lines.

#Thoracico-lumbar Region.#--The symptoms are similar to those of
disease in the thoracic region. Children while standing often assume a
characteristic attitude--the hips and knees are slightly flexed, and
the hands grasp the thighs just above the knees (Fig. 217). In this
way the weight is partly taken off the affected vertebrae and borne by
the arms. If the child is laid on its back and lifted by the heels,
the spine remains rigid. By this test a projection due to tuberculous
disease may be differentiated from one due to rickets, as in the
latter case the projection disappears.

[Illustration: FIG. 217.--Attitude in Pott's disease of
Thoracico-lumbar Region of Spine.]

The patient often complains of pain in the abdomen--which in children
may be mistaken for a simple "belly-ache"--and of pain shooting down
the buttocks and into the legs. If the cord is pressed upon at the
level of the lumbar enlargement the anal and vesical sphincters are
paralysed, and the reflexes are exaggerated.

_Psoas Abscess._--When an abscess forms, it usually occupies the
sheath of the psoas muscle, in which it spreads down towards the iliac
fossa, and into the thigh, passing beneath Poupart's ligament,
posterior and lateral to the femoral vessels. The communication
between the pelvis and the thigh is often very narrow, so that the
abscess cavity has to some extent the shape of an hour-glass. The pus
may reach the surface in the region of the saphenous opening, or may
spread farther down the thigh under cover of the deep fascia. In some
cases it is liable to be mistaken for a femoral hernia, as the
swelling becomes smaller when the patient lies down, and has an
impulse on coughing.

_Lumbar Abscess._--Sometimes the pus travels along the posterior
branches of the lumbar vessels and nerves to the lateral border of the
sacro-spinalis (erector spinae) and comes to the surface in the space
between the edges of the latissimus dorsi and external oblique
muscles--the triangle of Petit.

In rare cases it passes through the sacro-sciatic foramen and forms a
swelling in the buttock (_sub-gluteal abscess_); or it may pass
through the obturator foramen and reach the adductor region of the
thigh or even the perineum.

#Lumbo-sacral Region.#--Pott's disease in the lumbo-sacral region
usually affects adults, and, on account of the breadth of the
vertebral bodies and the limited range of movement in this segment of
the spine, is seldom accomp