Lecture 6 Nervous System II - HLSC 2P95 PDF

LECTURE 6 The Nervous System II Brain Brain anatomy Meninges Ventricles +CSF Cranial Nerves Arteries Autonomic Nervous System  GROSS ANATOMY Fig. 16- 16  The Cerebrum The cerebrum consists of: – Two hemispheres – Several lobes Frontal,...

LECTURE 6 The Nervous System II Brain Brain anatomy Meninges Ventricles +CSF Cranial Nerves Arteries Autonomic Nervous System  GROSS ANATOMY Fig. 16- 16  The Cerebrum The cerebrum consists of: – Two hemispheres – Several lobes Frontal, parietal, occipital, and temporal – Gyri and Sulci - increase surface area Hemispheric Specialization – Left hemisphere Speech center, writing, language, mathematics – Right hemisphere Analysis by touch, spatial visualization.  ANTERIOR Longitudinal Right cerebral fissure hemisphere Left cerebral Cerebral veins and hemisphere arteries covered by arachnoid mater Central sulcus Parieto-occipital Cerebellum sulcus POSTERIOR a Superior view. Figure 16.16a  The Cerebrum The cerebral lobes Frontal lobe – Conscious control of skeletal muscle Occipital lobe – Perception of Visiual stimuli Parietal lobe – Conscious perception of touch, pressure, vibration, pain, temperature, and taste Temporal lobe Conscious perception of auditory and ol factory – stimuli  Precentral gyrus Postcentral gyrus Central sulcus Parietal Lobe Frontal lobe of left cerebral hemisphere Occipital lobe Lateral sulcus Temporal lobe Cerebellum Pons Medulla oblongata Figure 16.17b  Major Divisions of the Brain (6) Left cerebral hemisphere Gyri CEREBRUM Sulci Conscious thought Fissures processes, intellectual functions memory storage and processing Conscious and subconscious regulation of skeletal muscle contractions Spinal cord CEREBELLUM Coordinates complex somatic Adjusts output of motor patterns other somatic Figure 16.1 motor centers in brain and spinal cord  DIENCEPHALON THALAMUS Relay and processing centers for sensory information HYPOTHALAMUS Centers controlling emotions, autonomic functions, and hormone production MESENCEPHALON Brain stem Processing of visual and auditory data Generation of reflexive somatic motor responses Maintenance of consciousness PONS Relays sensory MEDULLA OBLONGATA information to cerebellum Relays sensory information to thalamus and and thalamus the brain stem Subconscious somatic Autonomic centers for regulation of visceral and visceral motor centers function (cardiovascular, respiratory, and Fig. 16.1 digestive system activities)  Central sulcus Postcentral gyrus Precentral gyrus Diencephalon Corpus callosum 1. Thalamus 2. Hypothalamus Frontal lobe 3. Epithalamus Pineal gland (melatonin) Temporal lobe Cerebellum Mesencephalon Pons Medulla oblongata Figure 16.13a  Organization of the Brain Gray Matter & White Matter Organization The cerebrum consists of: Gray matter consists of cell bodies Cerebrum and cerebellum white matter is covered by the cortex (superficial layer of gray matter)  The Cranial Meninges Protects & supports the brain Surround the brain and the spinal cord Dura mater Cranium Cerebral cortex Arachnoid Cerebral mater cortex Pia mater Cerebellum Medulla oblongata Spinal cord Fig 16.3  ANTERIOR Loose Cranium connective Dura mater tissue and periosteum Subarachnoid of cranium space Epicranial aponeurosis Arachnoid mater Scalp Cerebral cortex covered by pia mater POSTERIOR Figure 16.4  Superior sagittal Cranial sinus Meninges Dura mater Subdural Arachnoid mater space Arachnoid Arachnoid trabeculae granulation Pia mater Falx cerebri Cerebral vein Subarachnoid space Cerebral cortex Folds of the Dura mater * Dural sinuses = large veins Dura Mater - Falx and Sinus Superior sagittal sinus Inferior sagittal sinus Cranium Dura Mater Falx cerebri Tentorium cerebelli Diaphragma sellae  sphenoid Falx cerebelli Transverse sinus Straight Sinus Transverse Sinus Figure 16.3b VENOUS RETURN JUGULAR VEIN VENOUS RETURN Superior sagittal sinus Transverse sinus Sigmoid sinus JUGULAR VEIN  The Cranial Meninges 2. Arachnoid Matter Smooth. does not follow sulci and gyri Subarachnoid space (network of collagen and fibres) Cerebrospinal fluid and arteries and veins 3. Pia Mater Inner most layer directly attached too the surface of the brain Follows the sulci and gyri of the brain Helps to anchor the larger blood vessels of the cerebrum  Subdural Subarachnoid Cranial space space Meninges Dura mater Arachnoid mater Arachnoid trabeculae Pia mater Cerebral vein Cerebral Perivascular space cortex b A detailed view of the arachnoid mater, the subarachnoid space, and the pia mater. Note the relationship between the cerebral vein and the subarachnoid space. Figure 16.5b  How csf is made and circulated Ventricular System of the Brain Ventricles are fluid-filled cavities Filled with cerebrospinal fluid Lined with ependymal cells Fluid transports nutrients to the CNS and transports waste away from the CNS CSF also provides cushion for the CNS CSF made in choroid plexus - Ependymal cells highly permeable capillaries  Ventricular System of the Brain Lateral ventricles in cerebral hemispheres Septum Interventricular pellucidum foramen Third ventricle Aqueduct of midbrain Inferior horn of lateral Fourth ventricle ventricles Cerebellum Central canal d Diagrammatic coronal section showing the interconnections between the ventricles Figure 16.2d Anterior horns of lateral ventricles Lateral ventricles Interventricular foramen Third ventricle Posterior horns of lateral ventricles Inferior horns of lateral ventricles Aqueduct of midbrain Medulla oblongata Fourth Central canal ventricle a Orientation and extent of the ventricles as seen in a lateral view of a transparent brain Fig. 16.2  Arachnoid granulations Circulation of Cerebrospinal Fluid Superior sagittal Made in the choroid sinus plexus Aqueduct of midbrain ~500ml/day Choroid plexus of fourth ventricle Central canal Circulating CSF ~150ml ……so CSF is replaced every 8 hours Filum terminale Figure 16.7  Superior Dura mater sagittal sinus Cranium (endosteal layer) Arachnoid granulation Fluid movement Arachnoid trabecula Cerebral Dura mater cortex (meningeal layer) Pia mater Subdural space Subarachnoid Arachnoid space mater Figure 16.7 BASIC ARTERIAL SUPPLY TO THE BRAIN Arteries of the Circle of Willis 1. Anterior communicating 2. Anterior cerebral 3. Internal Carotid Blood supply to 4. Posterior communicating brain 5. Posterior cerebral 6. Basilar 7. Vertebral  The Arterial Supply to the Brain Anterior communicating Internal carotid (cut) Anterior cerebral Posterior communicating Posterior cerebral Posterior cerebral Superior cerebeller Basilar Pontine Anterior inferior Vertebral cerebellar Posterior Inferior cerebellar Anterior Spinal Figure 22.13a  The Cranial Nerves There are 12 pairs of cranial nerves – innervate the periphery emerging from the brain (not the spinal cord) – Found on the ventrolateral surface of the brain – numbered beginning at the anterior aspect of the brain – They are numbered CN I to CN XII  Cranial Nerves Olfactory nerve (N I) Optic nerve (N II) Oculomotor nerve (N III) Trochlear nerve (N IV) Trigeminal nerve (N V) Abducens nerve (N VI) Facial nerve (N VII) Vestibulocochlear nerve (N VIII) Glossopharyngeal nerve (N IX) Vagus nerve (N X) Hypoglossal nerve (N XII) Accessory nerve (N XI) Figure 16.23b NERVE PRIMARY FUNCTION Olfactory nerve (N I) Special sensory (smell) Optic Nerve (NII) Special sensory (vision). Retina of the eye Oculomotor Nerve (N III) Motor, eye movements. Intrinsic eye muscles (diameter of the pupil). External muscles Trochlear Nerve Motor, eye movements (N IV) Trigeminal Nerve Sensory and motor, opthalmic branch (sensory), (N V) maxilary branches (sensory), mandibular branch Abducens Nerve (N VI) Motor, eye movements, lateral movements Facial Nerve (N VII) Sensory and motor, taste receptors on the tongue, and motor nuclei of pons, motor control of facial expression Vestibulocochlear Nerve (N VIII) Special sensory, balance and equilibrium, and hearing Glossopharyngeal Nerve (N IX) Sensory and motor, sensory on the tongue, pharynx, and palate, carotid arteris, motor form the motor nuclei of the medulla oblongata, pharynx and parotid salivary gland Nerve Primary Function Vagus Nerve (N X) Sensory and motor. Sensory of the pharynx, auricle, diaphragm, visceral organs. Visceral motor and motor nuceli in the medulla oblongata Motor to muscles of the palate and pharynx, motor to respiratory, cardiovascular, and digestive organs Accessory Nerve (N XI) Motor. Voluntary swallowing muscles of the soft palate and pharynx and muscles that control the vocal cords. Controls muscles of the neck and back. Hypoglossal Nerve (N XII) Motor, tongue movements “SOME SAY MARRY MONEY BUT MY BROTHER SAYS BIG BRAINS MATTER MORE” AUTONOMIC NERVOUS SYSTEM Outline: Somatic vs autonomic Sympathetic vs parasympathetic  Overview of the Nervous System Reminder… CENTRAL NERVOUS SYSTEM Information processing afferent division efferent division PERIPHERAL NERVOUS SYSTEM includes Somatic nervous Autonomic system nervous system Parasympathetic Sympathetic division division Special sensory Visceral sensory Somatic sensory receptors receptors receptors Smooth muscle Skeletal muscle Cardiac muscle Glands RECEPTORS EFFECTORS Figure 13.2 Autonomic Nervous System (ANS) Functions outside of our conscious awareness system makes routine adjustments in our body’s systems ex: homeostasis Regulates body temperature Coordinates cardiovascular, respiratory, digestive, excretory, and reproductive functions  Somatic vs. Autonomic General comparison Somatic Autonomic single neuron between cns and skeletal muscle cells 2 neurons between cns and organ only innervates skeletal muscle innervates smooth and cardiac muscle, glands, leads ONLY to etc. excitation Usually voluntary can be either excitatory or myelinated axons inhibitory usually involuntary Pre-ganglionic axon myelinated *sympathetic trunks SNS PSNS in cervical In lumbar and and sacral thoracic region region S-K  Vander Fig 6-40 PSNS SNS Pre-ganglion *trunks Post-ganglion  Sympathetic Parasympathetic CNS Preganglionic neuron PNS Preganglionic KEY Sympathetic fiber Neurotransmitters ganglion Acetylcholine Norepinephrine or Epinephrine Ganglionic only have neurons acetylcholine as the chemical Circulatory messenger system Postganglionic Parasympathetic fiber ganglion TARGET Figure 17.10  SNS Adrenal Medulla  SNS - “Fight or Flight” SNS dominant in stressfull situation releases nor or epinephrine ‘extra ability’ in times of stress total body response to a crisis e.g., increase heart rate, blood flow to brain, pupils dilate, gastrointestinal tract inhibited Inhibits non-eesential activities (digestive and urinary activities) Sympathetic trunks play a role in coordination  PSNS Parasympathetic NS controls “rest and digest” functions operate more independently  Parasympathetic NS Functions – Stimulation generally results in: relaxation food processing energy absorption – Major effects of parasympathetic stimulation Pupil constriction Secretion of digestive enzymes from: – Salivary glands, gastric glands, duodenal glands, pancreas, and liver Vander Fig 6-40 PSNS SNS  Vagus Nerve Major nerve of the PSNS Involved in cardio-respiratory regulations Heart and lung function  DUAL INNERVATION All of our organs have duel innervation SNS PSNS  Dual Innervation many organs innervated by both SNS and PSNS Important for homeostasis of important variables Cooperate to ‘fine tune’ various processes and organ function in general, have opposing effects – e.g., control of heart rate, vasoconstriction  Dual Innervation ….or, these two systems may have different, yet cooperative functions within the same organ system ex: PSNS - erection; SNS - ejaculation  Summary - Peripheral NS Afferent vs. Efferent Autonomic vs. Somatic NS SNS vs. PSNS Questions??