[Surgical approach to the middle ear of the guinea pig].

A total of 40 guinea pigs have been used: in 5 a general anatomical dissection of the temporal bone was utilized; in another 5 guinea pigs a submandibular approach was performed; and in the remaining 30 a superior approach was employed. The submandibular approach begins with an incision of 30 mm inside of and parallel to the inferior border of the mandible , identifying the masseter muscle, the salivary gland, the thymus and posterior belly of the digastric muscle and, finally, the tympanic bulla. In the superior approach a horizontal supra-auricular incision of 15 mm is used which, after dissecting the temporal muscle, permits the access to the external wall of the epitympanum.