What Is the Brachial Nerve?

Brachial plexus nerves are composed of cervical C5-8 and T1 nerve roots. The branches are mainly distributed in the upper limbs, and some small branches are distributed in the upper chest muscles, superficial back muscles, and deep cervical muscles.

Brachial plexus nerve

The main branches are: dorsal thoracic nerve, long thoracic nerve, axillary nerve, musculocutaneous nerve, median nerve, radial nerve, and ulnar nerve.

Brachial plexus nerves dominate the senses and movements of the upper limbs, shoulders, and chest.

Chinese name: Brachial plexus nerve
Foreign name: brachial plexus

Component 1: 5 ~ 8 anterior branch of cervical nerve
Component 2: First anterior branch of thoracic nerve

Brachial plexus is more concentrated and superficial behind the midpoint of the clavicle. Brachial plexus block anesthesia is often performed clinically here. The main branches of the brachial plexus are:

Brachial plexus myocutaneous nerve

Musculocutaneous nerve anatomy From the lateral bundle, it sends out obliquely through the rostral brachial muscle, descends between the biceps brachii and the brachialis muscle, and sends out branches to innervate the triceps. The terminal branch is slightly outside the elbow joint, penetrates the deep fascia to the skin, and is renamed the lateral cutaneous nerve of the forearm, which is distributed on the skin of the lateral side of the forearm.

Brachial plexus median nerve

Median nerve Two from the medial and lateral bundles, the two axillary artery clamped. The median nerve is formed at an acute angle and descends along the medial edge of the biceps brachii with the brachial artery down to the elbow fossa. The anterior circumflex muscle descends between the superficial forearm fingers and deep flexor muscles and passes through the carpal tunnel to the palm. The median nerve was first sent into the interstitial space, and then three common palmar nerves were issued, which were then divided into two palmar natural nerves to the opposite edge of 1 to 4 fingers.

The median nerve has no branches in the arms and emits muscle branches in the elbows, forearms, and palms, and governs all forearm anterior group muscles except the brachioradialis, ulnar carpi flexor, and deep flexor ulnar halves. In the palm of the hand, the dorsal muscle and the 1st and 2nd vermiform muscles are dominated by the adductors of the thumb. The dermal branch manages the sensation of the palmar 2/3 of the radial side of the palm, the palmar surface of the three halves of the radial side, and the middle and distal segments of the back.

The median nerve injury mostly occurs in the forearm and wrist. The main causes after injury are: Dyskinesia, manifested as inability of forearm to pronation, weakened wrist flexion, thumb, forefinger and middle finger flexion, thumb cannot do right palm movement; sensory disorders, It is manifested as sensory disturbance in the distribution area of the skin branch, especially in the distal segment of the thumb, forefinger and middle finger; hand deformity. The fish muscles atrophy, and the palms become flat, forming "ape hands".

Brachial plexus nerve injury

Brachial plexus ulnar nerve

Ulnar neuromuscular innervation From the medial bundle of the brachial plexus, from the axilla between the axillary arteries and veins, descending along the medial edge of the biceps brachii with the brachial artery, passing through the medial muscle space to the back of the arm, and then descending through the medial epicondyle The ulnar nerve sulcus is here superficially located. The ulnar nerve descends from the deep side of the forearm ulnar carpi flexor with the ulnar artery, and sends the dorsal branch of the ulnar nerve above the radial wrist joint. This trunk is divided into the superficial branch and the deep branch into the palm through the radial side of the pea bone.

The ulnar nerve sends out muscles in the forearm to control the ulnar carpi flexor and the deep finger flexors in the ulnar half; in the palm of the hand, the inner ulnar muscles, adductor hallucis, interosseous muscles, and third and fourth vermiform muscles are deeply innervated. The cutaneous branch of the ulnar nerve is distributed on the palm of the hand between the small fish and the ulnar half finger; on the back of the hand, it is distributed on the ulnar 1/2 of the back of the hand, on the ulnar side and on the radial half of the phalanx and the ring finger, and on the proximal finger. The skin on the side half.

Supra-humeral fractures can easily damage the ulnar nerve. The injured ulnar nerve is mainly manifested by weak wrist flexion, and the distal segment of the ring finger and the little finger cannot be flexed. The atrophy of the small fish is flat and the thumb cannot be adducted. The atrophy of the interosseous muscle and the deep groove between the metacarpals cannot be brought close to each other. ; Each metacarpophalangeal joint is over the body, and the interphalangeal joints of the fourth and fifth fingers are bent to form a "claw-shaped hand". Feel the loss of the inner edges of the palm and back of the hand.

Brachial plexus radial nerve

Radial neuromuscular innervation It is a thick nerve emitted by the posterior tract. It is initially behind the axillary artery, and then with the deep brachial artery backwards. It travels close to the radial nerve groove on the deep side of the triceps brachii and moves down to the front of the humerus. And deep branches. The superficial branch of the radial nerve descends from the deep side of the brachioradialis muscle with the radial artery, and turns to the back of the hand at the junction of the middle and lower thirds of the forearm. The deep branch of the radial nerve descends between the deep and superficial muscles behind the forearm, and the long branch reaches the wrist.

The radial nerve muscle innervates the triceps brachii, the radial brachii muscle, and all forearm posterior muscles. In addition to the above, dermal branches are also distributed on the skin behind the arms and forearms.

Fracture of the humeral shaft easily damages the radial nerve. After injury, dyskinesia is mainly manifested by paralysis of the forearm extensor muscles, unable to extend the wrists and fingers, and presents a "vertical wrist sign" when the forearm is raised; the sensory disturbance is most obvious in the "tiger mouth" skin on the back of the 1st and 2nd metacarpal space.

Brachial plexus axillary nerve

It originates from the posterior brachial plexus, with the posterior humerus artery around the back of the surgical neck of the humerus to the deep side of the deltoid muscle.

The hair muscles innervate the deltoid and small round muscles.

The dermal branches pierce through the posterior edge of the deltoid muscle and are distributed on the outer skin of the shoulders and the upper third of the arms.

The humeral surgical neck fracture, dislocation of the shoulder joint, or compression of the axillary rod can cause axillary nerve injury. After the injury, the deltoid muscle is paralyzed, the abduction of the shoulder joint is reduced or cannot be abducted, and the skin in the deltoid region is impaired. The muscles atrophy, the shoulders lose their rounded appearance, and the acromion peaks, forming a "square shoulder" deformity.

Brachial plexus thoracic nerve

It originates from the brachial plexus above the clavicle, descends along the outer side of the anterior serratus muscle, and innervates the muscle. Injury of this nerve can cause paralysis of the serratus anterior muscle, which is manifested as "wing-shaped shoulders".

Brachial plexus

It starts from the posterior tract and descends along the lateral margin of the scapula with the subscapular blood vessels and is distributed in the latissimus dorsi. Be careful not to damage this nerve when radical lymphectomy removes the lymph nodes. Do not perform back-hand movements after injury.