What Is the Cervical Plexus?

The cervical plexus is located deep in the upper part of the sternocleidomastoid muscle, in front of the medial scalene and scapular levator.

The cervical plexus is located deep in the upper part of the sternocleidomastoid muscle, in front of the medial scalene and scapular levator.

Chinese name

Cervical plexus

Foreign name

cervical plexus

Department

Anatomy

Cervical Plexus Overview

It is located on the ventral side of the scapular levator and medial scalene muscles, and on the deep side of the sternocleidomastoid muscle. The branches of the cervical plexus include: the muscular branch, the cutaneous branch, and the communication branch with the hypoglossal nerve and the accessory nerve.

The composition and location of the cervical plexus

Cervical plexus cervical plexus consists of the anterior branches of the first to fourth cervical nerves.

Cervical plexus

The branches of the cervical plexus have shallow and deep branches, and the shallow branch is also called the cervical plexus skin branch.

The cervical plexus branch is pierced near the midpoint of the posterior margin of the sternocleidomastoid muscle. It is superficial in position and spreads out to all sides. The piercing site is a blocking point for neck skin infiltration and anesthesia. The main shallow branches are:

1. The lesser occipital nerve (C2) rises along the posterior edge of the sternocleidomastoid muscle and is distributed on the skin of the occipital and upper part of the back of the auricle.

2. The great auricular nerve (C2, 3) runs forward along the surface of the sternocleidomastoid muscle to the auricle and its surrounding skin.

3 The transverse nerve of neck (C2, 3) traverses the sternocleidomastoid muscle, facing the front, and is distributed on the neck skin.

4 The supraclavicular nerves (C3, 4) have 2 to 4 branches outward and downward, and are distributed on the skin on the side of the neck, upper part of the chest wall, and shoulders.

The deep branches of the cervical plexus mainly dominate the deep cervical muscles, scapular levator muscles, subhyoid muscles, and the iliac crest.

5. Phrenic nerve (C3-5) is the most important branch of the cervical plexus. First outside the upper side of the anterior scalene muscle, and then descending to the inside of the muscle along the front of the muscle. It enters the thorax through the upper thorax between the subclavian arteries and veins. Diaphragm. The motor fibers of the septum nerve dominate the diaphragm, and the sensory fibers are distributed in the pericardial region of the thorax and abdomen. The septum nerve also branches off into the peritoneum below the diaphragm. It is generally believed that the sensory fibers of the right phrenic nerve are still distributed to the liver, gallbladder, and extrahepatic biliary tract. The main manifestation of phrenic nerve injury is paralysis of the zygomatic muscle on the ipsilateral side. Abdominal breathing weakens or disappears, and severe cases may have suffocation. Hiccups can occur when the phrenic nerve is stimulated.

6. The accessory phrenic nerve is more common on one side, starting from the anterior branch of the 5th to 6th cervical nerves, and adding the phrenic nerve to the posterior side of the subclavian vein.

Cervical plexus anatomy

In addition to the anterior branches of the spinal nerve roots of the neck 2 to neck 4 which are involved in the formation of the cervical and sacral nerves, there are also motor branches that dominate the oblique muscle group and the scapular levator muscle. The average length of the anterior branch after the cervical nerve root emerges from the intervertebral foramen. The average length of the main trunk (before the branch is formed to form the cervical plexus) is about 12.28 ± 3.01mm. , Shallow to the deep side of the sternocleidomastoid muscle, branching to form the cervical plexus. The motor branches of the spinal nerves of the neck 2, neck 3, and neck 4 are divided into shallow and deep parts. The superficial branch travels on the medial scalene and the superficial surface of the scapularis levator; the deep branch is the intermuscular bundle, which travels between the medial scalene muscle fibers and enters the scapularis after passing through. The cervical 2 spinal nerves are higher in position and branch early after exiting the intervertebral foramen. Their motor branches are small and travel outwards. They are distributed at the beginning of the anterior and medial scalene muscles and scapular levator muscles. The anterior branches of the cervical 3 and cervical 4 spinal nerves after exiting the intervertebral foramen go down to the upper edge and midpoint of the thyroid cartilage and branch out to form the cervical plexus. Enter the posterior scalene muscle and scapular levator muscle (intermuscular bundles are not measured). The superficial motor branches are relatively thick and constant, crossing the superficial surface of the upper 1/3 lower part of the medial oblique muscle and the upper part of the middle 1/3 downward, respectively, reaching and ending at the upper and lower ends of the middle 1/3 of the scapular levator muscle. Shallow surface. Sometimes the cervical spine 3 and / or the cervical 4 spinal nerve still have a second superficial motor branch that innervates the scapular levator muscle.

The cutaneous branch small occipital nerve (neck ₂ or neck ₃ ) rises along the posterior edge of the sternocleidomastoid muscle and is distributed on the skin of the occipital region and the upper third of the ear. The great auricular nerve (neck _{2 to 3} ), which rises obliquely across the superficial surface of the sternocleidomastoid muscle and is distributed on the skin of the back of the ear and the parotid gland. The transverse cervical nerve (necks _{2 to 3} ) traverses the superficial surface of the sternocleidomastoid muscle and is divided into upper and lower branches to the leading edge of the muscle. The upper branch and the neck branch of the facial nerve are anastomated (combined), and are distributed on the skin in the upper part of the neck; The supraclavicular nerve (necks _{3 to 4} ) descends at the posterior edge of the sternocleidomastoid muscle and is divided into three groups: inner, middle, and outer branches. It is distributed across the anterior chest wall and shoulder skin above the second rib level. . The cutaneous branches penetrate deep fascia at the midpoint of the posterior margin of the sternocleidomastoid muscle, so block anesthesia of the neck skin is often performed at this point.

The muscular branch emanates from the phrenic nerve, the deep cervical muscular branch and the descending branch of the cervical nerve, and innervates the iliac muscle, the cervical longus muscle, the anterior and medial oblique muscles, the scapular levator muscle, and the hypohyoid muscle group.