THE BONES. 83 



the axis of the shaft of the bone. 2. Tuberculwn maj us, on the outer side, 

 with three surfaces, for TO. supra-, infraspinatus, et Teres minor. 3. Tuber- 

 culum minus, anterior, for m. subscapularis. 4. Sulcus longitttdinalis, be- 

 tween the two tubercles, for the tendon of the Caput long, bicipitis. 5. Spina 

 tuberc. major, for m. pect. maj. et deltoid. 6. Spina tuberc. min., for m. teres 

 maj., latiss. dorsi, et coraco-brachial. 7. Collum humeri chirurgorum at the 

 superior sixth of the humerus and the point of transition into 



b. The middle piece, the body. Superior half cylindrical, inferior, triangu- 

 lar, prismatic. 



1. Surfaces : external, below the superior third a V shaped depression, for 

 m. Deltoideus. Internal anterior surface, for m. brachialis internus, oblique 

 from above, downwards, and from before, inwards, the course of the Art. 

 brachialis, presents: Foram. nutritium. Posterior surface below very broad, 

 for m. triceps. 



2. Edges, angles. Anterior, roundish, rough, the commencement of spina 

 tuber, major. External, above indistinct, below, sharp, before curved, for cap. 

 intern, tricip. et supinator longus. More obliquely below, likewise, sharp 

 from Spina tuberc. minoris for cap. intern, tricip. 



c. Inferior extremity flat, broad; presents, from without inwards: 1. Condy- 

 lus externus, for the extensor and supinator muscles. 2. Eminentia capitata s. ro- 

 tula, the small articular head, unites with the Radius of the fore-arm. 3. 

 Trochlea, it receives the Ulna. Above it we find Fossa ant. maj. for Proc. 

 coronoideus ulnae, minor, for the radius ; posterior, for Olecranon. 4. Condylus 

 internus, for the flexor muscles, pronator teres, and palmar, long., behind with a 

 flat groove, for nerv. ulnaris. 



Structure. At the extremities spongy tissue, in the body compact substance 

 and medullary cavitiy. 



Development commences early, second month, in the centre ; 

 both extremities still remain cartilaginous in the second year; then 

 at the superior extremity, for caput and tuberc. majus et minus, 

 three osseous nuclei appear; lastly, at the inferior extremity four 

 osseous centres. In the eighteenth to the twentieth year the ex- 

 tremities first unite with the centre piece, the inferior soonest. 



97. III. Ossa antibrachii, Bones of the fore-arm. 

 1. Ulna s. cubitus, Elbow. 



Position : on the inside of the radius, between upper arm and 

 hand, on the same side as the little finger. 



Shape : prismatic, triangular, rather twisted ; above thicker than 

 below ; longer than the radius. 



Direction: rather oblique from above, downwards and out- 

 wards. 



Connection: with the upper arm, the radius and cuneiform 

 bone by the ligam. capsulare sacciforme. 



a. Superior extremity, behind, has the hook-like process, Proc. anconaus s. 

 Olecranon, for the JLnconeus muscle, the extremity of which moves in the fossa 

 olecrani post. ; anteriorly, Proc. coronoideus, for m. Brachialis internus, the point 



