CUTANEOUS MUSCLES 431 



tissues. Thus we find the muscles of the well-trained race-horse full and 

 firm to the touch ; but if sufficient intervals of rest are not allowed between 

 his gallops, they will present a very different feel, being flabby and wasted, 

 and indicating that he has been " overworked." 



The voluntary muscles assume various shapes, according to their posi- 

 tions and offices. Sometimes they are merely long strips of muscular 

 tissue, with a very short tendon at each end, as in the levator humeri, 

 and are then called fusiform. At others their fibres radiate, as in the 

 latissimus dorsi, which is hence called a radiating muscle. A third set 

 are called penniform, from their fibres being attached to one side of a 

 tendon, or hipenniform, when they are fixed to both sides like the full 

 tail or wing feather of a bird. A muscle with two masses of its tissue 

 connected in the middle by a tendon is called digastric. 



The special nomenclature of muscles is founded upon: 1st, their posi- 

 tion, as tibialis, pterygoideus, zygomaticus ; 2nd, upon their action, as 

 flexor, extensor, levator ; 3rd, upon their direction, as obliquus, rectus, 

 trans versalis ; 4 th, upon their attachments, as scapulo ulnaris ; and 5 th, 

 upon their division into separate portions or heads, as biceps, triceps, 

 digastricus, etc. 



In describing each muscle it is usual to speak of it as having an origin 

 from one bone, or set of bones, and an insertion into another, the former 

 term being generally assigned to the more fixed division of the two. This is, 

 however, merely for the sake of convenience, and is entirely arbitrary. 



BuRS^ MUCOSA, which are shut sacs, varying in size fi'om that of a pea to 

 a moderate pear, and lined with synovial membrane (see page 395), are placed 

 on all the prominent points of bone over which tendons glide. Thus there 

 is a large one on the point of the hock, and another on the elbow, both of 

 which sometimes inflame and become filled with synovia, constituting the 

 states known as capped hock and elbow. A third situation is just above the 

 sesamoid bones, where the swelling from inflammation receives the name 

 of windgall. Where, as in the legs, the tendons have to glide to a great 

 extent, they are invested with synovial sheaths, which are bound down by 

 white fibrous tissue at the points where the strain is the greatest. In the 

 LIMBS the muscles are bound up into masses by strong but thin layers of 

 intercrossed white fibrous tissue, which receives the name of fascia. In 

 the horse this is very firmly attached to the surface of the muscles beneath, 

 and greatly interferes with the clean dissection of them. 



CUTANEOUS MUSCLES 



Immediately beneath the skin there is a thin layer of muscle, spread 

 over neai^ly the whole surface of the body, and called panniculus carnosus. 

 It is attached internally to some of the most prominent points of the 

 skeleton, chiefly through the intervention of the fascia, which binds down 

 the various groups of muscles. Externally it is inserted at short intervals 

 into the inner surface of the skin, and into the cellular membrane beneath 

 it. Its action is to throw the skin into folds or wrinkles, in so sudden a 

 manner as to dislodge flies or other instating insects. It is also powerful 

 enough to sliake off particles of dust or dirt which have fallen upon the 

 part, and are not glued to it by any adhesive matter 



