Pterygoideus externus

Pterygoideus externus

The pterygoideus externus is a muscle located in the head and neck region of humans and some animals. It is one of the muscles involved in the movement of the jaw and plays a crucial role in chewing and biting.

Anatomy

The pterygoideus externus muscle is a paired muscle, meaning it is present on both sides of the head. It originates from the lateral pterygoid plate of the sphenoid bone, which is located in the skull. From there, it extends downwards and forwards towards its insertion point.

The insertion of the pterygoideus externus muscle is on the mandible, specifically on the neck of the condylar process. This is the part of the mandible that articulates with the temporal bone to form the temporomandibular joint (TMJ).

Function

The main function of the pterygoideus externus muscle is to assist in the movement of the jaw. It works in conjunction with other muscles, such as the temporalis and masseter, to perform actions like chewing, biting, and grinding food.

When the pterygoideus externus muscle contracts, it pulls the mandible forward and sideways, allowing for lateral and protrusive movements of the jaw. This muscle also helps to stabilize the TMJ during jaw movements, preventing dislocation or excessive movement of the joint.

Clinical Significance

The pterygoideus externus muscle can be affected by various conditions, leading to dysfunction and pain in the jaw. Temporomandibular joint disorder (TMD) is a common condition that can cause discomfort and limited movement of the jaw. Dysfunction of the pterygoideus externus muscle can contribute to the development of TMD symptoms.

In some cases, excessive tension or spasm of the pterygoideus externus muscle can lead to a condition called trismus, which is characterized by difficulty in opening the mouth fully. This can be caused by factors such as trauma, dental procedures, or prolonged clenching of the jaw.