ARTICULATION OF THE ELBOW. 



66 



an inch below the internal condyle, having be- 

 tvteen it and this latter process a sinuosily in 

 which the ulnar nerve lies ; it is the prominence 

 of this ridge which determines the obliquity in 

 the direction of the humerus, observable when 

 its inferior articular extremity is placed on a 

 horizontal surface. 



Uehind and above the trochlea a large trian- 

 gular depression (fossa posterior) receives the 

 olecranon in extension of the fore-arm ; a simi- 

 lar depression of smaller size (fossa anterior ) 

 receives the coronoid process in flexion ; these 

 two fossa; are separated by a plate of bone, 

 often so thin as to be diaphanous, and some- 

 times they communicate by an aperture, the 

 longest diameter of which is transverse, as in 

 the quadrumana, carnivora, glires, and pachy- 

 dermata; Meckel is of opinion that the exist- 

 ence of this aperture in the human subject is 

 more frequent in the Negro and Papuas than 

 in the Caucasian race;* however it did not 

 exist in any one of three Negroes and four 

 Mulattoes which I dissected, while I possess 

 two specimens of it, and have seen several 

 others which occurred in Europeans : a second 

 small fossa frequently exists aoove in front of 

 the eminentia capitata, into which the head of 

 the radius is received in complete flexion. 



The superior extremity of the ulna presents 

 anteriorly a deep cavity, (the greater sigmoid 

 cavity,) which is concave from above down- 

 wards and convex in the transverse direction : 

 it is bounded behind by the olecranon and in 

 front by the coronoid process ; the surface of 

 this cavity is smooth and covered by cartilage, 

 with the exception of a rough transverse notch 

 which extends from the internal side nearly the 

 whole way across it, and the inequalities of 

 which are effaced in the recent state by a 

 cushion of soft adipose tissue : on the external 

 side of the coronoid process there is a small 

 smooth lateral surface, oval in shape, (the lesser 

 sigmoid cavity,) which is concave from before 

 backwards ; this depression is covered by an 

 extension of the cartilage of the greater sigmoid 

 cavity, and receives the internal side of the 

 head of the radius. 



The superior extremity of the radius forms a 

 shallow circular depression which receives the 

 lesser head of the humerus; this surface is 

 covered by a cartilage which extends over its 

 circumference on a circular surface applied to 

 the lesser sigmoid cavity of the ulna internally, 

 and embraced by the annular ligament in the 

 rest of its extent : the articular head of the 

 radius is supported on a cylindrical portion, 

 called its neck, which is much smaller in its 

 circumference, of about a finger's breadth long 

 and curved a little outwards, its junction with 

 the shaft of the bone beina marked internally 

 by a rough tubcrosity, the tubercle of the ra- 

 dius, into the posterior side of which the tendon 

 of the triceps is inserted. 



Ligaments.' The fibrous ligaments of the 

 elbow are four in number; 1st, the anterior 



* Handbuch cler menschlichen Anatomie, band 

 ii. 



ligament consists of oblique and perpendicular 

 fibres arising superiorly from the front of the 

 condyles and the part of the humerus imme- 

 diately above the two anterior articular fossa 1 , 

 and is inserted into the anterior edge of the 

 coronoid process of the ulna inferiorly ; 2d, the 

 posterior ligament is less distinct than the an- 

 terior, consisting of transverse fibres extending 

 from one condyle to the other, whicli become 

 more evident when the elbow is flexed; 3d, the 

 external lateral ligament arises from the ante- 

 rior surface of the external condyle by a thick 

 cord-like fasciculus of shining silvery fibres, 

 and spreads out into a broad flat expansion, 

 which is inserted into the whole length of the 

 annular ligament of the radius and into the 

 anterior and posterior margins of the lesser sig- 

 moid cavity of the ulna; the tendons of origin 

 of the aupinator brevis and extensor muscles of 

 the hand are intimately connected to the exter- 

 nal surface of this ligament, but can be easily 

 separated from it by careful dissection ; 4th, 

 the internal lateral ligament arises from the an- 

 terior surface of the internal condyle of the 

 humerus, and passing over the internal side of 

 the synovial capsule, divides into two portions, 

 an anterior and a posterior, the former of which 

 is inserted into the inner side of the coronoid 

 process, and the latter into the internal side of 

 the olecranon : this ligament presents more of 

 a flattened form, and is more easily separated 

 from the tendons of the muscles which cover it 

 than the external lateral ligament. 



The synovial capsule, having covered the ar- 

 ticular surface of the humerus, ascends above 

 this surface as high as an irregular continuous 

 line, including the two anterior articular fossae 

 in front, the posterior articular fossa behind, 

 and limited by the bases of the condyles late- 

 rally ; at the level of this line the capsule is re- 

 flected from the humerus, and descends on the 

 internal surfaces of the fibrous ligaments to be 

 expanded over the articular surfaces of the 

 radius and ulna, to the cartilaginous coverings 

 of which it adheres in the same intimate man- 

 ner as to that of the articular surface of the 

 humerus ; the portion of it corresponding to 

 the radius descends within the annular liga- 

 ment, below which it is reflected on the neck, 

 and thence continued over the head of that 

 bone; while it becomes attached to the ulna at 

 the line which circumscribes the greater and 

 lesser sigmoid cavities over the surfaces of 

 which it is extended ; this capsule, which is 

 rather tense where it lines the lateral ligaments, 

 is flaccid and sacculated anteriorly and poste- 

 riorly, so as not to interfere with the freedom of 

 flexion and extension of the elbow : below the 

 margin of the annular ligament and before it 

 is attached to the neck of the radius, it forms a 

 cul-de-sac so loose as to permit the rotatory 

 motions of that bone to be executed without 

 restraint. 



Several masses of adipose cellular tissue are 

 situated around the articulation external to the 

 synovial capsule, more especially in the articu- 

 lar fossae at the posterior margin of the olecra- 

 non : between the radius and ulna and in the 



