1. Dr. Ahmed Fathalla Ibrahim

2. THE EAR Is an organ of hearing & balanceIs an organ of hearing & balance Consists of three parts:Consists of three parts: 1.External Ear 2.Middle Ear 3.Internal Ear

3. THE EXTERNAL EAR AURICLEAURICLE EXTERNAL AUDITORY MEATUSEXTERNAL AUDITORY MEATUS

4. AURICLE: Shape:Shape: consists of a thin plate of elastic cartilage Function:Function: collects air vibrations Motor supply:Motor supply: facial nerve

5. EXTERNAL AUDITORY MEATUS Shape:Shape: a curved tube formed of elastic cartilage (outer 1/3) & tympanic plate of temporal bone (inner 2/3) Function:Function: conducts sound waves from auricle to tympanic membrane

6. THE MIDDLE EAR (TYMPANIC CAVITY) Definition:Definition: air-containing cavity in petrous part of tympanic bone, lined with mucus membrane Function:Function: transmits vibration of tympanic membrane to perilymph of internal ear Communications:Communications: 1.Anteriorly: with nasopharynx (through auditory tube) 2.Posteriorly: with mastoid antrum 3.Nerve supply: 3.Nerve supply: tympanic branch of glossopharyngeal nerve

7. THE MIDDLE EAR Roof:Roof: tegmen typani (thin plate from petrous temporal bone), separates middle ear from temporal lobe of brain Floor:Floor: thin plate of bone, separates middle ear from superior bulb of internal jugular vein

8. THE MIDDLE EAR Anterior wall:Anterior wall: 1.Superiorly: has 2 openings (for auditory tube & for canal of tensor tympani) 2.Inferiorly: thin plate of bone separating middle ear from internal carotid artery

9. THE MIDDLE EAR Posterior wall:Posterior wall: 1.Superiorly: has an opening (aditus to mastoid antrum) 2.Inferiorly: a conical projection (pyramid) for emergence of stapedius

10. THE MIDDLE EAR Lateral wall:Lateral wall: tympanic membrane Medial wall:Medial wall: 1.Promontory: rounded projection formed by cochlea oval closed 2.Fenestra vestibuli: oval opening, above & behind promontory, closed by base of stapes round closed 3.Fenestra cochleae: round opening below promontory, closed by secondary tympanic membrane backward downward 4.Prominence for facial nerve canal: runs backward above promontory & fenestra vestibuli then curves downward behind pyramid

11. THE TYMPANIC MEMBRANE Shape:Shape: a thin fibrous membrane between external & middle ear, has a small depression (umbo) produced by handle of malleus, divided into pars flaccida & pars tensa Nerve supply:Nerve supply: Outer surface: auricular branch of vagus Inner surface: tympanic branch of glossopharyngeal

12. AUDITORY OSSICLES MALLEUS: articulatesHead: articulates with body of incus Neck insertionHandle: firmly attached to medial surface of tympanic membrane, receives insertion of tensor tympani Anterior process Lateral process: attached to anterior & posterior malleolar folds of tympanic membrane

13. AUDITORY OSSICLES INCUS: articulatesBody: articulates with head of malleus articulatesLong process: articulates with head of stapes Short process: attached to tympanic cavity

14. AUDITORY OSSICLES STAPES: articulatesHead: articulates with long process of incus insertionNecK: receives insertion of stapedius Base: attached to fenestra vestibuli

15. MUSCLES OF OSSICLES TENSOR TYMPANI: Origin: auditory tube Insertion: handle of malleus Nerve supply: mandibular of trigeminal Action: damps down vibration of tympanic membraneSTAPEDIUS: Origin: pyramid Insertion: neck of stapes Nerve supply: facial Action: damps down vibration of stapes

16. FACIAL NERVE Course:Course: runs in facial canal then emerges through stylomastoid foramen Branches:Branches: 1.Nerve to stapedius taste fibers preganglionic parasympathetic fibers 2.Chorda tympani: carries taste fibers from anterior 2/3 of tongue & preganglionic parasympathetic fibers to submandibular & sublingual salivary glands taste fibers preganglionic parasympathetic fibers 3.Greater petrosal nerve: carries taste fibers from soft palate & preganglionic parasympathetic fibers to lacrimal, nasal & palatine glands

17. THE INTERNAL EAR petrous part of temporal boneLies in petrous part of temporal bone Consists of: 1.Bony labyrinth 2.Membranous labyrinth

18. BONY LABYRINTH Consists of: 1.Vestibule 2.3 semicircular canals 3.Cochlea They are cavities inside bone, filled with perilymph in which membranous labyrinth is suspended

19. MEMBRANOUS LABYRINTH Lodged within bony labyrinth Filled with endolymph & surrounded by perilymph Consists of: 1.Utricle & saccule: in vestibule 2.3 semicircular ducts: in semicircular canals 3.Cochlear duct: in cochlea

20. VESTIBULOCOCHLEAR NERVE Divides into: 1.Vestibular nerve: supplies utricle, saccule & semicircular ducts 2.Cochlear nerve: supplies cochlear duct