Unit 5 Part 2B
Cranial Nerves, Spinal Cord and Spinal Nerves
I. Cranial Nerves -- On Old Olympus' Towering Tops A Finn And German Viewed Some Hops
|1. Olfactory||Sense of Smell|
|3. Occulomotor||Eye movements: eyelids and eyeball|
|4. Troclear||Eye movements: move eye downward and laterally|
|5. Trigeminal||Face, scalp, teeth sensations, chewing movements|
|6. Abducens||Turning eyes outward|
|7. Facial||Sense of taste, contraction of muscles of facial expression, secretion of saliva and tears|
|8. Acoustic||Hearing, sense of balance (equilibrium)|
|9. Glossopharyngeal||Responsible for taste and sensing blood pressure|
|10. Vagus||Major nerve of Parasympathetic Nervous System. Lowers heart rate, blood pressure, increases digestion; connects to pharynx, larynx, heart lungs and stomach|
|11. Spinal Accessory||Shoulder movements, turning movements of head|
|12. Hypoglossal||Tongue movements|
II. Spinal Cord
a. 17 – 18 inches long
b. Extends from occipital bone to bottom of first lumbar vertebrae
c. Spinal cord tracts provide two-way conduction paths to and from the brain. (Ascending tracts – up to brain, Descending tracts down spinal cord to body).
d. Function – Transfers information to brain for processing and sends messages to body parts.
III. Spinal Nerves
a. 31 pair (8-C, 12-T, 5-L, 5 Sacrospinal, 1 Coccygeal)
b. Conduct impulses between spinal cord and parts not supplied by cranial nerves (appendages).
c. Dermatome – Area of skin surface supplied by single spinal nerve.
IV. Dermatome Areas
V. Autonomic Nervous System
a. Conduct impulses from spinal cord to
i. cardiac muscle (heart)
ii. smooth muscle
b. Regulate involuntary functions.
c. Consists of 2 divisions
i. Sympathetic nervous system
1. Functions as an emergency system during times of extreme stress or strenuous exercise. “Fight or Flight”
2. Ex. Accelerate heartbeat, relaxes bladder, dilates pupil, increases sweat.
3. Areas of Control are mainly found on the thoracic and lumbar areas of the spinal cord.
ii. Parasympathetic nervous system
1. Regulates fluctuations in everyday functions.
2. Ex. Increases peristalsis, contracts bladder, opens sphincter for defecation.
3. Autonomic nervous system functions to regulate body’s automatic, involuntary functions in order to quickly maintain or restore homeostasis.
4. Areas of control are the Vagus Cranial Nerve and the Medulla Oblongata.