Chapter 5 Flashcards
What does simulation of the motor cortex do?
The simulation of the motor cortex causes the opposite side of the body to react. The part depends on the area of stimulation.
Where does the motor cortex lie?
In front of the the Central sulcus. Therefore, it is also known as the precentral gyrus.
Write down the representation of the body in the motor cortex from the medial to lateral side.
Foot, leg, thigh, hip, trunk, shoulder, elbow, hand, fingers, neck, brow, eye face, lips, jaw, tongue, swallowing muscles and chewing muscles.
What is the path of the corticospinal tract?
The corticospinal tract carries fibres mostly from the motor cortex and little from other areas. It forms a part in f the internal capsule, goes through the cerebral peduncle, through the pons, medullary pyramids and at the caudal end of the hindbrain, most of the fibres decussates.
What are striated and smooth muscles?
Striated muscles are voluntary muscles, because they appear striped. The smooth muscles are involuntary muscles and they are not striped. The heart, however, is made up of striated muscles even though it is not under voluntary control.
What are the different types of effector systems?
The somatic motor control is a single motor neuron that makes direct synapse on the target.
The autonomic preganglionic system is where the neuron stimulates a ganglia which acts on a spread area. Sympathetic motor neuron system is where the neuron stimulates the adrenal medulla which secretes hormones into the bloodstream causing widespread action. The last system is called the neuroendocrine system where neurons are designed to directly secrete chemicals into the blood.
What makes the motor system?
Even though the precentral gyrus is the most important motor component of the brain, the activity of it is strongly influenced by the pallium, striatum, cerebellum and many other cortical areas.
How does the parts of the motor cortex work?(vague version)
The different cortical areas including the precentral gyrus makes a committee decision which is finally enabled by the striatum and pallidum.
Where is the supplementary motor cortex located and what is its role?
The supplementary motor cortex lies in medial part of the cerebrum in front of the lower limb part of the motor cortex. Its role is to plan and sequence complex movements.
What is the Broca’s area?
Broca’s region is a library that manages the movement of the jaw and tongue for speech and the movement of the fingers for writing. It is mostly present in the left hemisphere of people. In right handed people, it is always left hand side, whilst in left handed people it can be either.
What happens when the corticospinal tract is damaged?
When the corticospinal tract is cut at the level of the hindbrain, the fine movements of the fingers are lost. The opposite hand to the damaged side always finds it impossible to sew, write and pick small objects. If this lesions was accompanied by lesion to the striatum, the person will be affected by increased spasticity and hypereflexia.
What are modules?
Functional systems in the hindbrain and spinal cord where the neurons are connected in a particular fashion to do semiautomatic functions. There are modules for walking, running, and chewing. These allows us to concentrate on higher cognitive functions. It also improves efficiency as the motor cortex does not need to connect to every single muscle directly.
What is the hierarchy of modules?
Modules are arranged such that the basic survivals learnt over the million year vertebrae evolution is given higher priority. These module encompasses eating, drinking, defensive behaviours, and movement patterns to explore the immediate surrounding.
How does the module system work?
The cerebral cortex conveys the request to the hypothalamus which checks and organises the modules or refuses due to inappropriate environmental condition. This information is then relayed to the cerebral cortex or the midbrain. If the modules are fine, the midbrain will initiate the pattern by stimulating the inbuilt pattern in the hindbrain or the spinal cord which uses the visceral motor, somatic motor or both to achieve the request.
How is the hypothalamus separated and how are the behaviours attributed each part?
The hypothalamus is split into a medial and the mammillary bodies and the adjacent parts of the midbrain(the substantia nigra and the ventral tegmental area.
The medial part are responsible for defence, reproduction and ingestion. This area includes the VMH(ventromedial nucleus).
The second group of areas are responsible exploratory and foraging behaviours, running and other means of locomotion to explore the surroundings.
How are modules otherwise useful?
Modules make intrinsic patterns of reflexes that aims at eliminating a painful stimulus or avoiding it.
Where are the main modules found?
The brainstem has modules for movement of the head and the neck, chewing, licking, facial expression, vocalisation and control of breathing.
The spinal cord has modules for locomotion, posture, reaching and grasping.
What are the some control descending pathways other than corticospinal tract?
Corticobulbar tract Corticopontine tract Tectospinal tract Rubrospinal tract Reticospinal tract Vestibulospinal tract Serotonin fibres from the raphe nuclei Noradrenaline fibres from the locus coeruleus
What is the red nucleus and its role?
The red nucleus is a nucleus in the midbrain that is found in almost all animals that is responsible for the control of movement of the limbs. It is red due to high amounts of iron deposit in that area.
What is the raphe nuclei and its role?
The raphe nuclei is a nuclei in the hindbrain, which manufactures serotonin. Serotonin is involved in regulations of mood, the control of pain and regulation of the sleep-wake cycle.
what is the role of the cerebellum?
The cerebellum is concerned with coordination and correction of moment for the most efficient use of the body’s resources and eliminate possible damage. It compares the actual position of the body to the required position and alters certain things to maintain posture and balance.
Why is the cerebellum important in humans and primates?
It is important in humans because we have the most binocular vision and the ability to use our fingers for precise and skilled movement. This requires the cerebellum for the fine and smooth control.
In other primates, their lives depend on the cerebellum to correctly execute acrobatic leaps in tress,
What is the size of the cerebellum?
The cerebellum is relative tiny during birth. However, it quickly develops in the first six years of our lives to reach its original size. During the first six years, it completes the wiring of basic and commonly repeated movements.
Describe the arrangement of the cerebellar cortex.
The cerebellar cortex is made up of three layers. The outer layer is made by superficial molecular cells. The second layers is a vey thin layer of purkinje cell and the third layer is a thick, dense layer of the granular cells.
The thickness of each layer is relative same throughout the whole cortex.
Where are and what are the three deep cerebellar nuclei?
Deep in the cerebellar white matter there are three deep cerebellar nuclei. They are called the lateral(dentate nucleus), interposed and medial nucleus.
What is the role of the purkinje cells in the cerebellar cortex?
They are the output cells of the cerebellum. They project to the deep cerebellar nuclei.
What does the dentate nucleus project to?
The dentate nucleus projects to the thalamus which then projects to the cortex. It also projects to the brainstem and the spinal cord.
