Dr. Sami Zaqout Faculty of Medicine IUG

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2 Auricle External Ear External auditory meatus The Ear Middle Ear (Tympanic Cavity) Auditory ossicles Internal Ear (Labyrinth) Bony labyrinth Membranous labyrinth

3 External Ear Auricle External auditory meatus Outer third is elastic cartilage. Hairs Sebaceous glands Ceruminous glands Inner two thirds is bone.

4 External Ear The sensory nerve supply of the lining skin is derived from the Auriculotemporal nerve branch of mandibular nerve. Auricular branch of the vagus nerve. The lymph drainage is to the Superficial parotid lymph nodes Mastoid lymph nodes Superficial cervical lymph nodes.

5 Roof Floor Tegmen tympani Thin plate of bone Temporal lobe of the brain Internal jugular vein Middle Ear (Tympanic Cavity) Anterior wall Posterior wall Lateral wall Medial wall Openings into two canals Thin plate of bone Aditus to the mastoid antrum Pyramid Tympanic membrane Promontory Canal for the tensor tympani muscle Auditory tube Internal carotid artery Stapedius muscle Fenestra vestibuli Fenestra cochleae

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7 Tympanic Membrane Examination Otoscopic examination of the tympanic membrane is facilitated by first straightening the external auditory meatus by gently pulling the auricle: Upward and backward in the adult. Straight backward or backward and downward in the infant.

8 Tympanic Membrane Examination Normally, the tympanic membrane is pearly gray and concave. The adult the external meatus is about 2.5 cm long and is narrowest about 5 mm from the tympanic membrane. The tympanic membrane is extremely sensitive to pain and is innervated on its outer surface by the auriculotemporal nerve and the auricular branch of the vagus.

9 Tympanic membrane

10 Auditory Ossicles Malleus Incus Stapes Dr. Sami Zaqout Faculty of Medicine IUG Head Neck Long process Anterior process Lateral process Body Long process Short process Head Neck Two limbs Base

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12 Movements of the Auditory Ossicles Dr. Sami Zaqout Faculty of Medicine IUG

13 Auditory Tube Connects the anterior wall of the tympanic cavity to the nasal pharynx. Posterior third is bony. Anterior two thirds is cartilaginous. It serves to equalize air pressures in the tympanic cavity and the nasal pharynx.

14 Mastoid Antrum The mastoid antrum lies behind the middle ear in the petrous part of the temporal bone. It communicates with the middle ear by the aditus.

15 Mastoid Antrum Dr. Sami Zaqout Faculty of Medicine IUG Anterior wall Middle ear Posterior wall Lateral wall Medial wall Superior wall Inferior wall Sigmoid venous sinus Cerebellum Suprameatal triangle Posterior semicircular canal Temporal lobe of the brain Mastoid air cells

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17 Intrapetrous Part of the Facial Nerve Facial nerve in the temporal bone Chorda tympani

18 Intrapetrous Part of the Facial Nerve The greater petrosal nerve Nerve to the stapedius Chorda tympani Taste fibers from the mucous membrane covering the anterior two thirds of the tongue Preganglionic parasympathetic secretomotor fibers that reach the submandibular ganglion and are there relayed to the submandibular and sublingual salivary glands.

19 Tympanic Nerve

20 Infections and Otitis Media Pathogenic organisms can gain entrance to the middle ear by ascending through the auditory tube from the nasal part of the pharynx. Acute infection of the middle ear (otitis media) produces bulging and redness of the tympanic membrane.

21 Complications of Otitis Media Acute mastoiditis Meningitis and a cerebral abscess Facial nerve palsy Labyrinthitis with vertigo Thrombosis in the sigmoid sinus

22 Vestibule Bony labyrinth Semicircular canals Internal Ear (Labyrinth) Cochlea Utricle and saccule Membranous labyrinth Semicircular ducts Dr. Sami Zaqout Faculty of Medicine IUG Duct of the cochlea

23 The vestibule

24 Semicircular canals The superior canal is vertical and placed at right angles to the long axis of the petrous bone. The posterior canal is also vertical but is placed parallel with the long axis of the petrous bone. The lateral canal is set in a horizontal position

25 Cochlea

26 Utricle and saccule Located on the walls of the utricle and saccule are specialized sensory receptors, which are sensitive to the orientation of the head to gravity or other acceleration forces.

27 Semicircular ducts Whenever a movement of the head accelerates or decelerates, the endolymph in the semicircular ducts changes its speed of movement relative to that of the walls of the semicircular ducts. This change is detected in the sensory receptors in the ampullae of the semicircular ducts.

28 Duct of the cochlea The highly specialized epithelium that lies on the basilar membrane forms the spiral organ of Corti and contains the sensory receptors for hearing.

29 Vestibulocochlear Nerve Vestibular nerve: The utricle The saccule The ampullae of the semicircular ducts. Cochlear nerve: Spiral organ of Corti

30 Vestibulocochlear Nerve Dr. Sami Zaqout Faculty of Medicine IUG

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32 Digastric fossa Alveolar part The Mandible Base Body Angle External surface Medial surface Lateral surface Symphysis menti Mental foramen Mental spines Mylohyoid line Masseter M Genioglossus M Geniohyoid M Submandibular fossa Sublingual fossa Condyloid process Pair of rami Coronoid process Medial surface Mandibular foramen Lingula Inferior alveolar N + V Sphenomandibular ligament Temporalis M

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34 Temporomandibular Joint - Articulation Articulation occurs between: The articular tubercle and the anterior portion of the mandibular fossa of the temporal bone above The head (condyloid process) of the mandible below. The articular surfaces are covered with fibrocartilage. The articular disc divides the joint into upper and lower cavities.

35 Temporomandibular Joint Capsule The capsule surrounds the joint and is attached above to the articular tubercle and the margins of the mandibular fossa and below to the neck of the mandible.

36 Temporomandibular Joint Ligaments Dr. Sami Zaqout Faculty of Medicine IUG

37 Temporomandibular Joint - Synovial Membrane + Nerve Supply Synovial Membrane Lines the capsule in the upper and lower cavities of the joint. Nerve Supply Auriculotemporal and masseteric branches of the mandibular nerve

38 Temporomandibular Joint - Movements Dr. Sami Zaqout Faculty of Medicine IUG

39 Muscles of mastication

40 Masseter muscle

41 Medial pterygoid muscle Dr. Sami Zaqout Faculty of Medicine IUG

42 Lateral pterygoid muscle Dr. Sami Zaqout Faculty of Medicine IUG

43 Temporalis muscle.

44 Relations of the Temporomandibular Joint Anteriorly Posteriorly Laterally Medially Mandibular notch Masseteric nerve and artery Tympanic plate of the external auditory meatus Glenoid process of the parotid gland The parotid gland Fascia Skin Maxillary artery and vein Auriculotemporal nerve

45 Dislocation of the Temporomandibular Joint Dislocation sometimes occurs when the mandible is depressed. In this movement, the head of the mandible and the articular disc both move forward until they reach the summit of the articular tubercle.

46 Dislocation of the Temporomandibular Joint In this position, the joint is unstable, and a minor blow on the chin or a sudden contraction of the lateral pterygoid muscles, as in yawning, may be sufficient to pull the disc forward beyond the summit. In bilateral cases the mouth is fixed in an open position, and both heads of the mandible lie in front of the articular tubercles.

47 Dislocation of the Temporomandibular Joint Reduction of the dislocation is easily achieved by pressing the gloved thumbs downward on the lower molar teeth and pushing the jaw backward. The downward pressure overcomes the tension of the temporalis and masseter muscles, and the backward pressure overcomes the spasm of the lateral pterygoid muscles.

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