The temporal bone consists of four parts: petrous, mastoid, tympanic, and squa­mous. Tympanomastoidectomy is usually performed from the retroauricular approach, therefore the surgical anatomy will be described from this vantage point. In the lateral aspect of the temporal bone, the most important surface landmarkes are the following: The mastoid process is located laterally just behind the external auditory canal, and inferior to the temporalis line; this latter represents the promi­nence that the insertion of the temporalis muscle creates on the bone and extends anteriorly towards the zygomatic root. The temporalis line approximates the posi­tion of the middle cranial fossa just superior to the mastoid process and separates this process from the squamous part of the temporal bone. The spine of Henle, also called the suprameatal spine, is a small bony prominence in the lateral, posterior, and superior region of the bony external auditory canal. Immediately posterior to the Spine of Henle lies the cribriform area, within MacEwen’s triangle. The MacEwen’s triangle is delineated by the temporalis line superiorly, and anteriorly by a perpendicular line that travels tangentially to the posterior margins of the exter­nal bony meatus. The mastoid antrum lies deep to the surface of MacEwen’s trian­gle. An embryological remnant, Körner’s septum, can be encountered at the junction of the petrous and squamous parts of the temporal bone forming the antrum’s lateral roof. The prominence of the lateral semicircular canal and the bony labyrinth is in the medial side of the antrum. The antrum communicates with the posterior epitym­panum and middle ear via the aditus ad antrum. The body of the incus and the head of the malleus are suspended in the posterior epitympanic space by ligaments from the tegmen tympani. In front of the malleus’s head, one can recognize a bone spicu­lum that originates from the tegmen, Sheehy’s cog. The anterior epitympanic space is found in front of the cog and leads to the petrous apex anterior-medially and to the supratubal recess lateral to the tensor tympani muscle and its semi-canal ante­rior-inferiorly. The tensor tympani muscle ends in a tendon that curves laterally at the cochleariform process and attaches to the malleus neck. The long process of the incus joins with the stapes which lies in the oval window inferior to the tympanic segment of the facial nerve. The sinus tympani, a recess of variable depth, is found in the posterior wall of the tympanic cavity medial to the facial nerve. The opening of the sinus tympani is bordered by two osseous folds called the ponticulum and subiculum, The subiculum can be followed inferiorly to the area of the round win­dow niche.

Recently, a classication of tympanomastoid surgery has been proposed by the International Otology Outcome Group (IOOG) and adopted by several of the world’s otology societies [2]. The IOOG classication uses the acronym SAMEO to categorize mastoid bone operations, representing the stage of surgery, approach, mastoid bone extirpation, external bony wall repair, and mastoid cavity obliteration. The table depicts the accepted nomenclature to describe the different tympanomas­toidectomy procedures. (Table25.1).

During elevation of the muscle-periosteum ap, it is important not to tear the skin of the posterior ear canal. When exposure of the ear canal or middle ear is needed, incisions are created in the skin of the bony ear canal either before or after the muscle-periosteum ap is elevated. The retroauricular soft tissues and ap are then retracted for ample exposure of the mastoid process and linea temporalis. The surface anatomical landmarks of the lateral temporal bone, such as linea temporalis, spin of Henle, posterior wall of the EAC, area cribrosa, zygoma root, and mastoid apex should be identied.

This technique may be performed by microscopy or endoscopy, and by retroauricu­lar or transcanal approach. It is indicated for small cholesteatomas conned to the attic region. During atticotomy, a wide tympanomeatal ap is created and the exposed attic region is drilled through the meatus [1, 2]. A prominent tympano­squamous suture line is often reduced for maximal transcanal exposure. The body of the incus, the head of the malleus, and the tympanic segment of the facial nerve are seen. If the ossicles are involved with cholesteatoma, they are removed. Sheehy’s cog, which may sometimes prevent cleaning of diseased air cells in the anterior epitympanum is drilled to expose the supratubal recess [1]. If the pathology extends posteriorly and reaches the antrum, drilling of the external auditory canal must pro­ceed posteriorly to expose the antrum (atticoantrotomy). The resulting external auditory canal bony defect should be repaired to prevent recurrent retraction choles­teatoma. This procedure can be combined with a simple mastoidectomy and epi­tympanectomy, or performed without a previous mastoidectomy. In this latter case, drilling of the posterior external auditory canal continues in a retrograde fashion into the antrum using the outline of tegmen tympani as guide. The cholesteatoma or disease is removed by turning it from the inside to the outside, towards the ear canal (i.e., retrograde “inside-out mastoidectomy”). A modication of the standard attico­antrostomy was described by Bondy in 1910. In the Bondy procedure, only the disease in the attic region is resected without touching the middle ear and the ossic­ular chain [1, 2]. The Bondy procedure is only suitable for cholesteatomas limited to the attic that do not extend medial to the ossicular chain and into the middle ear.