Nerve Injuries of Lower Limb PDF

Nerve Injuries of Lower Limb December 7, 2024 www.gmu.ac.ae Intramuscular injection site in lower limb: – The gluteal region is a common site for intramuscular injection of drugs because the muscles are thick and large, providing a large area for venous absorption o...

Nerve Injuries of Lower Limb December 7, 2024 www.gmu.ac.ae Intramuscular injection site in lower limb: – The gluteal region is a common site for intramuscular injection of drugs because the muscles are thick and large, providing a large area for venous absorption of drugs. – Injections into the buttock are safe only in the supero- lateral quadrant of the buttock. – Complications of improper technique include nerve injury, hematoma, and abscess formation. 1. Injury to the superior gluteal nerve L4, L5, Causes: S1. 1. During hip replacement surgery Clinical features: - Weakened abduction of the hip due affection of the gluteus medius and minimus. – When a person is asked to stand on (Rt.) leg, the (Rt.) gluteus medius and minimus normally contract as soon as the contra-lateral foot leaves the floor, preventing tilting of the pelvis to the unsupported side.  In superior gluteal nerve (Rt.), when a person a is asked to stand on (Rt.) leg, the pelvis tilts on the unsupported side (Lt.), indicating that the gluteus medius& minimus on the contra- lateral side (Rt.) are nonfunctional.  This is referred to clinically as a positive Trendelenburg test. Injury to Sciatic Nerve (L4 and 5 and S1, 2, and 3) – It is situated at first midway between the posterior superior iliac spine and the ischial tuberosity. – Then midway between the tip of the greater trochanter and the ischial tuberosity Causes: 1. Penetrating wounds, 2. Fractures of the pelvis. 3. Dislocation of the hip joint 4. Badly placed intramuscular injections in the gluteal region Clinical features: A. Motor: i. Paralysis of hamstring muscles (weak hip extension still done by gluteus maximus) & (weak knee flexion is still done by sartorius (femoral) and gracilis (obturator). ii. All the muscles below the knee are paralyzed (wasting), with foot drop (gravity planter flexed).  B. Sensory :– Sensation is lost below the knee, except for a narrow area down the medial side of the lower part of the leg and the medial border of the foot as far as the base of big toe, which is supplied by the saphenous nerve (femoral nerve).  The result of operative repair of a sciatic nerve injury is poor.  Recovery is incomplete.  Loss of sensation in the sole of the foot makes the development of trophic ulcers inevitable. Sciatica:  Condition in which patients have pain in the lower back that spreads to the hip, buttocks, and leg (gets worse when you sit, cough, or sneeze) and tingling & numbness (along the posterior and lateral sides of the leg, and the lateral part of the foot). Causes: 1. Prolapse of an intervertebral disc with pressure on one or more roots of the lower lumbar and sacral spinal nerves. 2. Spondylolisthesis. 3. Pressure on sciatic nerve by an intra-pelvic tumor. 3. Injury to Common Fibular Nerve (Foot drop) – Because it winds subcutaneously around the fibular neck, leaving it vulnerable to direct trauma. Causes: 1. Fracture of the fibular neck. 2. Dislocation of the knee joint. Clinical features: A. Sensory : – Loss of sensation in the lateral aspect of the leg and most of the dorsum of the foot. B. Motor: – Damage of the common fibular nerve results in flaccid paralysis of all muscles in the anterior and lateral compartments of the leg (loss of dorsiflexion of ankle > foot drop and loss of eversion of foot > unopposed inversion (tibialis posterior is still functioning).  Foot drop makes the limb “too long” 4. Deep Fibular Nerve Entrapment “ski boot syndrome”: (L4 and 5 and S1 and 2) Causes: 1. Excessive use of muscles supplied by the deep fibular nerve (e.g., during skiing, running, and dancing) > muscle injury and edema in the anterior compartment. 2. Compression of the nerve by tight-fitting ski boots, especially where the nerve passes deep to the inferior extensor retinaculum. Clinical features: - Pain occurs in the dorsum of the foot and usually radiates to the web space between the first and second toes. 5. Injury to Tibial Nerve (L4: and 5 and S1, 2, and 3) – It is uncommon because it is protected position in the popliteal fossa. Causes: 1. It may be injured by deep lacerations in the fossa. 2. Posterior dislocation of the knee joint. Clinical features: – Paralysis of the flexor muscles in the leg and the intrinsic muscles in the sole of the foot > loss of planter flexion of ankle & flexion of toes. – Loss of sensation in the sole of the foot > trophic ulcers develop. N.B:  Inversion and eversion occur in the talo -calcaneal joint NOT in ankle joint 6. Obturator Nerve Injury:L2, L3 and L4 Causes: – It is rarely injured in: 1. Penetrating wounds. 2. Anterior dislocations of the hip joint. 3. It may be pressed on by the fetal head during labor. Clinical features: A. Motor: - All the adductor muscles are paralyzed except the hamstring part of the adductor magnus, which is supplied by the sciatic nerve & pectineus by femoral nerve. B. Sensory: – The cutaneous sensory loss is minimal on the medial aspect of the thigh. SENSORY INNERVATION OF LOWER LIMB