Anatomy and Physiology of the Nervous System: Sensory OrgansThe eyes and ears are sensory organs that support vision and hearing. When the anatomical structures are healthy andformed, and the physiology of the structures functions properly, then people are able to see and hear. However,interruption to the anatomy and physiology of the eyes and ears can jeopardize a person’s ability to use their senses totheir fullest potential. Understanding vision and hearing is made possible by studying the anatomy and physiology of theeyes and ears.Anatomy of the Eye:The anatomy of the eye is composed of external structures, internal structures, and muscles formovement.There are certain eye structures that assist with protection:Eyelids (palpebrae) and eyelashes: These are external structures that keep foreign material out of the eye.Upper eyelid muscle (levator palpebrae superior): This is an external structure controlled by the cranial nerve III(oculomotor) that allows for eyelid movement.Sclera:The sclera is covered by the conjunctiva. The palpebrae are lined with conjunctiva.Lacrimal gland:This is an internal structure that is located in the superior lateral area of the orbit and is where tearsare formed. Tears contain lysozyme. This is an antibacterial enzyme that flows across the eye, keeping the eyes moist.Tears drain into the lacrimal canals and into the medial corner of the eye. From there, the tears enter the nasal cavitythrough the nasolacrimal duct.Eye muscles that assist with eye movement.control how the eyeball moves (left to right and upand down). These muscles include:Four rectus musclesTwo angled muscles: These are also known as oblique muscles.Eye movements are coordinated by cranial nerves III (oculomotor), IV (trochlear), and VI (abducens), which allow forcomprehensive vision.Layers of the eye:The eye is made up of three different layers. The layers are important for permitting light to passthrough the eye, making it possible to see. All mammals have a similar structure of the eye with similar layers. The partsdepicted in the image form three layers: Outer layer, middle layer, and inner layer.Outer Layer: The outer layer is made up of:-Eyeball: The eyeball is a spherical three-layered structure filled with liquid.-Sclera: The sclera is the visible white part of the eye.-Cornea: The cornea is a transparent bulging portion that refracts and allows rays of light to pass through. It containsno blood vessels, but surrounding fluids nourish it.