Surgical Anatomy of the Middle Ear Cleft and Mastoid

Abstract

Surgical success in middle ear surgery is established in five principles: (1) a solid theoretical basis of the pathology; (2) detailed anatomical knowledge; (3) constant training in dissection laboratories; (4) close observation of more experienced surgeons; and (5) up-to-date and continuing medical education. An adequate surgical access results in a wide and safe operative field. Choosing the type of access depends on the pathology, patient-related factors and technical elements (available infrastructure of the surgical center and the surgeon’s experience).

This chapter’s main objective is to describe anatomical landmarks that will guide the surgeon through the dissection of the temporal bone. Thus, different levels of anatomical structures (landmarks) were presented, from superficial (lateral) to deep (medial) layers.

Level I structures refer to the superficial anatomy of the ear (the auricle itself, the mastoid and the hairline). Level II corresponds to the subcutaneous layer, including the external auditory canal, the linea temporalis, the mastoid process, and the temporalis muscle. Level III includes subperiosteal structures, such as Henle’s spine, the cribriform area, and the posterior wall of EAC. Level IV describes structures of the external auditory meatus (tympanosquamous and tympanomastoid sutures, the tympanic membrane and annulus, amongst others). Level V guides the surgeon in the superficial mastoid dissection. Level VI describes deep mastoidal structures. Level VII structures refer to a closed mastoidectomy and the facial recess. Finally, level VIII comprises structures involved in an open mastoidectomy.