Superficial structures of the neck: Cervical plexus

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Notes

Figure 1: Anatomy of the cervical plexus, anterolateral view.
Figure 2: Diagram of the cervical plexus and spinal root contributions.

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The cervical plexus is an important plexus of nerves which provide innervation to the head and neck. This plexus is located anteromedial to the levator scapulae and middle scalene muscles and deep to sternocleidomastoid - or SCM.

Now, the anterior rami of the spinal nerves C1, C2, C3 and C4 form the roots of the cervical plexus, which is an irregular series of nerve loops and the branches that arise from these loops.

Each participating ramus, except the first, splits into ascending and descending branches which unite with branches from neighboring spinal nerves to form the loops.

The superficial branches of the plexus, which initially pass posteriorly are cutaneous, or sensory, branches which innervate the skin, and the deep branches of the plexus, which includes the roots of the phrenic nerve and the ansa cervicalis, pass anteromedially and are motor branches which innervate the muscles of the neck. The cutaneous branches of the cervical plexus emerge around the middle of the posterior border of the SCM, and they supply the skin of the neck, superolateral thoracic wall, shoulder and scalp between the auricle and the external occipital protuberance.

Now let’s look at the four cutaneous nerves that innervate these areas. There are three nerves branching from the C2 and C3 loop. The lesser occipital nerve, which contains fibers from C2 supplies the skin of the neck and scalp posterosuperior to the auricle.

The great auricular nerve contains fibers from both C2 and C3 and ascends across the SCM to the inferior pole of the parotid gland, where it divides to innervate the skin over - and the sheath surrounding - the parotid gland, the mastoid process, the posteroinferior part of the auricle and an area of skin that extends from the angle of the mandible to the mastoid process.

There is also the transverse cervical nerve which also contains fibers from C2 and C3. It curves around the middle of the posterior border of SCM, passing anteriorly and horizontally across it, deep to the external jugular vein and the platysma to innervate the skin covering the anterior triangle.

Resumen

The cervical plexus is an important plexus of nerves that provide innervation to the head and neck. This plexus is located anteromedial to the levator scapulae and middle scalene muscles and deep to the sternocleidomastoid muscle. The cervical plexus forms from the anterior rami of spinal nerves C1, C2, C3, and C4. It is a mixed nerve plexus as it provides both sensory and motor nerve fibers. The sensory fibers provide sensation to the skin of the neck, upper chest, and shoulder regions, while the motor fibers provide innervation to the muscles in the neck, chest, and shoulder regions.

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