330 PRACTICAL ANATOMY. 



femur as the external condylar ridge. The inner lip is continued downward to 

 the adductor tubercle as the internal condylar ridge. The middle lip is continued 

 downward, and expands to form the popliteal surface of the femur. 



Her^< arc tlic brandies of the line a aspera disposed / 



The inner lip continues upward, around and below the lesser trochanter, as 

 the spiral line ; to the lower half of this spiral line is attached the vastus externus ; 

 to the upper, the capsule of the hip-joint. 



The outer lip of the linea aspera continues upward and outward, and ends at 

 the base of the great trochanter in the gluteal ridge for the gluteus maximus. 



The middle lip divides into an inner and an outer division. The inner breaks 

 up into two branches, one for the iliacus, the other for the pectineus muscle, both 

 of which continge the lesser trochanter. The outer division of the middle lip 

 of the linea aspera terminates above as a vertical ridge, midway between the 

 trochanters, as the linea quadrati, for the insertion of the quadratus femoris. 



Describe the attachment of muscles to the tliree lips of the trunk of the linea 

 aspera. 



To the outer, the short head of the biceps femoris and the vastus externus ; 

 to the inner lip, the vastus interims ; to the middle lip, the adductor brevis, adduc- 

 tor longus, and adductor magnus. 



THE PELVIC OUTLET. 



Locate : (i) The subpubic arch ; (2) the tuberosities of the ischium ; (3) the 

 tip of the coccyx ; (4) the ischio-pubic ramus on each side, and give its com- 

 position ; (5) the spine of the pubes ; (6) the symphysis pubis. 



Place the subject in the position shown in figure 229 /. c., flex the leg on 

 the thigh, the thigh on the abdomen, and abduct the thighs. Now fill the rectum 

 with cotton and sew the margins of the anus together. Do not take your stitches 

 too deeply one-fourth of an inch external to the junction of the skin and 

 mucous membrane is enough. 



Incisions. (i) Cut from the subpubic arch through the skin to the front 

 margin of the anus ; then from the posterior margin of the anus to the tip of 

 the coccyx ; (2) cut from one tuberosity of the ischium to the other ; (3) make 

 a circular incision around the anus just a little outside of the stitches employed 

 in sewing together the margins of the anus ; (4) now begin, and dissect back the 

 four flaps. The greatest care must be taken to keep the skin very thin thin 

 enough to see through. 



You have now removed the skin from the outlet of the pelvis. This space 

 is diamond in shape, and has the following boundaries : Two lines above and two 

 below will outline the space called the pelvic outlet (i) a line from the tuberos- 

 ity of the ischium to the subpubic arch on each side above ; (2) a line from the 

 tip of the coccyx to the tuberosity on each side below. This outlines two 

 triangles with their bases together on an imaginary line from one tuberosity to 

 the other. 



The anterior triangle is called the perineal ; the posterior, the ischio- 

 rectal. Continue removing skin until you have exposed a space as large as that 

 represented in figure 229. The next step is to introduce a sound into the 

 bladder, and retain it there by means of string tied tightly around the penis near 

 the end. 



A dissection of this region really consists of only two stages : (i) Of the 



