EAR DR. JAMILA EL MEDANY

VESTIBULOCOCCHLEAR ORGAN It is divided into: External ear. Middle ear (Tympanic cavity). Internal ear (Labyrinth).

EXTERNAL EAR Auricle : Attached to the lateral aspect of the head. External Auditory (Acoustic) meatus: A canal leading inwards. It is (S) shaped tube . (2.5 cm) in adults. Its lateral 1/3 is Cartilaginous. It is lined with Skin. It contains hairs, sebaceous and many Ceruminous glands

EXTERNAL AUDITORY MEATUS Its medial 2/3 is Bony. Formed mainly by the Tympanic Plate. It is lined by thin skin. Nerve Supply : Auriculotemporal nerve. Auricular branch of the vagus.

OTOSCOPY The meatus has to be straight. It is pulled In Children: Straight backward or downward and backward. In Adults : Upward and backward.

TYMPANIC MEMBRANE It is an oval, thin semitransparent membrane (1 cm) in diameter. It forms a Partition between the external meatus and the tympanic cavity.

ON OTOSCOPY Pars Flaccida: A shallow cone like central depression , its peak is the Umbo. Cone of light radiates antero inferior from the umbo. Pars Flaccida: The thin superior part of the membrane. Pars Tensa: The rest of the membrane. It is thick and taut.

NERVE SUPPLY The tympanic membrane is extremely sensitive to pain. Outer surface (mainly): Auriculotemporal nerve Auricular branch of the vagus. Internal surface: Glossopharyngeal nerve.

MIDDLE EAR It is an air- filled mucous membrane lined space in the temporal bone. It is between: Laterally: The Tympanic membrane. Medially: The lateral wall of the inner ear.

PARTS (1) Tympanic Cavity: A space directly internal to the tympanic membrane. (2) Epitympanic Recess: A space superior to the tympanic cavity.

CONNECTIONS (1) Anterior: Nasopharynx (2) Postero superior: Mastoid air cells.

ROOF Tegmental Wall: A thin plate of bone (Tegmen Tympani) on the anterior surface of the petrous part of temporal bone. It separates the cavity from: Middle Cranial Fossa.

FLOOR Jugular wall: It is a thin plate of bone. It separates the cavity from the Superior Bulb of IJV. It may be deficient or replaced by fibrous tissue.

LATERAL WALL Membranous: Almost totally it is the Tympanic Membrane. Superiorly: Epitympanic Recess.

MEDIAL WALL Labyrinthine 1. Promontory: A central bulge . Produced by the basal coil of the Cochlea 2. Tympanic Plexus. On the mucous membrane of the promontory. 3. Fenestra Vestibuli: (Oval Window) It is above and behind the Promontry. 4. Fenestra Cochlea (Round window). The windows lead to Perilymph of internal ear.

MEDIAL WALL 5. Prominence of facial canal: posterior and superior to the oval window. Produced by the Facial nerve in its canal. 6. Prominence of lateral semicircular canal.

OTOSCLEROSIS A pathological process affecting the mucosa of the Oval window and the mastoid process. They are transformed into bone. It is complicated by Deafness.

ANTERIOR WALL Carotid : Lower : A thin plate of bone. It separates the tympanic cavity from the Carotid Canal. Upper: Two openings Upper smaller: for the Tensor Tympani. Lower larger: for the Auditory Tube.

POSTERIOR WALL Mastoid area : A. Aditus A large irregular opening posterior to the epitympanic recess. B. Mastoid antrum : A cavity continuous with air filled spaces within the mastoid process. C. Pyramid: The tendon of Stapedius muscle emerges from its apex.

MASTOID ANTRUM Roof : Tegmen Tympani. Floor : Many openings To communicate with the mastoid air cells. Anterior : Middle ear & Aditus. Posterior: Sigmoid Sinus & Cerebellum. Lateral: Floor of Suprameatal Triangle. Medial: Posterior Semicircular Canal.

CONTENTS OF TYMPANIC CAVITY 1. Auditory Ossicles. 2. Muscles. 3. Nerves.

AUDITORY OSSICLES They extend from the tympanic membrane to the oval window. They are present at Birth. Not covered by Periosteum. Malleus: The largest and attached to the tympanic membrane. Stapes: Occupies the oval window . Incus: Between the two bones. Their decreased mobility in old age is responsible for degrees of Deafness.

TENSOR TYMPANI It lies in a bony canal above the Pharyngotympanic tube. Insertion: Handle of the malleus. Action: Pulles the handle medially. Tenses the tympanic membrane. Reduces the amplitude of its oscillations. Nerve supply : Mandibular

STAPEDIUS The smallest voluntary muscle of the body. Origin: From inside the pyramidal eminence. Insertion: Neck of the stapes. Action: Pulls the stapes posteriorly. Reduces the oscillatory range and prevents its excessive movements. Nerve supply : Facial nerve.

TYMPANIC NERVVE A branch of Glossopharyngeal nerve. Passes through the floor of the middle ear and onto the Promontry. Gives: Tympanic Plexus: It associates the Caroticotympanic Plexus to supply mucous membrane of middle ear. Lesser Petrosal nerve : To Otic Ganglion.

FASCIAL NERVE Enters: 1.Internal acoustic meatus in close company with the 8th nerve. 2. Facial Canal. It continues laterally between the inner and middle ears. It expands to form the Geniculate Ganglion.

FASCIAL NERVE At the posterior wall: Curves downward in a vertical direction. Lies : Medial to the Aditus. Behind the Pyramid. Exits: Through the Stylomastoid Foramen.

BRANCHES 1. Greater Petrosal nerve. It is the first branch from the Geniculate Ganglion. It carries preganglionic parasympathetic to the Pterygopalatine Ganglion. It supplies: Lacrimal , Nasal and Palatine glands.

BRANCHES 2. Nerve to Stapedius. 3. Chorda Tympani: It arises just before the facial nerve exits. It ascends to enter the middle ear through its posterior wall.

AUDITORY TUBE Connects the Tympanic Cavity to the Nasopharynx. Its Postero lateral 1/3 is bony. The remainder is Cartilaginous. Its walls are normally in apposition. The tube is actively opened by swallowing and yawing

AUDITORY TUBE Function : Equalizes pressure in the middle ear with the atmospheric pressure. It is a pathway of infection from the throat to the tympanic cavity and mastoid air cells. Nerve supply : tympanic plexus.

BONY LABYRINTH A series of bony cavities in the Petrous part of temporal bone. It is composed of: Cochlea. Vestibule. Semicircular Canals. They contain Perilymph.

BONY LABYRINTH Cochlea: It is shell shaped . Its first turn produces the Promontory. Vestibule : It is in a central position. It has the Oval and Round Windows in its lateral wall. Semicircular canals : Posterior, superior and Lateral. They communicate with the Vestibule.

MEMBRANOUS LABYRINTH It consists of: Four Ducts: Cochlear Three Semicircular Two Sacs: Utricle. Sacuule. It is filled with Endolymph. It is separated from the periosteum of the bony labyrinth by Perilymph.

COCHLEAR DUCT The cochlea is divided into two canals containing Perilymph by the centrally located cochlear duct. The duct has : Roof : Vestibular membrane. Floor : Basilar membrane. The Spiral Organ (organ of hearing) rests on the basilar membrane.

ORGANS OF BALANCE Utricle. Sacule Three Semicircular Ducts. The Utricosaccular Duct establishes continuity between all components of the membranous labyrinth.

ORGANS OF BALANCE The Endolymphatic Duct branches from it. It emerges onto the posterior surface of the petrous part of the temporal bone. It expands to form an Extradural Pouch Endolymphatic Sac.

VESTIBULOCOCHLEAR NERVE Divides into : A. Vestibular nerve : It enlarges to form the Vestibular Ganglion. It supplies: Three semicircular ducts. Utricle & Saccule. B. Cochlear nerve: It enters the base of the cochlea. It innervates the receptors in the Spiral Organ.