Atlas of Human Anatomy in Cross Section: Section 7. Lower Limb

Plate 7.17

Ronald A. Bergman, Ph.D., Adel K. Afifi, M.D., Jean J. Jew, M.D., and Paul C. Reimann, B.S.
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This section passes 2 cm below the knee joint. It cuts the head of the fibula (16) and the tibia (1). The popliteus muscle (8) is located in the interval between the fibula and tibia. Its blood supply is the inferior medial genicular artery (4). The plantaris muscle (12) is identified as well as the medial (7) and lateral (13) heads of the gastrocnemius muscle. The soleus muscle (14) is seen intruding between the popliteal artery and vein (10) and the two heads of gastrocnemius (7, 13). The patellar ligament (22) makes its last appearance in this section. Note the saphenous nerve (5) in the superficial (fatty) fascia. The plantaris muscle arises from the distal part of the lateral line of bifurcation of the linea aspera in close association with the lateral head of the gastrocnemius. The fiber bundles that make up plantaris give rise to a flat, short, fusiform belly and are united to a narrow tendon that extends along the medial edge of the calcaneal tendon to the posterior surface of the calcaneus where it attaches. Some tendinous fibers end in the fibrous tissue of this region. The nerve supply of plantaris (10) is a branch from the tibial portion of the sciatic nerve. This nerve arises in the popliteal space and enters the deep surface of the muscle. Plantaris is extremely variable in origin, structure, and insertion. The origin may be from the capsule of the knee joint, from the fascia of the leg, or from the tibia. Its tendon may terminate anywhere along its course in adjacent tissues. It may be absent in 7 to 8.5% of limbs, more commonly on the left side.

The deep terminal branches of the femoral nerve consist of six branches arranged, from medial to lateral, as follows: the saphenous nerve, nerve to vastus medialis, nerve to articularis genu, nerve to vastus intermedius, nerve to vastus lateralis, and nerve to rectus femoris.

The saphenous nerve (5) passes through the femoral triangle and enters the adductor canal. It passes between the dorsal border of the sartorius and the anterior border of the tendon of gracilis. It becomes superficial and descends with the great saphenous vein along the medial border of the tibia as far as the middle of the instep. The saphenous nerve is entirely sensory.

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