506 



APPLIED ANATOMY. 



just described but about 7.5 cm. (3 in. ) lower is made through the gluteus maximus, 

 and just below the edge of the pyriformis from without inward will be found the 

 great sciatic nerve, lesser sciatic nerve, sciatic artery, and the internal pudic nerve and 

 internal pudic artery crossing the spine of the ischium. 



Bursts. Covering the tuberosity of the ischium is a bursa which sometimes 

 suppurates and forms a sinus. It can readily be excised. These sinuses are often 

 bilateral. 



Gluteus maximus 

 and pyriformis 



Gluteus maximus 

 Sciatic artery 

 Sciatic nerve 



Gluteus maximus 

 and medius 



Gluteal artery and nerve 



Pyriforrr.is 

 _ Gluteus maximus 

 Internal pudic nerve 

 Internal pudic artery 



FIG. 508. Ligation of the gluteal, internal pudic, and sciatic arteries. 



THE HIP-JOINT. 



The hip-joint, like the shoulder, is a ball-and-socket joint, and, like it, moves in 

 all directions. The main function of the shoulder is mobility, but the functions of 

 the hip are mobility and support. To give the necessary support and security, the 

 band-like ligaments uniting the bones are strong and the extent of the movements is 

 restricted. Macalister ("Text Book of Human Anatomy," p. 179) points out that 

 while the shoulder has 118 degrees of motion around a sagittal axis, abduction and 

 adduction, the hip has only 90 degrees; around a coronal axis, flexion and exten- 

 sion, the shoulder has 170 degrees and the hip only 140 degrees. In the vertical 

 axis the shoulder rotates 90 degrees, while the hip rotates only 45 degrees. In 

 the upright position the centre of gravity falls in front of the axis of rotation of the 

 hip-joint. 



The head of the femur is 5 cm. (2 in.) in diameter and forms f of a sphere. 

 Below and behind its centre is the depression for the attachment of the ligamentum 

 teres. The acetabulum is much deeper than the glenoid cavity of the shoulder-joint 

 and its depth is increased by the cotyloid ligament around its edge. This makes the 

 joint air-tight and holds the femur in place by suction, hence it is called by Allis 

 ("An inquiry into the difficulties encountered in the reduction of dislocations of the 

 hip," Philadelphia, 1896) the sucker ligament. The acetabulum is incomplete at its 

 lower anterior edge, forming the cotyloid notch. The cotyloid ligament bridges 



