Lateral Pterygoid Muscle: Structure, Function & Diseases

The lateral pterygoid muscle is a masticatory muscle of the human dentition. Through it, the opening of the jaw is ensured. In addition, it allows the jaw to be pushed forward.

What is the pterygoid lateralis muscle?

The pterygoid lateralis muscle is a muscle of the temporomandibular joint. It is located on the inside of the lower jaw. The masticatory muscles in humans are controlled by four masseter muscles. They include the masseter muscle, the temporalis muscle, the medial pterygoid muscle and the lateral pterygoid muscle. Each of them has a different task and function in the jaw area. They include the movement of the lower jaw. The pterygoid lateralis muscle is called the external wing muscle. It is the only muscle that serves to open the jaw. In addition, it allows the jaw to move forward or sideways. It enables the so-called grinding movement to be performed with the jaw. The lateral pterygoid muscle stands out from the functional activity of the other muscles. It is the only muscle that is not responsible for closing the jaw. Instead, it can be used to open the jaw. The course of the lateral pterygoid muscle is almost horizontal. It is supplied by pterygoid lateral nerve.

Anatomy and structure

The mandibular nerve exits as a branch of the V. Cranial Nerve, the trigeminal nerve exits the cranial cavity through the foramen ovale. The sensitive portion of the nerve divides into four branches. They include the auriculotemporal nerve, the inferior alveolar nerve, the lingual nerve, and the buccal nerve. The motor portion of the mandibular nerve also divides into several branches. These then travel to the masseter muscles of the mandible and the floor of the mouth. They include the masseteric nerve, the profundal temporal nerves, the pterygoid nerves, and the mylohyoid nerve. Nervus massetericus innervates the masseter muscle. Nervi temporales profundi innervate the temporal muscle. Nervi pterygoidei supply the lateralis and medialis pterygoid muscles. The mylohyoid nerve is responsible for supplying the floor of the mouth muscles. The lateral pterygoid muscle has two muscle heads. One is located on the surface below the sphenoid bone, the os sphenoidale. There are two strong bony plates there, called the ala major. The lateral pterygoid muscle continues to pull over the lateral lamina to the bony process of the sphenoid bone. This is the pterygoid process. The second muscle head of the pterygoid lateralis muscle is located there.

Function and tasks

Each of the four muscles of the masticatory apparatus has different tasks and functions. The masseter muscle is the masticatory muscle and is responsible for jaw closure. The temporalis muscle is called the temporalis muscle and helps close and retract the lower jaw. The pterygoid medialis muscle is the inner wing muscle. It, too, serves to close the jaw. The lateral pterygoid muscle is called the external wing muscle. It is used to move the temporomandibular joint. It is used to initiate the opening of the mouth. It also allows the mandible to advance. This process is called protrusion. The movements are additionally amplified. This is done by the masseter muscle loop. Another function of the lateral pterygoid muscle is the masticatory gliding movements. These go from right to left and vice versa. This process is called laterotrusion. During laterotrusion, there is a unilateral contraction of the pterygoid lateralis muscle in the opposite direction. The mouth opening is continued by the suprahyal muscles in addition to the activity of the pterygoid lateralis muscle. These are four muscles that are part of the hyoid musculature. These are the digastric muscle, the mylohyoid muscle, the geniohyoid muscle and the stylohyoid muscle. The upper head of the ptergoid lateralis muscle guides the articular cartilage, the articular disc. Thus, it supports the movement of the temporomandibular joint in this way.

Diseases

The entire masticatory system is among the most sensitive systems in the body. The lateral pterygoid muscle has a central role in malpositions of the temporomandibular joint. Craniomandibular dysfunction is a condition in which there is a misalignment of the mandible to the maxilla. It is considered an umbrella term for structural or functional dysregulation.In addition, biochemical and psychological problems of the muscle or joint function are summarized under it. The diseases cause the two jaws not to meet optimally when biting together. As a result, there is a strong overload or incorrect load on the masticatory muscles. These strains lead to pain, irritation and swelling in both jaws. Craniomandibular dysfunction can be caused by genetic disposition, psychological stress or malocclusion. In addition, tooth fillings that are too high or faulty dentures such as crowns and bridges can trigger the disease. The loss of tooth substance due to caries, for example, is also one of the causes of craniomandibular dysfunction. Head, neck and back pain can be triggered by a dysfunction of the temporomandibular joint and the associated masticatory system. The masticatory and back muscles are closely interconnected and influence each other. Complaints such as tinnitus or other ringing in the ears, dizziness and visual disturbances often find their origin in a faulty masticatory organ. Difficulty swallowing, teeth clenching at night, increased salivation or toothache, as well as inflammation of the nerves are also among the complaints of the chewing apparatus. Infections or viral diseases such as herpes affect the oral region. There are effects on the movements of the jaw and their load.