Spinal Nerve Roots Complete Reference

These flashcards cover the key concepts and details related to spinal nerve roots, their functions, sensory distributions, reflexes, and notable clinical mnemonics.

C1

Neck flexion (head nod), minimal sensory, joins CN XII sometimes.

C2

Neck rotation and longus colli, sensory to posterior scalp, innervated by the Greater occipital nerve.

C3

Neck lateral flexion and levator scapulae, sensory to lateral neck, part of phrenic nerve.

C4

Innervates diaphragm (phrenic nerve), trapezius (minor), sensory to shoulder tip and lower neck.

C5

Shoulder abduction (deltoid), elbow flexion (biceps), sensory to lateral upper arm, involves the biceps reflex.

C6

Wrist extension and elbow flexion, sensory to thumb and lateral forearm, involving biceps and brachioradialis reflex.

C7

Elbow extension (triceps) and wrist flexion, sensory to middle finger, includes triceps reflex.

C8

Finger flexion, sensory to pinky, medial hand/forearm, involves grip strength.

T1

Finger abduction/adduction, sensory to medial arm, intrinsic hand muscles.

T2

Intercostals (upper), sensory to medial upper arm/axilla.

T3–T6

Intercostals (thoracic muscles), sensory to chest area (T4 = nipple).

T7–T12

Intercostals & abdominal muscles, sensory to abdomen (T10 = umbilicus).

L1

Hip flexion, sensory to inguinal region.

L2

Hip flexion, sensory to anterior thigh.

L3

Knee extension, sensory to anterior thigh/knee, partially involved in patellar reflex.

L4

Knee extension and ankle dorsiflexion, sensory to medial leg/medial foot, involves patellar reflex.

L5

Great toe extension and hip abduction, sensory to lateral leg/dorsum foot/big toe.

S1

Ankle plantarflexion and hip extension, sensory to lateral foot and small toe, involves Achilles reflex.

S2

Knee flexion and hamstrings, sensory to posterior thigh.

S3–S4

Innervates bladder, bowel, pelvic floor, sensory to perineum (saddle area), includes anal wink reflex.

S5

Minimal significant function, sensory to the coccygeal region.

Co1

No significant motor function, sensory to perianal skin.

Phrenic Nerve

Composed of C3, C4, C5, mnemonic: 'C3, 4, 5 keep the diaphragm alive.'

Biceps reflex

Involves spinal nerves C5–C6.

Triceps reflex

Involves spinal nerves C7–C8.

Patellar reflex

Involves spinal nerve L4.

Achilles reflex

Involves spinal nerve S1.

Anal wink reflex

Involves spinal nerves S3–S4.

Mnemonic for number of spinal nerves

'Breakfast at 8, Lunch at 12, Dinner at 5, Supper at 5, 1 cookie'.

Lower Limb Dermatomes

L4 = knee/medial leg, L5 = dorsum foot/big toe, S1 = lateral foot.

Thoracic Landmarks

T4 = nipple, T10 = umbilicus.