One important factor in acountryâs population density is its area. SouthAmerican countries, with their relatively largeland areas, tend to have low population densities.In Ecuador, the most densely populated country inSouth America, an average of only 118 peopleshare a square mile (46 people per sq. km).
Trochlear nerve: The nerve that controls the superior oblique muscle of the eye, one of the muscles that move the eye (extraocular muscles). Paralysis of the trochlear nerve results in rotation of the eyeball upward and outward (and, therefore, in double vision).The trochlear nerve is the fourth cranial nerve, and it is the only cranial nerve that arises from the back of the brain stem.aralysis of the trochlear nerve results in rotation of the eyeball upward and outward (and, therefore, in double vision). The trochlear nerve is the fourth cranial nerve, and it is the only cranial nerve that arises from the back of the brain stem.
The oculomotor nerve is a motor neuron that controls all but two of the extraocular eye muscles, the levator palpebrae superioris and the intrinsic eye muscles. The nerves originate in the mesencephalon and pass through the superior orbital fissure on its way to the eye.he vagus nerve is a mixed motor and sensory nerve. The sensory neurons convey information from the inferior pharynx, larynx and thoracic and abdominal organs. Somatic motor neurons innervate muscles in the soft palate, pharynx and intrinsic laryngeal muscles.