THE MUSCLES. 161 



and art. humeri profunda. The long head lies before M. deltoid. 

 and teres minor, behind M. subscapularis, teres major, latissim. 

 dor si. Or. : 1. Caput longum from external border of Scapula, 

 close beneath the articular fossa ; between teres major and minor. 

 2. Cap. externum from the external border of humerus to below 

 the centre. 3. Cap. internum from the internal border ; as far 

 almost as the condyle. Ins. : Olecranon (posterior surface and 

 lateral borders). Use : to extend the fore-arm. 

 Nerves : axiUar., radialis. 



296. 5. Anconxus parvus. 



Pos. : behind the elbow, short, triangular, continuation of Cap. 

 extern., M. tridpitis. Or. : close behind Condylus externus 

 humeri. Ins. : the superior external third of the Ulna. Use : 

 to extend the fore-arm. 



Nerves: radialis. 



297. 6. Subanconssus (of Theile). 



A thin muscular fasciculus. Or. : above the fossa intercondyl. 

 poster. Ins. : Capsule of the elbow articulation. Use : to stretch 

 the capsule. 



298. Fascia brachialis s. humeri, arises, above, from Clavi- 

 cula, Acromion, and Spina scapulse, internally, from the tendons 

 of pect. major, and latissim. dor si and the uniting tissue of the 

 axilla, envelopes the arm and terminates at the articulation of the 

 elbow. It consists almost entirely of circular fibres. The exter- 

 nal surface is separated from the skin by vessels and nerves which 

 the fascia provides with sheaths. 



From the internal surface two septa (ligg. intermuscularia) 

 pass off, which separate the flexor from the extensor muscles 

 (anconsei), and are attached to the external and internal angles of 

 the upper arm. 



299. Lig. intermuscul. externum arises from the anterior 

 border of the bicipital groove, and from the tendon of Deltoideus, 

 separating the brachialis intern, from the triceps ; is perforated 

 by nerv. radialis and art. brachial. profunda, which, at their 

 commencement, run in the posterior, then in the anterior region 

 of the arm. Lig. intermuscul. intern, by nerv. ulnaris, which 

 runs first before, then behind it. The particular sheaths which 

 pass off from these two large ones are : 



1. For M. deltoideus, arises from the posterior border of bi- 

 cipital groove below teres major, and from the tendon of coraco- 

 brachialis ; is thicker and triangular, 2. Sheath between M. 

 biceps and brachialis intern. 3. Canalis brachialis, for Vasa 



