Dominic Stone
The masticatory muscles, which are responsible for chewing food, consist of four main muscles: the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and facilitate jaw movement. The nerves that innervate these muscles are the focus of this discussion, as understanding their structure and function is crucial for diagnosing and treating associated disorders. The mandibular nerve, a branch of the trigeminal nerve, plays a significant role in innervating the masticatory muscles, contributing to their complex functions.
| Characteristics | Values |
|---|---|
| Nerve Supply Begins | 8th Week |
| Nerve Supply | Mandibular Nerve (V3) |
| Type of Nerve Supply | Motor |
| Nerve Supply Division | Trigeminal Nerve (CN V3) |
| Origin of Trigeminal Nerve | 1st Branchial Arch (Mandibular Arch) |
| Main Muscles Innervated | Temporalis, Medial Pterygoid, Lateral Pterygoid, Masseter |
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What You'll Learn
- The masseter muscle is innervated by the masseteric nerve, a branch of the mandibular nerve
- The medial pterygoid muscle is innervated by the medial pterygoid nerve, a division of the mandibular nerve
- The lateral pterygoid muscle is innervated by the lateral pterygoid nerves, divisions of the mandibular nerve
- The mandibular nerve is the largest and inferior-most division of the trigeminal nerve
- The trigeminal nerve exits the skull through the foramen ovale of the greater wing of the sphenoid bone
The masseter muscle is innervated by the masseteric nerve, a branch of the mandibular nerve
The masseter muscle is one of the four main muscles responsible for mastication, or chewing. These muscles originate from the surface of the skull and attach to the rami of the mandible at the temporomandibular (TMJ) joint. The primary function of the masseter muscle is to elevate the mandible, with a minor contribution to protrusion of the mandible.
The mandibular nerve is responsible for innervating all four muscles of mastication, which include the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles work together to produce mandibular movements for chewing food. The mandibular nerve has several branches that innervate the muscles in various patterns. For example, the medial pterygoid nerve, a division of the mandibular nerve, innervates the medial pterygoid muscle, while the lateral pterygoid nerve, another division of the mandibular nerve, innervates the lateral pterygoid muscle.
The masseter muscle's blood supply is derived from the masseteric artery, a branch of the maxillary artery, which is a branch of the external carotid artery. The masseteric nerve and artery work together to support the function of the masseter muscle in mastication.
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The medial pterygoid muscle is innervated by the medial pterygoid nerve, a division of the mandibular nerve
The muscles of mastication are a group of muscles that enable chewing movements of the mandible at the temporomandibular joint (TMJ). They enhance the process of eating and assist in grinding food. The four main muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid. These muscles attach to the rami of the mandible and facilitate jaw movement. The masseter muscle, for instance, raises the mandible when closing the mouth, with a minor contribution to protrusion of the mandible.
The mandibular nerve further subdivides as it innervates the four main muscles of mastication. The masseter muscle, for example, receives nerve input from the masseteric nerve, a branch of the mandibular nerve. Similarly, the lateral pterygoid muscle is supplied by a branch of the anterior division of the mandibular nerve, with its blood supply coming from the pterygoid branch of the second part of the maxillary artery.
The medial pterygoid nerve is one of the nerves responsible for innervating the medial pterygoid muscle, which is one of the primary muscles of mastication. This muscle helps to raise the mandible, contributing to the chewing motion of the jaw. The medial pterygoid nerve is a division of the mandibular nerve, which is itself a branch of the trigeminal nerve.
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The lateral pterygoid muscle is innervated by the lateral pterygoid nerves, divisions of the mandibular nerve
The lateral pterygoid muscle is a two-headed, fan-shaped muscle located in the infratemporal fossa of the skull. It is one of the four primary muscles of mastication, along with the medial pterygoid, temporalis, and masseter muscles. These muscles work together to enable chewing and biting by acting on the temporomandibular joint (TMJ). The lateral pterygoid muscle specifically helps in protruding and depressing the mandible when contracting bilaterally and rotating the mandible when contracting unilaterally.
The nerve supply to the muscles of mastication comes from the mandibular nerve, which is the third division of the trigeminal nerve (CN V3). The mandibular nerve is the largest and inferior-most division of the trigeminal nerve and is the only division that carries motor fibers. The lateral pterygoid muscle is innervated by the lateral pterygoid nerves, which are branches of the mandibular nerve. The mandibular nerve further subdivides as it innervates the four main muscles of mastication.
The lateral pterygoid nerve supplies one nerve to each head of the lateral pterygoid muscle. The nerve to the superior head and lateral half of the inferior head receives fibres from the buccal nerve, a branch of the mandibular nerve. On the other hand, the nerve to the medial half of the inferior head receives fibres directly from the mandibular nerve. The lateral pterygoid muscle also receives its blood supply from the pterygoid branches of the maxillary artery and the ascending palatine branch of the facial artery.
The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence, resulting in the protrusion of the mandible. A unilateral action of the lateral pterygoid muscle causes contralateral excursion, a form of mastication usually performed with the medial pterygoids. When acting independently, the lateral pterygoid muscle can move the mandible side to side. It is the only muscle of mastication that can assist in depressing the mandible (opening the jaw).
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The mandibular nerve is the largest and inferior-most division of the trigeminal nerve
The masseter muscle, one of the primary muscles of mastication, receives its nerve supply from the masseteric nerve, a branch of the mandibular nerve. The masseteric nerve provides sensory input to the masseter muscle, allowing it to elevate the mandible when closing the mouth. This muscle also contributes to the protrusion of the mandible. The medial pterygoid muscle, another key player in mastication, receives innervation from the medial pterygoid nerve, a division of the mandibular nerve. Similarly, the lateral pterygoid muscle, which is responsible for depressing the mandible, is supplied by the lateral pterygoid nerves, which are also divisions of the mandibular nerve.
The mandibular nerve has several branches that innervate the masticatory muscles in complex ways. The lateral pterygoid muscle, for example, demonstrates various innervation patterns and nerve perforation patterns. The deep temporal branches of the mandibular nerve innervate the muscles of mastication, while the maxillary artery and its branches provide the main arterial supply. The mandibular nerve is crucial in coordinating the functions of the masticatory muscles, ensuring their synchronised movement during the process of chewing.
The trigeminal nerve, from which the mandibular nerve originates, plays a significant role in the functioning of the masticatory muscles. Lesions affecting this nerve can lead to paralysis of the tensor tympani, resulting in hearing difficulties. Additionally, damage to the trigeminal nerve at the level of the pons can cause signs of hindbrain disease, including dysphagia, head tilt, facial paralysis, and ataxia of the limbs. Evaluating the muscles of mastication is an essential aspect of assessing the trigeminal nerve's health and functionality.
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The trigeminal nerve exits the skull through the foramen ovale of the greater wing of the sphenoid bone
The masticatory muscles are a group of muscles responsible for the chewing movement of the mandible at the temporomandibular joint (TMJ). They enhance the process of eating and assist in grinding food. The four main muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw. The mandibular nerve, a branch of the trigeminal nerve, innervates all four of these muscles.
The trigeminal nerve, also known as CN V, has three main branches, one of which is the mandibular nerve (CN V3). This nerve carries both sensory and motor fibres and is the only division of the trigeminal nerve that contains motor fibres. The mandibular nerve further subdivides as it innervates the four main muscles of mastication. The masseter muscle, for example, receives nerve input from the masseteric nerve, a branch of the mandibular nerve. Similarly, the medial pterygoid nerve, a division of the mandibular nerve, innervates the medial pterygoid muscle.
The foramen ovale is a crucial structure in the skull, allowing the passage of the trigeminal nerve and its branches. This nerve is responsible for the innervation of the masticatory muscles, as well as other muscles and sensory functions in the head and neck region. The greater wing of the sphenoid bone, through which the foramen ovale is located, is a vital anatomical landmark in this region.
Damage to the trigeminal nerve at the level of the pons can result in various signs and symptoms, including difficulties in hearing high notes due to paralysis of the tensor tympani muscle. Additional signs of hindbrain disease may also be observed, such as dysphagia, head tilt, facial paralysis, and ataxia of the limbs. Evaluation of the masticatory muscles forms part of the assessment of the trigeminal nerve function, as lesions or damage to this nerve can impact the function of these muscles and the overall process of mastication.
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Frequently asked questions
The masticatory muscles are innervated by the mandibular nerve, which is the third division of the trigeminal nerve (CN V3).
The four main masticatory muscles are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles are responsible for the movement of the jaw (mandible).
The primary function of the masticatory muscles is to facilitate chewing by moving the jaw. They enable cardinal mandibular movements such as elevation, depression, protrusion, retraction, and side-to-side motion.
