MT M4.7 special senses Flashcards
special senses
The nervous system is involved in the sensation of the environment around the body. The special senses are divisions of the nervous system that have specialized organs that are devoted to that sense. These organs are the ears, the eyes, the nose, and the tongue. These organs are directly innervated through the cranial nerves and detect hearing, sight, smell, and taste. Touch is also a special sense; however, it does not have a dedicated organ, and the nerves for this sense come from all over the body.
ophthalmology
The study of the eye and vision is called ophthalmology
Ophthalmologists
Ophthalmologists are medical physicians that specialize in the study of the eye.
Optometry
Optometry is the area of medicine that assesses the eye to detect vision problems
optometrist
an optometrist prescribes corrective eyewear. An optometrist attends a school of optometry.
otorhinolaryngology
The study of the ears, nose, and throat is called otorhinolaryngology. This is abbreviated ENT for ears, nose, and throat.
Otorhinolaryngologists
Otorhinolaryngologists are the physicians who specialize in this area of medicine.
Audiology
Audiology is the study of hearing
Audiologists
Audiologists assess a patient’s hearing and can prescribe hearing aids.
ear
The ear is an organ dedicated to detecting sound and maintaining balance. The human body has two ears, one on each side of the head. The ear has three sections, the outer ear, the middle ear, and the inner ear. Figure 4.12 shows the structures of the ear
outer ear
The outer ear functions to detect sound and then funnel that sound to the inner structures of the ear.
auricle
The outer ear consists of the auricle or pinna
external acoustic meatus or auditory canal
The outer ear consists of the auricle or pinna and the external acoustic meatus or auditory canal.
Tympanic membrane
The outer ear ends at the tympanic membrane
middle ear
The middle ear is an air-filled cavity in the temporal bone of the skull. It contains three small bones or ossicles that are involved in hearing, namely, the malleus, incus, and stapes.
ossicles
middle ear
It contains three small bones or ossicles that are involved in hearing, namely, the malleus, incus, and stapes.
sound waves reach the tympanic membrane
When the sound waves reach the tympanic membrane, it vibrates, and those vibrations travel through the ossicles to the oval window.
oval window
The oval window is the start of the inner ear, which contains the cochlea, vestibule, and the semicircular canals.
inner ear
The oval window is the start of the inner ear, which contains the cochlea, vestibule, and the semicircular canals.
cochlea
The cochlea has sensory receptors that sense hearing and transmit that information to the brain via the cochlear nerve.
The vestibule and semicircular canals detect the body’s equilibrium, balance, and position.
eye
The eye is an organ that is dedicated to the sense of sight. The human body has two eyes located on the face. The external structures of the eye are the orbit, the eyelids, the muscles of the eye, the conjunctiva, and the lacrimal apparatus.
orbit
The orbit is the cavity in the skull that contains the eyeball. This cavity is lined with fatty tissue to protect the eye and has several openings to allow nerves and blood vessels to travel to the eyeball
eyelids
The eyelids are thin coverings that protect the eyeball from intense light and foreign objects and also keep the eyeball moist.
six muscles of the eye
There are six muscles of the eye that hold the eyeball in place and allow for rotational movement of the eyeball.
conjunctiva
The conjunctiva is a mucus membrane that is on the inside of the eyelid and covers the eyeball. The conjunctiva protects the exposed surface of the eyeball.
lacrimal apparatus
The lacrimal apparatus produces, stores, and removes the tears that lubricate and cleanse the eye.
eyeball
The eyeball is the actual organ of vision. It contains the sclera, cornea, pupil, lens, ciliary body, choroid, vitreous body, and retina. These structures work together to allow light to pass through to the retina where sensory receptors transmit that information to the brain via the optic nerve to detect vision. Figure 4.14 shows these structures of the eye.
cornea
The cornea is the transparent anterior portion of the eyeball. It bends the light and directs the light through the lens to focus on the retina.
sclera
The sclera is the outer layer of the eyeball and is called the white of the eye. It ends at the cornea.
pupil
The pupil is the circular opening in the iris, which is the colored portion of the eye. The pupil expands and contracts to allow more or less light into the eye
lens
The lens is located behind the pupil, and it focuses the light on the retina. It is attached to the ciliary body, which is a smooth muscle that changes the shape of the lens and secretes aqueous humor that nourishes the cornea, the lens, and the surrounding tissues.
choroid
The choroid is an internal membrane that prevents the internal reflection of light within the eyeball.
vitreous humor
The vitreous humor is a jelly-like material behind the lens that maintains the shape of the eyeball.
retina
The retina is the innermost layer of the eye. It contains rods and cones, which are photoreceptor cells. Rods detect dim light and are used for night vision. Cones detect bright light and are used for color vision. These cells translate the light focused on the retina into nerve impulses sent to the brain via the optic nerve.
nose
The nose is an accessory organ of the respiratory system. It is divided into an external section consisting of the nares, which allow air to enter the nasal cavity, and an internal section. The internal section of the nose is divided by the nasal septum into right and left halves. These halves each contain three air passages that lead to the pharynx.
cilia
The mucous membrane of the nasal cavity contains receptor cells, called cilia, that detect molecules in the air associated with smell and send those messages to the brain via the olfactory nerve. Figure 4.15 shows the nasal cavity and the nares.
tongue
The tongue is located in the mouth and is made of skeletal muscle. It is an accessory organ of the digestive system, as it moves the food in the mouth while chewing and also moves the food to the back of the larynx to aid in swallowing.
tastebuds
The anterior surface of the tongue is covered with tastebuds that sense the sweet, sour, salt, and savory flavors of food.
facial, glossopharyngeal, and hypoglossal nerves
The tongue is innervated by the facial, glossopharyngeal, and hypoglossal nerves. Figure 4.15 shows the location of the tongue (A), inferior to the nasal cavity and posterior to the teeth.
