Explain (1)Outer,middle & inner ear with help of diagrams. (2)Eyes with diagram.

Asked by hanumaan | 1st Nov, 2010, 12:00: AM

Expert Answer:

Dear Student,
The outer ear has no bones. It is the external portion of the ear, which consists of the pinna, concha, and auditory meatus. It gathers sound energy and focuses it on the eardrum (tympanic membrane).
The visible part is called the pinna and functions to collect and focus sound waves. It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles.

The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has also been called the tympanic cavity, or cavum tympani. The eustachian tube joins the tympanic cavity with the nasal cavity (nasopharynx), allowing pressure to equalize between the middle ear and throat.

The inner ear is the innermost part of the vertebrate ear. It consists of the bony labyrinth, a system of passages comprising two main functional parts:

  • The cochlea is dedicated to hearing
  • The vestibular system is dedicated to balance

 

The Eye made up of three coats, enclosing three transparent structures. The outermost layer is composed of the cornea and sclera. The middle layer consists of the choroid, ciliary body, and iris. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels.
Within these coats are the aqueous humor, the vitreous body, and the flexible lens. The aqueous humor is a clear fluid that is contained in two areas: the anterior chamber between the cornea and the iris and exposed area of the lens; and the posterior chamber, behind the iris and the rest. The lens is suspended to the ciliary body by the suspensory ligament (Zonule of Zinn), made up of fine transparent fibers. The vitreous body is a clear jelly that is much larger than the aqueous humor, and is bordered by the sclera, zonule, and lens. They are connected via the pupil.

 


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Answered by  | 2nd Nov, 2010, 11:35: PM

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