Lecture 3 Nervous System PDF

Lecture 3 NERVOUS SYSTEM Color Index: Main text Boys' Slides Girls' Slides...

Lecture 3 NERVOUS SYSTEM Color Index: Main text Boys' Slides Girls' Slides Important Dr's Notes Extra Editing File OBJECTIVES List the subdivisions of the nervous system Define the terms: grey matter, white matter, nucleus, ganglion, tract, and nerve List the parts of the brain Identify the external and internal features of the spinal cord Enumerate the cranial nerves Describe the parts and distribution of the spinal nerves Define the term “dermatome” List the structures protecting the central nervous system Mention the clinical anatomy related to Lumbar Puncture The nervous system has three functions: Collection of sensory input: identifies changes occurring inside and outside the 1 body by using sensory receptors. These changes are called stimuli. Integration: processes, analyses, 2 and interprets these changes and makes decisions. Effects a response: by 3 activating muscles or glands (effectors) via motor output. Structural Organization Central Nervous System (CNS): Brain Spinal Cord Peripheral Nervous System (PNS): Nerves (cranial, spinal) Ganglia  The autonomic nervous system is also known as the efferent motor visceral nervous system. Nervous tissue consists of nerve cells (neurons) and supporting (neuroglia) cells. The axon is also called nerve fiber. (nerve fiber) (soma)  Nervous tissue is organized as: Grey matter: White matter: which contains the cell bodies & which contains the long the short processes of the processes of the neurons (no neurons, the neuroglia, and the cell bodies), the neuroglia, and blood vessels. the blood vessels. Short processes of the neurons = dendrites Long processes of the neurons = axons This is an example of a support cell. Nucleus = singular form Nuclei = plural form Ganglion = singular form Ganglia = plural form Remember… A group of A group of A group of nerve A group of nerve neurons within neurons outside fibers (axons) fibers (axons) the CNS is called the CNS is called within the CNS is outside the CNS nuclei. ganglia. called a tract. is called a nerve. The Brain The brain is a large mass of nervous tissue. It has four major regions: Diencephalon Cerebrum Thalamus Consists of two Hypothalamus cerebral hemispheres Subthalamus Epithalamus Cerebellum has 2 hemispheres (similar to the cerebrum) Brain Stem Midbrain Pons Medulla Oblongata  Cerebrum The largest part of the brain. 1 cerebrum has two hemispheres The two hemispheres are connected by a thick 2 bundle of nerve fibers called corpus callosum The surface shows ridges of tissue called gyri 3 separated by grooves called sulci gyri: plural gyrus: singular sulci: plural sulcus: singular Each hemisphere of the cerebrum is further divided into 4 lobes: Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe Tissue of the Cerebral Hemisphere 1 Outermost layer is called grey matter or cortex Deeper within the grey matter is the white matter; 2 composed of fiber tracts (bundles of nerve fibers), carrying impulse to and from the cortex (grey matter) Deeper within the white matter is the basal nuclei. 3 They help the motor cortex in regulating voluntary motor activities. (motor control). The basal nuclei has Grey matter in it Cerebellum The part of the brain that gives precise coordination and helps maintain equilibrium Similar to the cerebrum: It has 2 hemispheres and a convoluted surface 1 (‫)سطح معقد‬ The outer layer is made up of grey matter and 2 on the inside, it is made up of white matter The Spinal Cord It’s a two-way conduction pathway to the brain, and it is a major reflex center 42-45 cm long, cylindrical in 1 shape, and can be found in the vertebral canal From foramen magnum to L2 vertebra Continuous above with Medulla L1-L5 Caudal Tapering End Oblongata called Conus Medullaris Has Cervical Enlargement (for Has Lumbosacral upper limb muscles) Enlargement (for lower limb muscles) Foramen Magnum Gives rise to 31 pairs of spinal nerves Cauda Equina are the group of spinal nerves near the end Cross Section of the Spinal Cord Incompletely divided into 2 parts: Anteriorly: by a short, shallow median fissure Posteriorly: by a deep, narrow median septum composed of grey matter in the 1 center surrounded by white matter (contrary to cerebellum The lateral horns are not present in all of the and cerebrum) spinal cord (they’re only present in the The grey matter is arranged in a thoracolumbar region) 2 way that makes the letter H that contains: two anterior, two posterior, and two lateral horns  Protection of the CNS Bones of the skull Meninges Cerebrospinal and the vertebral (membranes): has Fluid: found in the column 3 layers subarachnoid space Dura Mater (outermost) Arachnoid Mater Pia Mater (middle) (innermost) Cerebrospinal fluid (CSF) 1 CSF is Constantly Produced by the Choroid plexuses inside the ventricles of the brain. 2 Most of the CSF drains from the ventricles into the subarachnoid space around the brain and spinal cord. A little amount flows down in the central canal of the spinal cord. 3 CSF is constantly drained into the dural venous sinuses (superior sagittal sinus) through the arachnoid villi. Peripheral Nerves May be sensory, motor, or mixed, and there are two types: Peripheral Nerves Spinal Cranial 31 pairs 12 pairs Attached to the spinal Attached to the cord brain Named and numberd Named & numbered according to the region from 1-12 of the spinal cord Cranial Nerves Helpful Video 12 pairs 4 pairs are mixed 5 pairs are motor 3 pairs are sensory trigeminal n. (5th) oculomotor n. (3rd) olfactory n. (1st) facial n. (7th) trochlear n. (4th) optic n. (2nd) glossopharyngeal n. abducens n. (6th) vestibulocochlear n. (9th) accessory n. (11th) (8th) vagus n. (10th) hypoglossal n. (12th) Spinal Nerves and Nerve Plexuses 31 pairs, each spinal nerve is attached by two roots: dorsal (sensory) & ventral (motor). 1 Dorsal root bears a sensory ganglion (DRG) Each spinal nerve exits from the 2 intervertebral foramen and divides into a dorsal and ventral ramus. The rami contain both 3 sensory and motor fibers The dorsal rami are distributed 4 individually, supply the skin and muscles of the back. The ventral rami form plexuses 5 (except in thoracic region where they form the intercostal nerves) and supply the anterior part of the body. Dermatomes Girls' Slides The segment of skin supplied by a segmental spinal nerve is called a ‘Dermatome’  Girls' Diagnostic Lumbar Slides Puncture It is one of the most commonly performed invasive tests in clinical medicine. Lumbar puncture (LP) occurs between L3 - L4 vertebrae for CSF collection. It is essential for the diagnosis of inflammatory and infectious disease of the nervous system (as meningitis) and in cases of subarachnoid hemorrhage. Girls' Slides MCQs 1 A- Groups of Which one of the following belongs to the ganglia? B- Groups of C- Groups of fibers D- Groups of fibers neurons outside the neurons inside the inside the CNS outside the CNS CNS CNS 2 The CSF is formed by which one of the following? A- Dura mater B- Arachnoid mater C- Choroid plexuses D- Dural sinuses 3 A patient is diagnosed with lumbar puncture as meningitis. At which level can we do this puncture? A- Between L2-L3 B- Between L4-L5 C- Between L3-L4 D- Between S1-S2 vertebrae vertebrae vertebrae vertebrae 4 At which one of the following sites is CSF finally drained? A- Subdural space B- Subarachnoid C- Arachnoid villi D- Dural venous space sinus Answer key: 1-A 2-C 3-C 4-D  Leaders Nisreen Alotaibi Omar Alattas MEMBERS Shaden Alotaibi Abdulhadi Alqahtani Danah Khallaf Turki Alanzi Elaf Alshamlan Talal Alrobaian Jana Alahaideb Abdulmalik Aldafs Dana Alotaibi Ahmad Addas Noorah Alkhilaiwi Salman AlHakeem Orjwan Alharthi Ziyad Bukhari Lana Alfouzan [email protected]