116 LABORATORY MANUAL OF HUMAN ANATOMY 



(ba) Dorsal ligaments of basal extremities of metacarpal bones 



(Ligg. basium [ossium metacarpalium] dorsalia). 



(bb) Volar ligaments of basal extremities of metacarpal bones 



(Ligg. basium [oss. metacarp.] volaria). 



(be) Interosseous ligaments of basal extremities of metacarpal 

 bones (Ligg. basium [oss. metacarp.] interossea). These 

 fill up the spatia interossea metacarpi and can be studied 

 to better advantage later, when the bases of the metacarpal 

 bones are separated from one another. 



Before leaving the joints of the carpus and metacarpus, the 

 synovial membranes and articular surfaces of the joint-cavities 

 should be carefully reviewed. (See Fig. 45.) Which joint-cavi- 

 ties are independent? Which communicate? Detach the meta- 

 carpus from the carpus and examine the articular surfaces. 

 Then separate the various bones of the carpus and metacarpus 

 from one another in order to see the extent of the various inter- 

 osseous ligaments and articular surfaces. 



Study the possible movements in the various joints under 

 examination. What muscles are especially concerned in the 

 various movements ? 



Metacarpophalangeal Joints (Articulationes metacarpophalangeae). 



These five joints are arthrodiae. What is an arthrodia? 

 Study- 



(a) Joint-capsules (capsulae articular es] . 



(b) Strengthening ligaments: 



(ba) Collateral ligaments (ligamenta collateralia) , one radial and 



one ulnar for each joint. 



(bb) Volar accessory ligaments (ligamenta accessoria volaria) (0. 



T. palmar ligaments). 



(c) Transverse ligaments of the heads of the metacarpal bones (Ligg. 



capitulorum [oss. metacarpalium] transversa). These have already 

 been examined (vide supra). 



Eaise the extensor tendon from the dorsal aspect of each 

 joint and note the absence of dorsal ligaments, their place being 

 taken by the extensor tendon. 



Of what movements is each metacarpophalangeal joint capa- 

 ble ? What are the muscles concerned in each case for the differ- 

 ent joints? 



Joints of the Fingers (Articulationes digitorum manus). 



Note that the thumb has one, the other digits two ginglymi. 

 What is a ginglymus ? Study 



