Chapter 1 Flashcards
Building blocks of the nervous system
Neurons
2 kinds of nerve fibers
Dendrites & Axons
Dendrites
afferent (sensory)
Axons
efferent (motor)
Neurotransmitter for movement
Acetylcholine (ACH)
Central Nervous System (CNS)
Brain & Spinal Cord
Peripheral Nervous System (PNS)
Cranial Nerves (12) & Spinal Nerves (31)
“Relay Station”
Thalamus- integrates sensory info and relays it to cortical areas. Receives info about motor impulses from basal ganglia & cerebellum and relays these to the motor areas of the cortex
Structures of the basal ganglia
caudate nucleus, lenticular nucleus (putamen & globus pallidus). Also, subthalamic nuclei & substantia nigra
Basal Ganglia
Plays an important role in inhibition and facilitation of movement. Damage can lead to unusual posture, involuntary movements (dyskinesias) and dysarthrias
Interconnected cavities filled with cerebral spinal fluid (CSF)
Cerebral Ventricles
Structure that produces CSF
Choroid plexus - contained in the ventricles
Four Ventricles
2 lateral ventricles are the largest and found below the corpus callosum, foreman of munro connects them to the 3rd ventricle, and the cerebral aqueduct connects it to the 4th ventricle.
Communication fiber tracts in the CNS (3)
Projection fibers, commissural fibers, and association fibers
Projection fibers
Transmit sensory (afferent) info to the brain from peripheral organs, transmit motor (efferent) info to muscles from the cortex
Corona Radiata
Projection fibers near cortex that are arranged in a fan like area
Internal Capsule
When projection fibers reach the level of the thalamus and basal gaglia they become compacted and concentrated in this area
Projection fiber pathways
Pyramidal pathway, extrapyramidal pathway, & vestibular-reticular system
Pyramidal pathway
Passes through area called pyramids in the brain stem and is responsible for initiating most skilled volitional movements
Groups of nerve fibers of the pyramidal pathway (2)
Corticalbulbar tract & corticalspinal tract
This group of nerve fibers sends neural info from cortex to cranial nerves via synapses w/ cranial nerve neurons in brain stem
Corticalbulbar tract
This group of nerve fibers sends neural info from cortex to spinal nerves via synapses with spinal nerves in spinal cord
Corticalspinal tract
Upper Motor Neurons (UMN)
The cell bodies of the corticalbulbar and corticalspinal tracts make up the UMN’s are located around the primary motor cortex
Lower Motor Neurons (LMN)
The axons of the corticalbulbar and corticalspinal tracts synapse at the level of the brain stem and spinal cord with neurons then travel to the cranial or spinal muscles
These fibers help maintain communication among structures within a hemisphere (intrahemispheric fibers)
Association fibers
This association fiber connects Broca’s area and Wernicke’s area
Arcuate Fasciculus (superior longitudinal)
These fibers connect corresponding areas of both hemispheres (intrehemispheric connectors)
Commissural fibers
Most important commissural fiber
Corpus Callosum - damage results in a disconnect between the two hemispheres
Logitudinal fissure
Separates the two hemispheres of the cerebrum
Fissure of Rolando
(Central sulcus) - divides anterior half of brain from posterior half
Sylvan fissure
(Lateral cerebral fissure) begins at the inferior frontal lobe and moves laterally/upward, areas around this fissure are important for speech
2 functional categories of the cortex
Primary cortex & association areas
Primary cortex
Responsible for specific motor or sensory info
Association areas
Responsible for interpreting sensory info and planning motor activity
Primary motor cortex
(Precentral gyrus)- Located in frontal lobe, controls voluntary movements of opposite side of body
Broca’s Area
Located in the left, posterior part of the frontal lobe at the juncture of the lateral and central fissures, important for controlling motor movements involved in speech
Premotor cortex
Frontal association area in front of the primary motor cortex important for planning and initiating complex voluntary movements
Primary sensory cortex
(post central gyrus) located in the parietal lobe just behind the central fissure and is a strip controlling and integrating somesthetic sensory impulses
Two gyri in the parietal lobe that are important for speech and language
Supramarginal gyrus & angular gyrus
Damage to the supramarginal gyrus
Could cause agraphia (difficulty writing) or conduction aphasia
Dame to the angular gyrus
Could cause naming, reading, writing difficulties as well as transcortical sensory aphasia
Parietal association area
Important for processing tactile information
Important gyri in the temporal lobe (3)
Superior temporal gyrus, middle temporal gyrus, and inferior temporal gyrus
Primary auditory cortex
Located in the temporal lobe important for receiving and interpreting auditory info
Wernicke’s Area
Located (partially) in the temporal lobe and is important for comprehending speech, written material, processing semantic and syntactic info, and nonverbal sounds
Temporal association area
Important for discriminating and processing auditory info and for language related processes
How voluntary movement occurs (7 steps)
- The premotor cortex makes a plan for the intended movement and codes it in a way the primary cortex will understand. (Note Broca’s area is the lower part of the premotor cortex.)
- The plan is sent to the primary cortex.
- The primary motor cortex sends the command and control information needed to execute the plan down through the brain via the pyramidal tract.
- If the info is for speech muscles the info is sent via the corticobulbar tract to the cranial nerves.
- -or–If the info is for other body movement it is sent via the corticospinal tract to the spinal nerve. - The vestibular-reticular system adjusts balance and posture before and during the movement.
- The cerebellum modulates the rate, force and direction of the movement.
- The extrapyramidal system adjusts muscle tone and posture to make the movement smooth and continuous.
Protective layers of the brain (bones, membranes, and fluids)
Skull, Meninges (membranes), and CSF
Skull
Encloses brain, brainstem inside a space called the cranial vault with the foramen magnum allowing the brain stem to connect to the spinal cord
Meninges 3 layers
Dura mater- most superficial, arachnoid mater- middle, pia mater- attached to the brain
Associated spaces around the meninges
Epidural – between inner bone of skull and dura, Subdural – beneath dura,
Subarachnoid – between arachnoid and pia mater- surrounds brain and spinal cord, connected to interior of brain through ventricular system and is filled with CSF
