The lesser occipital nerve, also known as the small occipital nerve, is a cutaneous branch of the cervical plexus. It provides sensory innervation to the skin in the upper posterior part of the neck and scalp.
Structure
Origin: The lesser occipital nerve typically arises from the ventral ramus of the second cervical nerve (C2), although it can sometimes receive contributions from the third cervical nerve (C3).
Nature: It is primarily a sensory nerve, carrying cutaneous sensory information from the regions it supplies.
Location
- Emergence: The nerve emerges from the side of the neck, around the area where the spinal nerve C2 exits between the cervical vertebrae.
- Course:
- Upon its emergence, the lesser occipital nerve ascends the side of the neck posteriorly.
- It courses close to and often winds around the posterior border of the sternocleidomastoid muscle.
- As it travels superiorly, it divides into multiple smaller branches that distribute to the skin.
- Terminal Area: The lesser occipital nerve primarily provides sensation to the skin of the upper lateral part of the neck and the scalp posterior and superior to the ear.
Functions
The primary function of the lesser occipital nerve is sensory innervation to specific regions of the upper neck and scalp. Unlike some other cervical nerves, the lesser occipital nerve doesn’t have motor functions; it is solely involved in conveying sensory information.
Sensory Functions
- Cutaneous Sensation: The lesser occipital nerve is responsible for conveying sensory information from the skin to the central nervous system. Specifically, it supplies sensation to the upper lateral part of the neck and scalp area that is posterior and superior to the ear.
- Types of Sensations: The nerve enables the perception of various types of sensory stimuli such as touch, temperature, and pain in its designated area.
- Pain Perception: Like other cutaneous nerves, the lesser occipital nerve is involved in transmitting pain signals from the regions it innervates.
- Reflex Actions: While its primary role is sensory, the information it carries can be part of reflex arcs, helping the body to react quickly to stimuli like heat or sharp objects, although this is more of an integrated function involving multiple parts of the nervous system.
Clinical Significance
The lesser occipital nerve has notable clinical relevance, particularly in the diagnosis and management of neuropathic pain conditions affecting the upper neck and scalp.
- Occipital Neuralgia: This nerve can be implicated in occipital neuralgia, a condition characterized by sharp, shooting pain in the occipital region. Diagnosis and treatment may involve nerve block procedures targeting the lesser occipital nerve.
- Tension-Type Headaches: Irritation or entrapment of the lesser occipital nerve may contribute to tension-type headaches. Its role in such headaches may be assessed via diagnostic nerve blocks.
- Surgical Procedures: During surgeries involving the neck or posterior scalp, care must be taken to avoid inadvertent injury to the lesser occipital nerve, which could result in sensory loss or neuropathic pain postoperatively.
- Nerve Blocks: For various forms of localized pain, nerve blocks targeting the lesser occipital nerve can be both diagnostic and therapeutic, aiding in the management of chronic pain conditions.
- Differential Diagnosis: In cases of unexplained upper neck or scalp pain, the lesser occipital nerve may be examined to rule out its involvement.
