Anatomy of Nervous System (Suez Canal University 2020-2021) PDF

Suez Canal University College of pharmacy (2020-2021) Anatomy of Nervous System  Nervous system Central nervous system Peripheral nervous system (CNS)...

Suez Canal University College of pharmacy (2020-2021) Anatomy of Nervous System  Nervous system Central nervous system Peripheral nervous system (CNS) (PNS) Somatic nervous Autonomic Brain: Includes: Spinal system nervous system 1- Cerebrum & cord Carry sensation & Sympathetic diencephalon control skeletal NS 2- Brain stem: muscle A-Midbrain Formed of: Para- B- Pons 1-Cranial nerves: 12 C- medulla pairs of nerves. Sympathetic 3- Cerebellum 2- Spinal cord: 31 NS pairs of nerve  Central Nervous System Brain Spinal Cord Hindbrain Forebrain Midbrain 4th Ventricle Cerebral Medulla Cerebrum Diencephalon Pons Aqueduct oblongata 2 Lateral Third Cerebellum Ventricle Ventricle  Nervous system Nervous system is divided Anatomically into: (A)- Central nervous system (B)- Peripheral nervous system: (A)- Central nervous system It is comprising the brain & spinal cord (these are parts of nervous system protected by bones) lie inside the skull & vertebral column. They covered by three layers of meninges; dura matter, arachnoid matter, and pia matter, they bath in cerebro-spinal fluid (CSF) which circulating in the ventricles of brain and central canal of the spinal cord. I- Brain The brain is protected inside the skull. It is formed of three parts; 1- Cerebrum (forebrain) 2- brain stem: it is the part of the brain Located between the cerebrum and the SC which includes three parts from above downwards: A. Midbrain B. Pons C. Medulla oblongata III- Cerebellum: part of brain lies behind the Pons & medulla separating from them a cavity called 4th ventricle. Cerebellum is responsible for: 1- Balance (Adjusting the postural muscles of the body). 2- Integration of muscle tone. 1- Cerebrum It is the largest part of the brain. It occupies the anterior & middle cranial fossae. It is divided into right and left cerebral hemispheres by median longitudinal fissure. Each hemisphere has three surfaces superolateral, medial and inferior - The surface of the cerebrum is not smooth but it forms of gyri (elevations) & sulci (depressions) for increasing the surface of the cerebral hemisphere. - The superficial part of the cerebrum is composed of nerve cell bodies or grey matter forming cerebral cortex while the deep layer consists of nerve fibers or white matter. - Deeply inside the hemisphere, there are a collection of masses of grey matter called (basal ganglia). - The two hemisphere are connected by a mass of white matter called corpus callosum. Inside each hemisphere contains a cavity (ventricle) for cerebro-spinal fluid circulation called (lateral ventricles). Internal structure of the cerebral hemisphere For descriptive purposes each hemisphere of the cerebrum is divided into lobes which take the names of the bones of the skull under which they lie: - Frontal lobe (contain motor gyri for the body) - Parietal lobe (contrains sensory areas) - Temporal lobe (auditory cortex) - Occipital lobe (contains visual cortex) The boundaries of the lobes are marked by central sulcus deep sulci. These are: parieto-occipital 1- Central sulcus sulci 2- lateral sulcus 3- Parieto-occipital sulcus Lateral sulcus  II- Brain stem Functions of Brain stem: 1- Provides pathway of tracts between cerebral cortex & spinal cord (tracts running between higher and lower neural centers). 2- Site of origin of nuclei of cranial nerves (from 3rd to 12th). 3- Site of emergence of cranial nerves (from 3rd to 12th). Brain stem is formed from three parts: A- Midbrain Lies just below the diencephalon, contains a duct called (cerebral aqueduct) which connects the 3rd and 4th ventricles of the brain. B- Pons: Wedged part between the midbrain & medulla. C- Medulla Oblongata: it is the Most inferior region of the brain stem.it continues downwards as spinal cord at the level of the foramen magnum.  spinal cord spinal cord is a slender column of nerve fibers that begins at the base of the brain as a continuation of the medulla oblongata & extends down through the vertebral canal inside the vertebral column. Spinal cord is covered by three meninges like the brain. From outwards inwards; dura mater , arachnoid and pia mater. It terminates near the intervertebral disk between the first & second lumbar vertebrae (Disc L1/2). The Spinal Cord gives 31 spinal nerves (segments). Spinal nerves are peripheral nerves attached to the spinal cord and exits from intervertebral foramen. The segments are grouped into: - 8 cervical segments - 2 thoracic segments - 5 lumbar segments - 5 sacral segment - One single coccygeal segment. Spinal cord and spinal nerves The section of the spinal cord is formed of H- shaped grey matter internally (occupying) the central position. Central Grey matter is surrounded externally by a larger area of “white matter” which occupies peripheral position of the cord. The white matter gets its name because it is mainly composed of nerve fibers called tracts.  Spinal nerves (Ventral & dorsal roots) Spinal nerves begin as roots; a ventral (anterior, motor) root and a dorsal (posterior, sensory) root. Ventral roots convey motor information. and dorsal roots contain afferent nerve fibers that convey sensory information. Each dorsal root attached to it, dorsal root ganglia which contain cell bodies of sensory neurons. Union of ventral & dorsal root forms the trunk of spinal nerve. Which is a mixed nerve. II- peripheral nervous system (P N S): It is not protected by bones it is divided functionally into: (B)- Peripheral nervous system: 1. Somatic component of afferent (sensory) & efferent (motor) neurons concerned with innervation of the skin, skeletal muscles & their tendon, joints & associated connective tissue. The somatic nerves are cranial and spinal nerves a) Cranial nerves are 12 pairs of nerve which arise from the brain. b) Spinal nerves are 31 pairs of nerves which arise from each segment of the spinal cord 2. Autonomic nervous system (visceral) component of afferent & efferent neurons: which concern with innervation of viscera, heart, blood vessels & glands. Autonomic nervous system is divided into sympathetic & parasympathetic nerves  Cranial Nerves: I - XII 12 Pairs of nerves, Numbered from one (I) to twelve (XII), Attach to Ventral surface of brain & exit brain through foramina in skull I + II attach to Forebrain (cerebrum + diencephalon) III-XII attach to Brainstem (midbrain, pons, medulla); 3rd & 4th cranial nerve exit from the midbrain. Middle four cranial nerves (5th, 6th, 7th & 8th) exit from the pons. The lower four cranial nerves 9th, 10th, 11th & 12th) exit from the medulla. Cranial nerves I Olfactory II Optic III Oculomotor IV Trochlear V Trigeminal (v1-3) VI Abducent VII Facial VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory XII Hypoglossal  Names and functions of the cranial nerves I Olfactory--------smell Sensation II Optic-------------vision III Oculomotor IV Trochlear Motor----extrinsic eye muscles VI Abducent V Trigeminal: divided into three branches (V1, V2, & V3 ): V1 Opthalamic-----Sensory-cornea, nasal mucosa, face skin V2 Maxillary------Sensory-skin of face, oral cavity, teeth V3 Mandibular---Motor-muscles of mastication Sensory-face skin, teeth, tongue (general) VII Facial-------------------taste Sensation for part of tongue. Motor------muscles of facial expression. VIII Vestibulocochlear---Sensory (hearing, equilibrium) IX Glossopharyngeal----Motor—one of pharynx muscle Sensory----tongue (general & taste) and pharynx X Vagus------------------Motor for muscles of the pharynx & larynx -Sensory----pharynx, larynx & abdominal organs XI Accessory-------------Motor------trapezius, sternocleidomastoid XII Hypoglossal----------Motor-for tongue muscles  Autonomic nervous system It is the involuntary component of the nervous system concerning with controlling smooth muscles, glands and regulating visceral functions as Heart rate, Blood pressure, Digestion & Urination. It is formed from: 1- Sympathetic system: they arise from the neurons of the lateral horn of the grey matter of the spinal cord in All thoracic segments & upper 2 lumbar segments so called thoraco-lumbar outflow. 2- Parasympathetic system: arise from (cranial nerves and sacral segment (S2,3,4) of sacral region of the spinal cord so called craniosacral outflow. Both of them have antagonistic function but they complementary to each other as they act together to perform optimal effects. Autonomic Nervous System  Parasympathetic and Sympathetic Divisions Length of Location of Division Origin of Fibers Fibers Ganglia Sympathetic Thoracolumbar Short Close to the region of the preganglionic spinal cord spinal cord and long From T1-to L2 postganglionic Parasympathetic Brain (cranial Long In the visceral nerves and sacral preganglionic effector spinal cord and short organs (S2,3,4) postganglionic 27 (craniosacral) Functions of the sympathetic and parasympathetic systems Sympathetic system Parasympathetic system Dilatation of the pupil. Constriction of the pupil. Acceleration of the heart. Slowing of the heart. Bronchodilatation. Bronchoconstriction. Inhibition of gut movements but Stimulant to gut movements but stimulant to the sphincters. inhibitory to the sphincters. Skin, produces sweating and No effect on the skin. erection of hair. Catabolic, consumes energy. Anabolic, save energy. Function in fight, flight, fright.. Function during rest, meals, sleep.