When the main vessels and nerves pass from the axillary space to the inner side of the arm, they become comparatively superficial in this latter situation. The inner border of the biceps muscle is taken as a guide to the place of the brachial artery for the whole extent of its course in the arm. In plate 11, the artery, b*, is seen in company with the median nerve, which lies on its fore part, and with the veins called comites winding round it and passing with it and the nerve beneath the fascia which encases in a fold of itself all three structures in a common sheath. Though the axillary vein is in close contact with the axillary artery and nerves, yet the basilic vein, d*, the most considerable of those vessels which form the axillary vein, is separated from the brachial artery by the fascia. The basilic vein, however, overlies the brachial artery to its inner side, and is most commonly attended by the internal cutaneous nerve, seen lying upon it in Plate 11, as also by that other cutaneous branch of the brachial plexus, named the nerve of Wrisberg. If a longitudinal incision in the course of the brachial artery be made (avoiding the basilic vein) through the integument down to the fascia of the arm, and the latter structure be slit open on the director, the artery will be exposed, having the median nerve lying on its outer side in the upper third of the arm, and passing to its inner side towards the bend of the elbow, as at b*, Plate 12. The superior and inferior profunda arteries, seen springing above and below the point b, Plate 12, are those vessels of most importance which are given off from the brachial artery, but the situation of their origin is very various. The ulnar nerve, f, lies close to the inner side of the main arterial trunk, as this latter leaves the axilla, but from this place to the inner condyle, Q, behind which the ulnar nerve passes into the forearm, the nerve and artery become gradually more and more separated from each other in their descent. The musculo-spiral nerve, g, winds under the brachial artery at the middle of the arm, but as this nerve passes deep between the short and long heads of the triceps muscle, P, and behind the humerus to gain the outer aspect of the limb, a little care will suffice for avoiding the inclusion of it in the ligature. The brachial artery may be so effectually compressed by the fingers on the tourniquet, against the humerus in any part of its course through the arm, as to stop pulsation at the wrist.