Spinal Cord Cranial Nerves

SPINAL CORD: (Myelon) →spinal cored freom the a tabulare narrow structure arising posterior part of the medulla oblongata in breain →It is about 45cm in long and zem in thick It comes out of the skull through. nough an opening of the back side called forcamen magnum and extend back ward through neureal canal of the vertebral column. The spinal cored does not entere within the caudal negion. Normally the caudal region of all vertebrates only the Vasculare meninges Filum terminald Seen and tapers down to forem →The teaminal point of spinal cored is known as conces-terminalis, from this a bunch of spinal nerves also originate which 100ks like a tail of horse so called as cauda equina. The fourth rentricle continue inside the spinal cond ascentral canal. →The spinal cond to cavened by the meninges like brain tie duna. mater arachnoid and pia mater The Ts of spinal cord showr Emmern grey mater and outer White maten and a central white maten Dorsal hinn Gray maten -centrial canal venteral hoan ventoral fissure canal →The grey matere looks in the form of butterfly shape having trực thin densial horn and two thick ventrial honn →The spinal cored és divided into tws compartment by a narrow densal fissure and a deep Ventreal fissure Functions: →It mainly conduct the impulse te and from brain. →It also plays animportant rule in reflex action coithout the tercrical cauda comy equina termined spinal Thoracle ances Lumban area. Sacral anca coccygeal arcea. PERIPHERAL NERVOUS SYSTEM: The nervous system which comling from C-N.S and innenvates on conduct inpulses System Various oreglan of the body called perciphanul n envous It is of toor types ) creanial nerves as spinal nerves. CRANIAL NERVES: The nereves which arise from the different part of the breain arre called cranial nereves There aree 12-Paires of creanial nerves numbered Roman numerical 1 The creanial nereres arre generally medullated and three typer like sensorey, Motore and Mixed →The creanial nerves carise from the breain by a dorsal noot and a ventical root. →The nerve which arcises from doresal root ane those anise from ventre al root are motore. sensory and →The mixed nerve arise friom ganglia and consists of both the dorsal most having Sensory and motore fibre. →The functions of all the body arce somatic and visceral →Somatic functions. arre performed by the help of body wall like skin and muscle →The viscereal functions are performed by intennal organs like the digestive system, cinculatory system, endocrine system According to the somatic and viscereal functions the nerves are Foure types like aj somatic sensory b) somatic motors visceral sensory & visceral motore nerves. →The twelve pairs of cranial nerves are Types of creanial Nenres Nature -supply impulse I- Olfactorey nerve somatic sensory from olfattery fromopticlobe supply impulse true the netina to danh II- optic nerve Motor nanve Anton concerto the eyemusck oculomotore nerve Treochlear neave Betheptielone superime -Somatic Motor nerve Beenfall Hiemest of all the cream'al nerve and also called pathetic neave 2-Trigeminal Mixed-lavenal side of medulla uppentip, cowsnep (It is the largest cranial nerve abs called dentine nerve) PINA -Abduceng Somatic Motors vantaal side caute Eye ball ares Facial Mixed- la teored siden a lowenjen, mise, Ding VIE - Auditory Somatic sensory-rental silk Sapply impulset the B-Glassopharyngeal- Mixed- Popterion side la Tongue & the Mind Mixed.. Medulla 2- vagus Somatic Meter-medruka - Spinal accessory Somatic motor Medalla. Mus des os messe as Muscles of Neck shoulde - Hypoglossal - Muscles of nack & tongue SPINAL NERVES: →The nerves which arise from the spinal cored arce called spinalncuves There are 31 Pairee & spinal nereres anising in pains from the different segments of spinal cords. They are ed into five groups categorised into caf 3 pairs -12 paires by Thoracic ) Lumbare - 5 pains d) Sacral 5 pains e) coccygeal 1 pairs All the spinal nerves are mixed types →The spinal nerves arcise in pains from the root and ventreal root. spinal cord by dorsal →The doresal root originates from the dorsal horn and ventreal root from the ventreal horn of the greey mattern of spinal cond. The doresal scoot consists of sent Sensory fibres which may may be Somatic sensory ore viscercal sensory →The rentral rionot consists of motor fibnes which may be comatic motore on visceral motore. The tws reoots through ha Unite to forem a spinalnenve which comes out emall- aperture between vertebrae called interventebral fertamen. →The aperture is guarded by a silvery white calconsecue gland known as glands of swammeredam. After its emergence from the intervertebral foramen the spinal nenve divides into three breamches namely Ramus dorsalis, Ramus ventralis and Ramus communicans (10) REFLEX ACTION: Reflex action is the reapid, spontaneous, unconscious, invduntany and automatic action towards a stimulus It is independent of the will of animals. It was first discovered by Marshall Hall in 1833. →Reflex actions are of theo types of Unconditioned reflex b) conditioned neflex as unconditioned refler: Refreχές Present in an ferom birth and are called unconditioned on iиволи ore simple reflex ongariem stanting on inherited i Phore ex: Rapid withdrawl of limbt when burent, closing ayes tohen an particles approach towards age. 30 lex: conditioned by conditioned reflex: conditioned reflex arce acquired by the animal during ite They are not life time through practice constant in individuals." on leanning and may be disappean on reappean It is not hereditary. Ian parley percformed a simple experiment on dogs to show conditioned reeflex, so he is known as the father of conditioned reflexes The reflex actiom arre brough about by the pants of nervous system called reflex ane. REFLEX ARC It is the Path way of nerve impulses genercated at the recepten due to the 'stimulas to reach the effector organ during reflex action. It has following five components D A receptore oregon? It is the sensiny cell, tissue or ongan which receives the Stimulus 3) sen sorey neuron; It is the neuron that conduct the Semsong impulse impulse from recepton oregan to c.N-S (spinal cord) Intermediate neuwin senseny Десерии ongon (Reflex arc) 12 Moter organ