Cervical spinal nerve 8
Encyclopedia
The cervical spinal nerve 8 (C8) is a spinal nerve
of the cervical segment.
It originates from the spinal column from below the cervical vertebra 7 (C7).
and ulnar nerve
s via the brachial plexus
, and therefore has motor and sensory function in the upper limb
.
, and continuing up slightly past the wrist on the palmar and dorsal aspects of the hand and forearm . Clinically a test of the pad of the little finger is often used to assess C8 integrity .
The particular muscles receive innervation from C8 (shown by specific nerve and spinal nerve segments; muscles in italics only have a minor contribution from C8) :
Spinal nerve
The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body...
of the cervical segment.
It originates from the spinal column from below the cervical vertebra 7 (C7).
Innervation
The C8 nerve forms part of the radialRadial nerve
The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...
and ulnar nerve
Ulnar nerve
In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...
s via the brachial plexus
Brachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
, and therefore has motor and sensory function in the upper limb
Upper limb
The upper limb or upper extremity is the region in an animal extending from the deltoid region to the hand, including the arm, axilla and shoulder.-Definition:...
.
Sensory
The C8 nerve receives sensory afferents from the C8 dermatome. This consists of all the skin on the little fingerLittle finger
The little finger, often called the pinky in American English, pinkie in Scottish English , or small finger in medicine, is the most ulnar and usually smallest finger of the human hand, opposite the thumb, next to the ring finger.-Muscles:There are four muscles that...
, and continuing up slightly past the wrist on the palmar and dorsal aspects of the hand and forearm . Clinically a test of the pad of the little finger is often used to assess C8 integrity .
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 .The particular muscles receive innervation from C8 (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 (C5Cervical spinal nerve 5The cervical spinal nerve 5 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 5 ....
, C6Cervical spinal nerve 6The cervical spinal nerve 6 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 6 ....
, C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Pectoralis minor - Medial pectoral nerve (C5Cervical spinal nerve 5The cervical spinal nerve 5 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 5 ....
, C6Cervical spinal nerve 6The cervical spinal nerve 6 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 6 ....
, C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Latissimus dorsi - Thoracodorsal nerve (C6Cervical spinal nerve 6The cervical spinal nerve 6 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 6 ....
, C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8)
Upper arm
- Triceps brachii - Radial nerve (C6Cervical spinal nerve 6The cervical spinal nerve 6 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 6 ....
, C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8)
Forearm
- Flexor carpi ulnaris - Ulnar nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
, C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Palmaris longus - Median nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Flexor digitorum superficialis - Median nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Flexor digitorum profundus - Median and Ulnar nerves (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Flexor pollicis longus - Median nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Pronator quadratusPronator quadratusPronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve...
- Median nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor carpi radialis brevis - Deep branch of the radial nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor digitorum - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor digiti minimi - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor carpi ulnaris - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Anconeus - Radial nerve (C6Cervical spinal nerve 6The cervical spinal nerve 6 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 6 ....
, C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Abductor pollicis longus - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor pollicis brevis - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor pollicis longus - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8) - Extensor indicis - Posterior interosseous nerve (C7Cervical spinal nerve 7The cervical spinal nerve 7 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 7 ....
,C8)
Hand
- Palmaris brevis - Superficial branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Dorsal interossei - Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Palmar interossei - Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Adductor pollicis - Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Lumbricals - Deep branch of ulnar nerve, Digital branches of median nerve
- Opponens pollicis - Recurrent branch of median nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Abductor pollicis brevis - Recurrent branch of median nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Flexor pollicis brevis - Recurrent branch of median nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Opponens digiti minimi - Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Abductor digiti minimi - Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
) - Flexor digiti minimi brevisFlexor digiti minimi brevis (hand)For the muscle of the foot, see Flexor digiti quinti brevis muscle The flexor digiti minimi brevis is a muscle in the hand that flexes the little finger...
- Deep branch of ulnar nerve (C8, T1Thoracic spinal nerve 1The thoracic spinal nerve 1 is a spinal nerve of the thoracic segment..It originates from the spinal column from below the thoracic vertebra 1 ....
)