Mandibular nerve (CN V3)
The mandibular nerve, or the mandibular division of the trigeminal nerve (CN V3), is the third division of the trigeminal nerve (CN V) which innervates parts of the human face. It is a mixed nerve, meaning that it contains both motor and sensory fibers.
The mandibular nerve originates from the trigeminal ganglion of Gasser and exits the skull through the foramen ovale. Once it reaches the viscerocranium, it divides into two divisions: anterior and posterior. Both divisions further divide into smaller branches that innervate the structures of the face. More specifically, the mandibular nerve transmits the sensory information from the lower third of the face, including the lower lip, mandible, preauricular and temporal areas, as well as the meninges and anterior and middle cranial fossae. Moreover, it is responsible for motor innervation of the masticatory muscles as well as the muscles that originate from the first pharyngeal arch.
In this article we will discuss the anatomy, functions and clinical notes related to the mandibular division of the trigeminal nerve.
|Origin||Trigeminal ganglion (of Gasser)|
|Type||Mixed: motor, sensory and autonomic fibers|
|Pathway||Trigeminal ganglion (middle cranial fossa) -> foramen ovale -> infratemporal fossa|
Direct branches (prior to bifurcation)
Meningeal branch of mandibular nerve
Branches of mandibular nerve to otic ganglion
Nerve to medial pterygoid muscle → Nerve to tensor veli palatini,
nerve to tensor tympani
Deep temporal nerves
Nerve to lateral pterygoid muscle
Inferior alveolar nerve → nerve to mylohyoid muscle → muscular branch to anterior belly of digastric muscle
Sensory: Skin of the buccal region, sensory supply to the tongue (anterior ⅔), temporal region;
Motor: Masticatory muscles, mylohyoid muscle, anterior belly of digastric muscle, tensor veli palatini muscle, tensor tympani muscle
- Origin and course
Origin and course
The sensory root of the mandibular nerve originates from the trigeminal ganglion. It has a short course across the middle cranial fossa, after which it exits the skull via the foramen ovale, and enters the infratemporal fossa.
The motor root originates from the motor nucleus of trigeminal nerve. It passes below the trigeminal ganglion without synapsing with it, and then through the foramen ovale. After traversing the foramen, it joins the sensory root of the nerve.
The mandibular division then passes between the medial pterygoid and tensor veli palatini muscles. Here it gives off the meningeal branch and the nerve to medial pterygoid muscle. Soon after, it bifurcates into its two divisions: a smaller anterior division and a larger posterior division.
- The anterior division ramifies and produces motor branches for the masticatory muscles, as well as one sensory branch, the buccal nerve, which innervates the cheek.
- The posterior division divides into three sensory branches: the auriculotemporal, lingual and inferior alveolar nerves. The latter gives off a motor branch which innervates the anterior belly of the digastric muscle and the mylohyoid muscle.
Let’s discuss the course and functions of the branches of the mandibular nerve.
The meningeal branch, also known as the nervus spinosus, is the earliest branch of the mandibular nerve. Even though it originates outside the skull, the nerve re-enters the neurocranium by going back through the foramen spinosum. Within the skull, it divides into the branches that accompany the main branches of the middle meningeal artery, innervating the dura mater of the middle cranial fossa.
Nerve to medial pterygoid
The medial pterygoid nerve emerges from the CN V3 right after the meningeal branch, prior to bifurcating into its two divisions. It gives off a few twigs that innervate the medial pterygoid muscle. The nerve then penetrates the medial pterygoid and reaches the tensor tympani and tensor veli palatini, which it also innervates.
Branches of the anterior division
The anterior division of the mandibular nerve gives off one sensory branch (buccal nerve), and three motor branches: masseteric nerve, deep temporal nerves and nerve to lateral pterygoid.
- The buccal nerve courses between the heads of the lateral pterygoid. It then descends over the masseter and anastomoses with the buccal branches of the facial nerve (CN VII). It innervates the skin of the cheek and buccal mucosa.
- The masseteric nerve passes anterior to the temporomandibular joint, providing a branch that innervates it. Then, it courses posterior to the tendon of the temporalis muscle and terminates by perforating the masseter, which it also innervates.
- The deep temporal nerves consist of one anterior and other posterior branch. The anterior branch usually originates from the buccal nerve, while the posterior branch is given off directly from the anterior division of the mandibular nerve. Both of them innervate the temporalis muscle.
- The nerve to lateral pterygoid originates from the anterior trunk and enters the lateral pterygoid muscle to innervate it.
Branches of the posterior division
The posterior division is mostly sensory, giving off three main branches:
The auriculotemporal nerve originates from a small loop composed of two roots that encircle the middle meningeal artery. The superior, somatosensory root carries fibers from the mandibular nerve (CN Viii) which pass through the otic ganglion without synapsing. The inferior, parasympathetic root receives postganglionic fibers derived from the glossopharyngeal nerve (CN IX) which arise in the otic ganglion; these fibers are destined for the parotid gland only. Both roots unite with each other to form a single trunk that courses deep to the lateral pterygoid muscle and posterior to the temporomandibular joint. It continues within the posterosuperior surface of the parotid gland where several small parotid branches arise (supplying parasympathetic/secretomotor branches to the parotid gland) before ascending over the zygomatic bone to give off several branches which include:
- anterior auricular nerves (supply auricle anterior to the external acoustic meatus i.e. the tragus)
- nerve to external acoustic meatus
- branch to tympanic membrane (supplies external surface, along with greater auricular nerve)
- superficial temporal branches (supply skin of posterior part of temporal region)
The lingual nerve passes deep to the lateral pterygoid, where it unites with the chorda tympani. It courses over the medial pterygoid towards the ramus of mandible. It provides the sensory innervation to the anterior ⅔ of the tongue, floor of the oral cavity and mandibular gingiva.
Inferior alveolar nerve
The inferior alveolar nerve descends deep to the lateral pterygoid muscle. It passes between the ramus of mandible and the sphenomandibular ligament to reach the inferior alveolar (a.k.a. mandibular) foramen. Prior to entering the inferior alveolar foramen, it gives rise to the nerve of mylohyoid muscle, of which a muscular branch to the anterior belly of digastric muscle is given off. These nerves provide motor innervation to the mylohyoid and anterior belly of the digastric muscle respectively, which are responsible for elevating the hyoid and the complex movements of the jaw (speaking, swallowing, chewing, and breathing). The inferior alveolar nerve resumes its course to reach the mandibular canal. Within the canal, it continues as the mental nerve, which is considered as the terminal branch of the inferior alveolar nerve. The mental nerve then passes the mental foramen of mandible to emerge on the face and innervate the lower lip.
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