Masseter muscle termination over the deep surface of the temporal fascia: look out the wrong path.

PURPOSE: The masticatory muscles have a common embryological origin. Despite numerous anatomical studies their close anatomical relationships are not always accurately described in anatomical treatises. An expansion of the masseter muscle inserted into the deep surface of the superficial temporal aponeurosis has been described. Despite the classical description of two transition bundles (Yoshikawa et al. in Kaibogaku Zasshi 37:206-217, 1962), the literature concerning these fibres has remained difficult to interpret. Given the clinical applications of the lengthening of the temporal muscle in myoplasty, it is important that we have accurate anatomical knowledge of it. METHODS: We dissected 14 embalmed or untreated anatomical cadaver heads with a sex ratio of 1 in order to analyse the aforementioned fibres and their variations. A radiologic study allowed us to understand the entanglement of the fibres. 10 craniofacial MRI were processed by 3D MPR reconstruction. RESULTS: The fibres were identified as an expansion of the posterior head of the masseter muscle and distinct from the two classically described transition bundles. These were present in all subjects of both sexes. We can systematically describe their origin, trajectory and termination. CONCLUSION: Fibres belonging to masseter muscle pass up to the zygomatic arch and terminate on the deep surface of the temporal fascia. Awareness of the nature and trajectory of these muscular fibres allows us to avoid taking "wrong path" when approaching the temporal muscle tendon on the coronoid process via the temporal fossa.

[The Anatomy Institutions of Jean Guinter d'Andernach (1487-1574), and André Vésale (1514-1564). ]. / Les Institutions Anatomiques de Jean Guinter d'Andernach (1487-1574), et André Vésale (1514-1564).

The text of the Anatomical Institutions of Johann Guinter von Andernach, in its original version, was published almost simultaneously in Paris and Basel in 1536. Guinter was then in his fiftieth year, and Andreas Vesalius who was his student in Paris between 1533 ans 1536, was only twenty-two years old. His studies being finished in Leuven and his thesis being published for the first edition in Leuven in February 1537, and for the second in Basel in March 1537, Vesalius went to Padua where he was named professor of anatomy and surgery. Vesalius, besides the reasons put forward in his dedicatory lettre to Johann Armenterianus, tried to have rapidly printed documents for his students. He published in this way in April 1538 the engraved version of the great plates which he had mostly drawn and used to support his demonstrations during sessions of dissection. For the accompanying text, he choosed the handbook of his Master Guinter von Andernach which he decided to edit incorporating modifications and which he published in Venice in 1538 by D. Bernardinus. The modifications made by Vesalius on the Guinter's text can be classified in several headings: minor adjustments, additions of anatomical comments, additions corroborating traditional physiology, and anecdotes peppering the text.