s are met with
as the result of the distension of lymph spaces and vessels
(_lymphangiectasis_); and in lymphangiomas, of which the best-known
example is the cystic hygroma or hydrocele of the neck.

GANGLION

This term is applied to a cyst filled with a clear colourless jelly or
colloid material, met with in the vicinity of a joint or tendon sheath.

The commonest variety--the _carpal ganglion_--popularly known as a
sprained sinew--is met with as a smooth, rounded, or oval swelling on
the dorsal aspect of the carpus, usually towards its radial side (Fig. 60).
It is situated over one of the intercarpal or other joints in this
region, and may be connected with one or other of the extensor tendons.
The skin and fascia are movable over the cyst. The cyst varies in size
from a pea to a pigeon's egg, and usually attains its maximum size
within a few months and then remains stationary. It becomes tense and
prominent when the hand is flexed towards the palm. Its appearance is
usually ascribed to some strain of the wrist--for example, in girls
learning gymnastics. It may cause no symptoms or it may interfere with
the use of the hand, especially in grasping movements and when the hand
is dorsiflexed. In girls it may give rise to pain which shoots up the
arm. Ganglia are also met with on the dorsum of the metacarpus and on
the palmar aspect of the wrist.

[Illustration: FIG. 60.--Carpal Ganglion in a woman aet. 25.]

The _tarsal ganglion_ is situated on the dorsum of the foot over one or
other of the intertarsal joints. It is usually smaller, flatter, and
more tense than that met with over the wrist, so that it is sometimes
mistaken for a bony tumour. It rarely causes symptoms, unless so
situated as to be pressed upon by the boot.

_Ganglia in the region of the knee_ are usually situated over the
interval between the femur and tibia, most often on the lateral aspect
of the joint in front of the tendon of the biceps (Fig. 61). The
swelling, which may attain the size of half a walnut, is tense and hard
when the knee is extended, and becomes softer and more prominent when it
is flexed. They are met with in young adults who follow laborious
occupations or who indulge in athletics, and they cause stiffness,
discomfort, and impairment of the use of the limb. A ganglion is
sometimes met with on the median aspect of the head of the metatarsal
bone of the great toe and may be the cause of considerable suffering; it
is indistingui