DISSECTION OF THE LOWER EXTREMITY 153 



The pectineus muscle (M. pectineus) should now be carefully 

 studied. Ascertain its exact form, position, origin, insertion, 

 action, and innervation. Note that it is covered by the fascia 

 pectinea (0. T. pubic portion of fascia lata). Observe the bursa 

 M. pectinei. 



Short Adductor Muscle (M. adductor brevis), Medial Circumflex 

 Artery, and Obturator Nerve. 



Cut through the M. pectineus at its origin and reflect it distal- 

 ward and lateralward. Avoid injury to the ramus anterior of 

 the N. obturatorius. Is an accessory obturator nerve present? 

 Dissect out the branches of the medial circumflex artery (A. cir- 

 cumflexa femoris medialis) in this region and review the artery 

 as a whole. Follow especially 



(a) Superficial ramus (ramus super ficialis). 



(b) Deep ramus (ramus profundus). 



(c) Acetabular ramus (ramus acetabuli). 



Clean the short adductor muscle (M. adductor brevis) and 

 study its form, position, origin, insertion, action, and innerva- 

 tion. Then cut through it at its origin and reflect it distalward 

 and lateralward. Now dissect out the posterior ramus of the ob- 

 turator nerve (N. obturatorius) and study the nerve as a whole. 

 How does it get into the thigh? What muscles receive their 

 motor innervation from it? How do the anterior and posterior 

 rami differ in their relations ? Which sends a branch to the hip- 

 joint? Which to the knee-joint? How is the obturator innerva- 

 tion of the hip and knee of interest in hip-joint disease? 



Other Muscles on Medial Side of Thigh. 



Study the form, position, origin, insertion, action, and inner- 

 vation of the following: 



(a) Gracilis ("slender") muscle (M. gracilis). 



(aa) Bursa M. sartorii propria. 



(ab) Bursa anserina. 



(b) Smallest adductor muscle (M. adductor minimus) (0. T. upper por- 



tion of adductor magnus). 



(c) Great adductor muscle (M. adductor magnus). 



(ca) Hiatus tendineus adductorius (already studied). 



Observe its double nerve-supply. 

 Detach (b) and (c) at their origins and reflect them. 



(d) External obturator muscle (M. obturator externus). 



(e) Psoas major ("larger lumbar") muscle (M. psoas major). 



(f) Iliac muscle (M. iliacus). 



The conjoined tendon of (e) and (/) may now be studied. 



