The greater occipital nerve is one of the major sensory nerves that arise from the spinal cord, specifically from the dorsal ramus of the second cervical spinal nerve (C2). It plays a key role in providing sensation to the skin along the posterior part of the scalp up to the vertex of the skull.
Structure
The greater occipital nerve initially exists as a branch of the C2 spinal nerve, running in close association with the lesser occipital nerve, which is often derived from C2 as well. The greater occipital nerve courses upward, piercing the trapezius muscle, and travels superiorly along the posterior aspect of the neck.
As it ascends, it typically crosses under or through the occipital artery. Upon reaching the scalp, the nerve generally branches out, giving off several smaller nerves that provide sensory innervation to the posterior part of the scalp.
Location
- Origin: Arises from the dorsal ramus of the second cervical spinal nerve (C2).
- Pathway: Moves upward along the side of the spinal column, passing between the first and second cervical vertebrae.
- Muscle Piercing: It pierces the trapezius muscle and becomes more superficial at that point.
- Scalp: After piercing the trapezius, the greater occipital nerve continues to travel upward to reach the scalp, where it branches out to supply sensation to the posterior and superior regions of the scalp.
- Other Landmarks: It often lies close to the occipital artery and may cross its path during its course.
The greater occipital nerve is a purely sensory nerve and does not provide any motor innervation. It is essential for transmitting sensory information from the posterior scalp to the brain, and it can be implicated in conditions like occipital neuralgia, where there may be sharp, shooting pain along the pathway of the nerve.
Functions
The primary function of the greater occipital nerve is sensory in nature. It is responsible for providing cutaneous sensation (i.e., sensation of the skin) to the posterior aspect of the scalp up to the vertex (top) of the skull.
Sensory Functions
- Cutaneous Sensation: The nerve provides sensation to the skin, allowing you to feel various types of touch, temperature, and pain. The skin areas it serves extend from the base of the skull up to the vertex. This includes your ability to feel light touch, pressure, heat, cold, and pain in that region.
- Pain Perception: The greater occipital nerve is a key player in transmitting signals related to pain at the back of the head. It’s often the culprit in conditions like occipital neuralgia, where there is a sharp, shooting pain in the occipital region.
- Proprioception: Although its primary role is in cutaneous sensation, it may have a minor role in proprioception—the sense of the relative position of one’s own body parts. For example, the nerve can transmit information about the tension or movement in the neck muscles to the central nervous system, albeit this is not its primary function.
Clinical significance
The greater occipital nerve holds significant clinical relevance, particularly in the diagnosis and treatment of various pain conditions affecting the head and neck.
Occipital Neuralgia
The greater occipital nerve is often implicated in occipital neuralgia, a condition characterized by sharp, shooting, or throbbing pain along the course of the nerve. This can be due to nerve compression, inflammation, or injury. Diagnosis often involves clinical history, examination, and sometimes, nerve block tests.
Tension-Type Headaches and Migraines
Irritation or entrapment of the greater occipital nerve can sometimes contribute to tension-type headaches or migraines. Pain often radiates from the back of the head and may spread to the frontal region. In some cases, a greater occipital nerve block is performed for diagnosis and treatment.
Nerve Block Procedures
The nerve is a target for nerve block injections to treat chronic headaches, occipital neuralgia, and even some types of migraines. A local anesthetic is injected around the nerve, which can provide temporary relief from pain by inhibiting the nerve’s ability to transmit pain signals.
Sensory Testing
In cases of suspected nerve damage, trauma, or other neurological conditions, the sensation in the area supplied by the greater occipital nerve may be tested as part of a comprehensive neurological examination.
Surgical Procedures
In some cases, surgical decompression or neurectomy (nerve removal) may be considered for severe, intractable pain related to the greater occipital nerve. However, these procedures are generally reserved for cases that do not respond to conservative treatment options.
