MUSCLES OF THE POSTERIOR LIMBS. 343 



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

 external, or group of the thejiar eminence, induce the movL-rnents of the thumb; Iho internal 

 or group of the hypothenar eminence, those of the little finder; and the middle group, occupy- 

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

 the hand a cuticularis tnuscle, the cutaneous palmuris (palmaris hrevis). 



The cutaneou>^ palmnris 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. 

 These 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, tlie process pf the trapezius and the scaphoides, are succeeded by a 

 tendon which is inserted into the 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 of the first metacarpal. 



3. The short flexor of (he thumb, a muscle adjoining the preceding, and which is 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 tlie 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 piialanx. 



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

 the process of the unciform bone, and iu the other to the inner part of the first phalanx. 



3. The opponent (opponens) of the little firiger, 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 sliort adductor of the thumb, because of 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, tliey incline these phalanges 

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



It may be adde<i tliat the lumhrici 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 

 superficial, middle, and deep glufeufi.^ 



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 aponeurosis 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 denomiaationa, see note, p. 230. 



