Table of Contents
A stabbing, severe pain on the side of the face, especially in the area of the cheek, skin over the mandible, and jaws, with a sudden onset and mostly subsiding in a few seconds or minutes, is a clinical condition known as tic douloureux or trigeminal neuralgia. It is an episodic pain event that may be triggered by brushing the teeth, talking, or even touching the face. The exact cause of the pain is unknown, but we know that the trigeminal nerve is the route that transmits this pain. Most commonly, the pain is felt in areas supplied by the maxillary and mandibular divisions of the trigeminal nerve, but occasionally, areas supplied by the ophthalmic division may get involved in pain. In the following words, we shall have a look at the origin, course, classification, and functional component(s) of the Maxillary nerve. We shall also discuss the branches, area of supply and functions of the maxillary nerve. Last but not least, we shall have a look at the diseases caused by damage to the maxillary nerve.
We already know that there are 12 pairs of cranial nerves that provide nerve supply to the structures present in the head and neck region of the body. Only the tenth cranial nerve is an exception that provides innervation to the viscera in the chest and abdominal cavity as well. The fifth cranial nerve is the trigeminal nerve (CN V) which is the main sensory nerve of the skin of the face as well as mucous membranes of the eyes, nose, paranasal sinuses, and mouth. As the name suggests, the trigeminal nerve is made up of three big divisions known as the ophthalmic division (CN V1), maxillary division (CN V2), and mandibular division (CN V3). Out of these three, the ophthalmic and maxillary divisions are purely sensory, while the mandibular division also contains some motor fibers that supply the muscles with mastication.
Classification and FunctionalComponents
The trigeminal nerve is a mixed nerve and contains general somatic afferents and special visceral afferents. The first two divisions i.e., ophthalmic and maxillary contain only general somatic afferent fibers. The mandibular division contains both sensory afferents and visceral motor efferents.
Origin and Course Of Maxillary Nerve
The trigeminal nerve, the parent nerve of the maxillary nerve, starts its route at the anterior aspect of the pons in the posterior cranial fossa. It moves forwards in the middle cranial fossa lying over the petrous part of the temporal bone and ends in a crescent-shaped ganglion, called a trigeminal ganglion, present in the Meckel cave. Meckel cave is a pouch formed by the dura mater (the outermost brain covering). Arising from the trigeminal ganglion, it enters the lateral wall of the cavernous sinus, it leaves the cranial cavity through a small opening called foramen rotundum. During its further course, it passes through the pterygopalatine fossa and continues as the infraorbital nerve. Outside the cranium, it divides into several different branches (discussed later).
Branches of the Maxillary Nerve
There are several branches of the maxillary nerve that innervate different structures. It also gives some twigs to the pterygopalatine ganglion participating in its sensory route formation. These branches are briefly discussed below:
The infraorbital nerve is the terminal continuation of the maxillary nerve. It enters the orbital cavity through the infraorbital fissure. It passes through the orbit lying over the roof of the maxillary sinus and becomes superficial, passing through the infraorbital foramen. It further gives many branches; the middle superior alveolar nerve, which supplies the upper premolar teeth; the anterior superior alveolar nerve, which innervates the upper front teeth, maxillary sinus, and part of the nasal cavity. The infraorbital nerve is the most common branch of the maxillary nerve involved in the pain of trigeminal neuralgia.
The zygomatic nerve is the branch given by the maxillary nerve in the pterygopalatine fossa. It leaves the pterygopalatine fossa along with a terminal branch of the maxillary nerve through the inferior orbital fissure. It divides into two branches; zygomaticotemporal and zygomaticofacial nerves.
The zygomaticofacial nerve emerges through a small foramen in the zygomatic bone and becomes superficial. It supplies the skin of prominence of the cheek. It also forms nerve plexus with the branches of the facial nerve and other branches of the maxillary nerve.
The zygomaticotemporal nerve travels in a canal of the zygomatic bone and emerges into the temporal fossa through a small foramen in the zygomatic bone. It pierces the temporalis fascia and becomes cutaneous. It supplies the skin of the temple. It also communicates with the branches of the facial nerve, like the auriculotemporal nerve. It also contains some parasympathetic fibers from the pterygopalatine ganglion that supplies the lacrimal gland. Occasionally, the zygomaticotemporal nerve is absent and is replaced by the lacrimal nerve (branch of the ophthalmic division of the trigeminal nerve) and vice versa.
Other small branches include the middle meningeal nerve accompanying the middle meningeal artery. The nasopalatine nerve innervates the nose and palate. Greater and lesser palatine nerves for the palate. Greater, lesser, and nasopalatine nerves also contain some parasympathetic fibers from the pterygopalatine ganglion. Posterior superior alveolar nerve, middle superior alveolar nerve, and anterior superior alveolar nerve, all three supplying the upper jaw.
Terminal Branches of the Maxillary Nerve
The maxillary nerve terminates by dividing into three branches; inferior palpebral, superior labial, and lateral nasal nerves, which supply the skin of the face (cheek area), upper lip, etc.
Nuclei of CN III Related to its Maxillary Division
The nuclei of cranial nerves are the collection of cell bodies of axons forming that cranial nerve. There are four nuclei of the trigeminal nerve. These include the main sensory nucleus, mesencephalic nucleus, spinal nucleus, and motor nucleus of the trigeminal nerve. All four nuclei collectively constitute the trigeminal system. Out of these four nuclei, only two (the main sensory nucleus and spinal nucleus) are concerned with maxillary nerve fibers.
Main Sensory Nucleus
This nucleus is present in the pons. The sensations of touch and pressure carried by the maxillary nerve are relayed here. The fibers coming here from the periphery have their cell bodies in the trigeminal ganglion. This also receives touch and pressure sensations from other divisions of the trigeminal nerve.
It is in the form of a column extending from the main sensory nucleus present in the pons, continuing through the medulla to the upper part of the spinal cord as far as the second cervical segment of the cord. The sensations of pain and temperature coming through the maxillary nerve fibers are relayed here. Pain and temperature sensations coming through other divisions of the trigeminal nerve, i.e., ophthalmic and mandibular, are also received here.
Maxillary Sensory Pathway and Trigeminal Lemniscus
General afferent fibers carry sensations from the area supplied by the maxillary nerve to the trigeminal nuclei. Carrier neurons at this step are first-order neurons. From the main sensory nucleus, the spinal nucleus, and the mesencephalic nucleus, the axons of the second-order neurons ascend upward in the form of a neuronal band or bundle named as trigeminal or spinal lemniscus to the thalamus. Thalamus is the main sensory collection center of the brain. From the thalamus, sensory information is directed to the cerebral cortex. Axons of the third-order neurons reach the somatosensory area located in the post-central gyrus of the cerebral hemisphere, where all the general sensory information from the body is received, integrated, and used for making an appropriate and proper response by the motor cortex and also used for decision making and thinking process of the brain.
Functions of the Maxillary Nerve
The maxillary nerve carries general sensations from structures formed from the maxillary prominence. These include the side of face, prominence of the cheek, skin over the maxilla, upper jaw and upper teeth, mucous membrane of the nose, hard palate, and mucous membrane of the maxillary sinus, etc. The sensations carried by the maxillary nerve are pain, temperature (both warmth and cold), pressure, touch (light and crude), vibratory stimulus (vibrations, etc.), and two-point discrimination, etc.
The sneeze reflex is a reflex of the upper respiratory tract. It is a forceful expulsion of lungs air via the nose and mouth. It is caused by irritation due to some noxious stimulus. The stimulus may be mechanical or chemical in nature. The sneeze reflex tries to remove the irritating stimulus. The irritation of the nasal mucosa sends signals to the sneezing centers present in the medulla oblongata. The afferent pathway is formed by the sensory fibers of the maxillary nerve that innervate the nasal mucosa. The medullary sneezing centers then send impulses to different muscles, such as the uvula and palate, that depress, and the back of the tongue is elevated to narrow down the air passageway. After that, there is a strong contraction of the chest muscles and especially the diaphragm, which forcefully expels the air out of the lungs. In this way, the body gets rid of that irritating stimulus.
Diseases Related to the Maxillary Nerve and Their Management
There are many diseases that affect the nervous system. Some of them are systemic, which affect the nervous system as a whole, and some are localized to particular nerves. We will limit our discussion to the trigeminal nerve, more specifically, its maxillary division along with its branches.
Trigeminal/Maxillary Nerve Palsy
Injury of the trigeminal nerve may result in sensory loss from a large part of the face and mucous membranes of the nose, paranasal sinuses, and mouth. In addition, muscles of mastication are paralyzed, resulting in problems with chewing and grinding the food. If the damage to the trigeminal nerve involves only its maxillary division, it can be called maxillary nerve palsy.
Causes of trigeminal/maxillary nerve palsy are diabetic neuropathy, aneurysm or tumor pressing the nerve, stenosis of the foramen from where the branches of the nerve leave the skull, inflammation (neuritis), multiple sclerosis or vascular diseases resulting in ischemia, etc. Trauma to the head can result in crush injury of the nerve. This can occur especially to the ophthalmic nerve due to road traffic accidents or falls resulting in orbital fractures.
The maxillary nerve can be clinically tested by different methods. One such method is the cotton and pin method. A piece of cotton is gently applied to the area supplied by the maxillary nerve. Lesions of the maxillary nerve result in loss of touch sensations. A blunt end pin can also be used to check pain sensations.
Acute severe stabbing or burning pain on the face in the area supplied by the 2nd and 3rd divisions of the trigeminal nerve (maxillary nerve and mandibular nerve). This is also known as tic douloureux. The pain is episodic and completely subsides when the acute attack is over. There is no facial muscle dysfunction. Usually, the pain is unilateral. The cause of trigeminal neuralgia is unknown yet. Pain can be triggered by talking, chewing, or even by a light touch on the face. Tic douloureux is one of the most painful conditions in which pain occurs. Treatment of trigeminal neuralgia involves the resection of one or more divisions of the trigeminal nerve. Pharmacological interventions include the use of NSAIDs and other analgesics.
Trigeminal Nerve Block
Nerve block means anesthetizing a nerve. A trigeminal nerve block is a procedure used in routine clinical practice. This block is performed for treatment of trigeminal neuralgia or other conditions in which suppression of pain from the area of supply if trigeminal nerve is required. This results in local anesthesia and analgesia in that area. In extremely painful conditions, a trigeminal nerve block can be performed to relieve that pain, but this is a temporary remedy, and treatment of the underlying cause is required for the complete dissolution of the pain.
The maxillary nerve (CN V2) is the second division of the trigeminal nerve, which is the third cranial nerve. It is purely a sensory nerve and contains general somatic efferent fibers as its functional components. The parent nerve, the trigeminal nerve, emerges from the mid-brain at its anterior aspect at the level of the pons. It passes forward in the posterior cranial fossa, rests on the petrous temporal bone in the middle cranial fossa, and ends at a crescent-shaped ganglion, the trigeminal ganglion, located in a pouch of dura mater. Here, it divides into three divisions; 1) Ophthalmic nerve (CN V1), 2) Maxillary nerve (CN V2), and 3) Mandibular division (CN V3).
The maxillary nerve runs through the lateral wall of the cavernous sinus, leaves the skull via foramen rotundum, passes through the pterygopalatine fossa, and continues in orbit as the infraorbital nerve. Branches of the maxillary nerve include the infraorbital nerve, zygomatic nerve, middle meningeal nerve, posterior, middle, and anterior superior alveolar nerves, nasopalatine nerve, and greater and lesser palatine nerves. Its terminal branches are inferior palpebral, lateral nasal, and superior labial nerves.
There are two out of four trigeminal nuclei are involved in the sensory pathway of the maxillary nerve, the main sensory nucleus, and the spinal nucleus.
The maxillary nerve supplies part of the cheek, the mucous membrane of the nose, the maxillary sinus, the palate, and the area over the upper lip. Sensations carried by the maxillary nerve include pain, touch, pressure, temperature, proprioception, etc. The maxillary nerve also forms the afferent pathway of the sneeze reflex.
Diseases related to the maxillary nerve include trigeminal/maxillary nerve palsy and trigeminal neuralgia (most commonly, the maxillary and mandibular divisions are involved). Causes include inflammation (neuritis), pressure due to tumors, ischemic injury, traumatic injury, exposure to toxins or drugs, and demyelinating diseases like multiple sclerosis, diabetic neuropathy, etc. Lesions of the midbrain involving the spinal lemniscus may result in the same signs and symptoms. Treatment involves the solution of the underlying cause by using either medications or surgical interventions. Trigeminal nerve block is also used in trigeminal neuralgia.
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Image source: Maxillary Nerve