The femoral vessels, O N W, in the upper third of the thigh traverse a triangular space, the base of which is formed by Poupart's ligament, D, whilst the sides and apex are formed by the sartorius, Q, and adductor longus muscles, T, approaching each other. In the undissected state of the part, the structures which bound this space can in general be easily recognised. A central depression extends from the middle of its base, D, to its apex, V, and marks the course of the vessels. Near the middle of Poupart's ligament, the vessels are comparatively superficial, and here the artery may be felt pulsating; but lower down, as they approach the apex of the triangle, the vessels become gradually deeper, till the sartorius muscle inclining from its origin obliquely inwards to the centre of the thigh, w, at length overlaps them. The inner border of the sartorius muscle at the lower part of the upper third of the thigh, W, guides to the position of the artery. Whilst traversing the femoral triangle, the vessels enclosed in their proper sheath are covered by the fascia lata, adipose membrane, and integument. In this place they lie imbedded in loose cellular and adipose tissue. The femoral vein, O, is on the same plane with the artery near Poupart's ligament; but from this place downwards through the thigh, the vein gradually winds from the inner to the back part of the artery; and when both vessels pass under cover of the sartorius, they enter a strong fibrous sheath, V, derived from the tendons of the adductor muscles upon which they lie. The artery approaches the shaft of the femur near its middle; and in this place it may be readily compressed against the bone by the hand. The anterior crural nerve, P, dividing on the outer side of the artery, sends some of its branches coursing over the femoral sheath; and one of these--the long saphenous nerve--enters the sheath and follows the artery as far as the opening in the great adductor tendon. The femoral artery, before it passes through this opening into the popliteal space, gives off its anastomatic branch. The profundus branch, N, springs from the outer side of the femoral artery usually at a distance of from one to two inches (seldom more) below Poupart's ligament, and soon subdivides. [Footnote] The femoral artery in a few instances has been found double. [Footnote: The ordinary length of each part of the main artery is stated on the authority of Mr. Quain. See "Anatomy of the Arteries," &c. ]