Auriculotemporal nerve - Auriculotemporalis: Ear-temporal nerve

The auriculotemporal nerve is a branch of the mandibular nerve (V3), launched from the superficial temporal artery and veins, and also provides sensory innervation to various regions on the side of the head.

Ear-temporal nerve, n. auriculotemporalis departs from the mandibular nerve near the foramen ovale in two bundles that cover a. meningea media. Further, the nerve goes along the medial surface of the articular process of the lower jaw and penetrates into the bed of the parotid gland, through which it passes upward into the temporal region.

The posterior and larger division of the mandibular nerve is for the most part sensory but receives a few filaments from the motor root. It divides into auriculotemporal, lingual,  and inferior alveolar nerves.

The  Auriculotemporal Nerve  ( n. Auriculotemporalis ) generally arises by two roots, between which the middle meningeal artery ascends. It runs backward beneath the Pterygoideus externus to the medial side of the neck of the mandible. It then turns upward with the superficial temporal artery, between the auricula and condyle of the mandible, under cover of the parotid gland; escaping from beneath the gland, it ascends over the zygomatic arch, and divides into superficial temporal branches.

Ear-temporal nerve, n. auriculotemporalis, mixed in composition. It contains sensory and secretory fibers coming up from the ear node. The nerve begins with two roots from the posterior surface of the mandibular nerve trunk, goes posteriorly, covering the middle meningeal artery, passes along the inner surface of the condylar process of the lower jaw, travels posteriorly and upward along with the capsule of the temporomandibular joint, located under the parotid gland, in front of the auditory canal. Heading further up, it ends in the skin of the temporal region.

 

On its way, the ear-temporal nerve gives off a number of branches:

1) parotid branches, rr. parotidei, depart from the ear-temporal nerve at the place of its passage under the parenchyma of the gland and connect to the temporal branch of the facial nerve. These branches mainly contain secretory fibers (from the ear node);

2) the nerve of the external auditory canal, n. meatus acustici externi penetrates the wall of the external auditory canal at the border between its bone and cartilaginous parts and innervates the skin of the external auditory canal;

3) branches of the tympanic membrane, rr. membranae tympani, two or three thin branches, approach the outer surface of the tympanic membrane, innervating its anteroposterior part;

4) anterior ear nerves, nn. auriculares anteriores, usually two of them, go to the anterior part of the auricle, innervate the skin of the tragus and parts of the curl;

5) superficial temporal branches, rr. temporales superficiales are the terminal branches of the ear-temporal nerve. The branch in the skin of the temporal region, have connecting branches with branches of the facial, frontal, and greater occipital nerves;

6) connecting branches with the facial nerve, rr. communicantes (cum Nervo faciali), join the latter behind the neck of the lower jaw.

 

Origin of Auriculotemporal nerve

The auricular-temporal nerve arises in the form of two roots from the posterior part of the mandibular nerve. The mandibular nerve is a branch of the trigeminal nerve (CN5), and the mandibular nerve exits the skull through the foramen ovale. These roots surround the middle meningeal artery (a branch of the mandible of the maxillary artery, which in turn is the terminal branch of the external carotid artery). The roots cover the middle meningeal artery and then converge to form a single nerve.

Course of Auriculotemporal nerve

The auricular-temporal nerve passes between the neck of the mandible and the sphenoid-mandibular ligament, gives off the parotid branches, and then turns upward, posterior to its head and, moving anteriorly, gives off the anterior branches to the auricle. Then it passes through the root of the zygomatic process of the temporal bone-deep into the superficial temporal artery.

Innervation of Auriculotemporal nerve

The somatosensory root (Superior) originates from the branches of the mandibular nerve (V cranial nerve) that pass through the auricular ganglion without synapsing. Then they form the somatosensory (upper) root of the ear-temporal nerve. The two roots reconnect, and shortly after branching off the secretomotor fibers to the parotid gland (parotid branches), the ear-temporal nerve is composed exclusively of somatosensory fibers that ascend to the superficial temporal region. There it supplies the auricle, the external auditory canal, the outer side of the tympanic membrane, and the skin in the temporal region (superficial temporal branches). It also bears several articular branches that feed the temporomandibular joint.

The parasympathetic root (lower) carries postganglionic fibers to the parotid gland. These parasympathetic, preganglionic secretomotor fibers originate from the glossopharyngeal nerve (CN IX), which is one of its branches, the tympanic nerve, which enters the tympanic cavity through the inferior tympanic canal. In the tympanic nerve and postganglionic sympathetic fibers that go with the arteries connected to the head, make the tympanic plexus on the promontorium. This plexus gives off a small stony nerve... This nerve synapse in the auditory ganglion and its postganglionic fibers form the inferior parasympathetic root of the ear-temporal nerve. The two roots reconnect, and shortly after the “merged” auro-temporal branch gives rise to parotid branches, which serve as the secretomotor fibers of the parotid gland. 

Clinical significance of Auriculotemporal nerve

This nerve, which runs posterior to the head of the condyle, is often damaged during temporomandibular joint (TMJ) surgery, causing ipsilateral paresthesia of the pinna and the skin surrounding the ear. It is the main nerve that supplies the TMJ along with the branches of the masticatory nerve and the deep temporal nerve. After parotidectomy, the nerves in the auriculotis nerve that previously innervated the parotid gland can reattach to the sweat glands in the same area. The result is cheek sweating when eating food ( Frey's syndrome ). Treatment includes the application of antiperspirant or glycopyrrolate to the cheek, Jacobsen's neurectomy along the promontory of the middle ear, and a skin flap lift with a tissue barrier (taken or cadaveric) to interrupt the wrong innervation of the sweat glands. Pain from mumps, a condition that can be caused by mumps, will be transmitted by the ear-temporal nerve and the greater auricular nerve to the brain.