The document discusses the development of the ear, including the external, middle, and internal ear structures. It describes how the otic placode invaginates to form the otic vesicle, which then develops into the membranous labyrinth. The ventral part forms the saccule and cochlear duct, while the dorsal part forms the semicircular ducts and utricle. The first pharyngeal pouch develops into the middle ear cavity and auditory tube, while the first pharyngeal cleft forms the external acoustic meatus. Various congenital deformities of the external ear are also mentioned.

1. Development of Ear
20-04-2015
Dr. Laxman Khanal
Assistant Professor
Department of Human Anatomy

3. External ear- sound collection
Pinna, EAM and outer layer of TM
Middle ear- sound conduction
Ear ossicles and inner layer of TM
Internal ear
•Sound wave to nerve impulse
•Equilibrium
Labyrinth (bony and membranous)

4. Q. Vestibulocochlear ganglia is derived from
a.Otic vesicle
b.Neural crest cells
c. Both a and b
d.Neuroectoderm of hindbrain

5. Development of Internal Ear
Otic Placode @22nd day
On each side of hindbrain

6. Invaginating placode Otic pit Otic vesicle
Forms membranous labyrinth

7. Q. Ductus reunion connect
a.Utricluar to saccular portion
b.Utricle to Semicircular duct
c. Cochlear duct to saccule
d.Membranous labyrinth to bony labyrinth

8. Ventral part
Saccules
Cochlear duct
Dorsal part
Semicircular duct
Utricle
Endolymphatic duct
Utriculo-saccular duct
Cochlear duct
Ductus reunions

9. Q. Which of the following parts of SCD fused during
opening to utricle ?
a. Dilated part of ant and post SCD
b. Non-dilated part of ant and post SCD
c. Dilated part of post and lat SCD
d. Non-dilated part of post and lat SCD

10. Development of Utricle and SCD
(Dorsal Part of Otic vesicle)
SCDs appear as flat out pocketing of Utricular portion
of Otic vesicle.
•Three pairs of SCD are formed –Ant/Post/Lat
One end of SCD form dilatation (Crus Ampullare) and
the other does not widen (Crus Nonampulare)
 Because two crus nonampullare fuse, there will be
3 crus ampullare and 2 crus nonampullare

12. Formation of Cochlea
• Mesenchyme surrounding CD Differentiate
into cartilage.
• Cartilage undergo vacuolization and form
Scala vestibuli and scala tympani.
• Lateral part of CD attached to the cartilage by
Spiral ligament and medial edge is attached
and supported by modiolus.

13. Q. Epithelium of which of the following part of
CD forms the Organ of Corti?
a. Outer ridge
b. Inner ridge
c. Endolymph
d. All of the above

14. Epithelium of CD form two ridge.
• inner ridge
•Outer ridge
Outer ridge forms inner
and outer rows of hair
cells covered by
tectorial membrane -
Organ of Corti

15. Q. Middle ear cavity develops from.
a.First pharyngeal pouch
b.Second pharyngeal pouch
c. First pharyngeal cleft
d.Second pharyngeal cleft

17. Development
of Middle Ear

18. Q. What is the motor nerve to stapedius muscle?
a.Mandibular nerve
b.Facial nerve
c. Glossopharyngeal nerve
d.Vagus nerve

19. First pharyngeal pouch
Distal part- tympanic cavity
Proximal part- auditory tube
Malleus /Incus and Tensor Tympani- 1st Arch
Stapes and Stapedius muscle- 2nd arch

21. Development of ext ear

22. •Six auricular Hillocks forms the Pinna.
•First pharyngeal cleft forms the EAM

23. •Six auricular Hillocks forms the Pinna.
•First pharyngeal cleft forms the EAM

24. External ear malformation
Preauricual pit

25. External ear malformation
Microtia

26. External ear malformation
Preauricualr
appendages

27. External ear malformation
Anotia

28. Congenital deafness
• Genetic cause
 Down’s syndrome
 Crouzon syndrome
 Treacher collin syndrome
• Retention of meatal plug
• Rubella infection
• Cytomegalo virus infection
• Malformation of middle and internal ear

29. Q. Vestibulocochlear ganglia is derived from
a.Otic vesicle
b.Neural crest cells
c. Both a and b
d.Neuroectoderm of hindbrain

30. Q. Ductus reunion connect
a.Utriclar to saccular portion
b.Utricle to Semicircular duct
c. Cochlear duct to saccule
d.Membranous labyrinth to bony labyrinth

31. Q. Which of the following parts of SCD fused during
opening to utricle ?
a. Dilated part of ant and post SCD
b. Non-dilated part of ant and post SCD
c. Dilated part of post and lat SCD
d. Non-dilated part of post and lat SCD

32. Q. Epithelium of which of the following part of
CD forms the Organ of Corti?
a. Outer ridge
b. Inner ridge
c. Endolymph
d. All of the above

33. Q. Middle ear cavity develops from.
a.First pharyngeal pouch
b.Second pharyngeal pouch
c. First pharyngeal cleft
d.Second pharyngeal cleft

34. Q. What is the motor nerve to stapedius muscle?
a.Mandibular nerve
b.Facial nerve
c. Glossopharyngeal nerve
d.Vagus nerve

35. Embryonic
structure
Adult derivative
Otic vesicle
Saccular portion
Utricular portion
Saccule, CD, Spiral ganglion
Utricle, SCD, vestibular ganglion and
endolymphatic duct
Pharyngeal
membrane 1
Tympanic membrane
Arch 1 Malleus, Incus, Tensor tympani
Arch 2 Stapes, Stapedius
Pouch 1 Middle ear cavity and auditory tube
Pharyngeal cleft 1 External acoustic meatus
6 auricular hillocks Pinna
MiddlearExtearInternalear