Comprehensive Anatomy Notes: Nerve
Injuries of the Upper and Lower Limbs
1. Introduction
Peripheral nerve injuries of the upper and lower limbs are clinically significant due to
their impact on motor, sensory, and autonomic functions. Nerves are vulnerable to
trauma, compression, laceration, and iatrogenic injury. Understanding nerve anatomy,
injury mechanisms, clinical presentation, and management strategies is essential for
medical students, physiotherapists, and surgeons. Peripheral nerves of the limbs
originate from the brachial plexus (upper limb) and the lumbar-sacral plexus (lower
limb), with complex branching patterns that influence the distribution of deficits. Injuries
can lead to weakness, paralysis, sensory loss, and impaired coordination.
2. Classification of Nerve Injuries
Peripheral nerve injuries are commonly classified using Seddon’s and Sunderland’s
systems:
2.1. Seddon Classification
1. Neurapraxia: Temporary conduction block without axonal disruption. Recovery
occurs within days to weeks.
2. Axonotmesis: Axonal damage with intact connective tissue; Wallerian
degeneration occurs distal to the injury. Recovery may take months.
3. Neurotmesis: Complete nerve transection; spontaneous recovery is unlikely
without surgical repair.
2.2. Sunderland Classification
● Expands on Seddon with five degrees of injury, ranging from mild conduction
block to complete nerve transection.
3. Upper Limb Nerve Injuries
3.1. Radial Nerve
The radial nerve arises from the posterior cord of the brachial plexus (C5–T1). It
supplies the posterior arm, forearm extensors, and sensory innervation to the posterior
arm and hand.
Mechanism of Injury:
● Midshaft humeral fractures
● Compression (Saturday night palsy)
● Iatrogenic injury during surgery
Clinical Features:
● Wrist drop due to loss of wrist and finger extension
● Sensory loss over the dorsal hand
Management:
● Splinting, physiotherapy, and surgical repair if nerve transection occurs
3.2. Median Nerve
Originates from lateral and medial cords of the brachial plexus (C5–T1). It passes
through the arm, forearm, and carpal tunnel to supply forearm flexors and thenar
muscles.
Mechanism of Injury:
● Supracondylar fractures
● Carpal tunnel syndrome
● Lacerations
Clinical Features:
● Loss of thumb opposition (“ape hand”)
● Sensory loss over lateral palm and fingers
Management:
● Nerve decompression for entrapment
● Tendon transfers for chronic loss
3.3. Ulnar Nerve
Arises from the medial cord (C8–T1) and travels posterior to the medial epicondyle.
Mechanism of Injury:
● Elbow fracture/dislocation
● Compression at cubital tunnel
Clinical Features:
● Claw hand deformity due to loss of intrinsic hand muscles
● Sensory loss over medial hand
Management:
● Splinting, cubital tunnel release, physiotherapy
3.4. Musculocutaneous Nerve
Arises from the lateral cord (C5–C7). Injury is rare but may occur due to trauma or
surgical procedures.
Clinical Features:
● Weak elbow flexion
● Loss of sensation on lateral forearm
4. Lower Limb Nerve Injuries
4.1. Sciatic Nerve
The sciatic nerve, the largest in the body, originates from L4–S3. It innervates the
posterior thigh muscles and splits into the tibial and common fibular nerves.
Mechanism of Injury:
● Hip dislocation
● Pelvic fractures
● Compression from gluteal injections
Clinical Features:
● Weakness in knee flexion, ankle plantarflexion/dorsiflexion
● Sensory loss in posterior thigh, leg, and foot
Management:
● Splints, physiotherapy, and surgical repair for transection
4.2. Common Fibular (Peroneal) Nerve
A branch of the sciatic nerve, it wraps around the fibular neck and is prone to injury.
Clinical Features:
● Foot drop (loss of dorsiflexion)
● Sensory loss on anterolateral leg and dorsum of foot
Management:
● Ankle-foot orthosis, physiotherapy, surgical decompression if needed
4.3. Tibial Nerve
Also a branch of the sciatic nerve, it runs posteriorly to supply the posterior
compartment of the leg and plantar foot.
Clinical Features:
● Weakness in plantarflexion and toe flexion
● Sensory loss on the sole of the foot
Mechanism of Injury:
● Popliteal fossa trauma
● Posterior tibial entrapment
4.4. Femoral Nerve
Originates from L2–L4, supplying anterior thigh muscles and skin over the anterior thigh
and medial leg.
Mechanism of Injury:
● Pelvic fractures
● Retroperitoneal hemorrhage
Clinical Features:
● Weak hip flexion, knee extension
● Loss of patellar reflex
5. Nerve Injury Mechanisms
1. Traumatic: Fractures, lacerations, dislocations
2. Compression: Prolonged pressure (Saturday night palsy, carpal tunnel)
3. Stretch: Hyperextension injuries
4. Iatrogenic: Surgery near nerve pathways
6. Clinical Assessment of Nerve Injuries
● History: Mechanism, onset, progression of symptoms
● Motor Testing: Strength of muscles supplied by the nerve
● Sensory Testing: Light touch, pinprick, temperature, vibration
● Reflex Testing: Patellar, biceps, triceps, ankle reflexes
● Electrodiagnostics: EMG, nerve conduction studies
7. Management Principles
1. Conservative: Splinting, physiotherapy, activity modification
2. Surgical Repair: Indicated in transections or severe entrapment
3. Tendon Transfers: Restore lost function in chronic injuries
4. Pain Management: NSAIDs, nerve blocks for neuropathic pain
8. Rehabilitation
● Early mobilization prevents joint stiffness
● Strengthening antagonist muscles
● Neuromuscular re-education
● Use of orthotic devices to prevent deformity
9. Prognosis
Recovery depends on injury type:
● Neurapraxia: Weeks to months
● Axonotmesis: Months, may require physiotherapy
● Neurotmesis: Surgical repair needed; full recovery rare without intervention
10. Summary
Peripheral nerve injuries of the upper and lower limbs significantly affect mobility,
dexterity, and quality of life. Accurate knowledge of nerve anatomy, injury patterns, and
clinical management is essential for healthcare providers. Early diagnosis, appropriate
intervention, and structured rehabilitation optimize recovery and minimize long-term
disability.
