Structure and Functions of the Ear – PST04103 Human Anatomy and Physiology
NTA Level 4 • Semester 1 • PST04103 Structure and Functions of the Ear Human Anatomy and Physiology • Source Session/Topic 10 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 10: Structure and Functions of the Ear Total Session Time: 120 minutes + 60 minutes assignment • None Learning Tasks By the end of this session students are expected to be able to: • Define Ear • Describe Structure and Function of the Ear • Explain Mechanism of Hearing and Balance Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Overhead Projector and Transparencies or Slide Projector/LCD and Computer • Handout 10.2: External and Middle Ear • Handout 10.3:Position of the Middle Ear • Handout 10.4: The Inner Ear SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |05minutes |Presentation |Definition of the Ear | | | |Buzzing | | |3 |50minutes |Presentation |Structure and Functions of the Ear | | | |Small group | | | | |discussion | | |4 |50minutes |Presentation |Mechanism of Hearing and Physiology | | | |Brainstorming |of Balance | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | |7 |60 minutes |Presentation |Take Home Assignment | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify STEP 2: Definition of the Ear (5minutes) |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What is the ear? | | | |ALLOW few pairs to respond and let other pairs to add on points not | |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • Ears are paired sensory organs comprising of: o The auditory system, involved in the detection of sound. o The vestibular system, involved with maintaining body balance/ equilibrium. STEP 3: Structure and Functions of the Ear (50minutes) |Activity: Small Group Discussion ( 20 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | | | |What are the Structure and Functions of the Ear | |ALLOW students to discuss for 10 minutes | | | |ALLOW few groups to present and the rest to add points not mentioned | | | |CLARIFY and SUMMARIZE by using the contents below | • The ear divides anatomically and functionally into three regions o The external ear o The middle ear o The inner ear • All three regions are involved in hearing. • Only the inner ear functions in the vestibular system. • The external ear (or pinna, the part you can see) serves to protect the tympanic membrane • (eardrum), as well to collect and direct sound waves through the ear canal to the eardrum. • About 1¼ inches long, the canal contains modified sweat glands that secrete cerumen, or earwax. Too much cerumen can block sound transmission External Acoustic Meatus (External Ear) • The external acoustic meatus extends from the deepest part of the concha to the tympanic membrane (eardrum), a distance of approximately 1 inch (2.5 cm). • Its walls consist of cartilage and bone. • The lateral one-third is formed from cartilaginous extensions from some of the auricular cartilages and the medial two-thirds is a bony tunnel in the temporal bone. • Throughout its length the external acoustic meatus is covered with skin, some of which contains hair and modified sweat glands producing cerumen (earwax). • Its diameter varies, being wider laterally and narrow medially. • The external acoustic meatus does not follow a straight course. • From the external opening it passes upwards in an anterior direction, then turns slightly posteriorly still passing in an upwards direction, and finally, turns again in an anterior direction with a slight descent. Tympanic Membrane • The tympanic membrane separates the external acoustic meatus from the middle ear. • It is at an angle, sloping medially from top to bottom and posteriorly to anteriorly. • It consists of a connective tissue core lined with skin on the outside and mucous membrane on the inside. • Around the periphery of the tympanic membrane a fibrocartilaginous ring attaches it to the tympanic part of the temporal bone. • At its center, a concavity is produced by the attachment on its internal surface of the lower end of the handle of malleus, part of the malleus bone in the middle ear. [pic]Refer to Handout 10.2: External and Middles Ear The Middle Ear • The middle ear is an air-filled, mucous membrane-lined space in the temporal bone between the tympanic membrane laterally and the lateral wall of the internal ear medially. • It is described as consisting of two parts: o The tympanic cavity immediately adjacent to the tympanic membrane o The epitympanic recess superiorly • It connects to the throat/nasopharynx via the Eustachian tube. • This ear-throat connection makes the ear susceptible to infection (otitis media). • The eustachian tube functions to equalize air pressure on both sides of the eardrum. • Normally the walls of the tube are collapsed. • Swallowing and chewing actions open the tube to allow air in or out, as needed for equalization. • Equalizing air pressure ensures that the eardrum vibrates maximally when struck by sound waves. • The middle ear communicates with the mastoid area posteriorly. • Adjoining the eardrum are three linked, movable bones called ossicles, which convert the sound waves striking the eardrum into mechanical vibrations. • The smallest bones in the human body, the ossicles are named for their shape. o The hammer (malleus) connected to the tympanic membrane. o The anvil (incus),