Musculus pterygoideus externus

Musculus pterygoideus externus, also known as the lateral pterygoid muscle, is an important muscle located in the head and neck region. In this article, we will discuss the anatomy, function, and clinical significance of the musculus pterygoideus externus.

Anatomy

The musculus pterygoideus externus is one of the muscles of mastication, along with the masseter, temporalis, and medial pterygoid muscles. It is a paired muscle, present on both sides of the face. The muscle originates from two distinct heads: the upper head and the lower head.

The upper head of the musculus pterygoideus externus arises from the infratemporal surface of the greater wing of the sphenoid bone. The lower head originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. These two heads merge to form a single muscle belly, which then inserts onto the condylar process of the mandible.

Function

The musculus pterygoideus externus plays a crucial role in the movement of the temporomandibular joint (TMJ) and the process of mastication. Its main functions include:

1. Protrusion of the mandible: The contraction of the musculus pterygoideus externus on both sides causes the mandible to move forward, allowing for the protrusion of the jaw.

2. Lateral deviation of the mandible: When only one side of the muscle contracts, it causes the mandible to move laterally towards the opposite side.

3. Assisting in opening the mouth: The musculus pterygoideus externus works in conjunction with other muscles of mastication to open the mouth.

Clinical Significance

The musculus pterygoideus externus is involved in various clinical conditions related to the temporomandibular joint (TMJ) and masticatory disorders. Some notable clinical aspects include:

1. Temporomandibular joint disorder (TMD): Dysfunction of the TMJ can lead to pain and limited movement of the jaw. The musculus pterygoideus externus is often implicated in TMD, and its evaluation is crucial in diagnosing and managing this condition.

2. Bruxism: Bruxism refers to the habit of grinding or clenching the teeth, often during sleep. Excessive activity of the musculus pterygoideus externus can contribute to bruxism, leading to tooth wear, jaw pain, and other associated symptoms.

3. TMJ surgery: The musculus pterygoideus externus may be involved in surgical procedures aimed at treating TMJ disorders. Surgeons may need to access and manipulate this muscle during certain interventions.