VAN 121: Veterinary Gross Anatomy-II (2+2)

Cerebrospinal system

THE CEREBROSPINAL SYSTEM

• It comprises of the central and peripheral nervous system. The central nervous system consists of brain and spinal cord. The peripheral nervous system includes the cranial and spinal nerves and visceral peripheral system.The visceral peripheral system or autonomus nervous system (ANS) is the visceral part of the nervous system.Its peripheral compomants are thoracolumabr and craniosacral outflows and central components of this system are placed within the CNS.
• The two substances called gray mater and white mater enters in the formation of central nervous system. The gray mater is brownish in colour, softer and more vascular and composed chiefly of nerve cells. The white mater is white in colour and composed of medullated nerve fibres.
• As both of the gray and white mater are fragile and soft, they are well protected against injuries by the meninges, skull and the vertebral column.
• The nerves are named according to their origin from the organs of the central and sympathetic systems as cranial, spinal and sympathetic nerves. The nerve fibre which carries the nerve impulses from the receptor to the higher centers like brain and spinal cord are called as sensory or afferent nerve fibres. The nerve fibres which carry the motor response to the effector organ are called motor or efferent never fibres. The branches of nerves distributed to the muscles are called muscular branches and those supplied to the skin are cutaneous branches and those supplying to the articulations are called as articular branches. Efferent nerves stimulating contraction of muscle are called motor nerves and those stimulating the contraction of walls of the vessels as vasomotor nerves. They are called secretory nerves when they stimulate the glands to secrete. Nerves are called inhibitory nerves when they diminish functional activities of organs. The nerves that control nutrition of the tissues to which they supplied are tropic nerves.
• The tissues or organs that receive the stimuli are called receptors. Receptors are classified according to position and kind of stimuli.
• Based on the position,
  • Exteroceptor – Receptors present on the outer surface of the body that receive different kind of external stimuli.

• Proprioceptors – Receptors present o the muscles tendon and join.
• Viseroceptors – Receptors present on the visceral organs.
• Based on the kind of stimuli 
  • Mecahanoceptors – Receptors used to received various mechanical stimuli viz pain, pressure etc.
  • Thermoceptors – Receptors used to receive temperature.
  • Baroceptors – Receptors used to receive pressure.
  • Nociceptors – Receptors used to received pain
  • Chemoceptors – Receptors used to receive chemical stimuli.