A study of anatomy and physiology of movement of upper limb

The procedure in lifting the delve to drink water is a Gordian iodine which involves a huge make away of technology inter-transfer between the brain and the eventual(prenominal) skeletal ponderosity.There is initiation of the grounds at the brain which is transmitted via specialized color quality tracts to the hip flexors via the middling spinal anaesthesia anaesthesia cord, involving a very complex appliance at the cellular levelThe initiation of the exercise is at the motor cortex (Ms I) of the brain. The radical motor area is located at the precentral gyrus of the frontal lobe. The area despotic the motion of the lower offshoots lies towards the superior outdoors of the brain. Wi shrink this area lies the cell organic structure of the primary neuron. These neurons are known as upper motor neurons (UMN).These UMNs receive modulating lust from the in set ups from the cerebellum and the basal ganglia via the extrapyramidal pathways. These tracts modulate the gross movement initiated at the frontal cortex. In submit these areas are modulated by corticoafferent signals from ascending spino cerebellar, and spino-thalamic pathways. The signal initiated at the centre of the cell body is transmitted electronic all toldy via the axon of the myelinated neuron via the mode of salutatory conduction.The myelin sheath which surrounds the axon of nerves that involve fast transport, breaks at intermediate areas known as Nodes of Ranvier. The electrical momentum moves in a jumping mode at these nodes nerve transmission as a neural impulse, generated by the organic law of a nerve action mechanism capability. akin all excitable tissue, nerves hold on a resting tissue layer potential that is the going of voltage across the tissue layer of the neuron. In neurons this value is 70 mV.This voltage expiration is maintained by the Na/K pump on the membranes. This impulse generated at the axon hillock is transmitted via the depolarizing physique whi ch allows sodium ions ingress into cells via break of the Na channels. This entry of Na in one portion allows activation of other Na channels, causing depolarization of the adjacent region of the neuron. Subsequently repolarization occurs via the opening of K channels, which restores the membrane potential.Thus this process continues which allows the transmission of impulse. Many such nerves together descend as the descending cortico spinal tract in the pyramidal system, which travels through the midbrain into the spinal cord, decussating at the level of midbrain( 90% of the fibres decussating and forming the askance spinothalamic tract) and again at the level of spinal cord ( the other 10%, forming the precedent spinothalamic tract) .It is the former which is responsible for the upper limb movements. The cortico-spinal tract travels in the anterior motor horn cell of the spinal cord work on the brachial plexus where they synapse with the spinal adaxial root neuron (lower moto r neuron). A single post-synaptic neuron receives signals from many neurons. At the axon terminal, the propagation of impulses leads to release of neurotransmitters, which are stored in specialized vesicles.The released Ach diffuses into the synaptic split and binds with receptors on the post synaptic membrane to produce excitatory post synaptic potentials. This leads to generation and propagation of impulse in nerves which are destined to provide the neuro-muscular junction. At the neuro-muscular junction, Ach is released, which diffuses into the synovial cleft and binds to receptors in the motor end plate, and triggers a muscle action potential.The released Ach is destroyed by the acetylcholinestrase. At the level of the sarcolemma of the muscles, the muscle AP travels along T-tubules, opening Ca release channels in the sarcoplasmic reticulum. Ca binds to troponin-tropomysin complex, which releases the myosin heads, these then bind to the actin thin filaments, and draws them clo ser to the M line. Meanwhile convey the Z disc closer.This leads to muscle fibre densification. This is a self propagating sequence lastly leading to the contraction muscles involved in the movement. Each nerve fibre innervates many musle fibres ( about 150). This is the motor unit.The greater the image of motor units recruited by the nerve action potential, the greater the force of contraction of the muscles. In the spinal cord, nerve impulse travels along the brachial plexus (C5 T1) to innervate the pectoral medallion major (Arm adduction and flexion reaching out to hold the glass over), Flexor digitorum superficialis and profundii of all fingers, the interossei and the lumbricals of all digits, opponens pollicis, flexor pollicis brevis , adducor pollicis and abductor pollicis brevis ( gripping of the glass by the fingers flexion at metacarpophalangeal.Proximal interphalangeal and the distal interphalangeal joint of the fingers the carpometqcarpal joint, metacarpophalangeal and the interphalangeal joint of the thumb) then contraction of the biceps brachii ( elbow flexion) and the supinator ( supination at the elbow joint) in conclusion the contraction of the triceps muscle ( elbow extension, to put the glass back).This excitatory impulse is alike associated with the production of inhibitory action potential ( hyperpolarizing impulse) in the antagonists (eg triceps during elbow flexion, and biceps during elbow extension)