84 SPECIAL ANATOMY. 



of which moves in the Fovea anterior ; the Basis in which the Olecranon and 

 Coronaid processes meet together, is thin and brittle; between the two : Fossa 

 sigmoidea maj., for the Trochlea of the upper arm ; minor on the outer border 

 of the Coronoid process for capitulum radii ; under that a rough, deep, triangular 

 surface, for m. supinator brevis. 



b. Centre piece, shaft, 1. Surfaces ; Anterior, Vblar above broad, with/oram. 

 nutritium. Muscles : flex, digit, et pollic. long., carpi ulnaris. Posterior surface : 

 somewhat convex, divided by a longitudinal line. Internal surface: above 

 very broad ; below narrow, and close beneath the skin, smooth. 



2. Borders. External, crista, the sharpest, particularly in the centre, dimin- 

 ishes below for abduct, long, et extern, brevis. pollic., ligam. interrosseum. Anterior 

 or internal, obtuse, for flex, digitor. comm., pronator quad. Posterior : commences 

 below the Okcranon, and is lost on the inferior fourth ; perceptible through 

 the skin. 



c. Inferior extremity, for M. pronator quadratus. Capitulum s. condylus ulna 

 unites with the inferior extremity of the Radius and the cuneiform bone. In- 

 ternal to the small head, Proc. styloideus, for ligam. laterale intern, of the hand 

 and fore-arm ; between the two a hollow, for ligam. triangulare. 



Structure. Compact in the centre, spongy at both extremities, particularly 

 at the elbow. Olecranon sometimes forms a special bone. 



Development: three osseous nuclei. The first appears in the 

 body at the thirty-fifth to the fortieth day of the fetus. The ex- 

 tremities only ossify with the sixth year, and the inferior first. 

 In the fifteenth to the sixteenth year the middle unites with the 

 superior, in the eighteenth to the twentieth year with the inferior 

 extremity. ' 



98. 2. Radius. 



Position : on the outer side .of the Ulna, on the same border as 

 the thumb, radial border. 



Shape: prismatic and triangular, above thin, below thick; in 

 the centre slightly curved. 



Connection: with the upper arm, rotula proc. cubital., Ulna, 

 the wrist, os lunare, naviculare. 



a. Superior extremity. 1. Capitulum radii, with a lateral, annular, articular 

 surface, circumferent. articular., for the fossa sigmoid. minor, and a superior, for 

 the rotula. 



2. Collum, five to six lines long, inferior limit of which : 



3. Tuberositas radii, for m. biceps, the tendon; behind, rough ; before, smooth. 



b. Central piece, shaft, slightly curved, internally concave. 1. Borders: an- 

 terior, blunt, commences from the tuberosity, passes obliquely outwards, and 

 terminates below, before the Proc. styloideus; posterior, above and below 

 slightly marked ; external, for ligam. interosseum, Crista, from the tuberosity to 

 a small articular surface below and internal. 



2. Surfaces : Anterior ; above, narrow ; below, broad ; with foram. Nutritium, 

 for m. supinator brevis, flex, pollicis long., digitor. commun. sublimis. External 

 surface, convex, for m. Pronator teres. Posterior surface, rather hollow, for 

 m. abduct, pollicis longus. 



b. Inferior extremity, thick, quadrangular, for m. pronator quadratus, with 





