Traumatic focal myositis of the temporalis muscle due to presumptive impingement between the zygomatic arch and coronoid process in two cocker spaniels with restricted mouth opening

Two middle‐aged, unrelated cocker spaniels were investigated for apparent jaw pain and slowly progressive restriction of mouth opening, in the absence of previous trauma or jaw‐locking episodes. Computed tomographic evaluation was suggestive of a dynamic impingement between the coronoid process of the mandible and the medial surface of the zygomatic arch, trapping the temporalis muscle. Bilateral, single‐session, partial resection of the coronoid process and zygomatic arch resulted in complete resolution of the clinical signs. This form of impingement should be considered when evaluating cases with a mechanically restricted, painful opening of the mouth.