Dr. Alba Lidia Pupo Gutiérrez Associated ProfessorSpecialist of Human Anatomy
Summary:INTRODUCTION TO NERVOUS SYSTEM.SPINAL MEDULLA - Generalities of nervous system.Gray and White matters, properties of thenervous system. - Spinal cord or medulla, extension,external and internal configuration.Meninges.
NERVOUS SYSTEM Is the most complex physical system know to mankind.
Excitability.Properties Conduction. Afferent.Functions Analysis and integration. Efferent.
SUBDIVISION OF NERVOUS SYSTEM• Topography or Descriptional: - Central and peripheral• Functional: - Autonomic and Somatic• Philogenetic: - Segmentary and suprasegmentary
SUBDIVISION OF NERVOUS SYSTEM Central. I. Topography Peripheral Brain Central Spinal medulla. Spinal nerves. Cranial nerves Peripheral Peripheral part of the autonomic nervous system
Somatic. II. Functional Autonomic.Somatic: In relation with the innervation of theosteomioarticular systemAutonomic: In relation with visceral innervation.
Segmentary. III. Philogenetic Suprasegmentary.Segmentary. Afferent or efferent directly relation withperiphery (Spinal medulla and brainstem)Suprasegmentary. Afferent or efferent relation throughthird neuron (Cerebelum, diencephalon andtelencephalon) .
Central Nervous System External Configuration Details of the surface of portions of Nervous System
Example Posterior Median sulcus PosterolateralAnterior SulcusmedianfissureAnterolateralSulcus
Internal configuration • Grey matter • White matter
Example:White matter Grey matter
Tracts or funiculusFibers in Central Nervous SystemTransporting the same information Lemmniscis: Medulla oblongata Pons Mesencephalon
Types of tracts: Afferents Efferents Spinocerebellars Posterior Gracillis Anterior Cuneatus
Nervous center Eff ere nts A ff ere st nReceptors Effectors Nervous pathways
Partial summary• The Nervous system is derived form the ectodermun.• The neuron is the structural unit of the Nervous system and the reflex arch is the morphofunctional unit.• The Nervous system is organized in grey and white matter.• The grey matter in the Central nervous system form nucleiand cortex while the white matter form tracts and funiculus. • The grey matter is form by the bodies of neuron.• The Nervous system are divided according to thetopography, functions and philogenetic aspects.• The reflex arch can be simple if participate two neurons andcomplex if participate more of two neurons.
SPINAL MEDULLA• Is an elongated part of the Central Nervous System.• Situated inside the vertebral canal• Length: 45 cm• Extends from the foramen magnum at the base of the skull to the junction between the first and second lumbar vertebrae.• Continuous cranially with the medulla oblongata• 31 segments
• Cervical enlargement: Supplying the upper limbs and extends from the third cervical to the second thoracic segments.• Lumbar enlargement corresponds to the innervation of the lower limbs, extending from the first lumbar to the third sacral segment.
Dorsal surface• Posterior median sulcus• Posterolateral sulcus: Dorsal roots of spinal nerves enter the cord• Posterior funiculus: In cervical and upper thoracic segments a longitudinal posteriorintermediate sulcus dividing into two large tracts: - Fasciculus gracilis (medial) - Fasciculus cuneatus (lateral)
Internal configuration• Grey matter Right Left• Is central: Column• In transverse sections this column are connected by a narrow transverse grey commissure, the whole resembling a letter H.• The commissure is traversed by the central canal.
-Anterior and posteriorcolumns-Some levels: Lateralcolumn (between thesecond thoracic and firstlumbar spinal cordsegments).-In transverse sectionsthe columns appear asprojections and calledhorns
TRACTS OF WHITE MATTER IN THE SPINAL MEDULLA. Fasciculi gracilis and cuneatus Lateral corticospinalAnterior and posterior spinocerebellar tracts Anterior corticospinalAnterior and lateral spinothalamic tracts
Central canal• Opening above into the fourth ventricle.• In the conus medullaris it expands as a fusiform terminal ventricle.• It contains Cerebral Spinal Fluid (CSF)
The spinal cord are surrounded by threemembranes: the meninges.Comprise the duramater (pachymeninx) andthe leptomeninges: the arachnoid materand pia mater.PACHYMENINX - DURA MATERIs the most external of the meninges.
Spinal dura mater• The periosteum of the vertebral canal is separated from the spinal dura mater by an extradural (epidural) space.• Extradural (epidural) space: it contains loose connective tissue, fat and venous plexus.
Subdural space• Between the spinal dura and arachnoid mater LEPTOMENINGES- ARACHNOID AND PIA MATERArachnoid mater: Surrounding the spinal cord is continuous with the cranial arachnoid mater. Arachnoid villiSpinal pia mater: Closely the surface of the spinal cord and passes into the anterior median fissure. They are separated by the subarachnoid space (CSF)
ARTERIAL BLOOD SUPPLY OF THE SPINAL CORDBranches of the vertebral, deep cervical,intercostal and lumbar arteries; these, withthe anterior and posterior spinal arteries,form longitudinal anastomotic channelsalong the cord.
Spinal posterior arteriesSpinal anterior arteries
VENOUS DRAINAGESpinal veins drain into plexiformlongitudinal channels.These vessels connect togetherwith the cerebellar veins andcranial sinuses.
MAGNETIC RESONANCE IN FRONTAL SECTION OF THE SPINAL MEDULLA IN CERVICAL REGION Enlargement Cervical spinal medulla
CONCLUSION• The spinal medulla is a segmentary structure of the Central nervous system that transmit the nervous impulses from and to the suprasegments.• The grey matter is situated in the central part as columns constituted by nucleus of motor neuron, somatic or autonomic and sensitives.• The white matter is situated surround the grey matter in funiculus and form ascendent and descendent tracts.• The meninges are membranes of connective tissue that protective structures of the Central nervous system with spaces between their.