THE MUSCLES OF THE LIMBS. 47 



In tlie Vertebrata above fishes, the following muscles, which 

 occur in Man, are very generally represented : 



JExtrinsio muscles attached to the pectoral and pelvic arches, 

 on the dorsal aspect. — In the fore-limb, the cleidomastoideus, 

 from the posterolateral region of the skull to the clavicle ; the 

 trapezius, from the skull and spines of many of the vertebrre 

 to the scapula and clavicle ; the rhomhoidei, from the spines 

 of vertebras to the vertebral edge of the scapula, beneath the 

 foregoing. Sometimes there is a tracheloacromialis, from the 

 transverse processes of the cervical vertebrae to the scapula. 



On the ventral aspect, the subclavius, which passes from the 

 anterior rib to the clavicle, may be regarded as, in part, a mus- 

 cle of the limb ; the peotoralis minor, from the ribs to the 

 coracoid. 



Between the dorsal and the ventral aspects muscular fibres 

 arise from the cervical and dorsal ribs, and pass to the inner 

 aspect of the vertebral end of the scapula : anteriorly, these are 

 called levator anguli scapulm • posteriorly, serratus magnus. 



An omohyoid muscle frequently connects the scapula with 

 the hyoidean arch. 



The posterior limb does not seem to offer any muscles ex- 

 actly homologous with the foregoing. So far, however, as the 

 recti abdominis, the obliquus extermis, and the fibres of the 

 erector spince, are attached to the pelvic girdle, they cor- 

 respond in a general way with the pre-axial, or protractor, mus- 

 cles of the pectoral arch ; and the ischio-coccygeal muscles, 

 when they are developed, are, in relation to the pelvic arcli, 

 retractors, though, owing to the relative fixity of the pelvis, 

 they act in protracting, or flexing, the caudal region. 



The psoas minor, proceeding from the under surfaces of 

 posterior dorsal (or lumbar) vertebrae to the ilium, or pubis, 

 is a protractor of the pelvis, but, as a hyposkeletal muscle, 

 has no homologue in the fore-limb. 



Extrinsic muscles attached to the humerus or femur, on 

 the dorsal aspect. — In the fore-limb there is the post-axial latis- 

 simcus dorsi passing from spines of dorsal vertebrse to the 

 humerus. On the ventral aspect, the pectoralis major extends 

 from the sternum and ribs to the humerus. 



In the hind-limb, the gluiceus maximus, so far as it arises 

 from the sacral and coccygeal vertebrae, and is inserted inti i 

 the femur, repeats the relations of the latissim,us dorsi. Iii 

 the absence of any thing corresponding with the sternum, or 

 the ribs, no exact homologue of the peotoralis major can be 

 said to exist, though the pectineus comes near it. The psoas 



