278 TEE MUSCLES. 



9. Lumbrici. 



These small muscles, which owe their name to the resemblance they bear to the 

 lumbricales or earthworms, are only three in number in Carnivora. They occupy the 

 interval between the four chief branches of the perforans tendon, from which they have 

 their origin ; they terminate, by a small fibrous digitation, on the extensor tendons of 

 the three external digits. It is often impossible to trace them so far; for they are 

 frequently observed to stop within and above the first phalanx of the digits for which 

 they are destined. Their functions cannot be rigorously defined in Carnivora. 



10. Metacarpal Interosseous Muscles. (Fig. 125, D, 16, 16.) 



These are four thick and prismatic muscular fasciculi, elongated from above to 

 below, bifid at their inferior extremity, placed parallel to one another, in front of the 

 flexor tendons, from which they are separated by a thin aponeurotic layer, and behind 

 the four large metacarpals. 



They have their origin on the posterior and lateral faces of these bones, as well as on 

 the posterior carpal and intermetacarpal ligaments. Each terminates, by the two 

 branches of its inferior extremity, on the great sesamoids of the digit to which it corres- 

 ponds. There they are continued by a small tendon, which joins the chief extensor of 

 the digit. These muscles oppose undue extension of the digits while the animal is stand- 

 ing, flex them on the metacarpal bones, and maintain the extensor tendons on the anterior 

 aspect of the phalanges. 



B. Muscles of the Anterior Foot in the Pig. 

 In our notes on the myology of this animal, we find : 



1. A muscle which originates in the substance of the metacarpo-supercarpal 

 ligament, and terminates on the proper extensor of the small external digit by a fibrous 

 strip joined to the external fasciculus of the first interosseous muscle ; it is also attached 

 to the external sesamoid. This is, no doubt, the representative of the short flexor of the 

 small digit in Man and the Carnivora. 



2. A single, but very voluminous lumbricus, fixed, at the one part, to the perforans 

 tendon, and at the other, to the proper extensor tendon of the small internal digit 

 (index), as in the preceding muscle. 



3. Four interosseous metacarpal muscles, similar to those in the Dog, and whose 

 terminal digitations join the proper extensor tendons. The interosseous muscles of the 

 two small digits are not only divided at their inferior extremity, but throughout their 

 whole length are observed to be two very distinct fasciculi, one superficial and external, 

 the other deep and internal. The fibrous membrane covering these muscles, and which 

 separates them from the perforans tendons, is much thicker than in the Carnivora. 



C. Muscles of the Anterior Foot in Solipeds. 



In Solipeds only two lumbrici and two interosseous metacarpal muscles have 

 to be described. 



1. The lumbrici originate at the right and the left of the perforans 

 tendon, above the sesamoid annular band of the perforatus. They each 

 terminate by a thin tendon, which is lost in the fibrous lamina enveloping 

 the elastic cushion of the ergot of the fetlock. 



2. The interosseous muscles (anterior lumbrici Percivall) have been 

 wrongly considered by French veterinary anatomists as lumbrici muscles, ' 

 and are described by them as the superior, or great lumbrici. Situated within 

 the rudimentary metacarpal bones, these two little muscles are formed of a 

 very delicate fleshy mass imbedded in the fibrous tissue surrounding the head 

 of the metacarpal bones, and of a long tendon which descends to the metacarpo- 

 phalangeal articulation, to be confounded with the band furnished to the 

 anterior extensor of the phalanges by the suspensory ligament. Sometimes 

 this tendon is directly united to one of the extensors of the phalanges. 



These two muscles represent the interossei of the lateral digits. With 

 regard to those of the median digit, they are transformed, as we have 

 already seen, into a fibrous brace which constitutes the suspensory ligament 

 of the fetlock. 



