MUSCLES OF THE TRUNK. 203 



The tepdon of the slerno-maxiUaris goes to the mastoid prooesa. The sterno-hyoideus 

 and thyroideus are thick and not digastric, and commence from the cartilage of the first 

 rib. 



The Oarnivora have no subscapuh-hyoidevs ; but they possess a very long scalenus, 

 which passes to the eighth rib, and a long muscle of the neck, which tends to become 

 divided into two lateral portions. 



SPINAL REGION OF THE BACK AND LOINS. 



This offers for study eight pairs of muscles, nearly all of which have 

 their iusertions extended over the dorso-lumbar spine, and are disposed in 

 several layers on each side of this long multifidious crest. These muscles 

 are, enumerating them according to their order of superposition : 1, The 

 trapezius ; 2, Great dorsal ; 3, Small anterior respiratory serratus ; 4, Small 

 posterior serratus; 5, Uio-spinalis (longissimus dorsi) ; &, Common intercostal; 

 7, Transversales of the hack and loins [semispinalis dorsi and lumborum). 



Preparation. — 1. Place the animal in the second position. 2. Eemove the slria 

 with the panniculus and the mass of olecranian muscles, to show, in a first operation, the 

 trapezius and great dorsal muscles (Fig. 102). 3. In a second operation, remove the 

 entire fore-limb, with the great dorsal muscle, whose mode of termination may then be 

 studied ; then prepare the two small serrated muscles. 4. Eemove these two muscles, as 

 well as the angulavis of the scapula and the splenius, to expose the common iutercostal 

 and ilio-spinalis (Fig. 106). The superior branch of the latter remaining covered by the 

 great complexus, excise this muscle, leaving only its insertions into tlie transverse 

 processes of the dorsal vertebrae, to show liow they are fixed between the two branches 

 of the ilio-spinalis (longissimus dorsi). 5. Dissect the transversales (semispinalis) by 

 removing the ilio-spinalis and the internal angle of the ilium. 



1. Trapezius. (Fig. 102, 1, 3.) 

 Synonym. — Dorso- and cervico-acromialis — Girard. 



Situation — Form — Structure. — This is a superficial membranous muscle, 

 situated on the sides of the neck and withers. Its shape is that of a triangle 

 whose base is upwards. It is aponeurotic, r t its upper border and in its 

 centre, which allows it to be distinguished, especially iii emaciated subjects, 

 into a cervical and a dorsal portion. The fleshy fibres of the first are 

 directed downwards and backwards; those of the second are oblique 

 forwards. 



Attachments. — By its superior aponeurosis, it is fixed to the cervical cord 

 and to the summits of the toBBBEaa^-processes of the first dorsal vertebrae, ^ 

 where it adheres to the external face of the great dorsal muscle. By' 

 its central aponeurosis and that of its summit, it is attached to the tuberosity 

 of the-«iB»«BBi» spine and the external scapular aponeurosis. Q 



Belations. — This muscle is covered by two aponeurotic planes, whose ~- 

 fibres cross its own at a right angle. Inwardly, it responds to the rhom- 

 boideus, splenius, angularis, sterno-prescapularis, the supra- and infra- 

 spinatus, and the great dorsal. 



Action. — It raises the shoulder, and carries it forward or backward, 

 according as one or other of its muscular portions contract. 



2. Great Dorsal. (Fig. 102, 2.) 

 '^Synonyms. — Dorso-humeralis— Girard. (Latistimus dorsi — Pereivall.) 



Form Situation — Structure — Attachments. — A very broad triangular 



muscle extended over the loins, back, and side of the thorax, and formed of . 

 an aponeurotic and a muscular portion. 



The aponeurosis is attached, by its superior border, to the summits 



