POSTERIOR PART OF LOWER EXTREMITY. 369 



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branches : (i) The communicans fibularis or communicans peronei ; (2) three 

 articular branches to the knee. (Fig. 264.) 



77*6' articular branches reach the joint how ? 



One goes with the anterior tibial recurrent artery. Two accompany the 

 external articular arteries, superior and inferior. Remember, nerve trunks that 

 supply muscles, supply the skin covering the muscles, and the joints the muscles 

 move. 



Describe the popliteal artery. 



It extends from the aperture in the adductor magnus muscle, to the lower 

 border of the popliteus muscle. It is a continuation of the superficial femoral 

 artery. In its course it gives off these branches : (i) Muscular to the borders of 

 the popliteal space ; (2) articular branches, five in number, called superior two 

 (internal and external), inferior two (internal and external), and one called the 

 azygos. These arteries, as above indicated, are all accompanied by articular 

 nerves from the popliteal branches of the great sciatic nerve. 



Short saphenons nerve is iiow formed, and where distributed / 



It is formed by the union of the communicans tibialis and communicans 

 fibularis branches of the internal and external popliteal nerves respectively, and 

 distributed to the posterior part of the leg and to the outer border of the foot. 



/// how many zvays is the scmimcmbranosns muscle inserted? 



In two ways : (i) Tendinously, into the inner tuberosity of the tibia ; (2) apo- 

 neurotically, in (a) ligament of Winslow, (<$) into internal lateral ligament of the 

 knee, (r) into the oblique line of the tibia, as the popliteal aponeurosis. Notice, 

 aponeuroses are named according to the name of the muscle they cover or 

 the surgical area they invest e. g., axillary, masseter, parotid, etc. 



Explain tlie insertion of the gracilis, semitendinosus, and sartorius. 



They are inserted into the upper one-third of the inner surface of the tibia, 

 below the tuberosity ; the gracilis and semitendinosus by tendon, the former one- 

 half inch the higher. The sartorius is inserted by a broad aponeurosis, which 

 completely covers in the insertions of the other two muscles. 



The ] icads of the gastrocnemius differ in origin how / 



The inner head arises above the condyle ; the outer, from the side of the 

 condyle. The latter seems to have been crowded out of place by the plantaris 

 muscle at least let this suggestion aid the memory. 



Geometrical Inventory of the Popliteal Space : 



Roof skin, superficial and deep fasciae. 



Floor femur, ligament of Winslow, popliteus muscle. 



Superior end aperture in the adductor magnus muscle. 



Inferior end oblique line of the posterior surface of the tibia. 



Superior border externally, the biceps muscle. 



Superior border internally, semitendinosus, semimembranosus, gracilis, and 

 sartorius muscles. 



Inferior border internally, inner head of the gastrocnemius. 



Inferior border externally, outer head of the gastrocnemius and plantaris. 



Shape diamond ; resembling two triangles with bases together. 



In the center are seen the internal popliteal nerve and popliteal vessels. 



Outer border the external popliteal nerve is in the sheath of biceps. 



