CHAPTER 1 – INTRODUCTION AND ORGANIZATION OF THE NERVOUS SYSTEM
• The nervous system is composed basically of specialized cells, whose function is to receive
sensory stimuli and to transmit them to effector organs, whether muscular or glandular.
• The nervous system of higher species has the ability to store sensory information received during
past experiences.
CENTRAL AND PERIPHERAL NERVOUS SYSTEM
• CNS : consists of the brain and spinal cord
• PNS : consists of the cranial and spinal nerves and their associated ganglia.
• In CNS, the brain and spinal cord are the main center where correlation and integration of nervous
information occur.
o Both brain and spinal cord are covered with a system of membrane --> Meninges;
Suspended in CSF ; further protected by the bones of the skull and the vertebral column.
o CNS is composed of large number of excitable cells and their processes --> Neurons;
supported by the specialized tissue --> Neuroglia; the long processe --> axons or nerve
fibers.
o Interior of the CNS :
• Gray matter : consist of nerve cells embedded in neuroglia
• White matter : consist of nerve fibers embedded in nerolgia. (White color due to
the presence of lipid material in myelin sheaths)
• In PNS, cranial and spinal nerves, which consist of bundle of nerve fiber or axons, conduct
information to and from CNS.
o They are relatively unprotected and are commonly damaged by trauma.
• ANS, the part of NS concerned with the innervation of involuntary structures.
o It is distributed throughtout the CNS and PNS.
o Divisions : SNS & PNS (both parts, there are afferent and efferent nerve fibers)
• SNS activities : Prepare the body for emergency
• PNS activities : Conserving and restoring energi
, MAJOR DIVISIONS OF THE CNS
£ SPINAL CORD
o It is situated within the vertebral canal;
o Surrounded by three meninges (dura mater, arachnoid, pia mater)
o Further protection by the CSF, in subarachnoid space.
o It is roughly cylindrical
o Begins at the foramen magnum, continues with medulla oblongata; Terminates in the
lumbar region.
o Below, spinal cord tapers off into the conus medullaris, from the apex of which a
prolongation of pia mater, the filum terminale (descend to attach to the back of the
coccyx)
o Along the entire length of the spinal cord; 31 pairs of spinal nerves attached by anterior
(motor roots) and posterior (sensory roots).
• Each root is attached to the cord by a series of rootles
• Each posterior nerve roots posses a posterior root ganglion (the cells of which
give rise to peripheral and central nerve fibers)
Structure of the Spinal Cord
• It is composed of gray matter (inner core), surrounded by white matter
§ Gray matter
• H-shaped pillar with anterior and posterior gray columns, or horns
• United by a thin gray commisure containing the small central canal
§ White matter
• Divided into anterior, lateral, and posterior white columns
• The nervous system is composed basically of specialized cells, whose function is to receive
sensory stimuli and to transmit them to effector organs, whether muscular or glandular.
• The nervous system of higher species has the ability to store sensory information received during
past experiences.
CENTRAL AND PERIPHERAL NERVOUS SYSTEM
• CNS : consists of the brain and spinal cord
• PNS : consists of the cranial and spinal nerves and their associated ganglia.
• In CNS, the brain and spinal cord are the main center where correlation and integration of nervous
information occur.
o Both brain and spinal cord are covered with a system of membrane --> Meninges;
Suspended in CSF ; further protected by the bones of the skull and the vertebral column.
o CNS is composed of large number of excitable cells and their processes --> Neurons;
supported by the specialized tissue --> Neuroglia; the long processe --> axons or nerve
fibers.
o Interior of the CNS :
• Gray matter : consist of nerve cells embedded in neuroglia
• White matter : consist of nerve fibers embedded in nerolgia. (White color due to
the presence of lipid material in myelin sheaths)
• In PNS, cranial and spinal nerves, which consist of bundle of nerve fiber or axons, conduct
information to and from CNS.
o They are relatively unprotected and are commonly damaged by trauma.
• ANS, the part of NS concerned with the innervation of involuntary structures.
o It is distributed throughtout the CNS and PNS.
o Divisions : SNS & PNS (both parts, there are afferent and efferent nerve fibers)
• SNS activities : Prepare the body for emergency
• PNS activities : Conserving and restoring energi
, MAJOR DIVISIONS OF THE CNS
£ SPINAL CORD
o It is situated within the vertebral canal;
o Surrounded by three meninges (dura mater, arachnoid, pia mater)
o Further protection by the CSF, in subarachnoid space.
o It is roughly cylindrical
o Begins at the foramen magnum, continues with medulla oblongata; Terminates in the
lumbar region.
o Below, spinal cord tapers off into the conus medullaris, from the apex of which a
prolongation of pia mater, the filum terminale (descend to attach to the back of the
coccyx)
o Along the entire length of the spinal cord; 31 pairs of spinal nerves attached by anterior
(motor roots) and posterior (sensory roots).
• Each root is attached to the cord by a series of rootles
• Each posterior nerve roots posses a posterior root ganglion (the cells of which
give rise to peripheral and central nerve fibers)
Structure of the Spinal Cord
• It is composed of gray matter (inner core), surrounded by white matter
§ Gray matter
• H-shaped pillar with anterior and posterior gray columns, or horns
• United by a thin gray commisure containing the small central canal
§ White matter
• Divided into anterior, lateral, and posterior white columns
