Anatomy & Organs

Nervus ophthalmicus – structure, function & diseases

Ophthalmic nerve

The ophthalmic nerve is the ocular branch of the trigeminal nerve and as such is involved in trigeminal perception. Due to its location in the human head, it mainly picks up sensory stimuli from the eye region. Functional restrictions can be a consequence of various neurological and inflammatory diseases.

What is the ophthalmic nerve?

As part of the larger trigeminal nerve, the ophthalmic nerve is one of three branches and in turn further branches into smaller nerves. Alternatively, medicine also knows it under the trivial name eye branch : The ophthalmic nerve collects sensory signals from the eye area with the help of numerous branches and transmits them to relevant processing centers located in the brain and spinal cord .

While other cranial nerves only transmit stimuli of a specific modality (sight, hearing, smell, etc.), the fibers of the ophthalmic nerve are considered to be generally somatosensitive; they are responsible for general body sensations, including pressure and pain. In the human nervous system , pain is partly due to very strong stimulation or inadequate stimulation of other sensory cells . In addition, there are specific pain receptors, which medicine also refers to as nociceptors . In addition to pressure and temperature, free nerve endings also register chemical substances that are potentially harmful.

Anatomy & Structure

The ophthalmic nerve divides into different branches and in this way helps to cover a larger field. The four branches of the ophthalmic nerve also branch out into finer nerves. The ramus tentorius or ramus meningeus recurrentrens connects to the dura mater in the cranial cavity.

The frontal nerve (Nervus frontalis) represents the second branch of the Nervus ophthalmicus; it leads inside past the eye muscles to the eye socket . The structure of the frontal nerve is divided into two parts and consists of the supraorbital nerve (“nerve above the eye socket”) and the supratrochlear nerve (“nerve above the rolling cartilage”). The lacrimal nerve (Nervus lacrimalis) lies next to the outer eye muscles. The fourth and final branch is represented by the nasal lid nerve (Nervus nasociliaris) with connections to the middle eye, conjunctiva and cornea as well as to the lacrimal ducts and nasal cavity . The nasociliary nerve also does not run in one strand, but separates into the ethmoid nerve, infratrochlear nerve and long ciliary nerve.

Function & Tasks

The task of the ophthalmic nerve is to transmit and combine signals. It does not have any sensory cells of its own and is not in direct contact with any of them, which is why humans are usually not consciously aware of its function. Exceptions are unpleasant temperature, pain and pressure stimuli, which can run through the ophthalmic nerve.

The signal transmission within the nerve occurs mainly with the help of electrical transmission. To do this, the nerve cell generates an electrical impulse that travels as an action potential across the found-like end of the neuron. The nerve fibers or axons of the cells in the ophthalmic nerve are longer than those of most nerve cells; the nerve is therefore only dependent on a few interconnections.

Different branches of the ophthalmic nerve perform different tasks in this context. The ramus tentorius innervates the dura mater, one of the meninges ; Irritation primarily causes pain, thereby warning the body not to put too much pressure on the skull, which could damage the sensitive part of the body.

The frontal nerve with its two branches supraorbital nerve and supratrochlear nerve connects the eyelid and the region to the nose to the sensory nervous system. The supraorbital nerve runs just under the skin at the upper edge of the orbit and forms the first trigeminal pressure point there. With a total of three trigeminal pressure points on each side of the face, doctors can determine whether and where lesions or functional restrictions of the trigeminal nerve are present.

The lacrimal nerve has two important functions: its sympathetic and parasympathetic nerve fibers signal the lacrimal gland to secrete fluid. The command comes from the spinal cord. In addition, the lacrimal nerve receives sensory information and transmits it to the brain. Various tissues are attached to the nasociliary nerve; it receives sensory stimuli from the eye membranes as well as the tear ducts and nasal cavity.

Diseases

Numerous nerve diseases can directly or indirectly affect the ophthalmic nerve. Affected people feel the consequences either as a reduced sensory system in the affected regions or they suffer from (often painful) perceptions that arise in the nervous system, although there is no triggering stimulus.

Peripheral and central lesions can limit or completely prevent the functioning of the ophthalmic nerve. A peripheral lesion is localized on the nerve itself and can occur, for example, as a result of an injury. This clinical picture manifests itself symptomatically by a lack of sensitivity in the affected area of ​​the face; in the case of the ophthalmic nerve, those affected no longer perceive any general sensory stimuli from the eye region. If only individual branches of the ophthalmic nerve are damaged, the loss of sensory function is limited to smaller areas. On the other hand, central lesions affect larger sections, since in this case the nerve nucleus in the brainstem is damaged.

Tumors in the myelin sheaths can also be considered as a cause of symptoms. Doctors refer to them as schwannomas and remove and/or irradiate them to treat them. Tenderness on the first trigeminal pressure point at the top of the orbit may indicate other causes; Inflammation of the paranasal sinuses (sinusitis), meningitis , increased intracranial pressure , swelling and other pathological abnormalities can irritate the ophthalmic nerve and thereby trigger an appropriate sensory reaction. In all cases, therapeutic measures depend both on the specific cause and on individual factors.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.