Special Senses (Auditory) Flashcards
(32 cards)
Parts of the ear:
- Outer (external) ear
- Middle ear (tympanic cavity)
- Middle Ear or Tympanic Cavity
- Medial Boundary
- Lateral Boundary
- Anterior Boundary
- Posterior Boundary
- Inner (internal) ear (labyrint)
o Pinna or auricle
o External acoustic meatus
o Tympanic Membrane or Eardrum
Outer (external) ear
➢ Shell-shaped structure surrounding the auditory canal opening
Pinna or Auricle
➢ A short narrow chamber about 1 inch long by ½ inch wide
➢ Curved into temporal bone of the skull
➢ Skin of walls lined with ceruminous glands which secretes a waxy yellow substance called ear wax, or cerumen
External Auditory Canal
➢ A thin membrane separating outer from middle ear
Tympanic Membrane or Eardrum
o Ossicles (malleus, incus stapes)
o Tensor tympani, stapedius
Middle ear (tympanic cavity)
➢ A small, air filled cavity within the temporal bone
Middle Ear or Tympanic Cavity
➢ A bony wall with 2 openings:
o Oval window
o Round window
Medial Boundary
➢ Tympanic membrane with handle of the malleus attached
Lateral Boundary
➢ Eustachian tube (connects middle ear and nasopharynx)
Anterior Boundary
➢ Mastoid process
o Ossicles in the Middle Ear
Posterior Boundary
➢ Malleus (hammer) attached to tympanic membrane
➢ Incus – anvil
➢ Stapes – stirrups, presses on the oval window of the inner ear
Ossicles in the Middle Ear
➢ Composed of 2 parts:
o Bony Labyrinth
o Membranous Labyrinth
Inner (internal) ear (labyrinth)
➢ Wall is bony – temporal bone
➢ Fluid inside is perilymph (one of the two types of cochlear fluids, the other being endolymph)
➢ Made up of:
▪ Cochlea
▪ Vestibule
▪ 3 semicircular canals
Bony Labyrinth
made up of scala vestibuli and tympani;
concerned with hearing
Cochlea
concerned with static equilibrium
Vestibule
concerned with dynamic equilibrium
3 semicircular canals
➢ Found inside the bony labyrinth
➢ Wall is fibrous
➢ Fluid inside is endolymph (fluid contained in the membranous labyrinth of the inner ear)
➢ Made up of:
▪ Scala media
▪ Utricle & Saccule
▪ 3 semicircular ducts
Membranous Labyrinth
inside bony cochlea
Scala media
inside bony vestibule
Utricle & Saccule
inside the semicircular canal
3 semicircular ducts
- Receptor for hearing
- Found in the cochlea
Organ of Corti
- A spiral bony canal turning 2 ¾ around a central bony axis (modiolus)
- A spial bony projection from modiolus (spiral lamina) makes also a 2 ¾ turns.
- Scala vestibuli and tympani contain perilymph. They communicate in heliotrema
- Scala media contains endolymph
o Incompletely divides the bony cochlea
➢ Scala vestibuli
➢ Scala tympani
Cochlea
- Composed of five filaments embedded in gelatinous matrix rich in mucopolysaccharides
- Secreted at the upper surface of interdental cells
Tectorial membrane