Pathway of Olfaction
From the receptors, through the cribiform plate of the ethmoid bone. They terminate (synapse) in the olfactory bulbs and axons from the olfactory bulbs project to the olfactory area of the temporal lobe.
What connections account for our emotional and memory-evoked responses to oders?
Connections to the Limbic system and the Hypothalamus.
Taste impulses are carried in which CN's and to what part of the brain?
CN's 7 & 9 to the Medulla Oblongata and Pons.
3 areas that taste fibers project to.
Limbec System, Hypothalamus, and the Thalamus.
What is the External auditory meatus?
- External Ear
- Opening in the temporal bone that provides a passage for sound waves to get to the middle ear.
What is an ear drum and what is it's function?
- External Ear
- Thin layer of connective tissue that divides the external and middle ear. Function is to transfer sound waves from the outer ear to middle ear and keep foreign objects out.
What 3 bones make up the Auditory Ossicles?
- Middle Ear
- Malleus: Attached to the tympanic membrane
- Incus: Between the malleus and stapes
- Stapes: Attached to the oval window of the inner ear.
What are the 2 windows found in the inner ear and what are their functions?
- Oval Window: Membrane that divides middle ear from the inner ear.
- Round Window: Another membrane-covered opening that lets the sound waves exit.
What is the Cochlea and how does it function?
- Shaped like a snail shell, it has an internal membrane with dendrites on it that are sound receptors called the Organ of Corti (Spiral Organ).
- Sound waves cause vibration of the oval window of the inner ear, fluid in the cochlea, and the Organ of Corti. These neurons in turn send the signals to medial geniculate nucleus of the thalamus and then to the temporal lobe.
Equilibrium is associated with which special sense?
What is Utricle and Saccule?
Two sacs that give us the sense of static equilibrium
What are Semicircular canals?
Systems of canals that give us the sense of dynamic equilibrium such as starting and stopping.
What are the receptors in vision and where are they found?
Rods and Cones which are found in the retina
What is a Fibrous Tunic and what 2 parts does it consists of?
- The Fibrous Tunic gives shape to the eyeball.
- Sclera: White part of the eye
- Cornea: Clear part of the sclera that allows light into the eye.
What are the 3 parts to the Vascular Tunic?
Innervated by CN3
- Choroid: Very vascular inner lining of the sclera
- Ciliary Body: Thickened area on the anterior choroids near the cornea
- Ciliary muscle: Controls the shape of the lens
How does the parasympathetic system affect the ciliary muscle and the iris?
- Stimulates the ciliary muscle to thicken the lens for near vision.
- Innervates circular muscle to constrict the iris.
Functions of the Iris
- Consist of the radial muscle (dilation) and circular muscle (constriction).
- Controls how much light gets into the eyeball.
- Sympathetic system innervates the radial muscle to dilate.
Fuctions of the Nervous Tunic
- Inner most layer of the eye
- Contains rods and cones attached to bipolar neurons. Rods and cones are photo-pigments that attach to the dendrites, when light hits them, they change shape.
- The Optic Nerve (CN II) innervates the bipolar neurons.
Rods Vs. Cones
- More rods than cones (20:1)
- Best for black and white vision
- working in dim light
- Functions better in bright light
- Best for color vision
What is a Macula Lutea and what can be found there?
Area of the central retina where there are mostly cones. A dent in this area where the light hits is called the Central Fovea of the Macula Lutea.
What is the Optic Disc?
Part of the retina where the optic nerve penetrates the retina. There are no rods or cones there, and is referred to as the blind spot.
What is the visual pathway?
From the retina, nerve impulses pass posteriorly as the optic nerve and cross at the optic chiasm. Then the fibers project to the lateral geniculate nucleus as the optic tracts. From the thalamus the fibers project posteriorly to the occipital lobe as the optic radiations.