MOTOR SYSTEM Flashcards
Explain motor system
Motor system is the part of the central nervous system responsible for voluntary and involuntary movements
The motor system comprises brain regions such as?
- Primary motor cortex
- Basal ganglia
- Cerebellum
- Spinal cord
What is the role of the brain stem in control of motor function?
The brainstem manages basic motor functions like posture and balance.
Talk about the cortical control of motor function?
The primary motor cortex, located in the frontal lobe of the brain, particularly the precentral gyrus.
Is responsible for voluntary movements.
Talk about the basal ganglia?
The basal ganglia are groups of nuclei situated deep in the brain. They are involved in the regulation of voluntary motor movements or habits.
(They are the backstage crew, making sure every action goes in without a hitch.
Another name for the limbic system is?
Paleo mammalian cortex
Functions of the limbic system?
The limbic system plays a role in
1. Emotions
2. Motivation
3. Olfaction
4. Behaviour
The limbic system consists of?
- Thalamus
- Hypothalamus
- Basal ganglia
- Cingulate gyrus
- Hippocampus
- Amygdala
Mention some clinical disorders associated with dysfunction of the limbic system
- Epilepsy
- Anxiety disorder
- Dementia
- Autism
The entorhinal cortex is a part of the cortical structures of the limbic system.
What does it do?
It interfaces between the hippocampus and neo cortex
The fornix is a cortical structure of the limbic system.
What does the fornix do?
Fornix is a white matter structure connecting hippocampus and brain structures such as mammillary bodies and septal nuclei.
What are some other structures in the sub cortical areas of the limbic system?
- Septal nuclei
- Hippocampus
- Amygdala
- Nucleus Accumbens
Septal nuclei is considered?
A pleasure zone
The hippocampus is associated with?
Consolidation of new memories and spatial environment.
The nucleus Accumbens is associated with?
The nucleus Accumbens is associated with Reward, pleasure and addiction
What role does the medial forebrain bundle play?
The medial forebrain bundle connects the hypothalamus to the limbic system, the frontal lines, septal nuclei and the brainstem reticular formation.
What connects the hypothalamus and the thalamus
The mammillothalamic fasciculus
The lentiform nucleus is composed of?
Putamen and Globus pallidus
What are the subdivisions of the amygdala?
- A large ventrolateral component containing the central and basolateral nuclei
- The dorsomedial division containing the corticomedial nucleus.
Random thing to know?
The Stria terminalis (amygdalo-hypothalamic fibre) carry autonomic and neuroendocrine information.
Talk about the Thalamus
The thalamus is located at the centre of the limbic system. It is the confluence (just like a secretary) of many neural pathways connecting to the cerebral cortex.
The Thalamus also maintain alertness and directs a person’s attention to sensory events.
Damage to the thalamus can cause?
- Motor impairments
- Tremors
- Attention problem
- Insomnia
- Memory loss
- Vision low or light sensitivity
- Disorders of the motor system
- Coma
Explain the Basal ganglia?
The basal ganglia are structures located at the top of the midbrain.
They regulate voluntary movements and maintenance of balance and posture..
The basal ganglia are also involved in cognitive and emotional behaviour linked with formation of habits and addictions.
What does the cingulate gyrus do?
Cingulate gyrus is part of the limbic cortex (the outermost region of the limbic lobe).
It is believed to;
1. Regulate emotions(primarily aggression)
2. Pain,
3. Control autonomic motor function
The frontal portion like sight and smell with memories of precious emotions.
Explain the Hippocampus?
The hippocampus is primary thought to be involved in storing long term memories and in spatial processing and navigation.
The hippocampus is also known as a site for neurogenesis, where nerve cells are created from adult stem cells
Damage to the Hippocampus would cause?
Memory impairment and Anterograde amnesia
In detail, discuss the Amygdala?
Amygdala is a small almond shaped structure that exists in 2 parts, each located in front of the corresponding Hippocampus in it’s respective temporal lobe.
It helps evaluate emotional Valence of situations, recognise threats and prepare the body for fight-or-flight reactions by increasing heart rate and breathing rate
Due to its close proximity to the Hippocampus, the Amygdala helps modulate memory storage. Especially memories adjusted with strong emotions
In simple terms, it gives colour to memories
Damage to the Amygdala would cause?
- Higher levels of aggression, irritability, poor emotional control, and inability to recognise emotions.
- It also affects a person’s ability to recognise fear, resulting in more risk taking.
Explain Panic attacks?
Panic attacks are brief spontaneously recurrent episodes of terror that generate a sense of impending disaster without a clearly identifiable cause
What is the anatomical area for face recognition and memory?
It is the multi-modal association area of the infero-temporal cortex.
The surgical removal of the hippocampus is called?
Hippocampectomy
The surgical removal of the Amygdala is called?
Amygdalectomy
Structural or functional bilateral amygdalectomy would lead to?
- Loss of fear
- Increased obedience
- Non-aggression
- Oral exploration of objects
- Hypersexuality
- Loss of emotionality
- Visual agnosia
- Bulemia
Male sexual behaviour is predominantly controlled by?
The medial pre-optic area of the hypothalamus.
How does the limbic system play a role in sexual behaviour in female?
Increased release of dopamine in the Amygdala also triggers sexual behaviours by increasing progesterone signalling in females
A lesion of the Amygdala caused by calcium deposits in the Amygdala is called
Urbach-wiethe Disease
The bilateral removal of the Amygdala would cause?
Kluver-Bucy syndrome
What are neurotransmitters?
Neurotransmitters are the brains chemical messengers, they orchestrate everything from muscle movement to mood.
Mention some neurotransmitters?
- Dopamine
- Acetylcholine
- GABA
- Glutamate
- Serotonin
- Norepinephrine
Talk about Dopamine?
In motor control, Dopamine fuels the basal ganglia (especially striatum) to promote Smith moment via the direct pathway and suppress unwanted motion via the indirect pathway.
Imbalance(too high, to low) of dopamine leads to?
When dopamine is too little, e.g Parkinson’s,
1. Stiffness
2. Tremors
3. Slowness
Too much dopamine(e.g L-dopa overdose causes
1. Dyskinesia (excessive movement)
Mention another function of Dopamine asides motor control?
- Dopamine plays a role in reward, motivation and learning.
Acetylcholine and it’s role in motor control?
In motor control, acetylcholine activated muscles at the Neuromuscular junction. (Somatic motor neurons) And modulates basal ganglia activity (striatal interneurons).
Effects of Imbalance of acetylcholine?
- Overactivity in basal ganglia
- Worsened rigidity
- Blockage which paralyses muscles
Mention other functions of acetylcholine asides motor control.
- It plays a role in Memory, attention, autonomic control (e.g, heart rate).
GABA and it’s role in motor control?
GABA means, Gamma AminoButyric Acid.
In motor control, GABA acts as the brake pedal. It inhibits activity in the basal ganglia (e.g striatum to Globus pallidus internal) and other motor circuits to refine movements and prevent chaos.
Effect of imbalance of GABA?
Too little GABA causes:
1. Uncontrolled movements e.g Huntington’s, chorea
Too much HABA causes:
2. Sluggishness
What are other functions or GABA asides motor control?
Anxiety reduction and sleep.
Glutamate and it’s role in motor control?
Glutamate is like gas pedal. Glutamate excites the motor neurons in the cortex, basal ganglia (e.g subthalamic nuclei) and spinal cord to drive movement.
Effect of glutamate imbalance?
Excess leads to Spasms, Seizures
Too little leads to, weakness or Paralysis
Serotonin and it’s effect on motor control?
Serotonin indirectly influences motor tone and coordination via brainstem (raphe nuclei) and spinal cord
Effect of serotonin imbalance?
Too little leads to;
1. Tremor
2. Poor coordination
Too much leads to;
1. Serotonin syndrome(shaking, rigidity)
Mention other functions of serotonin?
Serotonin affects
1. Mood
2. Appetite
3. Sleep
Norepinephrine and it’s effect on motor control?
Norepinephrine also known as Noradrenaline, boosts Arousal, and muscle tone via the locus coeruleus, aiding posture and readiness for action
Effects of Imbalance of Norepinephrine?
Excess causes; Jitteriness
Too little causes; fatigue, poor posture.
Other functions of Norepinephrine include;
- Attention
- Stress response
Explain Postural control?
Postural control is another name for maintenance of an upright posture in animals.
Postural control relies on a symphony of Neurotransmitters, integrated across the brain, spinal cord and muscles.
Mention the core systems involved in Postural control?
The core systems are;
1. Cerebellum - Fine tunes balance and coordination(uses glutamate and GABA)
2. Basal ganglia: Refined posture and movement (uses dopamine, GABA, ACh).
3. Brainstem- sets muscle tone and reflexes (uses glutamate, Acetylcholine)
4. Spinal cord: executes commands and reflex (uses glutamate, acetylcholine)
5. Vestibular system: senses head position, links to cerebellum/ brainstem.
What is the role of Neurotransmitters in posture?
- Dopamine: ensure smooth adjustments to stance
- Acetylcholine: triggers muscles contractions from standing (e.g alpha motor neurons).
- GABA: inhibits overcorrection, keeping posture stable.
- Glutamate: drives motor neurons to hold anti gravity muscles(e.g legs, back) active.
- Serotonin and Norepinephrine maintains baseline tone and shortness for upright readiness. E.g brainstem reticular formation.
What is CSF?
CSF means Cerebrospinal Fluid.
It is a clear, colourless fluid that surrounds and flows within the central nervous system (CNS); which comprises Brain and spinal cord
