Chapter 14 Anatomy

Front 1

peripheral nervous system (PNS)

Back 1

consists of the nerves that branch out from the brain and spinal cord. These nerves are the collecting link between the body and the central nervous system (CNS).

Front 2

Two functional divisions of the peripheral nervous system

Back 2

afferent division, which consists of all of the incoming sensory pathways; and the efferent division, which consists of all of the outgoing motor pathways.

Front 3

The peripheral nervous system may be further divided into subdivisions known as the:

Back 3

Somatic nervous system, which conducts information to and from nerves that are involved in voluntary activities such as skeletal muscle action
Autonomic nervous system, which stimulates organs and glands and is responsible for involuntary activities

Front 4

Cranial Nerves

Back 4

transmit sensory information and voluntary and involuntary messages throughout the body. There are 12 pairs of cranial nerves attached to the brain, with the majority of them extending from the brainstem.Many of the nerves are named for the area they innervate. made up of bundles of axons

Front 5

Mixed cranial nerves

Back 5

consist of axons of both sensory and motor neurons

Front 6

Sensory cranial nerves

Back 6

consist of sensory axons only, and motor cranial nerves consist mainly of motor axons.

Front 7

plexus

Back 7

As spinal nerves exit from the vertebral column, sometimes nerve fibers from several spinal nerves are reorganized to form a single peripheral nerve. This reorganization can be seen as a network of intersecting branches

Front 8

The 4 major nerve plexuses are:

Back 8

Cervical
Brachial
Lumbar
Sacral

Front 9

Cervical plexus

Back 9

Innervates skin, muscles of the neck and shoulder, and the diaphragm.

Front 10

Brachial plexus

Back 10

Innervates skin and muscles of the upper extremities.

Front 11

Lumbar

Back 11

Innervates the thigh and leg.

Front 12

Sacral

Back 12

The tibial, common peroneal, and sciatic nerves exit the sacral plexus and supply nearly all the skin of the leg, posterior thigh muscles, and leg and foot muscles.

Front 13

Myotomes

Back 13

are skeletal muscle or muscles supplied by efferent (motor) fibers of a given spinal nerve. There is some overlap causing some skeletal muscle organs to be innervated by motor axons from more than one spinal nerve.

Front 14

Neuritis

Back 14

is inflammation of a nerve. Symptoms may include neuralgia, paralysis, muscular atrophy, and hyperesthesia. An example is sciatica, or inflammation of the sciatic nerve.

Front 15

shingles

Back 15

Also known as Herpes zoster, is caused by a Varicella zoster virus of chickenpox and is usually very painful. It affects the skin of a single dermatome and lies dormant after an episode of chickenpox. It reactivates under stress or when the immune system is compromised.

Front 16

Bell's Palsy

Back 16

presents as unilateral paralysis of the facial nerve that may be due to trauma, compression, or infection of the nerve. Patients are often unable to close the eyelid or make facial movements on the affected side. It is most often temporary but, in some cases, may be irreversible.

Front 17

Tic Douloureux

Back 17

Also known as trigeminal neuralgia, this disorder causes pain that is due to compression or degeneration of the fifth cranial nerve, the trigeminal. It is characterized by recurring episodes of stabbing pain along the angle of the jaw, branching sometimes over the forehead, around the eyes, in the tongue, and lower lip. The pain can be so severe that it has sometimes been referred to as the "suicide disease."

Front 18

How many pairs of spinal nerves are there? Can you name them?

Back 18

31 pairs of spinal nerves. Cervical (8 pairs), thoracic (12 pairs), lumbar (5 pairs), sacral (5 pairs), and one pair of coccygeal nerves.

Front 19

What is a plexus? Name the four major pairs of plexuses.

Back 19

A plexus is a complex network formed by converging and diverging nerves. Cervical plexus, brachial plexus, lumbar plexus, and the sacral plexus.

Front 20

What is a dermatome? A myotome?

Back 20

Dermatomes are skin surface areas supplied by a single spinal nerve. A myotome is a skeletal muscle or group of muscles that receives motor axons from a given spinal nerve.

Front 21

List the names and numbers of the 12 pairs of cranial nerves.

Back 21

Olfactory I, optic II, oculomotor III, trochlear IV, trigeminal V, abducens VI, facial VII, vestibulocochlear VIII, glossopharyngeal IX, vagus X, accessory XI, hypoglossal XII.

Front 22

Identify the primary function of each pari of cranial nerves.

Back 22

Olfactory: sense of smell. Optic: vision. Oculomotor: eye movements, regulation of pupil size, accommodation, proprioception. Trochlear: eye movements, proprioception. Trigeminal: sensations of head and face, chewing movements, proprioception. Abducens: abduction of eye, proprioception. Facial: facial expressions, secretion of saliva and tears, taste. Vestibulocochlear: balance or equilibrium sense (cochlear branch—hearing). Glossopharyngeal: sensation of tongue, swallowing movements, secretion of saliva, aid in reflex control of blood pressure and respiration. Vagus: sensations and movements of organs supplied (e.g., slows heart, increases peristalsis, and contracts muscles for voice production). Accessory: shoulder movements, turning movements of head, movements of viscera, voice production, proprioception. Hypoglossal: tongue movements, proprioception.

Front 23

distinguish between a motor nerve, sensory nerve, and mixed nerve.

Back 23

Motor cranial nerves consist mainly of motor axons. Sensory cranial nerves consist of sensory axons. Mixed cranial nerves contain axons of sensory and motor neurons.

Front 24

What are the somatic effectors?

Back 24

Skeletal muscles

Front 25

State the principle of final common path as it applies to the somatic motor nervous system.

Back 25

This means that all of the somatic motor pathways involve a single motor neuron whose axon stretches from the cell body in the CNS all the way to the effector innervated by that neuron.

Front 26

Explain how the knee jerk reflex can be both a stretch reflex and a spinal reflex.

Back 26

It can be a spinal reflex because the center of the reflex arc lies in the spinal cord gray matter. It can be a stretch reflex because of the kind of stimulation used to evoke it.

Front 27

Do autonomic pathways follow the principle of final common path?

Back 27

No.

Front 28

Why is the sympathetic division of the ANS also known as the thoracolumbar division?

Back 28

The sympathetic preganglionic neurons have their dendrites and cell bodies within the lateral gray horns of the thoracic and lumbar segments of the spinal cord.

Front 29

Describe the path generally taken by an impulse along a sympathetic pathway from the CNS to an autonomic effector.

Back 29

The sympathetic pathway can branch along any of three paths: It can synapse with a sympathetic postganglionic neuron, it can send ascending or descending branches through the sympathetic trunk to synapse with postganglionic neurons in other ganglia, or it can pass through one or more ganglia without synapsing.

Front 30

Describe the pathway taken by an impulse traveling along a parasympathetic pathway.

Back 30

In a parasympathetic ganglion, preganglionic axons synapse with postganglionic neurons that send their short axons into the nearby autonomic effector. Therefore a parasympathetic preganglionic neuron usually synapses with postganglionic neurons to a single effector

Front 31

What is the difference between a cholinergic fiber and an adrenergic fiber? Between a cholinergic receptor and an adrenergic receptor?

Back 31

Axons that release acetylcholine are known as cholinergic fibers. Axons that release norepinephrine are known as adrenergic fibers. Acetylcholine released from cholinergic fibers similarly binds to cholinergic receptors to produce postsynaptic effects. Norepinephrine released from the adrenergic fibers bind to adrenergic receptors according to a lock-and-key model to produce regulatory effects in the postsynaptic cell.

Front 32

Name the two major types of cholinergic receptors and the two major types of adrenergic receptors.

Back 32

Cholinergic receptors: nicotinic and muscarinic. Adrenergic receptors: alpha and beta.

Front 33

What is the principle of autonomic antagonism? Give an example.

Back 33

The principle of antagonism is when both sympathetic and parasympathetic divisions continually conduct impulses to autonomic effectors, often exerting an opposite or antagonistic influence on them.

Front 34

Name the responses that occur in the fight-or-flight reaction. How does each of these prepare the body to expend a maximum amount of muscular energy?

Back 34

Increased heart rate: increased delivery of oxygen and glucose to skeletal muscles. Increased strength of cardiac muscle contraction: increased delivery of oxygen and glucose to skeletal muscles. Dilation of coronary vessels: increased delivery of oxygen and nutrients to cardiac muscle. Dilation of blood vessels in skeletal muscles: increased delivery of oxygen and nutrients to skeletal muscles. Constriction of blood vessels in digestive and other organs: shunting of blood to skeletal muscles. Contraction of spleen and other blood reservoirs: more blood discharged into general circulation, thus increasing delivery of oxygen and nutrients to skeletal muscles. Dilation of respiratory airways: increased loading of oxygen into blood. Increased rate and depth of breathing: increased loading of oxygen into blood. Increased sweating: increased dissipation of heat. Increased conversion of glycogen into glucose: increased amount of glucose available to skeletal muscles.

Front 35

Which division of the ANS is the dominant controller of autonomic effectors when the body is at rest?

Back 35

Parasympathetic division.

Front 36

Mechanoreceptors

Back 36

- touch, pressure, vibration, stretch, itch

Front 37

Thermoreceptors

Back 37

- change in temperature

Front 38

Photoreceptors

Back 38

- respond to photons

Front 39

Chemoreceptors

Back 39

- respond to chemicals
- smell, taste, blood chemistry

Front 40

Nociceptors

Back 40

- pain-causing stimuli

Front 41

Sensation is the awareness of changes in the internal and external environment

Back 41

Perception is the conscious interpretation of those stimuli

Front 42

Adaptation occurs when

Back 42

- sensory receptors are subjected to an unchanging stimulus
- receptor membranes become less responsive
receptor potentials decline in frequency or stop

Front 43

Main Aspects of Sensory Perception

Back 43

Perceptual detection- - detecting that a stimulus has occurred and requires summation
Magnitude estimation-- how much of a stimulus is acting
Spatial discrimination-identifying the site or pattern of the stimulus

Front 44

Back 44

Front 45

Five components of a reflex arc:

Back 45

1. Receptor – site of stimulus
2. Sensory neuron – transmits the afferent impulse to the CNS
3. Integration center – either monosynaptic or polysynaptic region within the CNS
4. Motor neuron – conducts efferent impulses from the integration center to an effector
5. Effector – muscle fiber or gland that responds to the efferent impulse