The Elbow.

The head of the radius can be felt 1 inch below the external condyle of the humerus when alternately pronating and supinating the flexed forearm.

The median vein is seen to bifurcate 1/2 inch below the middle of the bend of the elbow; deep to this, beneath the fascia, is the bifurcation of the brachial artery.

The biceps tendon can be traced vertically through the centre of the bend of the elbow with the forearm flexed.

The Forearm and Hand.

The lower half of the radius is easily felt, and the anterior border of the lower extremity forms a ridge 1 inch above the ball of the thumb, and just below is the radio-carpal articulation. Upon the middle of the posterior border of the lower extremity is the radial tubercle between the tendons of extensor longus pollicis and extensor carpi radialis brevior.

The posterior border of the ulna is subcutaneous throughout, and its lower extremity forms a rounded prominence anterior to which is the styloid process. Between the two lies the tendon of extensor carpi ulnaris.

The carpal bones form an arch bridged by the anterior annular ligament; the bony attachments of the latter form important landmarks.

The tubercle at the base of the third metacarpal can be felt 1 3/4 inches below the tubercle on the back of the lower end of the radius.

The prominences of the knuckles are formed by the heads of the metacarpal bones.

Anteriorly, the metacarpo-phalangeal articulations are situated 3/4 inch above the level of the web of the fingers.

The course of the radial artery is indicated by a line drawn from the bifurcation of the brachial artery to the tubercle of the scaphoid.

The upper third of the ulnar artery follows a curved line from the bifurcation of the brachial artery to the inner side of the anterior surface of the forearm; the lower two-thirds are on a line drawn from the front of the internal condyle to the pisiform bone. The course of the ulnar nerve corresponds to the whole of that line.

The median nerve may be mapped out by a line drawn from a point midway between the mid-point of the bend of the elbow and the internal condyle to a point midway between the two styloid processes.

The radial nerve follows the radial artery in the upper part of its course; at the junction of the middle and lower thirds of the forearm it winds round beneath supinator longus to the back of the forearm.

The summit of the superficial palmar arch is on the mid-point of a line drawn from the lowest transverse crease on the wrist to the root of the middle finger. The deep arch lies transversely midway between the lower border of the anterior annular ligament and the superficial arch.

The Lower Extremity.

The buttock extends from the crest of the ilium above to the gluteal fold below. The highest point of the iliac crest is on a level with the fourth lumbar spine; the anterior superior spine of the ilium limits the groin externally; the posterior superior spine indicated on the surface by a dimple, is on a level with the second sacral spine, and corresponds to the middle of the sacroiliac joint. A hand's breadth below the tubercle of the crest is the great trochanter of the femur, which is best felt if the limb is slightly abducted and rotated.

Nelaton's line, drawn from the anterior superior spine of the ilium to the ischial tuberosity, crosses the hip at the level of the upper border of the great trochanter.

The ischial tuberosity, in the erect posture, is overlapped by the lower border of gluteus maximus; it can be felt a little above the inner part of the gluteal fold. If the hip be rotated inwards, the lesser trochanter can be felt above the outer end of the gluteal fold.

Anteriorly the buttock is limited by the tensor fasciae femoris muscle.

At a point corresponding to the junction of the upper and middle thirds of a line drawn from the posterior superior spine of the ilium to the ischial tuberosity, the gluteal artery and great sciatic nerve enter the buttock; from this point the nerve passes downwards and outwards upon the ischium to a point midway between the tuberosity and the great trochanter.