The subcutaneous cellular tissue in front of the elbow contains some large veins, besides lymphatics and filaments of cutaneous nerves. As the subcutaneous veins in this region are those most frequently selected by surgeons for the operation of phlebotomy, and as un toward consequences sometimes result from a want of due care or of sufficient anatomical knowledge on the part of the operator, their situation and connexions should be carefully studied.
These veins are subject to much variety in their size, number, and situation : the following arrangement of them is that most uniformly adopted by authors as the normal one: three principal veins coming from the fore-arm enter the lower part of this region: 1st, the radial or cephalic on the external side courses along the external muscular prominence and ascends to the arm on the external side of the biceps ; 2d, the ulnar or basilic ascends over the in ternal muscular prominence and the internal condyle of the humerus to the inner side of the biceps ; 3d, the median vein ascending from the front of the fore-arm enters the apex of the triangular depression of the elbow, at which point it is usually augmented by a deep branch coming from the deep radial and ulnar veins, and immediately divides at an acute angle into two branches, one of which ascends on each side of the biceps ; the internal of these, called median basilic, runs obliquely upwards and inwards over the course of the brachial artery, and joins the basilic vein above the internal condyle ; its lower extremity is external to the brachial artery, which it crosses obliquely so as to get internal to it superiorly: the other division of the median vein, called median cephalic, passes obliquely upwards and outwards, external to the prominence formed by the biceps, and joins the cephalic at an acute angle above the external condyle.
The cephalic, the basilic, and the two divi sions of the median vein joining them, form a figure which somewhat resembles the Roman capital letter M.
The superficial lymphatic vessels follow the course of the veins ; those on the internal side are larger and enter small ganglions, varying in number from two to five, which are situated in the subcutaneous cellular tissue, above and in front of the internal condyle, where they are sometimes seen swollen and inflamed in consequence of inflammatory affections of the band or forearm.
The subcutaneous nerves are : branches of the internal cutaneous, usually three or four in number, the external cutaneous, and some twigs from the radial and ulnar nerves. The branches of the internal cutaneous pass down to the fore-arm, generally superficial to the basilic and median basilic veins, while the external cutaneous lies deeper than the ce phalic and median cephalic, with the latter of which it is more intimately connected. Some twigs from both the internal and the external cutaneous nerves are distributed to the inte guments behind the elbow.
Aponeurosis.—The aponeurosis of the region of the elbow is continuous with the brachial aponeurosis above, and with that of the fore arm inferiorly ; it is strong behind the elbow, where it receives an expansion from the tendon of the triceps, and has an intimate adhesion to the margin of the olecranon : on each side it is firmly attached to the condyles of the hu merus, sending off several layers from its internal surface, wbich form septa between the origins of the muscles of the fore-arm which arise from these processes : anteriorly it is spread over the triangular depression, where its strength is considerably increased by ex pansions which it receives from the tendons of the biceps and the brachimus anticus ; the ex pansion from the brachius anticus comes forward on the external side of the tendon of the biceps, and is lost over the external mus cular prominence of the fore-arm in front of the external condyle ; the expansion from the biceps forms a narrow band about half an inch in breadth where it is first detached from the tendon of that muscle ; it then descends obliquely to the inner side of the fore-arm, on the aponeurosis of which it is lost about two inches below the inner condyle. Superiorly this expansion crosses over the brachial artery, and its superior margin is defined by a lunated border to which the brachial aponeurosis is attached, while its inferior margin is con founded with the aponeurosis of the fore arm.