MUSCLES OF MASTICATION

 Muscles of Mastication

• Mastication is the process of chewing food in preparation for deglutition (swallowing) and digestion.
• All muscles of mastication originate on the skull and insert on the mandible. 
• All muscles of mastication are innervated by the mandibular division of the trigeminal nerve. 
•  All muscle of mastication are derivatives of the 1st pharyngeal arch.
• Movement of the mandible are classified as:  

1. Elevation 
2. Depression
3. Protrusion
4. Retrusion
5. Side-to-side (lateral) excursion 

• Mastication prepares food by chwing for deglutition and digestion.
• It is the 1st step in the breakdown of food by:

1.  Making smaller pieces from larger pieces( thus increasing the surface area for digestive breakdown).
2. Helping soften and lubricate the food with saliva.

BONES INVOLVED

Base of the skull and the mandible.

They articulate at the temporomandibular joint (between the squamous portion of the temporal bone {skull} and the condyle of the mandible)

MUSCLES INVOLVED

• 4 muscles of mastication:

1. Masseter
2. Temporalis
3. Medial pterygoid 
4. Lateral pterygoid

• All muscles of mastication are innervated by the mandibular division of the trigeminal nerve (nerve of the 1st pharyngeal arch).
• Mastication involves using the 4 muscles in different combinations to move the mandible in 1 of 3 planes in an antagonistic fashion:

1. Elevation - depression
2. Protrusion - retrusion
3. Side - to -side excursion

• Although the buccinator is not a muscle of mastication, it aids in keeping the bolus of food against the teeth to help in mastication.