The buccinator muscle is a muscle of the face, playing a role in various oral functions and facial expressions. It is a thin, quadrilateral muscle that contributes to the structure and movement of the cheeks.
Anatomical Position
The buccinator muscle is situated deeply within the cheek, forming the lateral wall of the oral cavity. Its origins are broad, arising from the outer surfaces of the alveolar processes of both the maxilla (upper jawbone) and the mandible (lower jawbone), specifically opposite the molar teeth. It also originates from the pterygomandibular raphe, a fibrous band that connects the buccinator to the superior pharyngeal constrictor muscle at the back of the mouth. This muscle extends horizontally forward, filling the space between the upper and lower jaws.
The fibers of the buccinator converge towards the angle of the mouth. Here, its fibers interlace with those of other facial muscles, particularly the orbicularis oris, forming a dense, fibromuscular structure known as the modiolus. The buccinator lies deep to several other facial muscles, including the zygomaticus major, risorius, levator anguli oris, and depressor anguli oris. The buccal fat pad covers the outer surface of the deep part of the buccinator, separating it from structures like the ramus of the mandible and the masseter muscle.
Role in Facial Movement and Function
The buccinator muscle functions to press the cheeks firmly against the teeth and gums. This action prevents food from accumulating in the space between the teeth and the cheek, keeping the food bolus centered in the oral cavity. Without its action, one might frequently bite the inside of their cheeks while eating. The buccinator also aids in swallowing by helping to move food towards the pharynx.
Beyond mastication, the buccinator is involved in actions involving the forceful expulsion or intake of air. It is the muscle involved in blowing, such as when playing a wind instrument like a trumpet, or in actions like whistling. This muscle also contributes to sucking motions. By pulling the corner of the mouth laterally and maintaining cheek tension, the buccinator contributes to various facial expressions, including smiling.
Clinical Relevance of Its Location
The specific location of the buccinator muscle makes it clinically significant in several medical and dental contexts. In dentistry, the pterygomandibular raphe, which serves as one of the buccinator’s origins, is a crucial anatomical landmark for administering the inferior alveolar nerve block. This local anesthetic injection numbs the lower jaw, teeth, and associated soft tissues, and dentists identify the raphe to guide the needle insertion. The buccinator itself can be pierced during certain dental injection techniques, particularly those targeting the pterygomandibular space.
The buccinator is related to the parotid duct (Stensen’s duct), which carries saliva from the parotid gland. This duct pierces through the buccinator muscle to open into the mouth opposite the second upper molar tooth. Conditions affecting the parotid gland or duct, such as blockages or infections, can involve the buccinator. Because the buccinator is innervated by the buccal branches of the facial nerve (cranial nerve VII), it is affected in conditions like facial paralysis (Bell’s Palsy), which can lead to difficulty with chewing and facial symmetry. Synkinesis (involuntary muscle movements) can also occur in patients with facial palsy.