Anatomy of the ear
Anatomy of the ear BIO 252
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This 4 page Class Notes was uploaded by Pauline A. Champlin on Wednesday January 27, 2016. The Class Notes belongs to BIO 252 at Clarion University of Pennsylvania taught by Dr. Bonita Bailey in Winter 2016. Since its upload, it has received 15 views. For similar materials see Human Anatomy and Physiology 2 in Biology at Clarion University of Pennsylvania.
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Date Created: 01/27/16
CH.16 EAR HEARING AND EQUILIBRIUM 1. EXTERNAL EAR The outer ear is a funnel for conducting airborne vibrations to the tympanic membrane (ear drum). A. AUDITORY CANAL (EXTERNAL ACOUSTIC MEATUS) i. Passage leading through the temporal bone to the tympanic membrane. It is lined with skin and supported by fibrocartilage. - Protected by guard hairs and contains ceruminous and sebaceous glands to form cerumen (ear wax). - The cerumen coats the guard hairs helping to bloc foreign particles from the canal. - The cerumen also contains lysozomes and has a low pH which inhibits bacterial growth. - The cerumen protects the skin and the tympanic membrane from absorbing water. - Usually dries out and falls out but of not it is compacted and causes hearing problems. 2. MIDDLE EAR A. 3 Auditory Ossicles *smallest bones in the human body.* i. MALLEUS - Elongated handle attached to the inner surface of the tympanic membrane. ii. INCUS - Triangular body that articulates w/ Malleus and Stapes. Suspended by a ligament from wall of cavity. iii. STAPES - Shaped like a stirrup. Has a head that articulates into the incus. Base is held by a ring like ligament in an opening called the oval window. 2 B. Muscles of the inner ear i. STAPEDIUS - Posterior wall of the cavity and inserts on the stapes. ii. TENSOR TYMPANI - Wall of auditory tube, inserts on malleus. Q: HOW TO DIFFERENTIATE BETWEEN MALLEUS, INCUS, AND STAPES? THE MALLEUS SITS ON THE TYMPANIC MEMBRANE WHICH IS CONNECTED TO THE AUDITORY TUBE. NEXT TO THE MALLEUS IS THE INCUS, AND THE INCUS IS CONNECTED TO THE STAPES WHICH IS CONNECTED TO THE OVAL WINDOW. 3. INNER EAR i. BONY LABRYINTH - Maze of temporal bone passageways. Lined by fleshy tubes called the MEMBRANOUS LABRYINTH. ii. MEMBRANOUS LABRYINTH - Lines the bony labyrinth. iii. VESTIBULE - Contains organs of equilibrium. Labyrinths begin with vestibule. iv. COCHLEA (Spiral Organ) - Organ of hearing. Coiled tube that arises from the anterior side of the vestibule. 1. SCALA VESTIBULI- Superior Chamber; filled with perilymph 2. SCALA TYMPANI - Inferior Chamber; filled with perilymph 3 *Both communicate with each other through a narrow channel at the apex of the cochlea. The Vestibuli starts begins near the oval window and spirals down to the apex, then the Tympani spirals back down to the base and ends at the round window. 3. COCHLEAR DUCT (ORGAN OF CORTI) – Separated by the vestibular membrane from the Vestibuli and from the Tympani by a basilar membrane. Filled with endolymph. 4
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