from their attachments along with a portion of
the digit concerned. In the hand, it is usually brought about by the
fingers being caught in the reins of a runaway horse, or being seized in
a horse's teeth, or in machinery. It is usually the terminal phalanx
that is separated, and with it the tendon of the deep flexor, which
ruptures at its junction with the belly of the muscle (Fig. 108). The
treatment consists in disinfecting the wound, closing the tendon-sheath,
and trimming the mutilated finger so as to provide a useful stump.

DISEASES OF MUSCLES AND TENDONS

_Congenital absence_ of muscles is sometimes met with, usually in
association with other deformities. The pectoralis major, for example,
may be absent on one or on both sides, without, however, causing any
disability, as other muscles enlarge and take on its functions.

_Atrophy of Muscle._--Simple atrophy, in which the muscle elements are
merely diminished in size without undergoing any structural alteration,
is commonly met with as a result of disuse, as when a patient is
confined to bed for a long period.

In cases of joint disease, the muscles acting on the joint become
atrophied more rapidly than is accounted for by disuse alone, and this
is attributed to an interference with the trophic innervation of the
muscles reflected from centres in the spinal medulla. It is more marked
in the extensor than in the flexor groups of muscles. Those affected
become soft and flaccid, exhibit tremors on attempted movement, and
their excitability to the faradic current is diminished.

_Neuropathic atrophy_ is associated with lesions of the nervous system.
It is most pronounced in lesions of the motor nerve-trunks, probably
because vaso-motor and trophic fibres are involved as well as those that
are purely motor in function. It is attended with definite structural
alterations, the muscle elements first undergoing fatty degeneration,
and then being absorbed, and replaced to a large extent by ordinary
connective tissue and fat. At a certain stage the muscles exhibit the
reaction of degeneration. In the common form of paralysis resulting from
poliomyelitis, many fibres undergo fatty degeneration and are replaced
by fat, while at the same time there is a regeneration of muscle fibres.

#Fibrositis# or "#Muscular Rheumatism#."--This clinical term is applied
to a group of affections of which lumbago is the best-known example. The
group includes lumbago, stiff-neck, and pl