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The masseter muscle is located on the side of the jaw. It originates from the zygomatic bone and extends to insert in the ramus and angle and body of the mandible. It is innervated by is innervated by the mandibular branch of the trigeminal nerve and is supplied by the masseteric artery. The masseter is one of the chewing muscles that elevates the mandible which pulls the mouth shut. It is also used during talking.
 Research Masseter
The medial pterygoideus (internal pterygoid) muscle is located on the side of the jaw. It is thick and quadrilateral in form, similar to the masseter muscle, which lies just above it. The muscle originates from the pterygoid fossa of the sphenoid bone and the tuberosity of the maxilla and extends downward and outward to the angle and ramus of the mandible. It is innervated by mandibular branches of the trigeminal nerve and supplied by the medial pterygoid artery. This muscle raises the lower jaw to close the mouth and is used in chewing.
Research Pterygoideus Medial
The risorius muscle (Albinus muscle; Santorini's muscle) is a narrow bundle of fibres that originate from the fascia just above the masseter muscle and extends horizontally forward to insert in the skin at the angle of the mouth. It is innervated by the facial nerve (VII cranial nerve) and supplied by the facial artery. This muscle pulls the side of the mouth backward and outward (toward the earlobe). It is one of the most variable of the facial muscles. Many people have no risorius muscle, while others have an expansive one. Some people have the muscle on one side only.
Research Risorius
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The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
©1993 - 2009 The Probert Encyclopaedia
Southampton, United Kingdom
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Abbreviations
