Descending Tracts , Cerebrum Flashcards
(160 cards)
1
Q
Which descending tract is associated with pathways concerned with voluntary, discrete, skilled movements (especially those of distal parts of limbs)?
A
Corticospinal Tract
2
Q
What is the function of the Reticulospinal tract?
A
It facilitates or inhibits the activity of the alpha and gamma motor neurons in the anterior gray column which can facilitate or inhibit voluntary movements or reflex movements.
3
Q
Which tract is concerned with the reflex postural movement in response to a visual stimuli?
A
Tectospinal tract
4
Q
Which tract is associated with facilitating or inhibiting alpha and gamma motor neurons in the anterior gray column which can facilitate activity of flexor muscle or inhibit activate of extensor or antigravity muscles?
A
Rubrospinal tract
5
Q
What is the function of the Olivospinal tract?
A
Plays a role in muscular activity
6
Q
Which descending tract facilitates activity of extensor muscles by acting on motor
neurons in anterior gray columns, inhibits activity of flexor muscles and is
concerned with postural activity associated with balance?
A
Vestibulospinal tract
7
Q
Which layer of the Cerebral cortex is known as the molecular layer, covered by Pia mater, contains glial cells and horizontal cells of Cajal in the its peripheral portion?
A
Layer 1
8
Q
What is Layer 3 of the cerebral cortex known as and what type of cells are located in this region?
A
It is also known as the External Pyramidal Layer and contains medium sized pyramidal cells.
9
Q
Which layer is known as the External Granular Layer and contains glial cells and small pyramidal cells with apical dendrites facing towards the periphery of the cortex?
A
Layer 2
10
Q
What type of cells are found in Layer V?
A
Glial cells & Large pyramidal cells ( Betz cells in the motor area.
11
Q
What is the other name given to Layer V?
A
Internal Pyramidal Layer
12
Q
Which layer of the cerebral cortex is also known as the Internal Granular Layer and contains mainly small granules cells, glia and some pyramidal cells?
A
Layer IV
13
Q
Which layer of the cerebral cortex is known as the Multiform layer?
A
Layer VI
14
Q
What are the different characteristics of Layer VI of the cerebral cortex?
A
Deepest layer. Adjacent to the white matter. Contains intermixed cells of varying sizes and shapes (granule cells, fusiform cells…). Bundles of axons leave the white matter.
15
Q
Which Broadman area has Giant cells of Betz found in this area?
A
Primary Motor Cortex ( Area 4) occupies Precentral Gyrus
16
Q
True or False? The Premotor Area and Secondary Motor cortex contains no Giant cells of Betz?
A
TRUE!!
17
Q
The Primary Motor cortex is located where?
A
The Precentral Gyrus - ( Broadman Area 4)
18
Q
Where is the Premotor Cortex (Secondary Area) located?
A
Occupies anterior part of precentral gyrus and posterior part of superior, middle and inferior frontal gyri
19
Q
Where does the Primary Motor Cortex( Area 4) receives afferents from?
A
Sensory Cortex
Premotor cortex( Area 6)
Thalamus
Basal Ganglia
Cerebellum
20
Q
Where does the Premotor Area( Secondary motor cortex - Area 6) receives afferents from?
A
Sensory cortex
Thalamus
Basal ganglia
21
Q
Which gyrus & Broadman area is known as the Primary Somesthetic Area?
A
Post Central Gyrus ( Areas 3,1&2)
22
Q
Where do descending fibres converge and pass through?
A
They converge in the corona radiata and pass through the posterior limb of the internal capsule
23
Q
What are the divisions of the internal Capsule?
A
Anterior limb
Genu
Posterior limb
24
Q
True or False? Fibers closest to the genu concerned with cervical portions of the body (i.e., head and neck)
* Fibers situated more posteriorly concerned with upper, then lower extremity
A
TRUE!!
25
Alpha motor neurons innervate?
Extrafusal Muscle fibres
26
Gamma motor neurons innervate?
Intrafusal Muscle fibres
27
What do sensory neurons do?
They carry information from Intrafusal muscle fibres to CNS
28
Where are Intrafusal Muscle fibres found?
Muscle spindles
29
In which lamina are somatic motor neurons localized in?
In lamina IX ( 9)
30
Which type of Muscle fibres have a LOW oxidative capacity?
Type IIB
31
Which type of Muscle fibres have a LOW glycolytic capacity?
Type I fibres
32
True or False? Type I has the largest motor neuron of all three muscle fibres.
FALSE!! Type IIB has the largest motor neuron, Type I has the smallest ,
33
What is the main storage fuel for Type I muscle fibres?
Triglycerides
34
What is the main storage fuel for Type IIa muscle fibres?
Creatine Phosphate and Glycogen
35
What are the main storage fuel for Type II b muscle fibres?
ATP and Creatine phosphate
36
True or False? Type IIa and IIb fibres are rich in myoglobin while Type I fibres are low in myoglobin.
FALSE!! Type I and IIa are RICH in Myoglobin while Type IIb is Low in Myoglobin
37
What colours are the different types of muscle fibres?
Type I - Red ( Rich )
Type IIa - Red ( Rich)
Type IIb - White ( Low)
Red = rich in myoglobin
White = low in myoglobin
38
Fill in the blanks. " Type I muscle fibres are used for ____________ activity while Type IIa and IIB fibres are used for ___________ activity."
Type I - Aerobic activity
Type II a & II b - Short term anaerobic
39
Which muscle type fibres have a very LOW mitochondrial density ?
Type IIB fibres
40
Which muscle type fibres have an Intermediate capillary density?
Type IIA fibres
41
Which muscle type fibres produces a very high power production and are very fast contraction time ?
Type IIB fibres
42
Which muscle fibres have a Low capillary density ?
Type II B fibres
43
Fill in the blanks. " Type I muscle fibres have a ______________ resistance to fatigue while Type IIB muscle fibres have a ____________ resistance to fatigue."
Type I - High resistance to fatigue
Type IIB - Low resistance to fatigue
44
What type of activity involves Type I muscle fibres?
Postural muscles
Long distance running
45
What type of activity involves Type IIa muscle fibres?
Middle distance running and swimming
46
What type of activity involves Type IIb muscle fibres?
Sprinting
47
Which descending tract is dedicated to innervation of motor nuclei of cranial nerves?
Corticonuclear or corticobulbar tract
48
Which descending tract provides a pathway by which hypothalamus can control sympathetic outflow and sacral parasympathetic outflow?
Reticulospinal tract
49
Where is the Red nucleus situated ?
In the Tegmentum of the midbrain at level of superior colliculus
50
Fill in the blanks. " The red nucleus receives Afferent impulses through connections with __________ & __________."
Cerebral cortex and Cerebellum
51
Where are higher centers of CNS associated with control of autonomic activity situated?
Cerebral cortex
Hypothalamus
Amygdaloid complex
Reticular formation
52
Fill in the blanks ." In relation to the descending autonomic fibres, Fibers arise from higher centers and cross midline in the _________."
Brainstem
53
Where do fibres of the Rubrospinal tract cross the midline?
At the level of the red nucleus
54
Where do fibres from the Tectospinal tract arise from?
Superior colliculus in the midbrain
55
Where do the Central cortex and Central nuclei of the cerebellum receive afferents from?
* From extensive areas of contralateral neocortex (by way of corticopontine – frontopontine, temporopontine- and then pontocerebellar –transverse pontine- projections)
*From ipsilateral proprioceptors in muscles, tendons and joints
(by way of anterior and posterior spinocerebellar and cuneocerebellar tracts)
*From vestibular apparatus
56
Where does the Cerebellar nuclei send its Efferent fibres to?
* Contralateral Thalamus ( Ventral lateral nucleus projecting on area 4
* Red nucleus
* Reticular formation bilaterally
* Ipsilateral vestibular nuclei
57
Where does the Inferior Olivary complex receive its AFFERENT fibres from?
Neocortical motor areas
Red nucleus
Spinal cord
58
Which nuclei relays information from spinal cord, vestibular nuclei
and cerebral cortex?
Precerebellar reticular nuclei
59
True or False? The corticospinal tract is not myelinated in infants.
TRUE!!
60
A lesion of the coticospinal tract ( pyramidal tract ) can present with what signs?
* Babinski sign
* Sometimes: absence of superficial abdominal reflexes (induced by stimulation with a safety pin on the abdomen).
* Sometimes: absence of cremasteric reflex. Cremaster muscle fails to contract when skin of medial side of thigh is stimulated.
* Loss of performance of fine-skilled voluntary movements, specially at distal end of limbs
61
What are the signs of a Extrapyramidal tract lesion?
* Muscle weakness of upper limbs (extensors) or lower limbs (flexors) with
little or no muscle atrophy (except secondary to disuse)
+ Spasticity or hypertonicity of muscles. Lower limb maintained in extension
and lower limb in flexion
+ Exaggerated deep muscle reflexes (faster and more brisk than in normal
patients
+ Sometimes: patella clonus
+ Stretch reflex: clasp-knife reaction. When passive movement of a joint is
attempted, there is resistance owing to spasticity of muscles. Muscles,
on stretching, suddendly give way
62
Where are upper motor neurons lesions take place?
Lesion of neural pathway above anterior horn cell of spinal cord or motor
nuclei of cranial nerves
63
Where do lower motor neurons lesions occur?
Lesions due to destruction (degeneration) of cell body in anterior gray column
or its axon in anterior root or spinal nerve
64
What are the symptoms s of a lower motor neuron lesion?
+ Muscle weakness (but with flaccidity)
+ Hypotonia
+ Decrease or loss of reflexes (hyporeflexia or areflexia)
+ At later time points: fasciculations (twitching of muscles), fibrillations
+ Muscle wasting/amyotrophy
+ Muscular contractures
+ Changes in skin, nail, hair (signs of end-stage muscle denervation)
+ Only muscles innervated by the damaged nerves will be symptomatic
+ No Babinski sign
65
What are examples of Lower motor neuron lesions diseases?
Motor neuron disease
. Adult: amyotrophic lateral sclerosis in adults: ALS – Charcot’s disease
. Children: spinal muscular atrophy (SMA) in infants caused by anomalies in
the SMN1 gene: SMA type I: Werdnig-Hofmann disease, SMA type II and III,
congenital SMA with arthrogryposis
+ Post-polio syndrome
+ Pseudobulbar palsy and progressive bulbar palsy
+ Spinal cord injury with nerve root compression
+ Poliomyelitis (affecting anterior horn cell)
+ Peripheral neuropathy (diabetic, alcoholic, inherited – i.e., Charcot-Marie-Tooth-,
gammopathy)
+ Guillain-Barre syndrome
66
The cerebral hemispheres are separated by what structure?
Longitudinal cerebral fissure
67
What is the name of the structure that connects right and left hemispheres of the brain?
Corpus callosum
68
What is the name of the fold of dura mater that separates the Cerebellum from the Cerebral hemispheres?
Tentorium cerebelli
69
Where is the lateral sulcus ( aka Sylvian fissure) located?
It is on the inferior surface of the hemisphere, extending laterally between the temporal and frontal bone.
70
The lateral sulcus divides into Three rami. What are they?
Posterior Ramus : Main part of the sulcus
Anterior ramus: short distance to frontal lobe
Ascending ramus: Short distance to frontal lobe
71
What is the Sylvian point and where is it located?
It is the nearest point of the skull to the lateral sulcus and it is found 30mm behind the zygomatic process of frontal bone.
72
Where is the Insula located?
It is located on the inferior surface of the hemisphere at the bottom of the lateral sulcus.
73
To what structure was the Insula bounded to in Embryonic life?
Corpus Striatum
74
Which sulcus begins on the posterior end of Corpus callosum?
Calcarine sulcus
75
Fill in the blanks. "The calcarine sulcus is joined at an acute angel by the ___________."
Parieto-occipital sulcus
76
What are the structures included in the Basal Ganglia?
* Corpus striatum composed of: caudate nucleus and lentiform nucleus
(in some books, nucleus accumbens included)
* Amygdaloid nucleus
* Claustrum [connects cortical (i.e., prefrontal cortex) to subcortical (i.e., thalamus) structures]- Role unknown
77
Which gyrus found in the Temporal lobe is associated with a receptive language area which extends in Parietal lobe?
The posterior part of the Superior Temporal gyrus , Planum Temporale"
78
True or False? The Plan Temporale is larger on the right side in Males but not Females.
FALSE!! It is larger on the LEFT side in MALES but not females.
79
What are the names of the regions concealing the insula?
Frontal, parietal and temporal opercula
80
Which sulcus divides the insulation into two regions?
Central sulcus
81
Fill in the blanks. " The Insula is outlined by a ____________."
Circular sulcus
82
What is the name given to the Inferior part of the Insula ( in region of stem of lateral sulcus ?
Limen Insulae
83
What separates the Lentiform nucleus from the Insula?
The external and extreme capsules with the Claustrum between
84
Fill in the blanks. " The cortex of the insula is involved in _______."
Involuntary activities such as control of viscera by autonomic nervous system.
85
What is the name of the structure that separates the Cingulate gyrus from the Corpus Callosum?
Callosal sulcus
86
Fill in the blanks. " The cingulate gyrus is separated from the superior frontal gyrus by __________."
The cingulate sulcus
87
What structure is found between the collateral sulcus and the calcarine sulcus?
Lingual gyrus
88
What structure is located Medially to the Olfactory sulcus?
Gyrus Rectus
89
What structure is located Laterally to the Olfactory sulcus ?
Orbital Gyri
90
What condition can arise if there is a Lesion located in the Medial Occipitotemporal gyrus ( Fusiform gyrus) ?
Prosopagnosia: disorder of face perception
(no recognition of familiar faces)
91
Which gyrus extend from the Occipital Pole to the Temporal Pole?
Medial occipitotemporal gyrus (fusiform gyrus)
92
What lines the lateral ventricles and what substance is it filled with?
It is lined with ependyma and filled with CSF
93
What structures does the Lateral ventricle communicate with the cavity of the third ventricle?
Through the inter ventricular foramen
94
Which structures make up Broca's speech area ?
Pars Opercularis and Pars Triangularis
95
What Broadman's number is Broca's speech area?
Broadman's Area 44&45
96
A lesion in Broca's speech area would cause ?
Expresssive Aphasia aka Non- Fluent Aphasia
97
Which structures are made up of commissural fibres ?
+ Corpus callosum
+ Anterior commissure
+ Posterior commissure
+ Fornix
+ Habenular commissure
98
What is the largest commissure?
Corpus callosum
99
What is the main tract in non-placental animals?
Anterior Commissure
100
True or False? Corpus callosum is ONLY found in Placental animals.
TRUE!!
101
The habenular nuclei receives afferent fibres from?
Amygdaloid nucleus and hippocampus
102
Which commissure is related to the inferior part of stalk of Pineal gland?
Posterior commissure
103
What is the Efferent system for the hippocampus that passes to the maxillary bodies?
Fornix
104
What is the function of the Comissure of the fornix?
It connects hippocampal formations of both sides.
105
Which association fibers has the largest bundle of nerve fibres?
Superior longitudinal fasciculus
106
Which association fiber connects the Primary motor speech area and gyro of the inferior surface of the Frontal lobe with the cortex of Temporal lobe?
Uncinate Fasciculus
107
What is the function of the Cingulum ?
It is a fasciculus found in the white matter of the Cingulate gyrus that connects the frontal and parietal lobes with the Hippocampal area.
108
Which association fibres connects the anterior part of the frontal lobe with the temporal and occipital lobes?
Superior longitudinal fasciculus
109
Which association fibres connects the frontal lobe with the occipital and temporal lobe ?
Fronto-Occipital fasciculus
110
What is the function of the Inferior longitudinal fasciculus?
It runs from the Occipital lobe to optic radiations
111
What are projection fibres?
Afferent and efferent nerve fibers passing to and from cerebral cortex must travel between large masses of of nuclei of gray matter.
112
Fill in the blanks. " The internal capsule is flanked medially by __________ &_____________ and laterally by the _________."
Medially - Caudate nucleus & Thalamus
Laterally - Lentiform nucleus
113
What are optic radiations ?
These are nerve fibers lying within most posterior part of posterior limb of internal capsule radiating towards calcarine sulcus.
114
Which part of the Internal capsule is located beneath lenticular (lentiform) nucleus with tracts involved in
auditory pathway from medial geniculate body to primary auditory cortex (Brodmann areas 41 and 42)?
Sublenticular portion
115
What is the blood supply for the Telo Chordiae?
Choroidal branches of ICA and Basillary arteries
116
A lesion in the Premotor area results in what condition?
IDEOMOTOR APRAXIA : deficits in ability to plan or complete motor actions. Able to explain how to perform an action, but unable to act out a
movement such as "pretend to brush your teeth“. However, automatic-voluntary dissociation. For example, they may not be able to pick up a phone when asked to do so, but can perform the action without thinking when the phone rings
117
What Broadman/s area is the Frontal Eye field?
Broadman area 8 &9
118
Where is the Supplementary motor are located?
It is located in the medial frontal gyrus on medial surface of hemisphere, anterior to paracentral lobule.
119
Where is the Frontal eye field located?
Extends from facial area of precentral gyrus into middle frontal gyrus (areas 8 and 9)
120
What is the function of the Aslant fasciculus ?
It connects superior frontal gyrus , (SFG), specifically the pre-supplementary motor area (pre-SMA), supplementary motor area
(SMA), and lateral SFG to the pars opercularis and pars triangularis and the anterior insula
121
Fill in the blanks. " _____________ connects the prefrontal area to the cerebellum through the Pontine nuclei."
Frontopontine fibres.
122
Which area of the brain is concerned with an individual's personality?
Prefrontal cortex
123
What connects the prefrontal cortex in both hemispheres?
Commissural fibers of forceps minor and major of corpus callosum
124
At what age does the prefrontal cortex mature?
Age 25 years
125
Where is the Secondary somesthethetic area located?
The superior lip of the posterior limb of lateral fissure
126
What is the main function of the Somesthetic association area?
To receive and integrate different sensory modalities
- Relates to past sensory experiences
127
An injury to the Somesthetic Association area can lead to what condition?
Astereognosis (or tactile agnosia if only one hand is affected) is the inability to identify an object by active touch of the hands without other sensory input, such as visual information.
Injury can also lead to apraxia
128
Where is the Somesthetic association area located ?
In the Superior Parietal lobe ( Area 5& 7)
129
Which Broadman area is the Primary Visual cortex?
Area 17
130
Where does the Primary Visual cortex receive afferent fibres from?
Lateral Geniculate body
131
What is the area for most perfect vision?
Macula lutea
132
Broadman area 18 & 19 is what area?
Secondary Visual Area
133
What is the function of the Secondary Visual Area?
To relate visual information received by primary visual area to past visual experiences.
134
What is the function of the Secondary Visual Area?
Associated with movements of the eyes when following an object .
135
What Broadman's area number is the Primary Auditory Area?
Areas 41 ( Granular layer) & 42 ( Homotypical layer)
136
Fill in the blanks. " The anterior part of the Primary Auditory area is associated with ____________ while the posterior part is associated with _________."
* Anterior part concerned with reception of sounds of low frequency
* Posterior part: sounds of high frequency
137
What is cortical deafness?
Refers to people who do not perceive any auditory information but whose hearing is intact
138
What is the main function of the Secondary Auditory area ( Area 22) ?
It is necessary for interpretation of sounds and association of auditory input with other sensory information.
139
Where is the sensory speech area of Wernicke?
It is located in the left hemisphere , mainly in superior temporal gyrus
140
What is the name of the association fibre that connects Wernicke's area to Broca's area?
Arcuate fasciculus
141
What is the main function for the Sensory speech area of Wernicke's ?
Permits understanding of written and spoken language. Allows a person to read a sentence, understand it and say it loud.
142
What are the areas of the brain involved with speech?
* Cortex
* Basal ganglia
* Cerebellum
143
Damage to Wenicke's area results in what condition?
Receptive aphasia - patient unable to understand but able to speak.
144
What gene is involved in development of cortex, cerebellum, and basal ganglia, all structures
important in production of speech?
FOXP2
145
Which genes are associated with language?
FOXP2, ERC1 and BCL11A
146
Which part of the brain is associated with complex language functions (i.e. reading, writing and interpretation of what is written)?
Angular Gyrus
147
A lesion in the Angular gyrus results in __________?
Gerstmann syndrome
- Finger tap agnosia, alexia (inability to read), acalculia (inability to use arithmetic operations), agraphia (inability to copy), and left-right confusion
148
Which part of the brain has a role in behaviour & discrimination ?
Association cortex
149
Where is the Supramarginal gyrus located?
It is located at the end of the posterior ramus of the internal capsule
150
Which part of the brain controls empathy towards other people ?
Right supra marginal gyrus
151
What is the function of the Supramarginal gyrus?
It is involved in identifying gestures and postures of other people.
152
What are the different types of Visual Hallucination?
* Charles Bonnet Syndrome: hallucinations of faces or cartoons, lilliputian-type in older people with significant vision loss
* Peduncular-type hallucinations: scary or deformed faces, and heads, people walking in a line, in dark environment
153
What happens when there is a lesion in the Lingual gyrus?
Visual memory dysfunction
. Role in word recognition
154
What happens when there is a lesion in the Parahippocampal gyrus?
Patients cannot visually recognize scenes even though they can recognize
the individual objects in the scenes (such as people, furniture, etc.).
Often considered the complement of the fusiform gyrus
155
What aspects are controlled by the dominant hemisphere of the brain?
Handedness, perception of language, speech
156
What aspects are controlled by the non-dominant hemisphere of the brain?
Spatial perception, recognition of faces and music
157
True or False? More than 90% of population is right-handed and left hemisphere dominant.
TRUE!!
158
What are the 5 A's of Dementia ?
+ Aphasia ( can't communicate properly): expressive (Broca area- Frontal lobe) or receptive (Wernicke area- Temporal lobe)
+ Amnesia ( memory loss) : Hippocampus (Temporal lobe)
+ Apraxia (unable to perform tasks or movements when asked, ) - --- (either premotor cortex or posterior parietal cortex)
+ Agnosia ( a patient is unable to recognize and identify objects, persons, or sounds using one or more of their senses ) ---- (mainly occipitotemporal border, but also posterior parietal cortex)
+ Abstract thought disturbances: inferior frontal gyrus and middle temporal gyrus
159
What is the name given to the posterior part of the Superior Temporal gyrus?
Planum Temporale
160
