320 



THE MUSCLES OF THE DOG 



The rhomboideus consists of three parts. The dorsal portion (Rhomboideus 

 thoracahs) is small; it arises from the fourth to the sixth or seventh thoracic 

 spine, and is inserted into the inner surface (chiefly) of the dorsal angle of the scap- 

 ula. The cervical portion (Rhomboideus cervicalis) arises from the ligamentum 

 nuchse as far forward as the second or third cervical vertebra, and is inserted into 

 the inner surface of the cervical angle of the scapula. The cephalic portion (Rhom- 

 boideus capitis) is a continuation of 

 the preceding which is inserted into 

 the occipital crest. 



The latissimus dorsi is extensive, 

 and has a fleshy attachment to the 

 last two ribs. Its lower edge blends 

 near the shoulder with the panni- 

 culus. 



The mastoido-humeralis con- 

 tains in front of the shoulder a 

 fibrous mass in which the clavicle is 

 embedded. Anterior to this it sepa- 

 rates into two diverging portions. 

 The dorsal portion (M. cleido-cervi- 

 calis) is attached to the median raphe 

 of the neck and to the occipital bone. 

 The ventral portion (M. cleido-mas- 

 toideus) is attached to the mastoid 

 process. The common mass posterior 

 to the clavicle and the fibrous inter- 

 section, which is attached to the 

 humerus, is homologous with the 

 clavicular portion of the deltoid of 

 man. 



The superficial pectoral muscle 

 is small. It arises on the sternum 

 from the first to the third costal 

 cartilage, and is inserted into the 

 anterior siu'face of the humerus. A 

 superficial slip detached from it is 

 inserted into the fascia of the fore- 

 arm. The deep pectoral has no pre- 

 scapular portion. It arises on the 

 sternum and costal cartilages from 

 the second costal to the xiphoid car- 

 tilage. It is inserted chiefly into the 

 internal tuberosity of the humerus, 

 but also by small slips into the ex- 

 ternal tuberosity and the fascia of 

 the arm. 



The serratus magnus shows no 

 clear division into cervical and thor- 

 acic portions. It arises from the last five cervical vertebrse and the first seven 

 or eight ribs, and is inserted into the upper part of the costal surface of the 

 scapula. 



The deltoid is clearly divided into scapular and acromial parts, the former 

 arising on the spine, the latter on the acromion of the scapula. Both end on the 

 deltoid tuberosity. 



Fig. 231. — Ventral Muscles of Head, Neck, and 

 Thorax of Doi:. 

 a, Mylo-hyoideus; b, digastricus; c, sterno-hyoiileus; 

 c', sterno-thyrokleus; d, sterno-eephalicu.s; e, brachio- 

 cephalicus; /, subscapularis; g, superficial pectoral; li, 

 deep ])ectoial; i, rectus abdominis; k, obliciuus abdoniinis 

 externus; /, long head of triceps; m, internal head of 

 triceps; n, biceps brachii; o, braehialis; 1, 1' , 1" , sub- 

 maxillary lymph glands; 2, thyroid gland; 3, external 

 jugular vein. (Ellenberger-Baum, Anat. d. Hundes.) 



