222 



RADIAL AND ULNAR ARTERIES. 



continue along the whole front of the forearm, 

 each in tolerably close proximity to the bone 

 whose name it bears.* The ulnar, by simply 

 continuing this course, arrives at the hand, 

 but the radial previously turns round the 

 outer side of the wrist to reach the first meta- 

 carpal interval, which it perforates. Each 

 now takes a curved course in the palm ; a 

 curve, whose convexity is forwards, whose 

 situation superficial or deep follows that 

 of the artery with which it is more imme- 

 diately continuous, and which, completed by 

 a branch or branches from its fellow, forms 

 that from the ulnar the superficial, that from 

 the radial the deep, palmar arch. 



Since either of these arches has a share 

 from both vessels, it might at first sight be 

 supposed that we are here presented with a 

 rare peculiarity in the uninterrupted artery 

 traceable from the radial through its palmar 

 arch to the ulnar, or vice versa. But their 

 apparent mutual continuity offers no difficulty 

 to the exact nominal definition of each vessel 

 and, obviously, the anastomosis differs from 

 that common to all arteries only in degree : 

 viz., in the greater freedom of communication 

 which is the consequence of the larger size of 

 the branches effecting it. 



The brachial artery, inclining somewhat 

 forwards in the lower part of its course, so as 

 to gain the angle of flexion of the limb, lies at 

 its termination on the brachialis anticus, where 

 this muscle becoming tendinous, covers the 

 coronoid process of the ulna previously to its 

 insertion into the apex of the rough non- 

 articular surface of this prominence. Here it 

 divides. 



The radial artery. Its relations. The 

 radial artery begins as the outer of the two 

 divaricating branches, and ends as the deep 

 palmar arch : in this course it offers three 

 chief variations of regional anatomy, which 

 will require a separate consideration. The 

 first of these divisions may be regarded as 

 terminating at the lower border of the radius, 

 the second at the superior extremity of the 

 first metacarpal space in the back of the hand, 

 and the third at the point where, after break- 

 ing up into the radialis indicis, magna pollicis, 

 and palmaris profunda vessels, the latter of 

 these, lying deeply in the inner side of the 

 palm, unites with the communicating branch 

 from the ulnar artery. 



(a.) In the forearm^ the artery is directed at 

 first downwards and externally, but afterwards 

 more vertically, so as to exhibit a slight curve, 

 whose convexity is upwards and outwards. 

 It thus corresponds for a very short distance 

 say one third of an inch to the coronoid 

 process of the ulna, and lies on the brachialis 

 anticus ; but in the whole of the remainder 

 of its length it is related to the anterior sur- 

 face of the radius, and is situated on the 

 muscles which immediately cover it. Crossing 

 the inner surface of the tendon of the biceps 



* It will be borne in mind, that here, as in all 

 descriptions of this part, the forearm is supposed to 

 be supine, and hanging vertically by the side of the 

 trunk. 



as this sinks to its insertion, it by turns comes 

 into contact with the cellular tissue on the 

 supinator radii brevis, and lies upon the 

 pronator radii teres, as this passes outwards 

 to its insertion ; then for a short distance the 

 radial origin of the flexor sublimis digitorum 

 sustains it, and next the flexor longus pollicis; 

 by the passage of whose muscular fibres in- 

 wards to their tendon, it is left opposed to 

 the pronator quadratus, but scarcely touching 

 it from the depth at which this muscle is 

 placed. To its outer side is the tendon of the 

 biceps, and, at first distantly, afterwards more 

 closely, the supinator radii longus, which 

 maintains the relation throughout the remain- 

 der of this portion of the vessel : in this 

 situation is also found the musculo-spiral 

 nerve, which descends under cover of the 

 inner border of the muscle, and passes away 

 from the lower part of the artery towards the 

 back of the wrist. To its inner side are suc- 

 sessively, the pronator radii teres in about the 

 upper half of the region, in the lower, the 

 tendon of the flexor carpi radialis ; and be- 

 neath this for a very short distance, that of 

 the flexor longus pollicis. The coverings of 

 the artery are merely the integuments and 

 fascia of the forearm, so that in the whole of 

 its length it is comparatively superficial : and 

 the ordinary cellular tissue surrounds the 

 vessel, while two venae comites accompany its 

 course. 



It may considerably facilitate finding the 

 artery in the living subject, to bear in mind 

 the superficial indices of its course : and from 

 what has been already stated it may be gather- 

 ed, that in the upper half of this region the 

 vessel is situated in a triangular hollow, whose 

 base is the brachialis anticus in the lower 

 part of the arm, whose outer side is the su- 

 pinator longus, and whose inner side is the 

 pronator teres. In the lower portion it oc- 

 cupies a linear and comparatively shallow de- 

 pression, between two tendons whose -margins 

 the fingers readily recognise through the skin, 

 viz. that of the supinator longus externally, 

 the flexor carpi radialis internally. A line, 

 therefore, from the inner border of the biceps 

 tendon, to the inferior apex of the triangle, 

 indicates with tolerable accuracy the first 

 subdivision of its course ; while another from 

 this point, parallel and equidistant to the two 

 tendons above named, marks it in the remain- 

 der of the forearm. 



(b.) In the wrist. This part of the artery 

 is considerably shorter than the preceding, 

 being scarcely one fifth of its length : its di- 

 rection is downwards and outwards from the 

 front of the forearm to the back and lower 

 part of the wrist. In this course, the vessel 

 lies on the external lateral ligament of the 

 wrist joint, and at its termination on the pos- 

 terior ligament of the same articulation ; and 

 corresponds to the scaphoid and trapezium 

 bones which are beneath these. It is covered 

 by skin and fascia, and at first situated at 

 some distance from the surface, becomes to- 

 wards its termination considerably more su- 

 perficial. In its course it is crossed obliquely 



