REGION OF THE ELBOW. 



63 



retiring in front, which cannot be effaced even 

 in the utmost extension of the fore-arm. The 

 anterior surface of this region when examined in 

 the arm of a muscular man presents a triangular 

 depression, in which is observed the confluence 

 of several large subcutaneous veins ; the base 

 of this depression is above ; the sides are 

 formed by two prominences, of which the ex- 

 ternal is larger and more marked than the in- 

 ternal, and the apex of the triangle is formed 

 inferiorly by the convergence of these pro- 

 minences, which consist of the two masses of 

 the muscles of the fore-arm which arise from 

 the condyles of the humerus. This triangular 

 depression is divided superiorly into two por- 

 tions by a prominence formed by the tendon 

 of the biceps; in the external or larger portion 

 the median cephalic vein is situated, the in- 

 ternal is occupied by the oblique course of the 

 median basilic vein and the trunk of the 

 brachial artery, the pulsations of which can 

 usually be felt and are even sometimes visible 

 in this space : the superficial radial or cephalic 

 vein and the two ulnar veins which contribute 

 to form the basilic are also apparent in this 

 region, being situated over the lateral mus- 

 cular prominences. In the arm of a corpulent 

 female, instead of the appearances here de- 

 scribed, the front of the elbow presents a 

 semiluriar fold or depression, the concavity of 

 which embraces the prominence formed by the 

 biceps. 



Laterally, the region of the elbow presents 

 two prominences formed by the condyles of 

 the humerus, of which the internal is more 

 marked and higher than the external : in the 

 arms of corpulent persons, on the contrary, 

 two depressions like dimples are placed over 

 the condyles. 



Posteriorly, the olecranon forms a remark- 

 able prominence, the situation of which varies 

 in its relation to the condyles of the humerus 

 according to the different motions of the fore- 

 arm ; in complete extension it is above the 

 level of these processes, in semiflexion it is on 

 the same level with them, and is below them 

 when the elbow is flexed to a right angle. 



On either side of the olecranon there is a 

 depression of which that on the internal side 

 is more marked ; pressure here produces a 

 painful sensation which is felt in the little 

 finger and the inner side of the ring-finger ; 

 in the depression external to the olecranon the 

 posterior edge of the head of the radius can 

 be felt rotating immediately below the external 

 condyle when pronation and supination of the 

 fore-arm are performed. An accurate know- 

 ledge of the relations of these parts is essential 

 to the forming an accurate diagnosis in cases 

 of fractures and dislocations in this region. 



Skin and subcutaneous tissue, The skin 

 covering this region is thin, smooth, and de- 

 licate in front ; it is furnished with hairs over 

 the lateral prominences, where it also contains 

 sebaceous follicles in greater numbers than 

 over the anterior depression. In consequence 

 of being very vascular and plentifully supplied 

 with nerves, the skin here is prone to inflam- 



mation, and is often the seat of small phlegmo- 

 nous abscesses and of erysipelas. Posteriorly 

 the skin is thicker, rough on the surface, and 

 generally thrown into transverse folds above 

 the olecranon, particularly in extension : it 

 abounds more in sebaceous follicles and hairs 

 here than on the anterior surface. The sub- 

 cutaneous cellular tissue in front consists of 

 two layers : one of these, more deep-seated, 

 forms a sort of fascia, between the layers of 

 which the subcutaneous veins and nerves are 

 situated; the other, superficial, is principally 

 composed of adipose tissue and varies very 

 much in thickness. In lean persons this latter 

 layer is often of extreme tenuity ; while the 

 other, on the contrary, is then thicker and more 

 closely adherent to the skin. This deeper 

 layer is considerably thicker over the anterior 

 angular depression than on the lateral pro- 

 minences: it sinks in between the pronator 

 radii teres and supinator longus in company 

 with the deep median vein, and is continuous 

 with the cellular tissue between the muscles 

 and around the articulation. Posteriorly the 

 subcutaneous cellular membrane is more loose 

 and lamellar : adipose tissue is almost always 

 absent in it over the condyles of the humerus, 

 and on the smooth posterior surface of the 

 olecranon, there is merely a subcutaneous 

 bursa mucosa between the skin and the peri- 

 osteum. 



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 : 



