560 DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 
The third division of the triceps may, indeed, be that representing the short head of 
Man. It lies immediately beneath the second head, and is so very intimately united 
with it that the two appear almost as one. The second division, however, has a more 
aponeurotic origin, and can be distinctly dissected from the third. The latter it is which 
is closely applied to the bone from the neck of the humerus to the intercondyloid fossa. 
It is in close apposition with, but does not overlap the long brachialis anticus, the 
fibres covering the whole of the flat back of the shaft of the humerus. It is inserted by 
short roundish tendon into the upper surface of the olecranon, the tendon, however, 
being much fused with the other insertions of the triceps and anconei. 
Anconeus internus.—This is a transverse slip of muscle, of considerable thickness (A.?, 
fig. 26), attached both to the third head of the triceps and to the origins of the three 
long palmar muscles. It arises from the inner condyle, along with the latter muscles, 
and is inserted into the olecranon beneath the upper ridge and between the head of 
triceps and third long palmar head. Action—a short flexor of the upper ulna. 
The anconeus externus (A.e) is slightly broader and more fan-shaped than is the internal 
muscle. It arises from the outside of the external humeral condyle, and also to its inner 
or olecranon side, filling in part the said fossa and also lower half of humerus; it passes 
backwards transversely, to be inserted into the upper and outer edge of the olecranon. 
The second head of the triceps overlies and partially hides this muscle. 
Biceps—While the triceps muscle is of vast bulk and with an additional head of divi- 
sion, the biceps, on the contrary, is only of moderate dimensions and single-headed (B). 
Its origin is by the usual long tendon from the upper edge of the glenoid cavity of the 
scapula; and, as inferred above, with but a moderate development of muscular belly, it 
terminates below in a tendon inserted into the bicipital tuberosity of the radius. The 
flexing power of this muscle is very limited; but its rather strong tendon above steadies 
the head of the humerus. 
There is no coraco-brachialis muscle ; but a part or continuation of the tendon of the 
extra supraspinatus appears to take the place of it. 
The brachialis anticus has two very distinct heads of origin. ‘The first head, which 
is large and fleshy, comes from the deltoid prominence, and, going downwards to the 
forearm, is inserted directly by tendon into the ulna opposite the biceps tendon. This 
so-called first portion of the muscle (B.a’, fig. 27) has a strong muscular belly; and its 
fibres above seem almost to be continuous with and derived from the extensive muscle 
of the shoulder, viz. the superficial layer of the deltoid. The second head of the 
brachialis anticus (4.a”) arises from the outer side of the neck of the humerus. It 
winds below this partially round the bone, and joins the first head on the outer side of 
the elbow-joint. This second portion in some respects represents the ordinary brachialis 
anticus. At its lower end and outer side it has intimate union by muscular fibres with 
the supinator longus, while it is also partly covered by that muscle and by the second 
abnormal head of the supinator longus arising from the deltoid ridge. 
