deep peroneal nerve.pptx777777777777777777

Study

1. The deep peroneal nerve (deep fibular nerve) function , disfunction and investigation The deep peroneal nerve (deep fibular nerve) is a branch of the common peroneal nerve, originating from the sciatic nerve in the lumbosacral plexus (L4-S2). It plays a crucial role in both motor and sensory functions of the lower leg and foot.

2. 1. Motor Function (Muscle Innervation) The deep peroneal nerve primarily supplies : the muscles responsible for dorsiflexion of the foot (lifting the foot upwards) , and toe extension.

3. Muscles Innervated I n the anterior compartment of the leg: 1. Tibialis anterior
dorsiflexes and inverts the foot.
2. Extensor hallucis longus
extends the big toe and assists in dorsiflexion.
3. Extensor digitorum longus
extends the toes and assists in dorsiflexion.
4. Fibularis (peroneus) tertius
assists in dorsiflexion and eversion of the foot. In the dorsum of the foot: 5. Extensor hallucis brevis – extends the big toe 6. Extensor digitorum brevis – extends the toes (except the little toe).

4. 2. Sensory Function The deep peroneal nerve provides sensation to a small but important area of the foot. Cutaneous innervation: It supplies skin sensation between the first and second toes (the first interdigital cleft). This area is clinically significant because injury or compression of the deep peroneal nerve can cause numbness or tingling in this region.

5. Dysfunction of the Deep Peroneal Nerve Dysfunction of the deep peroneal nerve (deep fibular nerve) can result in motor and sensory deficits, mainly affecting foot movement and sensation. This can lead to conditions like foot drop, weakness, and numbness . Causes of Deep Peroneal Nerve Dysfunction Several factors can lead to dysfunction, including: Trauma and Mechanical Injury Fibular head fractures – Since the common peroneal nerve wraps around the fibular neck before splitting into deep and superficial branches, fractures can lead to nerve compression or injury Knee dislocations – Can stretch or damage the nerve Ankle sprains or fractures – May compress the deep peroneal nerve near the ankle. Surgical complications Orthopedic procedures near the knee , leg , or ankle may accidentally damage the nerve .

6. C ompression Syndromes Anterior Tarsal Tunnel Syndrome Compartment Syndrome (Anterior Compartment Syndrome) Neurological Disorders and Systemic Conditions Diabetic neuropathy – Can affect the deep peroneal nerve, leading to weakness and sensory loss. Charcot-Marie-Tooth disease (CMT) – A hereditary neuropathy causing progressive muscle weakness in the lower legs. Peripheral nerve tumors or cysts (e.g., ganglion cysts) – Can compress the deep peroneal nerve

7. Symptoms of Deep Peroneal Nerve Dysfunction A. Motor Symptoms (Weakness or Paralysis) Foot Drop (inability to dorsiflex the foot The most significant symptom; the foot drags while walking, leading to a high-stepping gait ( steppage gait). Weak toe extension Difficulty lifting the toes, affecting balance and gait. Weak foot inversion (if tibialis anterior is involved)Difficulty turning the foot inward.

8. Sensory Symptoms (Numbness or Pain)Loss of sensation between the first and second toes (first interdigital space). Gait Abnormalities Steppage gait – The patient lifts the knee higher than usual to avoid foot dragging .

9. Clinical Examination History Taking Symptoms : Foot drop , weakness in dorsiflexion , numbness in the first web space , pain , tingling , or burning sensations .). Onset & Duration Sudden ( trauma ) vs . G radual ( neuropathy , compression ). Risk Factors : Diabetes , trauma , surgery , prolonged leg crossing , tight footwear .

10. Physical Examination Motor Function Weakness in dorsiflexion ( tibialis anterior, extensor hallucis longus ). Weakness in toe extension (extensor digitorum longus ). Gait analysis: High-stepping gait (due to foot drop). Sensory Testing:Diminished sensation over the first dorsal web space.

11. Investigation of the Deep Peroneal Nerve with Nerve Conduction Study (NCS) 1. Motor NCS Recording electrode : Over the extensor digitorum brevis muscle on the dorsum of the foot Stimulating electrode : Proximal stimulation at the fibular head . Distal stimulation at the ankle . Parameters measured : Distal latency ( time for impulse to reach the muscle ) Amplitude ( nerve fiber function ) Conduction velocity ( speed of impulse transmission )

12. Sensory NCS Recording electrode: Over the first web space (dorsum of the foot between the first and second toes). Stimulating electrode : At the ankle Measured parameters : Sensory nerve action potential (SNAP) amplitudeConduction velocity

13. Normal NCS Values (Approximate) for the Deep Peroneal Nerve Motor latency : ≤ 6.5 ms Motor amplitude : ≥ 2 mV Conduction velocity : ≥ 40 m/s Sensory amplitude : ≥ 4 µV Sensory conduction velocity : ≥ 40 m/s

14. Electromyography (EMG) Needle EMG helps assess denervation or chronic nerve injury. Muscles tested Tibialis anterior Extensor digitorum longus Extensor hallucis longus Peroneus tertius Findings Acute denervation Fibrillation potentials , positive sharp waves . Chronic changes Motor unit remodeling , large amplitude motor units .