MUSCULAR SYSTEM. 177 



of the human form. The trapezius (79. B. ,) the latissimus 

 dorsi (79. B. c,) the rhomboidei, serrati, sacro-lumbalis, multi- 

 fidus spin&y and most of the muscles of the back or extensors 

 of the spine are proportioned to the great weight which they 

 have to sustain in the movements of the trunk. The flexor 

 muscles of the ankle-joint, and those of the knee and of the 

 thigh are generally thin, lengthened, and feeble, compared 

 with the extensors of these joints, or when compared with 

 their development in many of the inferior mammalia. The 

 obliqui and the transversalis abdominis, here form strong 

 muscular parietes for the support of the heavy abdominal 

 viscera, the recti abdominis, are unusually short and thick in 

 man, and divided by distinct, transverse, tendinous intersec- 

 tions, and the small pyramidales are more constant than in 

 quadrupeds. The articulation -of the head of the humerus is 

 adapted for free and varied, rather than for powerful, move- 

 ments, and the pectorales (79. A. b,) the deltoid (79. A. e.) 

 and the scapular muscles, are short, broad, and of moderate 

 strength,, but the biceps brachii (79. A..f 9 ) the flexor carpi 

 radialis (79. A. ,) and ulnaris, the supinator radii longus 

 (79. A. h } ) the pronator radii teres (79, A. i,) and almost all 

 the other flexors of the fore-arm and those of the fingers, 

 are much more developed than the extensors of the same 

 joint ; so that while these extremities are unfit for supporting 

 the trunk in a horizontal position, they have the form and 

 movements best adapted for seizing or feeling outward ob- 

 jects, for manipulating the young, and for the various uses 

 to which they are applied in social intercourse and in the 

 arts. The great weight of the head, and its vertical position, 

 unsupported by a ligamentum nuchee, require the recti and 

 obliqui capitis, the splenius, complexus, and trachelo-mastoi- 

 deuSy the platisma myoides (79. A. c,) the sterno-cleido-mas- 

 toideuSy and nearly all the other muscles of the neck, to be 

 proportionally strong for the support and movement of that 

 heavy part. The teeth having little resistance to overcome, 

 by the general softness of the food, the temporal and mas- 

 seter muscles are of moderate size, and by the shortness of 

 the jaws the ordinary muscles of the face are confined to a 

 smaller extent of surface than in other mammalia, and their 

 actions consequently produce impressions more numerous 

 and diversified, and which are more visible from the nakedness, 



PART II. N 



