Question

1. How do the dural sinuses form?
2. Explain habituation.
3. Define the reticular formation in one sentence.
4. What is a common feature of cranial nerves III, IV, & VI?
5. What functions are usually attributed to the right cerebral hemisphere?

Answer 1

Ans-1

Dural venous sinus are located intracranially between the layers of dura matter( endosteal layer and meningeal layer). Unlike other vein in body, they run alone, not parallel to the artery. They does not contain valves which allow blood flow bi-directional in intracranial vein. Together dural venous sinus form major drainage pathway from brain predominantly to internal jugular vein. Main dural venous sinus are such as:

Paired: superior sagittal sinus, inferior sagittal sinus, straight sinus, occipital sinus and Intel cavernous sinus

Paired: transverse sinus, sigmoid sinus, superior petrosal sinus, inferior petrosal sinus, cavernous sinus, sphenoparietal sinus, and basilar venous plexus.

Ans-2

Habituation is form of learning in which organism decrease response to a stimulus after repetition. It means organism learn to stop responding from stimulus until no longer biological relevant. It is also known as the second nature of the organism. Habituation usually refer to reduction in innate behaviour rather than behavior acquired during conditioning.

Ans-3

Reticular formation has a projection to thalamus and cortex which play main role in alertness and sleep.

Ans-4

Cranial nerve third a oculomotor nerve, cranial nerve fourth trochlear nerve and cranial nerve six abducens having common feature to control the position of eyeball.

Ans-5

Right cerebral hemisphere control movement of the left side of the body. Damage to right cerebral hemisphere may result functional loss or motor skill impairment in left side of our body.