Examination Of S1 Nerve Root

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

 

EXAMINATION OF S1 NERVE ROOT

1. SENSORY EXAMINATION
2. REFLEXES
3. MOTOR EXAMINATION

SENSORY EXAMINATION

• Checking sensation in the dermatomal distribution of the S1 nerve, which includes lateral aspect of foot.

REFLEX EXAMINATION

• Testing the ankle reflex (Achilles reflex), which is primarily innervated by the S1 nerve root.

MOTOR SYSTEM EXAMINATION

• Testing strength and muscle bulk of the muscles innervated by the S1 nerve root,

MUSCLES INNERVATED BY S1

1. Peroneus Longus & Brevis
2. Flexor Hallucis Longus
3. Gastrocnemius
4. Lateral Hamstrings
5. Gluteus Maximus

 

A patient with a herniated disc at L5 – S1, (affecting the S1 nerve root) may find sharp waves or fibrillations.

A posterolateral herniated disc at L5 – S1 clearly causes S1 nerve root irritation

A foraminal herniated disc at L5 – S1 will cause L5 radiculopathy.