BIOL 129 Lecture Notes - Lecture 21: Optic Chiasm, Olfactory Epithelium, Levator Palpebrae Superioris Muscle
Document Summary
Cranial nerves: 12 paired nerves that come directly off of the brain. Carry four types of neurons: (1) general sensory (2) special sensory (3) somatic motor (4) parasympathetic motor. Olfactory tracts: bundles of special sensory axons extending from the brain. Olfactory bulbs: thickened, anterior parts of tracts that sit on top of the ethmoid bone. Olfactory axons protrude through the cribriform plate of the ethmoid bone. Olfactory epithelium: layer of cells containing olfactory sensory neuron bodies. Inhaled air passes over specialized receptors of olfactory neurons which are stimulated by odor molecules. Optic nerves pass from back of the eyeball to the brain and relay visual information from the retina. Some nerve fibers cross sides at the optic chiasm therefore visual information from both eyes goes to both right and left sides of the cerebrum. Function of tears: cleaning of eye surface, emotional display. Tears drain into the nasolacrimal duct which empties into the nasal cavity.
