CUTANEOUS MUSCLES. 385 
N one of the striated muscles, except the heart and the muscles of respira- 
tion, can go on acting without intervals of rest, during which repairs in 
their structure are effected. If, therefore, the voluntary muscles are to 
be brought into the highest state of vigour and development of size, they 
must be regularly exercised and rested at proper intervals. During the 
former condition blood is attracted to them, and at the same time that 
fluid itself is rendered more fit for the purposes of nutrition ; while during 
the latter period the increased flow of blood continuing allows for a com- 
plete reparation of the tissues. Thus we find the muscles of the well- 
trained racehorse 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 “ over- 
marked.” 
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 bipenniyorm, 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 : Ist, their posi- 
tion, as tibialis, pterygoideus, zygomaticus ; 2d, upon their action, as 
flexor, extensor, levator; 3d, upon their direction, as obliquus, rectus, 
transversalis ; 4th, upon their attachments, as scapulo ulnaris; and 
5th, upon their division into separate portions or heads, as_ biceps, 
triceps, digastricus, We. 
IN DESCRIBING EACH MUSCLE it is usual to speak of it as having an 
origin from one bone, or set of bones, and an znsertion 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& Mucos#, which are shut sacs, varying in size from that of a pea to 
a moderate pear, and lined with synovial membrane (see page 352), 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 
Limes 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 nearly 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 cf the fascia, which binds down 
c U 
