital fossa. 



Action. — This muscle carries the wing backwards at the shoulder joint. It is one of 

 the most powerful of the muscles which contribute to the production of the eflfective or 

 progressive stroke of the wing. 



Relations. — The anterior fibres of the muscle are concealed at their origin b}' the 

 cutaneous muscle of the neck, whilst the posterior are covered by the dorsal cutaneous 

 muscle. It rests upon the trapezius. 



Portion B., which is quite distinct, and separated by an interval from the preceding- 

 muscle arises by means of a delicate fascia covering the last three ribs, from the anterior 

 margin of the iliac bone. The fibres pass forwards towards the shoulder joint, and terminate 

 on a tendon, which, after passing along with that of portion A. through the fibrous pulley 

 above mentioned, is inserted into the posterior border of the shaft of the humerus, close 

 to, but slightly higher than the tendon of insertion of portion A. 



Action. — The action of this muscle is similar to that of the preceding. In conse- 

 quence of the greater obliquity of its fibres, however, its action is more powerful than that 

 of portion A. 



Relations. — Concealed at its origin by the dorsal cutaneous muscle, as well as by the 

 sartorius, it rests upon the ribs, intercostal, and infra-spinatus muscles. 



