When the body is in the dorsal recumbent position, Figs. XXII, XXIII. the anterior superior iliac spine is usually visible to the eye, and no palpation is needful in order to fix its position. In the obese, however, it is generally necessary to trace forward the iliac crest to its anterior termination. By tracing the iliac crests in a backward direction the " iliac tubercles" will be found, lying about 2 to 2 1/2 inches behind the anterior superior spines, and a line uniting these two tubercles (the intertubercular plane) corresponds to the level of the fifth lumbar vertebra. Still further backward, the posterior superior iliac spines will be found at the posterior termination of the iliac crest. (Fig. XVII, 15.)
A line which joins the posterior superior iliac spines cuts across the spine of the second sacral vertebra.
The pubic spine lies at the outer limit of the pubic crest. (Fig. XVIII, 6., Fig. XXII, 2.) In the male, it is advisable to invaginate the scrotum in order to locate the position of this spine; whilst in the female, owing to the prominence of the mons veneris, it is usually necessary to abduct the thigh, to feel for the rounded tendon of the adductor longus muscle, and to trace this tendon up to its origin from a depression on the pubic bone, which is situated immediately below and internal to the pubic spine.
In the erect position of the body the symphysis pubis is nearly horizontal, the inner or pelvic surface looking upwards and only slightly backwards, whilst the external surface faces downwards and a little forwards. The pubic crest is therefore practically directed forwards and the pubic arch backwards. A knife inserted horizontally backwards immediately above the pubic symphysis would pass above the upper limit of the prostate gland and below the promontory of the sacrum ; whilst if directed horizontally backwards below the symphysis pubis, it would pierce the prostate near its centre and pass below the level of the tip of the coccyx.