250 



COMPARATIVE ANATOMY 



of the forearm are provided by the navicular and lunate. The triquetrum 

 is separated from the head of the ulna by an interarticular cartilage. 



Metacarpus and Phalanges. The metacarpus consists of five cylin- 

 drical bones which articulate with the distal carpals on one side and with 

 the proximal phalanges on the other. In form the metacarpals are 

 miniature long bones. 



All the digits except the thumb have three phalanges each. 



2. The Lower Limb. The bones of the lower extremity are also 

 divided into four groups, hip, thigh, leg or shank and foot. The skeletal 



>METATARSALS 



PHALANGES<^ 



,PHALA^X3ES 

 iPOLLICIS 



METACARPALS<v 



CARPALS^ 

 PISIFORM ;- 



TRlQUETI^OvH" 



LUNATE- 'i 



ULNA- 



MULTANGULUM 

 'MAJUS 

 _MULTANGULUM 

 MINUS 

 ■CAPITATE 



^ NAVICULAR 



Fig. 207. — Human right foot (A) and left hand (B) viewed from the dorsal side. 

 Their fundamental similarity in structure notwithstanding their divergence in function 

 is striking. (Redrawn from Sobotta.) 



elements corresponding are the coxal or hip bone, femur, tibia and fibula, 

 tarsus, metatarsus, and phalanges. 



The Coxal Bone. The hip or coxal bone consists of three parts, a 

 dorsal ilium, and two ventral elements, pubis and ischium. The ilium 

 articulates dorsally with the sacrum, the two pubic bones meet in the 

 mid- ventral line in the pubic sjnnphysis. The pubis and ischium articulate 

 with one another above and below the large obturator foramen. Laterally, 

 in the region where the three elements of the coxal bone meet, is a cup-like 

 depression, the acetabulum, with which the head of the femur articulates. 

 The concavity of the acetabulum is divided into a smooth articular portion 

 and an acetabular notch to which the head of the femur is attached by the 



