What Is the Brachial Plexus?

The brachial plexus is composed of most of the fibers of the anterior branch of the 5th to 8th cervical nerves and the anterior branch of the 1st thoracic nerve. It exits through the oblique muscle space, travels above and below the subclavian artery, and enters the axilla through the back of the clavicle.

Brachial plexus

discuss

The brachial plexus is composed of most of the fibers of the anterior branch of the 5th to 8th cervical nerves and the anterior branch of the 1st thoracic nerve. It exits through the oblique muscle space, travels above and below the subclavian artery, and enters the axilla through the back of the clavicle.

The branches of the brachial plexus are distributed in the pectoralis upperalis muscles, upper limb muscles, superficial dorsal muscles (except trapezius), and the arms, forearms, hand muscles, joints, bones, and skin. The nerve roots that make up the brachial plexus first synthesize the upper, middle, and lower trunks, and each trunk is divided into anterior and posterior strands above or behind the collarbone. The lateral strands are formed from the upper and middle stems and the anterior thigh Self-made into the inner bundle, after the three-dried femoral confluence into a rear bundle. Three bundles surround the axillary artery from the inside, outside, and the back, respectively.

The brachial plexus is more concentrated behind the midpoint of the clavicle, and its location is superficial and easy to touch. It is often used as an anesthesia site for brachial plexus block.

Chinese name

Brachial plexus

Foreign name

brachial plexus

Branch distribution

Upper thigh muscles

Local composition

Upper and lower clavicle

The branches of the brachial plexus can be divided into the upper and lower clavicle according to the local position of the brachial plexus.

The upper branches of the clavicle are short muscle branches that originate from the roots and trunk of the brachial plexus, and are distributed in the deep cervical muscles, superficial dorsal muscles (except trapezius), and some pectoral and upper limb muscles and upper limb band muscles.

1. Long thoracic nerve (C5 C7): It starts from the nerve root, enters the axilla through the back of the brachial plexus, and descends along the lateral thoracic artery along the surface of the anterior serratus muscle, dominating this muscle. Injury to this nerve can lead to paralysis of the serratus anterior muscle and the appearance of "winged shoulders".

2. Dorsal scapular nerve (C4, C5): After it is emitted from the corresponding spinal nerve root, the penetrating oblique muscle crosses the scapular levator muscle backward, and descends with the dorsal scapular artery between the scapula and the spine and is distributed to the rhombus Muscles and scapular levator muscles.

3, suprascapular nerve (C5, C6): starting from the upper trunk of the brachial plexus, walking backward through the upper scapular notch into the superior ganglia fossa, and then accompanied by the superior scapular artery around the lateral scapular ganglia into the ganglia Fossa, distributed in the superior and inferior ganglia muscles and shoulder joints.

The lower branch of the clavicle originates from the three bundles of the brachial plexus, mostly long branches, divided into muscular branches and cutaneous branches, distributed in the muscles and skin of the shoulders, chest, arms, forearms and hands.

1. The subscapular nerve (C5-7) originates from the posterior tract and descends along the front of the subscapular muscle to dominate the subscapular and great round muscles.

2. The medial pectoral nerve (C8, T1) starts from the medial bundle, passes through the axillary vein and the axillary artery and bends forward, converging with a branch of the lateral thoracic nerve, entering and dominating the chest from the deep side. Small muscle, part of the fiber through the pectoralis major muscle dominates the pectoralis major muscle.

3. Lateral pectoral nerve (C5 ~ C7): It starts from the lateral bundle of the brachial plexus, crosses the front of the axillary artery and vein, passes through the clavicle fascia, and travels to the deep side of the pectoralis major muscle. muscle.

4. Thoracodorsal nerve (C6 ~ 8): It starts from the posterior tract and follows the lateral edge of the scapula with the subscapular blood vessels descending and dominates the latissimus dorsi. In radical mastectomy, care should be taken not to damage this nerve when removing axillary lymph node groups.

5. Axillary nerve (C5, 6): The axillary nerve originates from the posterior plexus of the brachial plexus, passes through the four holes, and runs around the humerus surgical neck to the deep side of the deltoid muscle. The muscle branches innervate the deltoid and small round muscles. The dermal branch (outer arm epithelial nerve) penetrates from the posterior edge of the deltoid muscle and is distributed on the skin of the shoulder and upper part of the outer arm. Fracture of the surgical neck of the humerus, dislocation of the shoulder joint or compression of the axillary rod may damage the axillary nerve and cause deltoid muscle paralysis, the arm cannot be abducted, and the skin feeling in the deltoid muscle area is lost. Due to the deltoid muscle atrophy, the shoulder bones protrude and lose their rounded appearance.

6, musculocutaneous nerve (C5 ~ 7): from the lateral bundle obliquely through the coccybrachid muscle, through the biceps and humerus muscle descending, dominate the muscles to control these three muscles. The terminal branch (dermal branch) penetrates the deep fascia just below the elbow joint and continues as the lateral cutaneous nerve of the forearm, distributed on the skin on the outside of the forearm.

7, the median nerve

8, ulnar nerve

9.Radial nerve

10, medial arm cutaneous nerve

11, medial forearm cutaneous nerve