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Ear Anatomy - External ear, Middle ear, Inner ear
Ear Anatomy - External ear, Middle ear, Inner ear
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Ear Anatomy - External ear, Middle ear, Inner ear
- 1. Ear Submitted by : •Amit Kumar Shah • Deepashree sah • Kiran Gautam • Kiran Kathayat • Neelam Bist • Nischala Raut • Sangita Bhajagain • SimRan Shrestha • Sudhakar tharu Submitted TO : Department of anatomy Madan Bhandari Academy of Health Sciences
- 2. • Organ ofhearing & equilibrium • Also called phonoreceptor • Functions : Maintain the body balance and receive sound waves • The ear is divided into 3 parts: i. External ear ii. Middle ear iii. Inner ear Ear : Introduction
- 4. • Outer partof ear • Made from elastic connective and cartilage connective tissue • Filled with air • Divided into three parts i. Pinna (Auricle) ii. External auditory meatus (ear canal) iii. Tympanic membrane (Ear drum) External ear
- 5. Pinna • Visible portionof the ear • Having yellow elastic cartilage • Immovable • Concha is the deepest depression (leads to external acoustic meatus) • Funnel-like shape plays an important role on gathering sound waves from the environment • Lowest part- soft & consist of connective tissue lobule Concha Lobule
- 7. • Injury (bleeding)of auricle may lead to deformed auricle i.e. cauliflower ear
- 8. External auditory meatus(EAM) • 24mm long • S-shaped curved • Extended from base of pinna (Concha) to inner side (TM) • Conducts sound waves from the concha to the tympanic membrane • It is divided into two parts: a. Cartilaginous part : • Yellow elastic cartilage. • Skin covering cartilage is thick and contains ceruminous glands which secrets wax/cerumen. b. Bony part • Skin lining the bony canal is thin and continuous over the tympanic membrane. It is devoid of hair and ceruminous glands.
- 9. Cartilage : outer1/3rd (8 mm) Bony : Inner 2/3rd (16 mm) Cartilaginous part Cartilage Bony part Bone
- 10. Tympanic membrane • Placedobliquely at an angle of 55° • At the end of the Ear canal (EAM) • 1 cm in diameter • Semitransparent oval membrane • Separate outer ear from inner ear • Forms partition between external acoustic meatus and tympanic cavity • Vibrates in response to sound pressure wave
- 11. 1. Pars tensa: •Greater part of tympanic membrane • Tightly stretched • Made up of radial & circular fibres 2. Pars flaccida: • Between anterior & posterior mallear folds • Loose & thin (lacks of fibres) • More reliable to rupture • Cross internally by chorda tympani nerve Parts of Tympanic Membrane Pars Tensa Pars Flaccida Anterior mallear fold Posterior mallear fold
- 12. Otoscopic (ear) examinationTake care of your ears
- 13.
- 14. Venous drainage 1. Reteromandibularvein – formed by union of Superficial temporal & maxillary vein 2. Facial vein 3. External jugular vein 4. Internal jugular vein
- 15. • Cube shaped •Narrow air-filled space • Lies in the petrous part of the temporal bone between the external ear and the internal ear • Connected anteriorly with the nasopharynx by pharyngotympanic/auditory tube/eustachian tube • Posterosuperiorly connected with the mastoid cells through the mastoid antrum. middle ear / Tympanic cavity / tympanum Tympanic Cavity Eustachian tube Mastoid air cells Mastoid antrum Eustachian tube
- 16. Has 2 parts: •Tympanic cavity proper (space opposite to tympanic membrane) • Epitympanic recess (space superior to tympanic membrane) Tympanic cavity proper Epitympanic recess
- 17. • 3 tinybones (collectively called the auditory ossicles) i. Malleus (Hammer) ii. Incus (Anvil) iii. Stapes (Stirrup) Malleus :- • Hammer shaped • Largest laterally placed
- 18. Incus :- • Anvilshaped Stapes :- • Stirrup shaped • Smallest • Most medially placed
- 19. 2 muscles ofMiddle Ear tensor tympani stapedius
- 20.
- 21. • Shaped likea narrow box with 6 walls: 1. Tegmental wall (roof) 2. Jugular wall (floor) 3. Membranous wall (lateral) Middle cranial fossa Tegmen tympani IJV Boundaries of Middle Ear
- 22. 4. Labyrinthine wall(medial) 5. Carotid wall (anterior) 6. Mastoid wall ( posterior) Promontory ICA Eustachian tube Tensor tympani Mastoid antrum
- 23.
- 24. inner ear • Liesin petrous part of temporal bone • Also known as Labrynth or Auris Interna
- 25. • Two Labyrinthpresent :- A. Bony Labyrinth 1. 3 semicircular cannals 2. Vestibule lotolith organ 3. Cochlea B. Membranous Labyrinth • It is enclosed by Bony labyrinth • Between bony and membranous labyrinth is perilymph fluid • Fluid inside membranous labyrinth is endolymph fluid
- 26. A. Bony Labyrinth 1.Semicircular canals :- • Three tiny interconnected fluid filled tubes • Placed at right angle to each other • Three canals open into the vestibule by I. Anterior or superior II. Posterior III. Lateral (Horizontal)
- 27. 2. Vestibule • Knownas Otolith organ (due to presence of granules of calcium carbonate) • As it is formed by Utricle & Saccule • Central part of bony labyrinth • Sensory receptor is Macula (balance posture) 3. Cochlea • Coiled structure like a snail shell • Inner part • Has :- Broad base → Continuous to vestibule Apex (Cupala) → Narrow, coiled centrally (ending part) • Cross section has 3 compartments Scala Vestibuli (Above) Scala Media or Cochlear duct Scala tympani (below)
- 28. o Scala vestibuli& Scala tympani - perilymph present. o Scala vestibuli - communicates with scala tympani at the apex of cochlea by a small opening called helicotrema. o Scala media – endolymph present Helicotrema
- 29.
- 30. B. MEMBRANOUS LABYRINTH •Cavity filled with endolymph • Parts:- 1. Organ of of Corti / duct of Cochlea 2. Organ of Static balance / The utricle and saccule with maculae 3. Organs of kinetic balance / Semicircular ducts with cristae
- 31. 1. Duct ofthe Cochlea / Scala Media • Present between scala vestibule & scala tympani • Triangular in cross-section • Floor – formed by basilar membrane (presence of hair cells i.e. Organ of Corti or auditory receptors) • Roof – formed by vestibular or Reissner’s membrane • Outer wall – formed by bony wall of cochlea • Hair is embedded in the gelatinous membrane called membrane tectoria
- 32. 2. Saccule &Utricle • Saccule lies anteroinferiorly of vestibule • Utricle lies posterosuperiorly of vestibule • Utricle is larger than saccule • Utricle receives the ends of 3 semicircular ducts through 5 openings • They are static balance receptors • Maculae are receptors that give information about position of head
- 33. 3. Semicircular ducts •Lies within corresponding canal • Each ampulla, end organ present called Crista or Cupola or ampullary crest • Crista respond to pressure change in endolymph caused by movements of the head