4. BONY LABYRINTH
• Total length – 18 mm
• Three parts from before backwards:
1. Cochlea
2. Vestibule
3. Three semicircular canals
• Contains perilymph
• It is a series of intercommunicating bony cavities
within the petrous temporal bone and contains the
membranous labyrinth.
5. MEMBRANOUS LABYRINTH
• It consist of closed system of intercommunicating
membranous sacs and ducts within the bony
labyrinth.
• It is filled with endolymph.
• It presents from before backwards three parts:
1. Cochlear duct (contains spiral organ of corti)
2. Saccule and utricle
3. Three semicircular ducts
24. Venous drainage
Labyrithine vein – Superior petrosal
Transverse sinus
other veins drain: Into superior
petrosal
inferior
petrosal
IJV
25. Applied Anatomy
Meniere’s disease
• Due to distention of endolymph and degenerative changes
in the organ of corti.
• Patient complains of persistent attacks of nausea, vomiting, tinnitus &
progressive deafness.
28. Rinne’s test: Patient finds vibrating tuning fork louder when placed on
mastoid process than when placed in front of affected ear
B.C > A.C
29. Weber’s test: Bone conduction is better on the side of diseased middle
ear when the vibrating tuning fork is placed on the centre
of forehead
B.C>A.C
30. APPLIED ASPECTS
• Tinnitus- peripheral cochlear disease
• Vertigo – labyrinthine dysfunction
• Motion sickness – vertigo, headache, nausea,
vomiting. Caused by excessive stimulation of
utricle and saccule.
• Meniere’s disease- paroxysmal attacks of
vertigo, tinnitus, progressive impairment of
hearing.