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52 Cards in this Set

  • Front
  • Back
lobes of the brain
- frontal lobe
- occipital lobe
- parietal lobe
- temporal lobe
sulcus
or sulci (pl.) - shallow grooves in the surface of the brain, that divide each hemisphere into lobes

it surrounds the gyri
gyrus
ridge on the cerebral cortex;

it is generally surrounded by one or more sulci
What is located in the postcentral gyrus?
PRIMARY SENSORY CORTEX

the main sensory receptive area for the sense of touch
What is located in the precentral gyrus?
PRIMARY MOTOR CORTEX

It controls movements of specific body parts.

The precentral gyrus is in front of the postcentral gyrus from which it is separated by the central sulcus.
What lobe of the brain contains the primary motor cortex?
FRONTAL LOBE
What lobe of the brain contains the primary sensory cortex?
PARIETAL LOBE
regions of the brain stem
- midbrain
- pons
- medulla oblongata
- reticular formation
The medulla oblongata becomes what structure when it exits the cranial cavity?
spinal cord
What is white matter?
- component of the CNS
- contains myelinated axons, that run together in bundles called tracts (ascending and descending)

- tracts function as the "highways" along which sensory input travels to the brain and motor output travels from the brain to skeletal muscles and other effectors.
What is gray matter?
- component of the CNS
- contains dendrites and cell bodies, and short nonmyelinated axons
- portions of sensory neurons and motor neurons found in grey matter

- function of grey matter is to route sensory or motor stimulus to interneurons of the CNS in order to create a response to the stimulus through chemical synapse activity. Grey matter structures (cortex, deep nuclei) process information originating in the sensory organs or in other grey matter regions. This information is conveyed via long axons, which form the bulk of the cerebral, cerebellar, and spinal white matter.
What is a synonym for anterior?
VENTRAL
What is a synonym for posterior?
DORSAL
What is contained in the DORSAL HORN?
collection of 2nd order sensory cell bodies, and axons of interneurons as well as axons of incoming sensory neurons
What is contained in the VENTRAL HORN?
collection of cell bodies of lower motor neurons (LMN)
What forms a spinal nerve?
Within the spinal canal the anterior and posterior roots unite to form a mixed spinal nerve.
What cell bodies are contained in the dorsal root ganglion?
cell bodies of first order (primary) afferent or sensory neurons. No synapses occur here!
What are the branches of the spinal nerve?
- dorsal ramus
- ventral ramus
- meningeal branch
- rami communicantes
What is a dermatome?
Area of skin that provides sensory input to the CNS via the posterior roots of one pair of spinal nerves or via the trigeminal (V) nerve.
What goes out of the ventral root?
nerve impulses from the CNS
What comes into the dorsal root?
nerve impulses from sensory receptors in the skin, muscles, and internal organs into the CNS. Dorsal root contains only sensory axons.
A ventral branch of the root contains what type of fiber?
motor
How many neurons are in sensory and motor chains?
SENSORY CHAINS - 3 neurons. The sensory receptor receives the signal, and passes the signal down a chain of three neurons that ends at the sensation-specific cortical region. The thalamus is the relay station for all sensory info going to the cortex. It contains cell bodies of all the 3rd order sensory neurons.

MOTOR CHAINS - 2 neurons.
The cortical region communicates to the end muscle via a chain of two neurons. The 2nd (lower) motor neuron plus the NMJ constitute the motor unit. The ventral horn contains the cell bodies of lower motor neurons.
Thus, there are no synapses between ventral horn and NMJ.
What is the lateral horn?
collection of cell bodies of preganglionic sympathetic fibers. These are efferent myelinated fibers and will pass out of the spinal cord through the ventral root. Lateral horn is only located in the spinal cord between the levels of T1-L2 (L3): thoracic and upper lumbar segments of the spinal cord, where it contains autonomic motor nuclei, which are clusters of cell bodies of autonomic motor neurons that regulate the activity of cardiac muscles, smooth muscle, and glands.
What are the rami communicantes?
Nerve that connects two other nerves. Communicating branches between the anterior ramus of the spinal nerve and the ganglia of the sympathetic trunk. More specifically, it usually refers to one of the following:

- White rami contain sympathetic preganglionic axons (myelinated), that connect anterior ramus with the ganglia of sympathetic trunk. Only the thoracic and first two or three lumbar nerves have white rami communicantes.

- Gray rami contain sympathetic postganglionic axons (unmyelinated) that connect ganglia of the sympathetic trunk to spinal nerves.

Grey rami comm. outnumber (превосходят численно) the white rami.
What part of the spinal column can the rami communicantes be found?
anterior and lateral to the vertebral column, on both sides
What is the primary afferent neuron?
Or sensory or receptor neurons - carry nerve impulses from receptors or sense organs toward the CNS. Afferent neurons communicate with specialized interneurons.
What do 1st, 2nd and 3rd order neurons refer to?
1. First-order neurons conduct impulses from somatic receptor into the brainstem or spinal cord. From the face, mouth, teeth, and eyes, somatic sensory impulses propagate along cranial nerves into the brainstem. From the neck, trunk, limbs, and posterior aspect of the head, impulses travel along spinal nerves into the spinal cord. Their cell bodies are in the dorsal root ganglia or the sensory ganglia of cranial nerves. The central process of these neurons will synapse on 2nd order neurons.

2. Second-order neurons conduct impulses from the brainstem and spinal cord to the thalamus. Axons of 2nd order neurons decussate (cross over to the opposite side) in the brainstem of spinal cord before ascending to the ventral posterior nucleus of the thalamus. Thus, all somatic sensory information from one side of the body reaches the thalamus on the opposite side. These will synapse on cells (third order neurons) located in the thalamus.

3. Third-order neurons conduct
What is decussation?
crossing over to the opposite side
Where do 2nd order sensory neurons originate and terminate?
o. - cell bodies are in the dorsal horn or various sensory nuclei of the brainstem.
t. - ventral posterior nucleus of the thalamus.
Where do the 3rd order sensory neurons originate and terminate?
o. - thalamus
t. - primary somatosensory cortex
Where do the upper motor neurons originate and terminate?
o. - the motor region of the cerebral cortex or the brain stem
t. - LMN in the ventral horn
Where does the lower motor neuron originate and terminate?
o. - ventral horn
t. - effector (muscle).

What parts of the body are controlled by the visceral system?
blood vesscles, the heart, lungs, and the internal organs
Compare and contrast the autonomic and somatic systems.
1. The somatic nervous system operates under conscious control: the ANS usually operates without conscious control.

2. Sensory input for the SNS is mainly from somatic senses and special senses; sensory input for ANS is from interoceptors, in addition to somatic senses and special senses.

3. The axons of somatic motor neurons extend from CNS and synapse directly with an effector. Autonomic motor pathways consist of two motor neurons in series. The axon of the first neuron extends from CNS and synapses in an autonomic ganglion with the second motor neuron; the second neuron synapses with an effector.

4. The output (motor) portion of the ANS has 2 divisions: sympathetic and parasympathetic. Most body organs receive dual innervation; usually one ANS division causes excitation and the other causes inhibition.

5. SNS effectors are skeletal muscles; ANS effectors include cardiac muscle, smooth muscle, and glands.
Where do the autonomic sympathetic neurons originate and terminate?
?
How many neurons are involved in the autonomic motor nervous system?
?
What comprises the parasympathetic system?
?
What are alternative terminations for the 2nd order sensory pathways?
?
Describe the 3 sensory pathways.
- posterior column-medial lemniscus
- anterolateral p/w
- trigeminothalamic p/w
What type of information is contained in the pathway that synapses in the dorsal horn?
Pain impulses enter the spinal cord, where they synapse primarily on the dorsal horn neurons in the marginal zone and substantia gelatinosa of the gray matter of the spinal cord. This area is responsible for regulating and modulating the incoming impulses. Two different pathways, the spinothalamic and spinoreticular tracts, transmit impulses to the brainstem and thalamus. Spinothalamic input is thought to effect the conscious sensation of pain, and the spinoreticular tract is thought to effect the arousal and emotional aspects of pain.

What type of information is contained in the pathway that synapses in the medulla oblongata?
Information from the skin, skeletal muscle and joints.
What is contained in the posterior column-medial lemniscus pathway?
Nerve impulses for touch, pressure, vibration, and conscious proprioception in the limbs, trunk, neck, and posterior head ascend to the cerebral cortex.
What is contained in the anterolateral (spinothalamic) pathway?
Nerve impulses for pain, temperature, itch, and tickle from the limbs, trunk, neck, and posterior head ascend to the cerebral cortex.
What is contained in the trigeminalthalamic pathway?
Impulses for most somatic sensations (tactile, thermal, pain and proprioceptive) from the face, nasal cavity, oral cavity, and teeth ascend to the cerebral cortex.
What is a nuclei?
A cranial nerve nucleus is a collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerves. Axons carrying information to and from the cranial nerves form a synapse first at these nuclei. Lesions occurring at these nuclei can lead to effects resembling those seen by the severing of nerve(s) they are associated with. All the nuclei excepting that of the IV nerve supply nerves of the same side of the body.
What are cuneate and grassile nuclei?
Cuneate nuclei - A group of neurons in the inferior part of the medulla oblongata in which axons of the cuneate fasciculus terminate.

Grassile nuclei - a group of nerve cells in the inferior part of the medulla oblongata in which axons of the gracile fasciculus terminate.
What are the branches of the trigeminal nerve?
The trigeminal nerve (the fifth cranial nerve, also called the fifth nerve, or simply CNV or CN5) is responsible for sensation in the face. Sensory information from the face and body is processed by parallel pathways in the central nervous system.

The fifth nerve is primarily a sensory nerve, but it also has certain motor functions (biting, chewing, and swallowing). These are discussed separately.

The trigeminal nerve is the largest of the cranial nerves.

Three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory. The mandibular nerve has both sensory and motor functions.

What is a homunculus (sensory cortex map)?
A body map based on the amount of cerebral cortex used to process sensory receptors.
Describe the corticospinal pathway.
(Upper Motor Neurons)
Fibers from precentral gyrus and nearby cortical areas descend through the internal capsule, cerebral peduncles, pons, and pyramids.
Most cross in pyramidal decussation in caudal medulla and form lateral corticospinal tract.
Uncrossed fibers (anterior corticospinal tract) will cross in the anterior white commissure before ending in the spinal gray matter.
Describe the corticobulbar pathway.
- white matter pathway connecting the cerebral cortex to the brainstem. The 'bulb' is an archaic term for the medulla oblongata; in modern clinical usage, it sometimes includes the pons as well. The word 'bulbar' therefore refers to the nerves and tracts connected to the medulla, and also by association to the muscles thus innervated, those of the tongue, pharynx and larynx.

Function
The muscles of the face, head and neck are controlled by the corticobulbar system, which terminates on motor neurons within brainstem motor nuclei. This is in contrast to the corticospinal tract in which the cerebral cortex connects to spinal motor neurons, and thereby controls movement of the torso, upper and lower limbs.



Where does movement initiate?
- in the primary motor area of cerebral cortex.

- primary motor area is in the frontal lobe just anterior to the central sulcus