The lesser occipital nerve or small occipital nerve is a cutaneous spinal nerve. It arises from second cervical (spinal) nerve (along with the

greater occipital nerve The greater occipital nerve is a nerve of the head. It is a spinal nerve, specifically the medial branch of the dorsal primary ramus of cervical spinal nerve 2. It arises from between the first and second cervical vertebrae, ascends, and then p ...

). It innervates the

scalp The scalp is the anatomical area bordered by the human face at the front, and by the neck at the sides and back. Structure The scalp is usually described as having five layers, which can conveniently be remembered as a mnemonic: * S: The ski ...

in the lateral area of the head posterior to the

ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...

Structure

The lesser occipital nerve is one of the four cutaneous branches of the cervical plexus.

Origin

It arises from the (lateral branch of the

ventral ramus The ventral ramus (pl. ''rami'') (Latin for ''branch'') is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami. Shortly after a spinal n ...

) of cervical spinal nerve C2; it may also receive fibres from cervical spinal nerve C3. It originates between the

atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...

, and

axis An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to: Mathematics * Axis of rotation: see rotation around a fixed axis * Axis (mathematics), a designator for a Cartesian-coordinat ...

Course and relations

It curves around the accessory nerve (CN XI) to come to course anterior to it. It then curves around and ascends along the posterior border of the

sternocleidomastoid muscle The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

; rarely, it may pierce the muscle. Near the cranium, it perforates the

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the ...

. It is continues upwards along the scalp posterior to the auricle.

Distribution

The lesser occipital nerve distributes branches to the skin. It gives off an auricular branch, which supplies the skin of the upper and back part of the auricula, communicating with the mastoid branch of the great auricular. This branch is occasionally derived from the

Variation

Rarely, the lesser occipital nerve may be duplicated or triplicated. It varies in size.

Function

The lesser occipital nerve supplies part of the

near the auricle. It connects with the

great auricular nerve The great auricular nerve is a cutaneous nerve of the head. It originates from the cervical plexus, with branches of spinal nerves C2 and C3. It provides sensory nerve supply to the skin over the parotid gland and the mastoid process of the tempor ...

, the

, and the auricular branch of the facial nerve.

Clinical significance

Problems with the lesser occipital nerve cause

occipital neuralgia Occipital neuralgia (ON) is a painful condition affecting the posterior head in the distributions of the greater occipital nerve (GON), lesser occipital nerve (LON), third occipital nerve (TON), or a combination of the three. It is paroxysmal, la ...

Nerve block Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. Local anesthetic nerve block (sometimes referred to as simply "nerve block") is a short-term block, ...

is difficult due to variation in the course of the nerve.

History

The lesser occipital nerve may also be known as the occipitalis minor nerve, or the small occipital nerve.

Additional images

File:Gray784.png, Dermatome distribution of the trigeminal nerve

References

External links

* * http://www.dartmouth.edu/~humananatomy/figures/chapter_47/47-2.HTM * http://www.dartmouth.edu/~humananatomy/figures/chapter_47/47-6.HTM {{Authority control Optic nerve