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CONGENITAL ANOMALIES OF EAR. ANATOMY ANATOMY OF EAR Both functionally and anatomically, it can be divided into three parts. Both functionally and anatomically,

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Presentation on theme: "CONGENITAL ANOMALIES OF EAR. ANATOMY ANATOMY OF EAR Both functionally and anatomically, it can be divided into three parts. Both functionally and anatomically,"— Presentation transcript:

1 CONGENITAL ANOMALIES OF EAR

2 ANATOMY

3 ANATOMY OF EAR Both functionally and anatomically, it can be divided into three parts. Both functionally and anatomically, it can be divided into three parts. External earExternal ear Middle earMiddle ear Inner earInner ear

4 External Ear Portion external to the tympanic membrane. Portion external to the tympanic membrane. The AuricleThe Auricle elastic cartilageelastic cartilage External Auditory CanalExternal Auditory Canal Lateral Portion – Lateral Portion – cartilaginouscartilaginous containing ceruminous and sebaceous glands.containing ceruminous and sebaceous glands. Medial Portion- Medial Portion- BonyBony no skin appendagesno skin appendages comprises two-thirds of the total canal in adultscomprises two-thirds of the total canal in adults

5 Middle Ear This is an air-containing space which communicates with the nasopharynx via This is an air-containing space which communicates with the nasopharynx via the eustachian tube. the eustachian tube. Normally sealed laterally by the tympanic Normally sealed laterally by the tympanic membrane. Its function is to transmit and amplify sound waves from tympanic membrane to the stapes footplate Its function is to transmit and amplify sound waves from tympanic membrane to the stapes footplate

6 Middle Ear.. Tympanic membrane Tympanic membrane OvoidOvoid conical shapeconical shape pars flaccidapars flaccida pars tensa.pars tensa. Ossicles Ossicles involved in sound conduction involved in sound conduction MalleusMalleus IncusIncus stapesstapes

7 Inner Ear consists of a fluid-filled labyrinth which functions to convert mechanical energy into neural impulses. consists of a fluid-filled labyrinth which functions to convert mechanical energy into neural impulses. labyrinth –two parts labyrinth –two parts Bony labyrinthBony labyrinth Membranous labyrinthMembranous labyrinth

8 Inner Ear.. The bony labyrinth - three main divisions : The bony labyrinth - three main divisions : Vestibule - just medial to the oval window, and contains the utricle and the saccule, two organs of balance.Vestibule - just medial to the oval window, and contains the utricle and the saccule, two organs of balance. The Cochlea - a snail-shaped chamber anterior to the vestibule.It communicates with the middle ear via the round window.The Cochlea - a snail-shaped chamber anterior to the vestibule.It communicates with the middle ear via the round window. The Semicircular Canals -detect angular acceleration. They consist of a superior, posterior and lateral, or horizontal canalsThe Semicircular Canals -detect angular acceleration. They consist of a superior, posterior and lateral, or horizontal canals

9 Inner Ear.. The bony labyrinth is subdivided into smaller compartments by the membranous labyrinth. The bony labyrinth is subdivided into smaller compartments by the membranous labyrinth. Fluid surrounding the membranous labyrinth is called perilymph; fluid within is called endolymph. Fluid surrounding the membranous labyrinth is called perilymph; fluid within is called endolymph. Organ of Corti – lies in membranous labyrinth. Organ of Corti – lies in membranous labyrinth.

10 EMBRYOLOGY

11 Embryology of Ext. ear Development of the Development of the external ear begins during the fourth week of gestation as six mesenchymal Proliferations enlarge to Proliferations enlarge to form ridges known as the hillocks of His.

12 Embryology of Ext. ear.. These hillocks, which surround the first branchial groove or primitive meatus, fuse to form the primitive auricle by the third month of gestation. These hillocks, which surround the first branchial groove or primitive meatus, fuse to form the primitive auricle by the third month of gestation. The EAC develops from the first branchial groove beginning in the eighth week of gestation. The EAC develops from the first branchial groove beginning in the eighth week of gestation.

13 Embryology of Ext. ear.. Epithelial cells from the meatus proliferate forming a solid core of cells, known as the meatal plug. Epithelial cells from the meatus proliferate forming a solid core of cells, known as the meatal plug. This solid core will then recanalize to form the epithelial lined EAC, but not until the sixth or seventh month of gestation. This solid core will then recanalize to form the epithelial lined EAC, but not until the sixth or seventh month of gestation.

14 Congenital anomalies of Auricle Anotia –total absence of auricle. Anotia –total absence of auricle. Microtia –pinna is rudimentary & malformed. Microtia –pinna is rudimentary & malformed. Protruding or Bat ears Protruding or Bat ears Auricular appendages or Accessory auricles – contain a bar of elastic cartilage. Auricular appendages or Accessory auricles – contain a bar of elastic cartilage. Congenital aural sinuses – commonly found in preauricular region. Congenital aural sinuses – commonly found in preauricular region.

15 Congenital anomalies of Auricle Congenital aural fistulae – open superiorly in the floor of the EAM & inferiorly at the anterior border of SCM Congenital aural fistulae – open superiorly in the floor of the EAM & inferiorly at the anterior border of SCM Congenital syndromes ass. with microtia & deformities of pinna – Congenital syndromes ass. with microtia & deformities of pinna – Potter’s syndromePotter’s syndrome Treacher Collins syndromeTreacher Collins syndrome Fraser syndromeFraser syndrome Otomandibular syndrome of KonigsmarkOtomandibular syndrome of Konigsmark Branchio-otic dysplasiaBranchio-otic dysplasia

16 Congenital anomalies of EAC Congenital meatal atresia & stenosis Congenital meatal atresia & stenosis Can occur unilaterally or bilaterallyCan occur unilaterally or bilaterally Usually accompained by auricular deformity.Usually accompained by auricular deformity.

17 Embryology of Middle ear The core of cells forming meatal plug, migrates medially toward the outgrowth of the first branchial pouch, which will eventually form the middle ear cleft. The core of cells forming meatal plug, migrates medially toward the outgrowth of the first branchial pouch, which will eventually form the middle ear cleft. The meatal plug contacts the middle ear cleft by the ninth week of gestation. The meatal plug contacts the middle ear cleft by the ninth week of gestation.

18 Embryology of Middle Ear.. Ossicular development begins in the fourth week and, at this time, the malleus and incus appear as a fused mass. Ossicular development begins in the fourth week and, at this time, the malleus and incus appear as a fused mass. Separation into two distinct ossicles typically occurs by the eighth week of gestation. Separation into two distinct ossicles typically occurs by the eighth week of gestation.

19 Embryology of Middle Ear.. The first branchial arch, Meckel’s cartilage, contributes to the development of the head and neck of the malleus and the body and short process of the incus. The first branchial arch, Meckel’s cartilage, contributes to the development of the head and neck of the malleus and the body and short process of the incus.

20 Embryology of Middle Ear.. The second branchial arch, Reichert’s cartilage, leads to the development of the manubrium of the malleus, the long process of the incus and the stapes suprastructure. The second branchial arch, Reichert’s cartilage, leads to the development of the manubrium of the malleus, the long process of the incus and the stapes suprastructure. By the sixteenth week of gestation, the ossicles are of adult size. By the sixteenth week of gestation, the ossicles are of adult size.

21 Congenital anomalies of Ext. & Middle Ear External & middle ear abnormalities are generally associated and classified into 3 types External & middle ear abnormalities are generally associated and classified into 3 types Type 1 (mild) –Type 1 (mild) – Auricle is normal Auricle is normal EAC is small or atretic EAC is small or atretic Tympanic cavity is normal or small Tympanic cavity is normal or small Middle ear structures show minor deformities Middle ear structures show minor deformities

22 Congenital anomalies of Ext. & Middle Ear Type 2 (medium) – Type 2 (medium) – Pinna is rarely normalPinna is rarely normal EAC is aplasticEAC is aplastic Middle ear cavity is reduced in sizeMiddle ear cavity is reduced in size Malleus & incus are deformed & fixedMalleus & incus are deformed & fixed Facial nerve always takes an abnormal courseFacial nerve always takes an abnormal course

23 Congenital anomalies of Ext. & Middle Ear Type 3 (severe) – Type 3 (severe) – Pinna is severely malformed or absentPinna is severely malformed or absent EAC is absentEAC is absent Tympanic cavity is either very small or missingTympanic cavity is either very small or missing Associated inner ear deformitiesAssociated inner ear deformities More commonly encountered as part of craniofacial syndromesMore commonly encountered as part of craniofacial syndromes

24 Embryology of Inner Ear Inner ear development from the otic placode begins during the third week of gestation. Inner ear development from the otic placode begins during the third week of gestation. Invagination of the otic placode to form the otic vesicle is apparent by week four, and by the sixth week the semicircular canals have taken shape. Invagination of the otic placode to form the otic vesicle is apparent by week four, and by the sixth week the semicircular canals have taken shape.

25 Embryology of Inner Ear.. The utricle and saccule have formed by the eighth week The utricle and saccule have formed by the eighth week The three Semi circular canals appear as outpouchings from posterior part of the vestibule The three Semi circular canals appear as outpouchings from posterior part of the vestibule

26 Embryology of Inner Ear.. The membranous labyrinth is entirely developed by fifteen weeks gestation and ossification of the surrounding otic capsule is complete by twenty-three weeks gestation. The membranous labyrinth is entirely developed by fifteen weeks gestation and ossification of the surrounding otic capsule is complete by twenty-three weeks gestation. Development of the cochlea begins during the seventh week, and by week twelve the complete two and a half turns have formed. Development of the cochlea begins during the seventh week, and by week twelve the complete two and a half turns have formed.

27 Congenital anomalies of Inner Ear Aplasia – as a result of genetic factors or toxic influence caused by certain forms of maternal illness during first trimester Aplasia – as a result of genetic factors or toxic influence caused by certain forms of maternal illness during first trimester Michel type – complete failure of inner ear development.Michel type – complete failure of inner ear development. Mondini type – incomplete development of the bony &membranous labyrinth.Mondini type – incomplete development of the bony &membranous labyrinth. Scheibe type – cochleocaccular aplasiaScheibe type – cochleocaccular aplasia Alexander type – mambranous cichlear aplasia.Alexander type – mambranous cichlear aplasia.

28 Congenital anomalies of Inner Ear Abiotrophy – degeneration of parts of the auditory apparatus. Abiotrophy – degeneration of parts of the auditory apparatus. Essentially ectodermal – of the cochlear duct or scala media e.g. Waardenburg’s syndrome, Cogan syndromeEssentially ectodermal – of the cochlear duct or scala media e.g. Waardenburg’s syndrome, Cogan syndrome Essentially mesodermal – of the sensory end organs e.g.Alport’s syndrome, Marfan’s syndromeEssentially mesodermal – of the sensory end organs e.g.Alport’s syndrome, Marfan’s syndrome Essentially neuroectodermal – of the nerve element e.g.von Recklinghausen’s syndrome.Essentially neuroectodermal – of the nerve element e.g.von Recklinghausen’s syndrome.

29 Conditions displaying middle &inner ear abnormalities Treacher Collins syndrome Treacher Collins syndrome Apert’s syndrome Apert’s syndrome Klippel Feil syndrome Klippel Feil syndrome Turner syndrome Turner syndrome Patau syndrome Patau syndrome Edward’s syndrome Edward’s syndrome Down’s syndrome Down’s syndrome Pierre Robin syndrome Pierre Robin syndrome


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