ARTICULATION OF THE ELBOW. 



65 



the olecranon so prominent, in consequence of 

 which extension of the elbow can be carried 

 farther than in the adult. At the same period 

 the lesser sigmoid cavity of the ulna is pro- 

 portionally smaller, and the annular ligament 

 of the radius much more extensive. 



Varieties. When a high division of the 

 brachial artery takes place, it often happens 

 that the radial artery takes a superficial course, 

 sometimes under and occasionally over the 

 aponeurosis to its usual destination. The pos- 

 sibility of this occurrence should be constantly 

 held in recollection in performing phlebotomy 

 in this region, as it is evident that the vessel, 

 when thus superficially situated, is exposed to 

 be wounded by the lancet of the operator. 



In considering the relative advantages pre- 

 sented by each of the superficial veins which 

 may be selected for phlebotomy, it is necessary 

 to remark that the operation may be performed 

 on any of the veins at the bend of the arm ; 

 on the cephalic and basilic veins it is un- 

 attended with any danger; not so, however, 

 when either the median basilic or median 

 cephalic is the vessel selected. When bleed- 

 ing in the median basilic vein about the mid- 

 dle of its course, if the lancet should transfix 

 the vein, there is danger of the instrument 

 wounding the brachial artery, an accident of 

 serious consequence ; the risk of this accident 

 is not so great when the vein is opened near 

 its lower part, as the brachial artery retires 

 from it here towards the bottom of the trian- 

 gular depression of the elbow; besides the 

 occasional risk of wounding the radial artery, 

 which, in consequence of a high bifurcation 

 of the brachial, sometimes follows the super- 

 ficial course already alluded to, the branches 

 of the internal cutaneous nerve may be wholly 

 or partially divided ; in which latter case sharp 

 pains are usually felt extending along the 

 course of these nerves. Opening the median 

 cephalic vein may be performed without ap- 

 prehension of injury to the brachial artery; 

 the external cutaneous nerve however, the 

 trunk of which lies behind this vein, may suffer 

 a puncture, in consequence of the lancet being 

 pushed too deeply, the consequences follow- 

 ing which have been in many instances a pain- 

 ful affection extending along the branches of 

 this nerve to their terminations. In those un- 

 fortunate cases in which the brachial artery is 

 punctured, should the wound in the artery 

 not be closed and united by properly regulated 

 pressure, the consequence likely to ensue may 

 be one of the following: 1, the blood escap- 

 ing from the wound in the artery may become 

 diffused through the cellular membrane of the 

 limb extending principally upwards towards 

 the axilla along the sheath of the vessel, (the 

 diffused false aneurism ;) 2, the blood which 

 escapes from the artery may be circumscribed 

 within a limited space by the cellular mem- 

 brane which surrounds it becoming condensed, 

 ( the circumscribed false aneurism ;) 3, the 

 wounded orifices of the artery and vein may 

 remain in apposition, and adhere to each other, 

 allowing the blood to pass from the artery 



directly into the vein, constituting the affection 

 called aneurismal varix ; 4, or a circum- 

 scribed sac may be formed between the artery 

 and vein, having a communication with both 

 vessels, the varicose aneurism. 



(J. Hart.) 



ELBOW (ARTICULATION OF THE), 



ayxuv, cubitus ; Fr. coude ; Germ, elbogen ; 

 Ital. gomito. The elbow or humero-cubital 

 articulation is an angular ginglymus formed by 

 the inferior articular extremity of the os humeri 

 and the superior articular extremities of the 

 radius and ulna, the surfaces of which are, in 

 the recent state, covered with a cartilaginous 

 incrustation, and kept in apposition by an ex- 

 tensive synovial capsule, an anterior, a poste- 

 rior, and two strong lateral ligaments. 



The muscles which cover this articulation 

 are, the brachiaeus anticus, the inferior tendon 

 of the triceps, and some of the muscles of the 

 fore-arm anteriorly, the triceps and anconaeus 

 posteriorly, and the superior attachments of 

 several of the muscles of the fore-arm laterally. 



Bones. The lower part of the humerus is 

 flattened before and behind, and curved a little 

 forwards : an obtuse longitudinal ridge, on a 

 line corresponding to the lesser tuberosity at 

 its superior extremity, divides it into two slo- 

 ping surfaces anteriorly, while posteriorly it 

 presents a broad, flat, triangular surface: a 

 sharp ridge on each side terminates below in a 

 rough tuberosity, called a condyle ; the exter- 

 nal condyle is the smaller of the two, and when 

 the arm hangs loosely by the side, it is directed 

 outwards and forwards : the internal condyle 

 is much larger, more prominent, and directed 

 inwards and backwards : a line let fall per- 

 pendicularly from the most prominent part of 

 the greater tuberosity above would fall upon 

 the external condyle; the internal condyle 

 bears a similar relation to the centre of the 

 superior articular head of the humerus. The 

 inferior articular surface extends transversely, 

 below and between the condyles, and presents 

 a series of eminences and depressions ; begin- 

 ning at the external side, a small spheroidal 

 eminence, the eminentia capitata or lesser head, 

 situated on the front of the external condyle, 

 directed forwards and received into the circular 

 cavity on the head of the radius, internal to 

 this is a small grooved depression which lodges 

 the internal part of the border of that cavity : 

 the remainder of this surface forms a sort 'of 

 pulley, to which the greater sigmoid cavity of 

 the ulna corresponds ; this, which is called the 

 trochlea, presents a large depression placed be- 

 tween two raised ridges : the depressed portion 

 of the trochlea winds round the lower extre- 

 mity of the humerus in an oblique direction 

 from before backwards and a little outwards, 

 being broader behind than in front ; its external 

 border forms a semicircular ridge, smooth in 

 front and sharp behind, the anterior part of 

 which corresponds to the division between the 

 radius and ulna; its internal margin also forms 

 a semicircular ridge, sharper and more promi- 

 nent than the external, and which projects half 



F 



