79 



the external and internal condyle ^ the latter being considerably the 

 longer ; and running upwards from the condyles upon the borders of 

 the bone are the condyloid ridges, of which the external is the most 

 prominent. Immediately in front of the trochlea is a small depression 

 for receiving the coronoid process of the ulna 

 daring flexion of the fore-arm ; and immedi- Fi S- 35 * 



ately behind it a large and deep fossa, for con- 

 taining the olecranon process in extension. 



Development. By seven centres ; one for 

 the shaft, one for the head, one for the tu- 

 berosities, one for the eminentia capitata, one 

 for the trochlea, and one for each condyle, 

 the internal preceding the external. Ossifica- 

 tion commences in the diaphysis of the hu- 

 merus soon after the clavicle ; in the head and 

 tuberosities, during the second and third years 

 of infantile life ; in the eminentia capitata 

 and trochlea during the third and sixth years ; 

 and in the condyles during the twelfth and 

 fifteenth. The entire bone is consolidated at 

 twenty. 



Articulations. With the glenoid cavity of 

 the scapula, and with the ulna and radius. 



Attachment of Muscles. To twenty-four ; by 

 the greater tuberosity to the supra-spinatus, in- 

 fra-spinatus, and teres minor ; lesser tuberosity, 

 subscapularis ; anterior bicipital ridge, pectoralis 

 major ; posterior bicipital ridge and groove, teres 

 major and latissimus dorsi ; shaft, external and 

 internal heads of the triceps, deltoid, coraco- 

 brachialis, and brachialis anticus ; external con- 

 dyloid ridge and condyle (condylus extensorius}, 

 extensors and supinators of the fore-arm, viz. 

 supinator longus, extensor carpi radialis lon- 

 gior, extensor carpi radialis brevior, extensor 

 communis digitorum, extensor minimi digiti, 

 extensor carpi ulnaris, anconeus, and supinator brevis ; internal con- 

 dyle (condylus flexorim\ flexors and one pronator, viz. pronator radii 

 teres, flexor carpi radialis, palmaris longus, flexor sublimis digitoruni, 

 and flexor carpi ulnaris. 



! 



* The humerus of the right side ; its anterior surface. 1. The shaft of the 

 hone. 2. The head. 3. The anatomical neck. 4. The greater tuberosity. 

 5. The lesser tuberosity. 6. The bicipital groove. 7. The anterior bicipital 

 ridge. 8 The posterior bicipital ridge. 9. The rough surface into which the 

 deltoid is inserted. 10. The nutritious foramen. 11. The eminentia capitata. 

 12. The trochlea. 13 The external condyle. 14 The internal condyle. 15. 

 The external condyloid ridge. 16. The internal condyloid ridge. 17. The 

 fossa for the coronoid process of the ulna. 



