Neural Control and Coordination
Central nervous system
- CNS Coprises brain and spinal cord
- Brain and spinal cord are protected externally by the presence of meninges by 3 layers –(i) Outer duramater, (ii) middle – arachnoid and (iii) Inner pia mater.
- Human brain possess 3 parts – (i) Fore brain (ii) mid brain and (iii) Hind brain, named as prosencephalon, mesencephalon and Rhombencephalon respectively.
- Fore brain consists of important parts such as cerebrum (largest / complex), olfactory lobes (pair) as to provide the sense of smell, 4 lobes such as frontal, parietal, Temporal and occipital lobes, Diencephalon.[Epithalamus, Thalamus amol Hypothalamus]
- Cerebrum consist of 2 cerebral hemispheres connected by corpus callosum.
- The 3 functional areas of cerebrum are sensory, motor and association area.
- Association area is responsible for memory, learning and reasoning.
- The cerebral cortex possess the surface that is highly coiled and folded by gyrus and sulcus (up / down respectively).
- Nervous tissue, anteriorly possesses a choroid plexus to produce cerebrospinal fluid and behind epithalamus.
- Epithalamus, which is not formed of nervous tissue, epithalamus consist of a pineal body to produce a hormone melatonin (Biological clock of body).
- Pituitary gland is attached with hypothalamus through infundibulum.
- Behind hypothalamus, there exists mammillary bodies for the purpose of recollecting memory.
- Hypothalamus is a thermostat and also controls thirst, Appetite satiety centre.
- Mid brain possess corpora quadrigemina that consists one pair of superior colliculi (light) and interior colliculi (hearing).
- The scattered masses of grey matter is called as basal ganglia, which contains the largest nucleus called as corpus striatum.
- Degeneration of basal ganglia results in parkinson’s disease.
- Rhombencephalon possess cerebellum (2nd largest), pons varolii, and medulla oblongata.
- Cross sectional view of Cerebellum, shows a branching tree like arrangement of white and grey matter called as Arbor Vitae (Tree of life)
- Pons (PRG – Pontine Respiratory group) consists of pneumotaxic centre and Apneustic centre
- Medulla oblongata consists of posterior choroid plexus and M.O has certain functions such as heartbeat, breathing, sneezing, Coughing ‘Vomiting
- Mid brain + Pons + medulla ⇒ Brain stem.
- Limbic system comprises certain components of cerebrum and diencephalon which controls food habits, sex behaviour and Emotions.
- Brain possess 4 ventricles (hollow fluid filled spaces) such as
(i) Lateral ventricles
(ii) Third ventricles
(iii) Fourth ventricle that is connected to spinal cord.
- Foramen of monro connects (i) and (ii); Cerebral aqueduct connects (ii) and (iii)
- Foramen of luschka and magendie connects fourth ventricle and central canal of S.C(spinal cord)
- CSF (Cerebrospinal fluid) is secreted by anterior / Posterior choroid plexus found inside the Ventricles of brain, central canal of spinal cord, subarachnoid space around brain and spinal cord.
- CSF Protects brain by acting as shock absorbing medium, also provides buoyancy to brain, acts as Excretory medium of brain.
- CSF reduces the weight of the brain from 1.4 kg to 0.18 kg
- Human spinal cord (Myelin) ranges from 42-45 cents in adult that are protected by vertebral column.
- Spinal cord possess cervical and Lumbar enlargement at C4-T1 and L1-L2 respectively, which is to control forelimbs and hindlimbs respectively.
- After L2 , the spinal cord tapers with the most distal bulbous part called conus medullaris.
- At the end of spinal cord, there exists a collection of nerve roots, which looks like a horse tail named as cauda equina.
- Filum terminale is the long slender filament that is at the tapering end which anchors the spinal cord within the vertebral column.
Part-1: Watch this video for the topic from 2:19 to 7:49
Part-2: Watch this video for the topic from 24:22 to 55:20
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