120 



THE BONES. 



groove is single, and looks outwards. The inferior articular surface resembles that of animals, 

 except that the condyle is more distinct. 



C. Forearm (Fig. 80). — The two bones of the forearm, as we have already seen, only articu- 

 late by their extremities; they are separated from one another in their middle part. The 

 superior extremity of the radius corresponds with the condyle of the humerus ; that of the ulna 

 articulates with the humeral trochlea. The coroiioid process belongs to the ulna. At the 

 lower extremity of the forearm, it is reiniirked : 1. That the radius corresponds with tlie greater 

 portion of the cnrpus, while the ulna only articulates with the pyramidalis. 2. Tliat the radio- 

 carpal articulation is protected outwardly and inwanlly by two small osseous prolongations — 

 the styloid processes of thu ulna and radius. 



D. Hand. — 1. Carpus (Fig. 81). — The carpus of Man is composed of eight bones — four in 

 each row. The three tirst of the upper row articulate with the radius ; the fourth responds to 



F.2. 



Fig. 8U. 



RIGHT HUMAN HUMERUS (ANTERIOR 

 SURFACE). 



1, Shaft ; 2, head ; 3, neck ; 4, greater tu- 

 berosity ; 5, lesser tuberosity ; 6, bici- 

 pital groove ; 7, interior bicipital groove ; 

 8, posterior bicipital ridge ; 9, rough sur- 

 face for insertion of deltoid; 10, nutrient 

 foramen; 11, eminentia capitata ; 12, 

 trochlea; 13, external condyle; 14, in- 

 ternal condyle ; 15, external condyloid 

 ridge; 16, internal condyloid ridge; 17, 

 fossa for the coronoid process of ulna. 



HUMAN ARM-BONES (FRONT VIEW). 



1, Shaft of ulna ; 2, greater sigmoid notch j 

 3, lesser sigmoid notch ; 4, olecranon 

 process ; 5, coronoid process ; 6, nutrient 

 foramen ; 7, ridges for insertion of in- 

 terosseous membrane ; 8, capitalum ulnae ; 

 9, styloid process; 10, shaft of radius; 

 11, its head ; 12, its neck ; 13, its tube- 

 rosity ; 14, oblique line ; 15, lower end 

 of bone ; 16, styloid process. 



the ulna. In the bones of the lower row, the trapezium responds to the metacarpal of the thumb 

 and that of the index; the trapezoides to the latter only, the os magnum am unciform to the 

 metacarpals of the medius, annularis, and little finger. The pisiform bone and the cuneiform 

 process of the unciform convert the posterior face of the carpus into a channel. 



2. Metacarpus (Fig. 81).— The five metacarpals of Man are parallel to each other; they 

 articulate by their superior extremities witli the bones of the carpus, and by their inferior ex- 

 tremities witii the phalange-s. They are all concave in their middle portion, and tiiickened at 

 their ends. Tlie metacarpal of the thumb is the shortest and strongest. The others diminish 

 in volume from the fourth to the first. 



