lateral pterygoid muscle Archives — SmilesCare - Dental education

Overview Mastication (Chewing) is the first stage of digestion of food. Muscles of Mastication helps in grinding the food to make them small in size in the oral cavity. Grinding the food is very important, it makes the food smaller in size. Smaller the size of the particle will increase the surface area. This food can then be swallowed with ease and further chymified with the help of enzymes as it moves along the alimentary canal. Many different structures like Teeth, Bone (Mandible and maxilla) and muscles like tongue and masticatory muscles work together to enable a person to chew the food. Embryologically, the muscles of mastication are developed from the first pharyngeal arch. Muscles Of Mastication Primary Muscles Of Mastication There are many muscles which help in mastication. First, we will discuss primary muscles which are as follow: MasseterTemporalisMedial pterygoidLateral pterygoid Accessory Muscles Of Mastication There are some other muscles that help in mastication. Their names are as follows. Suprahyoid Muscles MylohyoidGeniohyoidStylohyoidDigastric Infrahyoid muscles SternohyidThyrohyoidOmohyoid Now, in this article, we will know about the Anatomy, attachment innervation and action of these muscles individually. Masseter Muscle It is the strongest in all muscles. Masseter muscle is quadrangular in shape, and it can be divided into two parts: Deep and Superficial. Lateral aspect of Masseter Muscle Origin Superficial layer: Tendinous aponeurosis from the zygomatic process of the maxilla and anterior 2/3 of the inferior border of the zygomatic arch.Deep layer: Medial aspect and inferior border of posterior one-third of the zygomatic arch Insertion Superficial Part: Lower border of the lateral surface of the mandible.Deep Layer: Upper part of the ramus and coronoid process. Functions of Masseter Muscle The masseter muscle functions as a powerful elevator of the jaw.Lateral movement of the mandible Retraction of mandible Nerve Supply The masseter muscle is innervated by Messetric Nerve derived from the mandibular division of the Trigeminal nerve. Blood supply Vascular supply from the masseteric branch of the maxillary artery. Temporalis Muscle Temporalis Muscle is the fan-shaped muscles originated from temporal fossa of the skull. It is a large muscle which covers the temporal bone of the skull. The primary function of this muscle is to elevate the mandible. Lateral aspect of temporalis muscle Origin of Temporalis Muscle The inferior temporal line across the entire temporal fossa, including parts of the parietal and most of the squama of the temporal bones. Insertion As a tendon on Coronoid Process of the mandible. Blood supply of Temporalis Muscle Vascular supply of the Temporalis Muscle is via branches of the superficial temporal and maxillary arteries. Nerve Supply Anterior and posterior deep Temporal nerve from mandibular division of trigeminal nerve. Function Elevation of mandibleRetraction of the mandible: by Posterior and middle portion of the muscle. Lateral Pterygoid Muscle The Lateral Pterygoid Muscle has two heads of origin, smaller Superior head, and larger inferior head. Lateral Pterygoid Muscle Origin Superior Head: Infratemporal region of the greater wing of the sphenoid bone.Inferior Head:Lateral surface of the lateral pterygoid plate. Insertion At the neck of the mandible and various structures of the TMJ. Nerve Supply Branch of the buccal nerve from the mandibular division of the trigeminal nerve. Blood Supply Pterygoid branch of the maxillary artery. Function Depresses the mandible so, It is also called a jaw opener muscle.Protrudes forward for opening the jaw.It also helps to side movement of the mandible. Medial Pterygoid Muscle The Medial Pterygoid Muscle is the deepest situated muscle of mastication. Medial pterygoid muscle Origin Deep head of lateral pterygoid plate and maxillary tuberosity Insertion In the medial angle of the mandible Nerve Supply Mandibular division of the trigeminal nerve Blood Supply Pterygoid branch of the 2nd part of maxillary artery Function Elevates the mandibleCloses the jawSide to side movement Accessory Masticatory Muscles Digastric Two bellies unite by tendonAct as a depressor muscle adding to the action of lateral pterygoid muscle Mylohyoid It is a flat triangular muscle.A secondary role in mastication as a depressor of the mandible.Mylohyoid muscle elevates the floor of the mouth to help in deglutition. Geniohyoid Short and narrow muscle which lies over mylohyoid muscle.It depresses the mandible.