Nervous System PDF

The Nervous System Gross Anatomy of Brain and Spine Cord Basics of Neurophysiology Sensory Organs The Compounds Development of the embryonic nervous system fom the ektodermal germinal sheet. The Grey Matter  Synapsis 2 mitochondria...

The Nervous System Gross Anatomy of Brain and Spine Cord Basics of Neurophysiology Sensory Organs The Compounds Development of the embryonic nervous system fom the ektodermal germinal sheet. The Grey Matter  Synapsis 2 mitochondria Axon terminus with vesicles containing transmitter substance synaptic cleft/ gap post-synaptic dendrite 6  Synapsis EM detail of neuro-neural synapse in the brain or spinal cord. The axon terminal contains many seed-like synpatic vesicles containing transmitter substances. The intercellular cleft between the axon and the contacted dendrite can be seen. Just below the dendritic cell membrane is a dark, filamentous post-synaptic density. 7 5 The White Matter  Glia – The Oligodendrocytes These are the cells responsible for the myelin wrapping of axons of 11 the central nervous system. Function Of Oligodendrocytes  Glia – The Astrocytes Since astrocytes touch both capillaries and neurons, they are thought to play an important intermediary role in the nutrition and metabolism of neurons. Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, dendrites and myelinated as well as unmyelinated axons, glial cells (astroglia and oligodendrocytes), synapses, and capillaries. contains numerous cell bodies and relatively few myelinated axons. gray matter areas of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump, rather than coursing through the axon, increasing the speed of transmission of all nerve ] The liquor system of the brain Cerebrospinal fluid (CSF) is a clear, colorless fluid found in the brain and spinal cord. It is produced by the specialized ependymal cells in the choroid absorbed in the arachnoid granulations. about 500 mL is generated every day. provides basic brain inside the skull. CSF also serves a vital function in cerebral autoregulation of cerebral CSF is derived from blood plasma and is largely similar to it, except that CSF is nearly protein- free compared with plasma and has some different electrolyte levels. CSF contains approximately 0.3% plasma proteins. CSF is normally free of red blood cells and at most contains fewer than 5 white blood cells per mm3 (if the white cell count is higher than this it indicates inflammation or infection). The ventricles of the brain Pair of lateral ventricles 3rd ventricle 4th ventricle  Blood supply of the brain right internal left internal carotid artery carotid artery (frontal, vertebral parietal and arteries temporal lobes) ( occipital lobe and 63 cerebellum)  Blood supply of the brain anterior cerebral artery anterior cranial groove internal carotid artery arterial circle ( circulus arteriosus) posterior cerebral artery cerebellar artery branches to brain stem vertebral artery 64 Posterior cranial groove udden NUMBNESS or weakness of face, arm, or leg, specially on one side of the body. Sudden CONFUSION, trouble speaking or understanding speech. Sudden TROUBLE WALKING, dizziness, loss of balance or coordination. Venous Drainage of the Brain 17  Frontal Lobe Functions: How we know what we are doing within our environment (Consciousness). How we initiate activity in response to our environment. Judgments we make about what occurs in our daily activities. Controls our emotional response. Controls our expressive language. Assigns meaning to the words we choose. Involves word associations. 19  Parietal Lobe Functions: Location for touch perception. Goal directed voluntary movements. Manipulation of objects. Integration of different senses that allows for understanding a single concept. 20  Temporal Lobe Functions: Hearing ability Memory aquisition Some visual perceptions Catagorization of objects. 21  Occipital Lobe Functions: Vision 22 23 The basal ganglia = grey matter on both sides of the 3rd ventricle caudate nucleus and lentiform nucleus (consisting of putamen and globus pallidus) represent the EXTRA-PYRAMIDAL MOTOR SYSTEM 24  Brain Stem Deep in brain, connects to spinal cord vice versa. Site of sensory and motoric nuclei of cranial nerves. Contains several „centers“ of involontary functions like Breathing ( CO2-receptors ) Heart Rate Swallowing and vomiting Reflexes to seeing and hearing Controls sweating, blood pressure, digestion, temperature (Autonomic Nervous System). Affects level of alertness. Ability to sleep. Sense of balance (Vestibular Function), and others more. 25  The brain stem posterior aspect lateral aspect pons rhomboid fossa spinal bulb 26 The brain stem 27  Brain stem and cerebellum pons cerebellum 4th ventricle 29  Cerebellum The cerebellum is situated in the posterior cranial groove. It is separated from the occipital cerebral lobe by the tentorium cerebelli. It is connected to the brain stem by three pedunculi and thus co-informed about every motion and the actual Its motoric efferences coordinate involuntarily every motion and allow automatic motions like walking, swimming, cycling, etc. 30 Several aspects of the cerebellum 31  The Cranial Nerves & The Sensory Organs There are twelve pairs of cranial nerves; they are attached to the brain and are transmitted through foramina in the base of the skull. The pairs are named from before backward as follows: 1st. Olfactory. 7th. Facial. 2d. Optic. 8th. Acoustic. 3d. Oculomotor. 9th. Glossopharyngeal. 4th. Trochlear. 10th. Vagus. 5th. Trigeminal. 11th. Accessory. 6th. Abducent. 12th. Hypoglossal. 61  I II III IV V VII VI VIII XI IX XII X 62 1st cranial nerve: Olfactory erve The Sense of Smell 32  sensory epithelium & olfactory tract olfactory fibers olfactory bulb Ist cranial nerve 33 Smell and taste are closely connected with each others, and they are “old“ functions of the brain under an evolutionary perspective. This is why the guiding structures and the cortical area are “buried“ deep inside the brain. 2nd cranial nerve: The Optic nerve And The Sense of Vision 34  3rd, 4th, And 6th Cranial Nerves: Oculomotor, Trochlear, And Abducent Nerves These motoric nerves supply all extra-opthalmic muscles and enable voluntary, synchronous, and coordinated motions of both eyes. ( The oculomotor nerve also supplies the ciliar muscle and is so responsible for accomodation and adaptation 35  5th Cranial Nerve: Trigeminal Nerve The three branches supply the chewing muscles ( mot.), the skin of the face, the mucosa of the mouth, and the teeth ( sens.) Ophthalmic nerve V/1 Maxillary nerve V/2 Mandibular nerve V/3 V/1: the opthalmic nerve V/2: the maxillary nerve V/3: the mandibular nerve  7th Cranial Nerve: The Facial Nerve The nerve supplies somatic motor fibers to the muscles of the face, scalp, and auricle, the Buccinator and Platysma, the Stapedius, the Stylohyoideus, and posterior belly of the Digastricus; Briefly spoken, this nerve is responsible für facial expression, chewing, swallowing, and pronouncement!!! The few sensory fibers suplly the anterior part ( the “Tip“ ) of the tongue. ( see below) 39 8th cranial nerve: Acoustic/ auditory nerve Cochlear nerve: the sense of hearing Vestibular nerve: the sense of balance 40 9th Cranial Nerve: Glossopharyngeal Nerve This nerve conducts sensory impressions from the tongue,, palate, and pharynx.  11th Cranial Nerve: The Accessory Nerve Motoric supply of the muscles in the neck. 42  12th Cranial Nerve: The Hypoglossal Nerve Motoric supply of tongue and mouth The autonomic nervous system Sympathetic and para-sympathetic innervation of inner organs 10th cranial nerve: the vagus nerve This nerve represents the major component of the para – sympathetic system.  Peripheral Nervous System Peripheral nerves consist either of afferent or of efferent, or of both types of fibers: Afferent ( sensory ) fibers guide information ( from receptors ) towards the spine/ cerebrum. Efferent ( motoric ) fibers guide ( motoric ) impulses from the cerebrum ( cerebellum, spine ) to the muscles. The medullary spine ( medulla spinalis ) 8 cervical segments 12 thoracic segments 5 lumbar & 5 sacral segments medullary cone 49  Location of tracts in medullary bulb and spine Fasciculus gracilis SENSORY Fasciculus cuneatus TRACTS Cortico-spinal tract MOTORIC TRACTS  The motor tract Cerebrospinal tract = pyramidal tract The sensory tract  Transverse section through medullary spine posterior/dorsal horn central canal anterior/ventral horn grey matter white matter The peripheral nerves leave the vertebral canal through openings between the vertebrae ( foramina intervertebralia). The cervical and lumbar peripheral nerves form „networks“ ( cervical and lumbar plexus ). There they receive sympathetic fibers and form „mixed“ nerves that supply the limbs ( arms and legs ). 2 thoracic ( inter- costal) nerves 53 cervico-brachial plexus nerves of the arm Nervous supply of the arm anterior aspect posterior aspect lumbar plexus nerves of the leg  Nervous supply of the leg anterior aspect posterior aspect