Ay The deep veins follow the arteries of the leg, leading finally to the femoral vein.
1. The great saphenous vein travels with the saphenous nerve and passes anterior to the medial malleolus, where it is accessible for venous puncture or catheter insertion. It ascends along the medial aspect of the leg and thigh and finally empties into the femoral vein within the femoral triangle.
2. The lesser saphenous vein travels with the sural nerve and passes posterior to the lateral malleolus. The lesser saphenous vein ascends along the lateral aspect of the leg and finally empties into the popliteal vein within the popliteal fossa.
C. The communicating venous system connects the deep and superficial veins with valves that allow flow of blood only from the superficial veins > deep veins. Incompetent valves allow backflow of blood into the superficial veins (superficial veins < deep veins). This backflow causes dilation of the superficial veins that leads to varicose veins.
D. Clinical consideration. Deep venous thrombosis is a blood clot (thrombus), most commonly within the deep veins of the lower limb. It may lead to pulmonary embolus and usually is caused by venous stasis (e.g., from prolonged immobilization, congestive heart failure, or obesity), hypercoagulation (e.g., with oral contraceptive use or pregnancy), or endothelial damage. The nidus of deep venous thrombosis is stagnant blood behind the cusp of a venous valve (venous sinus). Treatment includes intravenous heparin for 5—7 days followed by treatment with warfarin (Coumadin) for 3 months. (Coumadin is contra indicated in pregnant women because it is teratogenic.)
III. LUMBOSACRAL PLEXUS (Figure 19-2). The components of the lumbosacral plexus include:
A. The LI—5 and SI—4 ventral primary rami of the spinal nerves
B. Anterior and posterior divisions, formed by rami dividing into anterior and posterior divisions
C. Branches. The six major terminal branches are:
3. Superior gluteal nerve (L4, L5, SI)
4. Inferior gluteal nerve (L5, SI, S2)
5. Common peroneal nerve (L4, L5, SI, S2), which divides into the superficial and deep peroneal nerves
6. Tibial nerve (L4, L5, SI, S2, S3), which combines with the common peroneal nerve to make up the sciatic nerve
Ilioinguinal nerve ienitofemoral nerve
Ilioinguinal nerve ienitofemoral nerve
Figure 19-2. The lumbosacral plexus. The rami, divisions, and six major terminal branches are shown. The posterior divisions and branches are shown in black. The pudendal nerve is also shown which was discussed previously. (See Chapter 16 II A and VI B, Figure 16-2, and Table 17-2.)
D. Clinical considerations. Herniation of intervertebral disks is the most common injury that affects the lumbosacral plexus (see Chapter 1 I D 15 and Table 1-2).
IV. NERVE LESIONS (Table 19-1)
A. Femoral nerve injury
1. The femoral nerve may be injured by trauma at the femoral triangle or pelvic fracture.
2. Paralysis of the iliacus and sartorius muscles occurs so that flexion of the thigh is weakened.
3. Paralysis of the quadriceps femoris muscles occurs so that extension of the leg is lost (i.e., loss of knee-jerk reflex).
4. Sensory loss occurs on the anterior aspect of the thigh and the medial aspect of the leg.
B. Obturator nerve injury
1. The obturator nerve may be injured as a result of anterior dislocation of the hip or during radical retropubic prostatectomy.
3. Sensory loss occurs on the medial aspect of the thigh.
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