106 SPECIAL ANATOMY. 



2. Caput humeri = | of a sphere, the axis of which forms a 

 very oblique angle with the Corpus Humeri. Both are covered 

 with cartilage. 



b. Lig. s. labrum glenoideum, a ring on the margin of, and for the purpose of 

 deepening, the articular cavity which however does not enclose the entire 

 articular head ; consists of fibrous tissue. Vide Interarticular Cartilages. 



c. Lig. capsulare humeri, from the margin of the articular cavity to the 

 Cottum humeri and the two Tubercula, forming a bridge over the groove be- 

 tween them and the tendon of the biceps; a loose spacious capsule which 

 above has one to two openings, by which a communication is established be- 

 tween the synovial capsule of this joint and the bursce of the mm. infrappinal. 

 and subscapular. Is protected, below, in the axilla, by the areolar tissue be- 

 tween the tendons of the mm. subscapular. and teres minor above and exter- 

 nally by the tendons of the m. supraspinatus before, by the m. subscapularis ; 

 behind, by the tendons of the mm. supra-, infra-spinatus, teres minor ; above, 

 even strengthened by a Lig. accessorium of the Proc. coratoid, and by the ten- 

 don of the long liead of the Biceps on the anterior aspect ; lastly, by the 



d. Arch or vault, which is formed over the joint by the acromion, Proc. 

 coracoid., Lig. coraco-acrorniak, and m. deltoideus. 



Movements : 



1. Forwards and backwards. The head of the humerus rolls 

 upon its own axis. The escape of the head anteriorly is pre- 

 vented by the coracoid process. The scapula performs at the 

 same time a movement of rotation. 



2. Outwards, abduction. The head of the humerus glides 

 from above downwards, and presses upon the inferior portion of 

 the capsule, the upper arm may even be conveyed to the skull ; 

 the scapula remains immoveable. 



3. Inwards* adduction. The arms crossed over the chest. 



4. Rotation outwards and backwards, inwards and forwards is 

 of little extent. 



121. Connection of the Upper with the Fore-arm, Jlrticul. 

 cubito-huineralis. H inge-j oint. 



Articular surfaces. 



a. Of the Humerus : 



J. Trochlea. 



2. Rotula. 



3. Fossa cubital, post., for Olecranon. 



4. ant., for proc. Coronoid. 



b. Of the Fore-arm : 



1. Fossa sigmoid. ulnse, for the trochlea. 



2. Cavitas glenoid. radii, for rolula. 



