Cervical spinal nerve 8

Cervical spinal nerve
The plan of the cervical and brachial plexuses.
The spinal cord with spinal nerves.
Details
Latin	Nervi spinalis
*Anatomical terminology* [edit on Wikidata]

The cervical spinal nerve 8 (C8) is a spinal nerve of the cervical segment.^[1]

It originates from the spinal column from below the cervical vertebra 7 (C7).

Innervation

The C8 nerve forms part of the radial and ulnar nerves via the brachial plexus, and therefore has motor and sensory function in the upper limb.

Sensory

The C8 nerve receives sensory afferents from the C8 dermatome. This consists of all the skin on the little finger, and continuing up slightly past the wrist on the palmar and dorsal aspects of the hand and forearm.^[2] Clinically a test of the pad of the little finger is often used to assess C8 integrity.^[3]

Motor

The C8 nerve contributes to the motor innervation of many of the muscles in the trunk and upper limb. Its primary function is the flexion of the fingers, and this is used as the clinical test for C8 integrity, in conjunction with the finger jerk reflex.^[3]

The particular muscles receive innervation from C8^[2] (shown by specific nerve and spinal nerve segments; muscles in italics only have a minor contribution from C8) :

Trunk

Pectoralis major - Medial and lateral pectoral nerves (C5, C6, C7, C8, T1)
Pectoralis minor - Medial pectoral nerve (C5, C6, C7,C8, T1)
Latissimus dorsi - Thoracodorsal nerve (C6, C7, C8)

Upper arm

Triceps brachii - Radial nerve (C6, C7,C8)

Forearm

Flexor carpi ulnaris - Ulnar nerve (C7, C8, T1)
Palmaris longus - Median nerve (C7,C8)
Flexor digitorum superficialis - Median nerve (C8, T1)
Flexor digitorum profundus - Median and Ulnar nerves (C8, T1)
Flexor pollicis longus - Median nerve (C7,C8)
Pronator quadratus - Median nerve (C7,C8)
Extensor carpi radialis brevis - Deep branch of the radial nerve (C7,C8)
Extensor digitorum - Posterior interosseous nerve (C7,C8)
Extensor digiti minimi - Posterior interosseous nerve (C7,C8)
Extensor carpi ulnaris - Posterior interosseous nerve (C7,C8)
Anconeus - Radial nerve (C6, C7,C8)
Abductor pollicis longus - Posterior interosseous nerve (C7,C8)
Extensor pollicis brevis - Posterior interosseous nerve (C7,C8)
Extensor pollicis longus - Posterior interosseous nerve (C7,C8)
Extensor indicis - Posterior interosseous nerve (C7,C8)

Hand

Palmaris brevis - Superficial branch of ulnar nerve (C8, T1)
Dorsal interossei - Deep branch of ulnar nerve (C8, T1)
Palmar interossei - Deep branch of ulnar nerve (C8, T1)
Adductor pollicis - Deep branch of ulnar nerve (C8, T1)
Lumbricals - Deep branch of ulnar nerve, Digital branches of median nerve
Opponens pollicis - Recurrent branch of median nerve (C8, T1)
Abductor pollicis brevis - Recurrent branch of median nerve (C8, T1)
Flexor pollicis brevis - Recurrent branch of median nerve (C8, T1)
Opponens digiti minimi - Deep branch of ulnar nerve (C8, T1)
Abductor digiti minimi - Deep branch of ulnar nerve (C8, T1)
Flexor digiti minimi brevis - Deep branch of ulnar nerve (C8, T1)

Additional Images

Cervical spinal nerve 8

References

↑ American Medical Association Nervous System -- Groups of Nerves
1 2 Drake et al. Gray's Anatomy for Students. Second Edition (2010).
1 2 Aland et al. University of Queensland School of Medicine Clinical Skills Handbook 2010

Spinal nerves

Cervical	C1 C2 C3 C4 C5 C6 C7 C8 anterior Cervical plexus Brachial plexus posterior Posterior branches of cervical nerves Suboccipital – C1 Greater occipital – C2 Third occipital – C3

Thoracic	T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 anterior Intercostal Intercostobrachial – T2 Thoraco-abdominal nerves – T7–T11 Subcostal – T12 posterior Posterior branches of thoracic nerves

Lumbar	L1 L2 L3 L4 L5 anterior Lumbar plexus Lumbosacral trunk posterior Posterior branches of the lumbar nerves Superior cluneal L1–L3

Sacral	S1 S2 S3 S4 S5 anterior Sacral plexus posterior Posterior branches of sacral nerves Medial cluneal nerves

Coccygeal	anterior Coccygeal plexus posterior Posterior branch of coccygeal nerve

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