Cervical plexus

Cervical plexus

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Cervical plexus is a nerve plexus in the neck region that is formed by the anterior rami of the first four cervical vertebrae (C1-C4). It lies deep within the neck, beneath the sternocleidomastoid muscle, and is responsible for providing sensory and motor innervation to various structures within the neck, head, and shoulders.

Anatomy

The cervical plexus is composed of the anterior rami of the first four cervical spinal nerves. These nerves branch out to supply the skin and muscles of the neck, the upper shoulders, and part of the head. The plexus is divided into two parts: a superficial (sensory) part and a deep (motor) part.

Superficial Branches

The superficial branches of the cervical plexus emerge around the midpoint of the posterior border of the sternocleidomastoid muscle. These branches include:

• Lesser occipital nerve: Supplies sensation to the skin of the neck and scalp posterosuperior to the ear.
• Greater auricular nerve: Supplies sensation to the skin over the parotid gland, the ear, and the area from the angle of the mandible to the mastoid process.
• Transverse cervical nerve: Supplies sensation to the anterior region of the neck.
• Supraclavicular nerves: Supply sensation to the skin over the clavicle and the upper part of the chest.

Deep Branches

The deep branches of the cervical plexus are primarily motor and include:

• Ansa cervicalis: Supplies motor innervation to the infrahyoid muscles.
• Phrenic nerve: Arises from the 3rd to 5th cervical nerves (predominantly C4) and innervates the diaphragm, playing a crucial role in breathing.
• Branches to the prevertebral muscles, scalene muscles, and levator scapulae.

Function

The cervical plexus performs several functions, including:

• Providing sensory innervation to the skin of the neck, ear, back of the head, and the upper chest.
• Supplying motor innervation to some of the muscles of the neck.
• Playing a vital role in the respiratory system through the phrenic nerve, which is essential for diaphragm movement.

Clinical Significance

Knowledge of the cervical plexus is important in clinical medicine for several reasons. It is often involved in nerve block procedures to provide anesthesia for surgeries in the neck region. The phrenic nerve's role in breathing makes it a critical nerve in conditions that affect respiratory function. Injury to the cervical plexus can result in sensory loss or motor dysfunction in the areas it innervates.

See Also

• Brachial plexus
• Nerve block
• Spinal nerves