Test 4 FINAL Flashcards
(98 cards)
1
Q
The brain:
A
-3 pounds and 2% of your body weight
-the number of neurons is the reason humans have superior cognitive skills
-the surface of the brain is the cerebral cortex and is made of neuronal cell bodies(gray)
2
Q
What structures protect and nourish the brain?
A
The meninges, the blood-brain barrier, the cerebral arteries, and the waste removal
3
Q
a. The meninges
A
-adds another layer of protection for the brain
-going in, you have the scalp, the skull, the dura mater, the arachnoid mater, subarachnoid space filled with blood vessels, the CSF, and the pia mater(innermost layer). The brain floats on this watery surface.
***Blood vessels that run on the surface of the brain are located on top of the pia mater in the subarachnoid space
4
Q
b. Blood-brain barrier
A
-the cells of the capillaries and the cells surrounding the brain form a selective blood-brain barrier.
5
Q
What is the function of the blood-brain barrier?
A
-prevents most pathogens, bacteria, and viruses from leaving the bloodstream and entering the brain. Also limits or eliminates the effects of many drugs on the brain (except hallucinogens)
6
Q
What is the body’s way around the blood-brain barrier?
A
the circumventricular organs, create an alternative route for the neuropeptides and hormones
7
Q
c. Cerebral arteries
A
Bring oxygenated blood to the heart to the brain, and the veins carry deoxygenated blood from the brain back to the heart. The two arterial systems are
-the internal carotid arteries
- the vertebral arteries
8
Q
d. waste removal
A
the VENOUS system acts as a waste disposal system, carrying both deoxygenated blood from the brain and old or used CSF from the ventricular system. The venous system dumps both products into the internal jugular veins, where they return to the heart.
9
Q
a. Prominent fissures (what is a fissure?)
A
it is a deep groove.
10
Q
what is the longitudinal fissure?
A
separates the two hemispheres
11
Q
what is the central fissure?
A
separates the frontal lobe from the parietal lobe
12
Q
what is the lateral (Slyvian) fissure?
A
separates the parietal lobe from the temporal lobe
13
Q
What is agyria and what happens when you have it?
A
condition that result in a smooth brain. It causes severe motor, intellectual, and psychological disability.
14
Q
frontal lobe
A
functions- reasoning, planning, and voluntary motor movement
15
Q
Parietal lobe
A
function- sensory perception and sensory interpretation
16
Q
Temporal lobe
A
function- some memory is housed here, also processing and understanding of auditory information
17
Q
Occipital lobe
A
function- visual processing
18
Q
For approximately 85% of the pop., the ____ hemisphere operates for lang., and the ____ hemisphere functions for such extra-linguistic features such as stress and intonation
A
left, right
19
Q
what do the myelinated fibers do?
A
-the myelinated fibers form the medullary center of the brain and account for all the inter- and intrahemispheric axonal connections. These connections account for the efficiency with which external info is analyzed, synthesized and transferred from one place to another and adequate responses are formulated and executed.
-These interconnecting fibers keep all brain areas informed of data processed, decisions made, activities undertaken and actions performed.
20
Q
what are the three broad types/fibers of the medullary center?
A
- projection fibers
- association fibers
- commissural fibers
21
Q
- what are projection fibers?
A
-travel vertically to connect the cortex (brain’s outer layers) with the brainstem and the spinal cord structures.
-course down from Corona Radiata to Internal Capsule, which has 3 important section:
22
Q
what are the 3 important sections when the projection fibers course down from corona radiata to internal capsule?
A
-anterior limb
-genu
-posterior limb
23
Q
what does the anterior limb do?
A
this section contains cortico-pontine fibers that monitor the frontal projections
24
Q
Genu?
A
site of the corticobulbar fibers that descend to innervate the cranial nerve nuclei and play an important role in motor-speech processes
25
Posterior limb:
known to contain the corticospinal fibers that project to the spinal motor neurons
26
what are the two types of projection fibers?
-motor projection fibers (corticospinal fibers and corticobulbar fibers)
-sensory projection fibers
27
Motor projection fibers
-**corticospinal fibers broadly originate from the motor cortex and terminate in the spinal cord**. They form the pyramid in the medulla before crossing the midline and entering the spinal cord
-**corticobulbar fibers originate from the motor cortex and terminate in the brainstem**
28
Sensory projection fibers
these collect cutaneous and proprioceptive sensations from the skin and joints and project into the CNS.
-enter the SC through the dorsal horns
29
2.what are association fibers?
provides efficient bidirectional channels for communication among cortical areas within each hemisphere. They are also important in refined and integrated behavioral responses
-pathology here- results in a disconnection bn areas within a hemisphere
30
what are short association fibers?
U-shaped fibers that bend around a sulcus and connect to adjacent gyri. Arcuate fasciculus.
***The arcuate fasciculus is an important communication link among the lobes. It connects Wernicke’s area (Temporal lobe) to Broca’s area (frontal lobe). Arcuate fasciculus. This pathway is significant to the normal acquisition of language functions.
31
Long association fibers
1. superior longitudinal fasciculus: fiber type that connects the frontal lobe to the occipital lobe. many fibers from the parietal lobe curve around as the arcuate fasciculus and project to the temporal lobe
2. inferior longitudinal fasciculus: connects the temporal lobe with the occipital lobes
3. cingulum: c-shaped AF that connects the medial, frontal, and parietal cortices with the temporal cortex
4. uncinate fasciculus- travels parallel with the inferior longitudinal fasciculus and connects the orbital frontal gyri to the rostral region in the temporal lobe
32
Commissural fibers
these run horizontally and connect the cortical areas in both hemispheres. Most of these fibers are included in the corpus callosum, and the remainder constitute the anterior commissure
33
Corpus callosum (commissural fiber)
**connecting all the corresponding cortical areas in both hemispheres**. The corpus callosum bridges these two hemispheres together.
-the fibers of the CC allow each hemisphere to access memory traces, experiences, and unique learning abilities of the contralateral hemisphere.
- the commissurotomy produces the split-brain, where the hemispheres act independently of one another, separates the corpus callosum to reduce seizures
34
anterior commissure (commissural fiber)
a second fiber bundle that originates from the ventral temporal lobe and connects the amygdaloid complexes in both olfactory systems
35
why is blood supply important?
the brain requires constant blood supply; neurons have high metabolic rates and do not store energy reserves in the form of glycogen, the blood system brings carbs/sugars along with oxygen required to release the energy they carry
-if the blood supply is interrupted either through a blockage or hemorrhage, nerve cells do not receive their needed nutrients, they then die and are not replaced
36
what are the two arterial systems that the brain receives blood from?
1. vertebral arteries- these are paired and travel up the back of the neck, and enter the cranial cavity at the foramen magnum
2. Carotid arteries- also paired, they pass up anteriorly through the neck and give off bilateral internal carotid arteries, the internal carotids enter the cranial cavity at the level of the hypothalamus. The external carotids travel up and go towards the face.
37
A. Vertebral arteries
after they pass through the foramen magnum, the 2 vertebral arteries lie on the ventral surface of the medulla, each gives off a large branch
38
1. Posterior inferior cerebellar artery?
brings blood to part of the medulla and to the posterior inferior portion of the cerebellum
-the 2 vertebral arteries join back together, forming the midline basilar artery
39
2. Midline basilar artery?
this artery gives off 2 pairs of large arteries, the anterior cerebellar arteries and the superior cerebellar arteries
40
a. anterior cerebellar artery
(1 of the large arteries of the midline basilar artery) supplies part of the *medulla and pons,* and the anterior portion of the cerebellum
41
b. superior cerebellar arteries
(1 of the large arteries of the midline basilar artery) supplies the entire superior surface of the cerebellum
42
both the ____ and ____ arteries give off smaller arteries that go to the adjacent portions of the Medulla and Pons
cerebellar and basilar
43
The basilar artery terminates at the upper level of the ____ where it_____ into 2 ________ ______ arteries
Pons, bifurcates, posterior cerebral
44
3.Posterior cerebral arteries
these carry blood up to the posterior portions of the cerebral hemispheres, primarily to the occipital lobes and ventral and medial portions of the temporal lobes
45
B. Internal carotid arteries?
as these arteries enter the cranial cavity, each pair gives off a small posterior communicating artery which passes posteriorly and then joins the posterior cerebral arteries
46
1. Posterior communicating artery
these pass posteriorly and join the posterior cerebral arteries (communicating arteries)
-the internal carotid also gives off small, ophthalmic arteries which follow the optic nerves of the retina of the eye
47
2. Ophthalmic arteries
these follow the optic nerves to the retina of the eye
-the largest portion of each internal carotid artery continues to the lateral sulcus as the middle cerebral artery
48
3. Middle cerebral artery
--the MCA courses in the lateral sulcus and gives off many branches, some go to large areas of the lateral surface of the cerebral hemisphere, and others go into the deep substance of the cerebral hemispheres and the diencephalon
-just before entering the lateral sulcus, each middle cerebral artery gives off a slightly smaller branch called the *anterior cerebral artery*
49
4. Anterior cerebral artery
each of these courses along the medial surface of hemispheres, going anterior to then superior to the corpus callosum, their branches go to the medial surface of the frontal and parietal lobes
-before reaching the medial surface of the hemisphere, the 2 anterior cerebral arteries are interconnected by a *small anterior communicating artery*
50
5. Small anterior communicating artery
runs from one anterior cerebral artery to the other
51
d. Circle of Willis
on the brain's interior surface lies a roughly circular arrangement of interconnected arteries called the circle of willis that joins the arterial supply of the brain's 2 arterial systems (vertebral and internal carotids)
52
What are the connections between blood vessels (between arteries particularly)?
**Anastomoses**- a functional adaptation that provides an alternate vascular route to vital organs in case an artery is blocked; blood can flow in either direction depending on where the blood pressure is greater
53
Frontal lobe
largest lobe, contains the prefrontal cortex, broca's area, premotor cortex, and primary motor cortex
54
Prefrontal cortex
associated with cognition, personality, decision making, social behavior, executive control (**goal-directed behavior**, includes restraint, initiative, and order)
55
damage to prefrontal cortex
lateral region: depressive apathetic profile
anterior and medial regions: manic impulsive profile
56
Broca's area
-**-Broadmann's Area 44 & 45**
located near the edge at the lateral fissure, 2 main parts
-pars triangularis (support interpretation of language, especially the planning of verbal responses)
- Pars opercularis (initiates and coordinates speech organs for the production of lang.)
57
Damage to Broca's area
causes **broca's aphasia** (lang. disorder that causes limited verbal output) can also see co-occurring **apraxia of speech**(programming disorder that includes difficulty planning articulators for speech
58
Premotor cortex
involved in selecting and planning complex voluntary motor movements of the body (can be speech, hand and finger movements, hand-eye coordination)
59
Damage to the premotor cortex
**apraxia**; patients have trouble completing motor commands and tasks because they can't recruit the motor plan to execute the task
-Ex: showing a peace sign when asked to salute
60
Primary motor cortex
activates motor plans of areas 44 and 6 by sending motor signals to muscles to move
61
damage to the primary motor cortex
hemiparesis/hemiplegia (one-sided weakness or paralysis)
62
Parietal lobe
concerned with spatial orientation and cross-modality integration; contained within this lobe is the primary sensory cortex, somatosensory association cortex, angular gyrus, and the supramarginal gyrus
63
primary sensory cortex
processes, receives, and perceives, sensory info from the body
- processes somatosensory info such as vibration, proprioception, fine touch, pain, temperature, and stereognosia
64
Primary Sensory Cortex
Damage
results in **astereognosis**, loss of pain, touch, or proprioceptive sensation; also, where the phantom limb syndrome occurs
65
somatosensory association cortex
influences the *fine motor movements* needed for fluent speech by providing sensory feedback; research has also shown that this area also contains a writing circuit
66
Angular gyrus
lang area associated with **reading and math abilities**
Damage here results in reading disorder (*dyslexia*), disorders of math (*dyscalculia*), and disorders of lang. (*dysphasia*).
67
supramarginal gyrus
(parietal) inolved in phonological system (stores auditory representations of phonemes and phonemic combinations)
68
Damage to the supramarginal gyrus
phonological dyslexia (difficulty sounding out unfamiliar or nonsense words)
- ex: phope read as phone; unfamiliar words can often be misperceived as other known words
69
Occipital lobe
contained within this, you have visual cortices
-**primary visual cortex** is where visual information is received and processed (contralateral in nature
70
Damage to occipital lobe
from a stroke, tbi, etc can result in blindness, Ex: Anton's syndrome
71
Temporal lobe
contains inferior temporal area, parahippocampal gyrus, fusiform gyrus, Primary Olfactory cortex, primary and secondary auditory cortices, and Wernicke's area
72
Inferior temporal area
associated with reading of facial emotions as well as auditory hallucinations
73
Parahippocampal gyrus
contains the hippocampus, plays a role in declarative memory
74
Fusiform gyrus
important for naming objects as well as recognizing and remembering the object; acts as a lexicon
Damage-anomia (word recall difficulty)
75
Primary olfactory cortex
receives and processes sensory info from nose for smell; has connections to the limbic system
76
Primary and secondary auditory cortices
primary auditory cortex (initial cortical region that receives auditory info from the auditory pathway and Heschl's gyrus, involved in hearing
-Damage:deafness
77
Wernicke's area
**AREA 22**, attaches meaning to auditory info (especially speech and lang.)
Damage- **Wernicke's aphasia** (fluent aphasia that involves issues with auditory comprehension, verbally fluent but filled with jargon and paraphasia. Lang. is incomprehensible, written lang. mirrors spoken lang, with fluidity
78
Cingulate cortex
involved in cognitive control (problem solving), as well as perception of pain, autobiographical memory and managing risky behaviors
-damage- problems with memory and risky behavior
79
Insular cortex
temporal lobe; additional language area, divided into two parts:
**post-dorsal** (sensorimotor functions) and **anterior portion** (specializes in orofacial programs and emotions)
damage- results in global aphasia
80
TBI (caused by blow to the head) what are the two types
1. open head injury-object penetrates the skull and damages the brain
2. Closed Head Injury- force causes brain injury without penetrating skull (two types:
acceleration-deceleration and impact based)
81
Cerebral Palsy
non-progressive brain disorder that affects movement, posture, and balance and possibly speech and/or swallowing
causes: lack of oxygen, prematurity, infections, brain hemorrhages, jaundice, and head injury
82
What are the 4 types of cerebral palsy?
**Spastic** (muscle stiffness), **dyskinetic** (muscle tone), **ataxic** (incoordination), and **mixed** (more than one motor problem)
83
Stuttering
Considered a cerebral disorder due to probable neurophysiological differences in the brains of those who stutter versus those who don’t
84
Pyramidal system
direct voluntary motor system that controls gross motor movement
85
-Extrapyramidal system
indirect motor system that controls involuntary movements; involved in posture, muscle tone, and reflexes as well as the coordination and modulation of movements
86
what are the 8 level division of control?
A. Conceptual level
B. The Planning level
C. The Motor Programming Level
D. Motor control circuits
E. Direct motor pathway (pyramidal system)
F. Indirect Motor system (extrapyramidal system)
G. Final Common Pathway
H. Sensory System
87
1. The conceptual level
we form an intention which involves the entire cerebral cortex with the prefrontal cortex and limbic system playing major roles in the process
88
2. The Planning Level (2 parts)
1. Linguistic planning- non-motor in nature, takes what we want to express and applies language concerning meaning, grammatical structure, and the social way we communicate an expression (form, content, and use). DOMINANT PERISYVIAN REGION IS ENGAGED HERE
2. Motor planning- motor planning for phoneme production takes place. PREMOTOR CORTEX AND SUPPLEMENTARY MOTOR AREAS ARE IMPORTANT IN THIS PHASE
89
3. The Motor Programming Level
Involves the execution of phonemes in time and space; to execute proper production, the speech organs (articulators) must move accurately concerning the articulatory target, timing, muscle tone, and force
--Sensory feedback involving mid-production corrections is also involved
90
4. Motor Control Circuits (2 circuits important to speech)
-**Basal ganglia circuit**: the system is central to the indirect motor system (*extrapyramidal)*, regulates cortically initiated motor activity by modifying it; it refines
movements by suppressing extraneous movements to precise and target motor activity. (They have loops and neurotransmitters that regulate muscle tone and posture to smooth muscle movement.)
- **CEREBELLAR CIRCUIT**: automatically incorporates feedback for coordinating skilled, sequential, voluntary muscle activity. The cerebellum constantly monitors all cortical motor output to muscles by receiving input from the motor cortex, brainstem, reticular reflex networks, and SC. Coordinates movement through a motor feedback loop.
91
5. Direct Motor Pathway (Pyramidal System)
- Involves the following tracts:
-**Lateral Corticobulbar tract** (controls muscles of head and neck & speech muscles),
**Lateral Corticospinal tract**, and **anterior corticospinal tract**
-Betz cell bodies are located in cerebral cortex, and their axons move through either the** lateral corticobulbar** (axons that course through here connect with cranial nerve nuclei in *brainstem*, which then goes to the muscles) or **lateral corticospinal tract** (the axons that move through here synapse directly to the ventral horn cells of *spinal cord *which connects directly to muscles)
-The pyramidal system is voluntary, it controls gross motor movements which are unrefined, it becomes refined through the basal ganglia and cerebellar circuits in the *extrapyramidal system*,
92
Upper motor neurons and what their damage does *direct motor pathway
originate in the motor cortex and terminate in the brainstem/within the SC.
-damage: spastic muscles due to overactive muscle tone (hypertonia) and overactive flexes (hyperreflexia)
93
Lower motor neurons and their damage *direct motor pathway
originate in BS in the cranial nerves or spinal cord in the spinal nerves and terminate at the **neuromuscular junction**
Damage: results in flaccid muscles, hypotonia, and a lack of reflexive movements (hyporeflexia); also might see fasciculations (contraction of some individual muscle fibers but not all within a muscle)
94
Speech issues with pyramidal damage *direct motor pathway
-***Dysarthria***-slurred or uncoordinated speech (spastic and flaccid)
- **Spastic dysarthria**- UMN damage, stiff muscles, speech is strained/strangled with harsh voice, monopitch, hypernasality, slow speech rate, and imprecise consonants
- **Flaccid dysarthria**: LMN damage, flaccid muscles, resulting in speech with a breathy voice, mono pitch, and short phrases
95
6. Indirect Motor System (extrapyramidal system)
-Controls involuntary movements involved in posture, muscle tone, and reflexes as well as the coordination or modulation of movements.
**Damage here-** loss of coordination and modulation that leads to dyskinesias (movement disorders): tremors and dystonia (distorted posture)
-speech problems depend on where the damage takes place: **hyperkinetic dysarthria** (too much movements caused by basal ganglia damage, speech is harsh, loud, and imprecise consonants, and distorted vowels) and **hypokinetic dysarthria** (too little or too much dopamine, substantia nigra, too much causes increased impulsivity, too low causes stiff, rigid, and slow movement
96
The tracts of the indirect motor system
Tracts of the indirect motor system:
Tracts in this system:
-**2** originate in the cortex and go down into the brainstem and midbrain:
o Corticoreticular-inputs into Reticular Formation
o Corticorubral-inputs into midbrain
-**4** originate in the brainstem and input in various places along the spinal cord:
o Rubrospinal
o Vestibulospinal
o Reticulospinal (plays a role in swallowing concerning reflexive movement)
o Tectospinal
97
Final Common Pathway
-nerve-muscle relationship
-skeletal muscles have two types of fibers:
1. **Extrafusal fibers**: Alpha motor neurons (facilitate movement; influenced by pyramidal system)
2. **Intrafusal fibers**: gamma motor neurons (involved in proprioception, influenced by extrapyramidal system)
-the muscles that contract for speech have smaller motor units
98
The gamma motor system
firing causes intrafusal fibers to contract, which is detected by
sensors in the fibers; these send sensory signals to brainstem to AMNs, (alpha motor neurons) which then send
motor signals to extrafusal fibers to shorten, matching the length of the intrafusal fibers
-The indirect system keeps muscles prepped for movement
