MUSCLES OF THE POSTERIOR LIMBS. 343 



and variety of the movements of its various parts. They are divided into three groups : the 

 external, or group of the thenar eminence, induce the movements of the thumb; the internal, 

 or group of the hypothenar eminence, those of the little finger ; and the middle group, occupy' 

 ing the metacarpal spaces, comprising the interosseous muscles. In addition, there is found in 

 the hand a cuticularis muscle, the cutaneous palmaris (palmaris hrevis). 



The cutaneous palmaris occupies two-thirds of the hypothenar eminence; its fibres are 

 directed downwards and inwards. It corrugates the skin on the ulnar border of the hand. 



A. Muscles of the Thenar Eminence. 

 The.>e muscles, nearly all present in the Dog, are : 



1. The short adductor of the thumb, whose fibres, leaving the lower portion of the anti- 

 brachial aponeurosis, the process of the trapezius and the scaphoides, are succeeded by a 

 tendon which is inserted into tiie upper extremity of the first phalanx of the thumb. 



2. The opponent (opponens) of the thumb, which passes from the anterior part of the 

 trapezium to the external border, and near the anterior face oi' the first metacarpal. 



3. The short flexor of the thumb, a muscle adjoining the preceding, and which ia resolved 

 into two series of fibres— a deep and a superficial. 



4. The short adductor of the thumb, a triangular muscle, occupying the outer half of the 

 hollow of the palm. It is attached to the os magnum, along the entire length of the third 

 metacarpal bone and, by a tendon, to the sesamoid and supero-internal tuberosity of the first 

 phalanx of the thumb. 



B. Muscles of the Hypothenar Eminence. 

 These muscles are : 1. The abductor of the little finger, a small fusiform muscular body, which 

 is attached, above, to the pisiform bone, and below to the supero-internal part of the first phalanx. 



2. The short flexor of the little finger, situated without the preceding, fixed in one part to 

 the process of the unciform bont , and in the other to the inner part of the first phalanx. 



3. The opponent (opponens) of the little finger, a triangular muscle, situated below the 

 preceding. It is inserted into the process of the unciform bone, then into the inner border of 

 the fifth metacarpal and the adjacent portion of its anterior face. 



C. Interosseous Muscles. 



" The interosseous muscles are situated in each interosseous space, two for each space, and 

 are divided into dorsal and palmar. As there are four interosseous spaces, there ought to be 

 eight muscles; but it is usual to exclude the short adductor of the thumb, because (if its 

 special insertions ; this reduces the total number of interosseous muscles to seven — four dorsal 

 and three palmar. 



"These small muscles arise from the lateral faces of the metacarpals to the lateral and 

 upper portions of the first phalanges. By their contraction, they incline these phalanges 

 laterally, and consequently carry the corresponding digit inwards and outwards." 



It may be added that the lumbrici muscles are small muscular and tendinous fasciculi, 

 annexed to the tendons of the deep flexor of the phalanges ; their tendons terminate on the 

 external side of the four last digits, in becoming blended with the interossei. 



Article III. — Muscles of the Posterior Limbs. 

 These form four principal groups : the muscles of the croup, thigh, leg, and foot. 

 Muscles of the Gluteal Region, or Croup. 



This region is composed of three superposed muscles, which are applied 

 to the ilium, and are distinguished according to their relative situation as the 

 suf)erficial, middle, and deep gluteus.'^ 



They are covered by a thick fibrous fascia — a prolongation of the aponeurosis 

 of the great dorsal — which is continued backwards over the muscles of the 

 posterior crural region, where it is confounded with the superficial layer of the 

 fascia lata. This gluteal apotieurosis is fixed to the external angle of the ilium 

 and the supersacral spine. By its deep face it gives attachment to several 

 fasciculi of the superficial and middle glutei. 



' For the justification of the employment of these new denominations, see note, p. 230 



