AnatomyofNervousSystem.pdf

Anatomy of Nervous System Prepared by: E. Asistio  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS)...

Anatomy of Nervous System Prepared by: E. Asistio  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS) Autonomic Somatic Nervous Brain Spinal Cord Nervous System System (SNS) (ANS) Sympathetic Parasympathetic Prepared by: E. Asistio Prepared by: E. Asistio Protecting and Meninges Supplying of the Cerebrospinal Fluid Nervous System Blood Supply Prepared by: E. Asistio  1st Layer: Dura Mater Meninges (sing. Meninx) Latin: “Tough Mother” Composed of leather-like tissue Layers of membranes that cover the CNS and PNS 2nd Layer: Arachnoid Membrane Looks like spider’s web in cross- section 3rd Layer: Pia Mater Latin: “Pious Mother Transparent membrane sticking closely to the outside of the brain Infection (due to virus or bacteria) in meninges leads to condition known as meningitis. Meningitis causes headache, stiff neck, followed by incoherence, drowsiness, coma, and death. Tumors in the meninx's tissues are referred to as meningiomas. Prepared by: E. Asistio Meninges Prepared by: E. Asistio Prepared by: E. Asistio  CSF has similar composition as blood Cerebrospinal Fluid (CSF) plasma. CSF floats brain within the skull. Protective fluid around the brain and spinal cord CSF circulates through: subarachnoid space – between arachnoid membrane and pia mater central canal – a small central channel that runs the length of spinal cord cerebral ventricles – four large internal chambers of the brain. Ventricles are hollow spaces in the brain. CSF is produced by choroid plexus – networks of capillaries that protrude into the ventricles from the pia mater. New CSF is made three times a day Old CSF is reabsorbed into the blood supply at the top of the head. Prepared by: E. Asistio Cerebrospinal Fluid (CSF) Purposes: Protective fluid around the brain and spinal cord Cushions the brain. Prevents the neuron from giving maladaptive response due to pressure (ex: tumor that leads to seizure) Hydrocephalus “water on the brain” CSF is blocked by a tumor. This results to buildup of fluid in the ventricles that causes the walls of the ventricles, and thus the entire brain, to expand. For children, this prevents normal growth of brain which may lead to mental retardation. Hydrocephalus is treated by draining the excess fluid from the ventricles and trying to remove the obstruction. Prepared by: E. Asistio Cerebrospinal Fluid Circulation Prepared by: E. Asistio  The brain receives nutrients through Blood Supply blood supply. Blood supply to the brain flows through carotid arteries (sides of neck) and vertebral arteries (back of the skull). Brain cannot store energy and interruptions of blood supply could lead to damages. Significant damage occurs less than 3 minutes after the heart stops. Brain death is the working definition of death Parts of brain without BBB: Pituitary gland Median eminence Area postrema Preoptic recess Paraphysis Pineal gland Endothelium of choroid plexus Ischemia - lack of oxygen Hemorrhagic - bleeding  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS) Autonomic Somatic Nervous Brain Spinal Cord Nervous System System (SNS) (ANS) Sympathetic Parasympathetic Prepared by: E. Asistio Spinal Cord The spinal cord is part of the CNS within the vertebral column. It extends from medulla to the first lumbar vertebra. The spinal cord communicates with all the sense organs and muscles except those in the head. The cord is shorter than the vertebral column. The central canal runs down in the center of the spinal cord. Spinal Cord White matter – composed of myelinated axons Grey matter - H-shaped, densely packed with cell bodies and dendrites. Dorsal Horns Ventral Horns Prepared by: E. Asistio Spinal Cord Axons from sensory neurons are found in the dorsal roots. They carry information about touch, position, pain, and temperature. Axons from motor neurons are found in the ventral roots. They are responsible for movement. The cell bodies are found in the ventral horns. Prepared by: E. Asistio Spinal Cord Pairs of spinal nerves are attached to the spinal cord – one on the left and one on the right—at 31 different levels of the spine. Each of these 62 spinal nerves divides as it nears the cord and its axons are joined to the cord via one of two roots: the dorsal root or the ventral root. Prepared by: E. Asistio Spinal Cord 31 segments of spinal cord 8 cervical nerves – serve the area of the head, neck, and arms 12 thoracic nerves – serve most of the torso 5 lumbar nerves – serve the lower back and legs 5 sacral nerves – serve the backs of the legs and the genitals 1 coccygeal nerve Prepared by: E. Asistio Damage to the spinal cord results in loss of sensation (of both the skin and internal organs) and loss of voluntary movement in parts of the body served by nerves located below the damaged area. Quadriplegic (quad meaning four – loss of four limbs) – Cervical damage that leads loss of sensation and inability to move the arms, legs, and torso. Paraplegic – Lumbar-level damage that leads to loss of sensation and inability to move the lower torso and legs. Arms and upper torso are retained. A Prepared by: E. Asistio  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS) Autonomic Somatic Nervous Brain Spinal Cord Nervous System System (SNS) (ANS) Sympathetic Parasympathetic Prepared by: E. Asistio  BRAIN Hindbrain Midbrain Forebrain Prepared by: E. Asistio Hindbrain The posterior part of the brain, consists of the medulla, the pons, and the cerebellum Prepared by: E. Asistio  Hindbrain It is divided into two - Myelencephalon and Metencephalon. Metencephalon contains two major structure – Pons and Cerebellum. Medulla or Medulla Oblongata The most posterior division of the brain Function: Regulates heart rate, blood pressure, and respiration Have roles in sleeping, sneezing, and coughing Important Structures: Reticular formation - a complex network of about 100 tiny nuclei that runs along the midline of brainstem from medulla up into the midbrain. Plays important role in regulation of sleep and arousal The cranial nerves originating in the medulla control vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing. Prepared by: E. Asistio  Hindbrain It is divided into two - Myelencephalon and Metencephalon. Metencephalon contains two major structure – Pons and Cerebellum. Pons Means “bridge” in Latin. Anterior and ventral to the medulla Functions: Transmits information about body movements Involvements on attention, sleep and arousal, and respiration Prepared by: E. Asistio  Hindbrain It is divided into two - Myelencephalon and Metencephalon. Metencephalon contains two major structure – Pons and Cerebellum. Cerebellum Means “little brain” in Latin. Large hindbrain structure with many deep folds An important sensorimotor structure – coordinating and control of movements, maintaining muscle tone, and regulating balance. Damage in cerebellum affects skilled movements and speech production. Prepared by: E. Asistio Midbrain (Mesencephalon) It is divided into two - Tectum and Tegmentum Two divisions of Midbrain: Tectum Roof /dorsal/top half of the midbrain Tectum is the Latin word for “roof.” Tegmentum Intermediate level/ventral/bottom half of the midbrain. Tegmentum is the Latin word for “covering”. The tectum covers the tegmentum, but the tegmentum covers several other midbrain structures. Prepared by: E. Asistio Midbrain (Mesencephalon) It is divided into two - Tectum and Tegmentum Tegmentum Significant structures: Periaqueductal Gray Gray matter situated around cerebral aqueduct. Has important role in perception of pain specifically mediating the analgesic (pain-reducing) effects of opioid drugs. Substantia Nigra Literally means “black stuff” Motor nuclei that is an important component of sensorimotor system Degeneration occurs in Parkinson’s disease Red Nuclei Located within the reticular formation Communicates motor information between spinal cord and the cerebellum. Prepared by: E. Asistio  Forebrain It is divided into two - Diencephalon and Telencephalon Two divisions of Forebrain: Diencephalon Thalamus Hypothalamus Telencephalon Cerebral Cortex Limbic System Basal Ganglia Prepared by: E. Asistio Diencephalon: Thalamus and Hypothalamus Prepared by: E. Asistio  Diencephalon composed of two structures: Thalamus and Hypothalamus Thalamus Two large-lobed structure on top of the brain stem. Have most of sensory system Function Transmit sensory signals to the cerebral cortex. Relay system Involved in state of arousal and consciousness Prepared by: E. Asistio  Diencephalon composed of two structures: Thalamus and Hypothalamus Hypothalamus Hypo means below Below the anterior of thalamus Function Regulation of motivated behaviors (feeding, drinking, temperature regulation, sexual behavior, sleeping) Directs Autonomic Nervous System (ANS) Directs portion of PNS that controls glands and organs. Important Structure Pituitary gland – hypothalamus regulates release of hormones Optic chasm – point which optic nerves from each eye come together. Mamillary bodies – sense of direction and memory Prepared by: E. Asistio  Telencephalon Cerebral Cortex including limbic system and basal ganglia Composed of: Gray matter – small unmyelinated neurons White matter – layer below cerebral cortex that has myelinated axon Prepared by: E. Asistio  Telencephalon Cerebral Cortex including limbic system and basal ganglia Cerebral Cortex Outer portion of the cerebral hemispheres Cerebrum is a Latin word for “brain.” Cortex is a Latin word for “bark” or “shell.” Prepared by: E. Asistio Appearance and important terms of Cerebral Cortex: Convoluted (furrowed) – increasing the amount of the cortex without increasing the volume *Lissencephalic – smooth-brained Prepared by: E. Asistio  Fissures – large furrows Sulci (sing. sulcus) – small furrows or valleys Gyri (sing. gyrus) – Ridges or hills between sulci/fissures Prepared by: E. Asistio Longitudinal Fissure divides the brain into Left and Right hemisphere The two hemisphere are connected by connecting tracts called cerebral commissures – corpus callosum and anterior commissure Prepared by: E. Asistio  Lobes Central and Lateral Fissures – divide the hemispheres into lobes Lobes are not functional units (having one set of function). Named after the skull bones that lie above them Prepared by: E. Asistio  Sensory cortex – processing incoming information from sensory system The cerebral cortex is divided Motor cortex – provides command for voluntary movements into three functional areas: Association cortex – connects and integrate sensory and motor functions Prepared by: E. Asistio  Occipital Lobe Other side of central sulcus Functional Area Primary visual cortex - provides the initial cortical processing of visual information. Analysis of visual input to guide behavior Damage Cortical blindness - has normal eyes and pupillary reflexes, but no conscious visual perception and no visual imagery. *extensive damage to the striate cortex of the right hemisphere causes blindness in the left visual field (that is, the left side of the world from the viewer’s perspective) and vice versa.  Parietal Lobe Between occipital lobe and central sulcus Functional Area Primary Somatosensory Cortex - located in postcentral gyrus. Analyzes sensation from the body (touch, pain, position, temperature) Other areas – perceiving location of objects and our body. Directing our attention Additional functions Processing Information about touch and body location Monitors all the information about eye, head, and body positions and passes it into brain areas that control movement Prepared by: E. Asistio  Temporal Lobe lateral portion of each hemisphere, near the temples. Functional Area Primary auditory cortex – located in superior temporal gyrus. Provides the initial cortical processing of sound information. Inferior temporal cortex – identifies visual patterns. Medial temporal cortex – important in certain kind of memories. Additional functions Hearing and understanding spoken language Facial recognition Perception of movement Damage Prepared by: E. Asistio Tumor – auditory or visual hallucinations  Frontal Lobe Extends from the central sulcus to the anterior limit of the brain Functional Area Primary motor cortex – located in precentral gyrus. Provides the highest level of command to the motor systems. Broca’s area – speech production Prefrontal cortex Dorsolateral prefrontal cortex – top and side of frontal lobe. Function: attention, working memory, planning behavior Damage: apathy, personality change, lack of ability to plan Orbitofrontal cortex – above and behind the eyes Function: impulse control Prepared by: E. Asistio Damage: emotional disturbance and impulsivity  Limbic System Limbic means border. Structures on the margins of cerebral cortex Regulation of motivated behavior - fleeing, feeding, fighting, and sexual behavior Important Structure Hippocampus – Greek for seahorse Function: Learning and memory Damage: Anterograde amnesia – difficulty to form new long-term declarative memory (facts, language, personal experience) Amygdala – almond-shaped Function: Fear, rage, aggression. Interacts with hippocampus during encoding and storage of emotional memories. Damage: Inability to respond appropriately to dangerous situation Prepared by: E. Asistio  Limbic System Cingulate cortex– fold of cortical tissue on surface of cerebral hemisphere. Divided into: Anterior cingulate cortex (ACC) Function: Some influence on autonomic functions. Decision making, error detection, anticipation of reward, empathy. Processing of pain (physical and social Posterior cingulate cortex (PCC) Function: Eye movement, spatial orientation, memory Septal Area – electrical stimulation results is pleasurable while lesion results to uncontrollable rage and attack behavior Olfactory bulbs – receive and process information about smell Mamillary bodies – sense of direction and memory Fornix – Fiber pathway connecting mammillary and hippocampus. Functions in memory Prepared by: E. Asistio  Basal Ganglia Group of subcortical structures lateral to the thalamus Function: Voluntary motor control Important Structure: Caudate nucleus Putamen Globus pallidus Nucleus accumbens – role in experience of reward. Damage: Implicated in Parkinson’s disease, Huntington’s disease, ADHD, and OCD Prepared by: E. Asistio  Peripheral Nervous Central Nervous System System (PNS) (CNS) All nerves exiting the brain and spinal cord – carrying Brain and Spinal Cord sensory and motor messages to and from Tissues encased in bone other parts of the body Covered in 3 layers of Tissues not encased in membrane bone Cells do not regenerate Covered in 2 layers (Permanent damage) Cells regenerate (With With Cerebrospinal Fluid recovery) Without Cerebrospinal Fluid Prepared by: E. Asistio  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS) Autonomic Somatic Nervous Brain Spinal Cord Nervous System System (SNS) (ANS) Sympathetic Parasympathetic Prepared by: E. Asistio  Nervous System Central Peripheral Nervous Nervous System (CNS) System (PNS) Somatic Autonomic Brain Spinal Cord Nervous Nervous System (SNS) System (ANS) Parasympath Midbrain Hindbrain Sympathetic etic Forebrain Prepared by: E. Asistio Two Divisions Somatic Nervous System (SNS) Autonomic Nervous System (ANS) Prepared by: E. Asistio Somatic Nervous System (SNS) Part of PNS that interacts with external environment – sensory and motor. Composed of: Afferent nerves – carry sensory signal from organs to CNS Efferent nerves – carry motor signals from CNS to skeletal muscles Prepared by: E. Asistio Autonomic Nervous System (ANS) Part of PNS that regulates body’s internal environment. Critical in regulatory functions: blood circulation, secretion, digestion, urination, defecation, etc. Composed of: Sympathetic Parasympathetic Prepared by: E. Asistio Autonomic Nervous System (ANS) SYMPATHETIC PARASYMPATHETIC Autonomic nerves projected from Autonomic nerves projected CNS in lumbar and thoracic from brain and sacral regions regions of spinal cord. of spinal cord Prepares the body for action Act to conserve energy Stimulate, organize, and mobilize energy sources in threatening Provide rest, repair, and situations energy storage Fight-or-flight system Parasympathetic changes are Sympathetic changes are indicative of psychological indicative of psychological arousal relaxation Prepared by: E. Asistio Prepared by: E. Asistio Each autonomic target organ receives opposing sympathetic and parasympathetic input Prepared by: E. Asistio Cranial Nerves Prepared by: E. Asistio