Ear ossicles MalleusMalletHammer Largest ossicle Parts Head Neck

Ear ossicles

Malleus-Mallet(Hammer) Largest ossicle Parts Head Neck Anterior process Lateral process Handle

Parts Head-body of incus Neck-pars flaccida, chorda tympani Anterior process- anterior ligament-petrotympanic fissure Lateral process-tympanic sulcus Handle-tympanic membrane tensor tympani muscle

Incus-anvil Body: head of malleus Long process: lentiform nodulehead of stapes Short process: fossa incudisposterior wall of tympanic Cavity. Lentiform process/nodule: Head of Stapes - Incudo stapedial joint.

Stapes-stirrup Headlong process of Incus Neckinsertion of stapedius Anterior and posterior crus. Footplateoval window/ fenestra vestibuliannular ligament

Ossicular ligaments and Joints Malleus Anterior ligament Superior ligament Incus Posterior ligament Superior ligament Stapes Annular ligament Joints Incudomalleolar – saddle Incudostapedial joint-ball and socket

Otosclerosis Common hereditary disease Normal laminar bone is removed by osteoclasts and replaced by unorganised bone of greater thickness, vascularity and cellularity.

AUDITORY TUBE

AUDITORY TUBE It is an osseo cartilagenous tube Communicates anterior wall of middle ear cavity with lateral wall of nasopharynx. Length: 36 mm It is directed downwards forwards and medially

AUDITORY TUBE Parts: Bony 12 mm in length Cartilagenous 24 mm in length

Bony part It has two ends Lateral end is broader which opens into anterior wall of middle ear. Medial end gives attachment to cartilagenous part of the auditory tube

Relations: Medially: Carotid canal which transmits ICA with sympathetic plexus Lateral: T. M. J, spine of sphenoid, chorda tympani nerve Superior: canal for tensor tympanic muscle

Cartilagenous part • Made up of triangular plate of fibrocartilage. • Situated in a groove on base of skull-sulcus tubae

Cartilaginous part • Apex of the cartilage is attached to medial end of bony part of tube.

Cartilaginous part • Base/Medial end of tube forms a projection of mucous membrane in lateral wall of nasopharynx -Tubal elevation.

Cartilaginous part • Base forms roof and medial wall of tube. • Rest of the area is filled by fibrous membrane. 26

• Relations Anterolaterally: • Tensor Veli palatini • Mandibular nerve • Otic ganglion • Nerve to medial pterygoid • Middle meningeal artery • Chordatympani nerve

Posteromedially; • Apex of petrous temporal bone, Levator Veli palatini muscle • Above Sulcus tubae • Below Superior constrictor

• Blood supply: a)Ascending pharyngeal artery b) Middle meningeal artery • Nerve supply: • Bony part; tympanic plexus • Cartilagenous part: Meningeal branch of mandibular nerve • Opening: Pharyngeal branch of pterygopalatine ganglion

• • • Development: Tubotympanic recess Functions: Equalises pressure outside and inside tympanic membrane It is always open except and closed at rest and during deglutition Muscles that open tube are A) Salpingopharyngeus B)Levator veli palatini C) Tensor Veli palatini

Applied Anatomy

ET Function Tests • VALSALVA TEST – Principle: positive pressure in the nasopharynx causes air to enter the Eustachian tube 33

• In the immediate viscinity of the orifice of the eustachian tube (entrance middle ear), lies pharyngeal tonsil. Its obstruction, due to excessive tonsillar size (adenoids), may produce accumulation of fluid behind the tympanic membrane.

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