Nursing Entrance Exam

The Eye Each eye is a slightly irregular spheroid with an average diameter of 24 mm (almost 1 inch) and a weight of about 8 g (0.28 oz.). The eyeball shares space with the accessory structures of the eye within the orbit, which includes the extrinsic eye muscles, the lacrimal gland, the cranial nerves, and the blood vessels that supply the eye and the adjacent portions of the orbit and face. The wall of the eye contains three distinct layers, or tunics : an outer fibrous tunic, an intermediate vascular tunic, and an inner neural tunic (retina). The visual receptors, or photoreceptors, are located in the neural tunic. The eyeball is hollow – its interior can be divided into two cavities. The large posterior cavity is also called the vitreous chamber. The smaller anterior cavity is subdivided into the anterior and posterior chambers. In part, the shape of the eye is stabilized by the vitreous body and the clear aqueous humor that fills the anteriorcavity. 4. Hearing and Balance: The special senses of equilibrium and hearing are maintained by the inner ear, which is a receptor complex located in the petrous part of the temporal bone of the skull. By monitoring gravity, rotation, and linear acceleration, equilibrium sensations yield information about the position of the head in space. Hearing also allows us to detect and interpret soundwaves. The basic receptor mechanism for both hearing and balance is the

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