Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Introduction ++ 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: Squamosa Mastoid Petrous Tympanic The following muscles are attached to the mastoid process: Sternocleidomastoid Splenius capitis Longissimus capitis Digastric Anterior, 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)|Print Anterior Mandibular fossa Parotid Posterior Mastoid Superior Epitympanic recess (medially) Cranial cavity (laterally) Inferior Parotid The 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)|Print Medial Lateral semicircular canal and VII nerve Superior Tegmen Anterior Zygomatic arch Lateral Squamosa (scutum) Inferior Fossa incudis Posterior Aditus Boundaries of the tympanic cavity are: Table Graphic Jump Location|Download (.pdf)|Print Roof Tegmen Floor Jugular wall and styloid prominence Posterior Mastoid, stapedius, pyramidal prominence Anterior Carotid wall, eustachian tube, tensor tympani Medial Labyrinthine wall Lateral Tympanic membrane, scutum (laterosuperior) The auricle is attached to the head by Skin An extension of cartilage to the external auditory canal cartilage Ligaments Anterior ligament (zygoma to helix and tragus) Superior ligament (external auditory canal to the spine of the helix) Posterior ligament (mastoid to concha) Muscles Anterior auricular muscle Superior auricular muscle Posterior auricular muscle Notch 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 eye Diplopia Aural discharge The 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 ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.