List the 12 Cranial Nerves and their functionsThe 12 cranial nerves are: I) Olfactory, for smell; II) Optic, for seeing; III) Oculomotor, which controls eyelids and the pupil/lens within the eye; IV) Trochlear, which moves eyeballs; V) Trigeminal, which controls face and jaw muscles; VI) Abducens, which controls eyeball motion; VII) Facial, which controls tear and saliva glands, and facial expressions; VIII) Vestibulocochlear, which controls hearing; IX) Glossopharyngeal, which controls taste and swallowing; X) Vagus, which controls the gastrointestinal tract; XI) Accessory, controlling head and shoulder movement; and XII) Hypoglossal, controlling tongue movements for speech, and swallowing.
Name the 2 Cranial Nerves that supply the tongue and which part of the tongue each supply.
The two cranial nerves that supply the tongue are the Glossopharyngeal nerve, which supplies the pharyngeal part of the tongue, near the back of the throat, and the Hypoglossal nerve, which supplies the surface of the tongue.
Gustatory refers to one’s sense of taste.
Olfactory refers to one’s sense of smell.
List the Cranial Nerve providing the sense of smell and the cranial bone it exits through the skull.
The Olfactory nerve provides sense of smell; it is attached to the ethmoid bone.
Describe the pathway of tear formation; listing each structures role until the tear reaches your nose.
Tears begin in the lacrimal gland, located above the eye toward the outside of one’s face. From here, they drain through the punctum and into medial eyelids. They then flow into the canaliculi, and from here they go down the lacrimal sac, located near the nose, before being released onto the nose.
List and describe each structure associated with the eyeball and it’s function. (See picture on page 565)
The eyeball consists of the sclera, which is the white part controlling the eye’s shape; the cornea, which focuses light; the anterior chamber angle, which allows the eye to drain through the trabecular meshwork; the iris, which controls the amount of light entering the eye through contracting the pupil; the lens, which helps focus light as it reaches the retina; the vitreous cavity, which connects the back of the eye to the front; the retina, which interacts with light to produce electrical signals; the macula, which provides focus; the choroid, which provides nutrients for the retina; and the optic nerve, which transmits data from the retina to the brain.
List the eye muscles, their actions and their nerves that control them.
The eye muscles consist of the medial muscle, the inferior muscle, the superior recti muscle, and the inferior oblique muscle, as well as the levator papebrae muscles, all of which are controlled by the oculomotor nerve. These muscles are responsible for eyeball movement. The superior oblique muscle is controlled by the trochlear nerve, and is responsible for eyeball rotation; and lateral rectus muscle, controlled by the abducens nerve, allows for lateral movement in the eye.
Define and describe Rod Cells and Cone Cells.
Rod cells and cone cells are different types of photoreceptors found in the retina. Rod cells allow us to see shapes and forms, while cone cells allow to individuate different colors.
What is the name of the “Blind Spot” of the eye, and what forms it?
The blind spot of the eye is named the punctum caecum. It is formed by the optic disk obscuring an area of the visual field.
Explain Macular Degeneration and it’s effects to your sight.
Macular degeneration is when the macula, located within the retina, is damaged. This causes worsening vision, with a loss of focus or gaps of vision in the middle of the visual field.
What role does Schlemm’s Canal play in Glaucoma and how is Glaucoma treated? Can it lead to blindness if untreated? Why?
Schlemm’s Canal transfers aqueous humor formed in the anterior chamber and delivers it to various blood vessels. Glaucoma is the result of not enough aqueous humor being distributed. This can lead to a buildup of pressure that damages the optic nerve, and can cause blindness if it remains untreated.
Explain cataract formation and what causes it.
Cataracts are formed as a result of generating lens proteins, resulting in cloudy or obscured vision. Cataracts are most commonly caused through degeneration associated with aging, although other causes such as diabetes and smoking can be contributing factors.
Explain the following:
Convergence is the simultaneous motion of both eyes, controlled by the medial rectus muscle.
Accommodation is the process of the eye maintaining focus at various distances.
Refraction is the bending of light by eye structures to maintain focus.
Explain the problems associated with:
Myopia “Near Sighted”
Myopia is the inability to see clearly at long distances.
Hyperopia “Far Sighted”
Hyperopia is the inability to see clearly at close distances, as with reading.
Astigmatism is when light is not evenly focused on the retina. This can cause either blurry or distorted vision.
What is Rhodopsin and it’s function?
Rhodopsin is a light-sensing protein located in the rod cells of the retina. Its function is to allow for sight in dark conditions.
Which cells are used by your eyes at night, and during the day?
Cells used at night by the eye are rod cells, as they can function in low light and still distinguish various shapes. Cone cells are used during the day and can distinguish and sense color.
What is Nystagmus? Consuming too much of what can cause it?
Nystagmus is a series of quick, involuntary eye movements that can compromise vision. It can be caused by consuming too much alcohol.
List all of the structures of the ear and their functions. (See page 583)
The ear consists of three parts: the outer ear, the middle ear, and the inner ear. The outer ear consists of the auricle, which is the cartilage that forms the external ear; the auditory canal, which transmits sound coming from the auricle; and the eardrum outer layer, which transfers sound to the middle ear. The middle ear consists of the eardrum, connecting to the outer ear; the tympanic cavity, which contains three bones known as the malleus, incus, and stapes, which sense sound vibrations. The inner ear consists of the oval window, connecting the inner and middle ear; semicircular ducts, which sense balance; the cochlea, which interprets sound into information that can be processed by the brain; and the auditory tube, which drains fluid away from the middle ear and into the throat.
Define Otitis Media. Who gets it more frequently and why?
Ottis Media refers to an inflamed middle ear, generally caused by virus or bacteria infection. It most commonly affects children more than adults, due to physiological differences of the eustachian tube: in children, the eustachian tube is more horizontal, making it difficult for fluid to drain. Children also generally have weaker immune systems than adults.
What are Ossicles? Name them.
Ossicles are tiny bones located in the middle ear. They include the malleus, the incus, and the stapes. Their function is to transmit sound from the ear to the cochlea, which interprets sound.
What are the 2 Cranial Nerves associated with the Ear and what does each control?
The two cranial nerves associated with the ar are the vestibular nerve, which is responsible for balance and equilibrium; and the cochlear nerve, which connects the cochlea to the brain, and responsible for how our brain interprets various sounds.
Explain the purpose of :
The semi-circular canals are three tubes in the inner ear: the horizontal canal, the superior canal, and the posterior canal. The tubes contain hair cells which sense vibrations, and interpret sound waves into information sensed by the brain.
The vestibule is a chamber in the bony labyrinth of the inner ear containing the utricle and saccule.
The cochlea is an organ in the inner ear containing fluid that is sensitive to vibrations. These vibrations are transmitted into electrical signals that interpret various sounds.
Define each of the following and tell their roll in hearing:
Sound refers to sound energy that is transmitted in the air, where it is picked up by the ear, beginning with the auricle.
Frequency is a measurement of sound that determines the overall pitch, such as low frequencies for bass and high frequencies for higher-pitched sounds.
Wavelength in sound is measured by the distance between the peaks made in the waves. The length of the wavelength determines the type of sound, as well as the pitch.
Conduction deafness occurs when the outer or middle ear is damaged, and therefore unable to transmit sound waves effectively to the inner ear. Conduction deafness can be caused by damage to either the ear drum, or the ossicles located in the middle ear.
Sensorineural deafness is caused by damage to the inner ear, which causes hearing loss due to an inability to successfully process sound waves transmitted from the outer and inner ears. This can be caused due to trauma, or infection.
Tinnitus is when sounds are heard, although no sound is actually present. This is commonly described as a type of ringing sensation.
Meinier’s Syndrome is a disorder characterized by feeling off balance, or vertigo, as well as possibly tinnitus or loss of hearing. This is theorized to be a genetic disorder, although it can also be caused by external factors.
Motion sickness is a type of nausea experienced by feeling off balance, or when the brain interprets motion visually, but without the inner ear also sensing motion, such as when sitting still but also riding on a train.