4. Mention if the following statements are true (T) or false (F). Give reason.

(a) Sometimes medicines dropped into the eyes come into the nose and even throat.

(b) Ciliary muscles regulate the size of the pupil.

(c) Yellow spot of the retina is the region of the colour vision.

(d) The auditory nerve is purely for perceiving sound.

(e) Malleus, incus and stapes are collectively called ear ossicles.

(f) Short-sightedness and hyperopia are one and the same thing.

(g) Blind spot is called so because no image is formed on it.

Solution:-

(a) True

A nasolacrimal duct conducts the secretion into the nasal cavity.

(b) False

Ciliary muscles regulate the size of the lens.

(c) True

The fovea centralis, or yellow spot, is located at the back of the eye, almost in the centre of the eyeball’s horizontal axis. This area has the greatest concentration of sensory cells, notably cones. As a result, this is the brightest vision as well as the colour vision zone.

(d) False

The auditory nerve responsible for sound as well as for the body balance.

(e) True

The middle ear comprises three little bones known as the malleus, incus, and stapes, or hammer, anvil, and stirrup in common language, as well as a eustachian tube that connects the middle ear cavity to the throat.

(f) False

Short-sightedness is myopia and hyperopia is long-sightedness.

(g) True

The blind area is located to the side of the yellow spot on the nasal side. Because there are no sensory cells here, this is a visionless zone. This is where the nerve fibres from all of the retina’s sensory cells converge and bundle together to form the optic nerve, which leaves the eyeball.