TY - CHAP M1 - Book, Section TI - Anatomy of the Ear A1 - Chan, Yvonne A1 - Goddard, John C. PY - 2019 T2 - K.J. Lee’s Essential Otolaryngology: Head and Neck Surgery, 12e AB - The temporal bone forms part of the side and base of the skull. It constitutes two-thirds of the floor of the middle cranial fossa and one-third of the floor of the posterior fossa. There are four parts to the temporal bone:SquamosaMastoidPetrousTympanicThe following muscles are attached to the mastoid process:SternocleidomastoidSplenius capitisLongissimus capitisDigastricAnterior, superior, posterior, auricular (The temporalis muscle attaches to the squamosa portion of the temporal bone and not to the mastoid process.)The auricle (Figure 13-1) is made of elastic cartilage, the cartilaginous canal of fibro-cartilage. The cartilaginous canal constitutes one-third of the external auditory canal (whereas the eustachian tube is two-thirds cartilaginous), the remaining two-thirds is osseous. Innervation of auricle is outlined in Figure 13-2.The skin over the cartilaginous canal has sebaceous glands, ceruminous glands, and hair follicles. The skin over the bony canal is tight and has no subcutaneous tissue except periosteum.Boundaries of the external auditory canal are:Table Graphic Jump Location|Download (.pdf)|PrintAnteriorMandibular fossaParotidPosteriorMastoidSuperiorEpitympanic recess (medially)Cranial cavity (laterally)InferiorParotidThe anterior portion, floor, and part of the posterior portion of the bony canal are formed by the tympanic part of the temporal bone. The rest of the posterior canal and the roof are formed by the squamosa.Boundaries of the epitympanum are:Table Graphic Jump Location|Download (.pdf)|PrintMedialLateral semicircular canal and VII nerveSuperiorTegmenAnteriorZygomatic archLateralSquamosa (scutum)InferiorFossa incudisPosteriorAditusBoundaries of the tympanic cavity are:Table Graphic Jump Location|Download (.pdf)|PrintRoofTegmenFloorJugular wall and styloid prominencePosteriorMastoid, stapedius, pyramidal prominenceAnteriorCarotid wall, eustachian tube, tensor tympaniMedialLabyrinthine wallLateralTympanic membrane, scutum (laterosuperior)The auricle is attached to the head bySkinAn extension of cartilage to the external auditory canal cartilageLigamentsAnterior ligament (zygoma to helix and tragus)Superior ligament (external auditory canal to the spine of the helix)Posterior ligament (mastoid to concha)MusclesAnterior auricular muscleSuperior auricular musclePosterior auricular muscleNotch of Rivinus is the notch on the squamosa, medial to which lies Shrapnell membrane. The tympanic ring is not a complete ring, with the dehiscence superiorly.Meckel cave is the concavity on the superior portion of the temporal bone in which the gasserian ganglion (V) is located.Dorello canal is between the petrous tip and the sphenoid bone. It is the groove for the VI nerve. Gradenigo syndrome, which is secondary to petrositis with involvement of the VI nerve, is characterized by:Pain behind the eyeDiplopiaAural dischargeThe suprameatal triangle of Macewen triangle is posterior and superior to the external auditory canal. It is bound at the meatus by the spine of Henle, otherwise called the suprameatal spine. This triangle approximates the position of the antrum medially. Tegmen mastoideum is the thin plate over the antrum.Trautmann triangle is demarcated by the bony labyrinth, the sigmoid sinus, and the superior petrosal sinus or dura.Citelli angle is the sinodural angle. It is located between the sigmoid sinus and the middle fossa dura plate. Others consider the superior side of Trautmann triangle to be Citelli angle.Solid angle is the angle formed by the three semicircular canals.Scutum is the thin plate of bone that constitutes the lateral wall of the epitympanum. It is part of the squamosa.Mandibular fossa is bound by the zygomatic, squamosa, and tympanic bones.Huguier canal transmits the chorda tympani ... SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/10/12 UR - accesssurgery.mhmedical.com/content.aspx?aid=1172368665 ER -