Anatomy, Head and Neck, Buccinator Muscle

The fibers of the buccinator muscle have their origin from three areas due to which this muscle has three muscular bundles.[2] Two of the muscular bundles have a bony origin. The maxillary bundle arises from the buccal portion of the alveolar process of maxilla, mandibular bundle arises from the buccal portion of the alveolar process of the mandible, and the longitudinal bundle arises from the pterygomandibular raphe.[1] Raphe connects the posterior fibers of this muscle with the anterior portion of a pharyngeal muscle, i.e., superior constrictor muscle.[1] The fibers of all the three bundles run in the anterior direction and descent through the modiolus thus, forming the musculature of the cheek.[3] They insert and blend with fibers of orbicularis oris muscle. Fibers of maxillary bundle blend with fibers of orbicularis oris muscle at the mandibular lip, fibers of mandibular bundle run upward at the maxillary lip and fibers of the longitudinal bundle at the oral commissure to insert into the upper and lower lip.[12]  

On the lateral aspect, this muscle is related to the ramus of mandible, muscle of mastication (masseter and medial pterygoid muscle), the buccal fat pad, and the buccopharyngeal fascia. On the medial aspect, its covering is the submucosa and mucosa of the cheek.

The buccinator muscle is pierced by the parotid duct (Stenson's duct) after it crosses the masseter muscle and turns medially at the anterior border of the muscle to open in the oral cavity into a small papilla opposite the maxillary second molar.

The crestal attachment of buccinator muscle, although a rare phenomenon, may lead to difficulty in routine oral functions and restoring the edentulous area. 

As the parotid duct pierces the buccinator muscle, it should be identified and preserved during surgery such as while raising buccinators flap. Small to moderate-sized defects of the oral cavity can have reconstruction with the buccinator flap, which is easy and quick to raise. It replaces mucosa with mucosa and correlates with a very low degree of morbidity of the donor site. It is remarkably elastic, thus can be stretched easily to conform to defects with a complex shape.

Hyperactivity of the buccinators muscle can cause excessive pressure on the underlying hard tissues resulting in narrow arches and malocclusion.[13][14]

Damage to the facial nerve can lead to paralysis of the buccinator muscles, which can lead to difficult mastication as the non-functioning of this muscle can cause repeated laceration of the cheek mucosa.

Abnormal attachment of this muscle may interfere with the proper prosthodontic management and in maintaining oral hygiene. It will also restrict the cheek and lip movement leading to difficulty in mastication and phonation.

The muscle has been shown to have an indirect involvement during parafunctional movements.

Clinical implication in Prosthodontics:

In the oral cavity, inward forces by the orbicularis oris and the buccinator muscle get balanced by the outward forces of the tongue. While making an impression for a completely edentulous patient, molding must be done by muscle function in such a manner that it is in harmony with the surrounding musculature.

Buccinator along with orbicularis oris and pharyngeal constrictor forms a functional unit (buccinator mechanism) which is essential for orofacial functions (swallowing, sucking, whistling, chewing, vowel pronunciation). If buccinator is weakened or paralyzed, food tends to accumulate in the vestibule during chewing.

Buccinator muscle plays a role in stabilizing the denture by gripping the polished surface of the denture. Also, the longitudinal fibers hold the bolus of food between the teeth during mastication. The maxillary bundle of this muscle tends to raise the upper denture, whereas the mandibular bundle of this muscle depresses the lower denture, thus aiding in denture stability and retention.

The fascial spaces confine early infection, but since the spaces communicate with each other, as the infection progresses, the inflammation can involve the other spaces. The buccal space is the fascial space limited superomedially and inferomedially by fibers of the buccinator muscle originating from alveolar processes of maxilla and mandible. Thus, the roots of the posterior teeth are related to this space. Any infection in the parotid may extend to the buccal space and vice versa.[15]