Human Anatomy Lecture 14 - Neuroanatomy - BRAIN - Almaaqal University - PDF

Academic year 2022-2023 ‫فرع جراحة الفم والوجه والفكين‬ ‫كلية طب االسنان‬ 2ed year Human Anatomy Lecture 14...

Academic year 2022-2023 ‫فرع جراحة الفم والوجه والفكين‬ ‫كلية طب االسنان‬ 2ed year Human Anatomy Lecture 14 Neuro anatomy BRAIN By:Dr.Nada hashim AL JASSIM Snell R.S. Clinical Anatomy by regions, 9th Edition, Lippincott Williams & Wilkins, [2012 For more detailed instructions, any question, cases need help please post to the telegram group of the session  The Nervous System Neuroanatomy is the study of the structure and organization of the nervous system. The nervous system is a complex network of nerves and cells that carry messages to and from the brain to the rest of the body Nervous System The nervous system is divided into two main parts: 1-the central nervous system, which consists of the brain and spinal cord 2-peripheral nervous system, which consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves and their associated ganglia. Functionally, the nervous system can be further divided into the  somatic nervous system, which controls voluntary activities,  autonomic nervous system, which controls involuntary activities. The nervous system, together with the endocrine system, controls and integrates the activities of the different parts of the body  1- Central Nervous System The central nervous system (which consists of the brain and spinal cord) is composed of 2 major cell types; the neuron and the neuroglia(glial). Neuron represent the structural and functional cells in the nervous system which responsible for receiving sensory input (Sensory or Afferent neurons) from the external world, for sending motor commands to our muscles (Motor or Efferent neurons).  consist of nerve cells and their processes,  neuroglia supporting nervous tissue for neurons. The neurons have three basic parts a cell body ,and two extensions called an axon , and a dendrite Within the cell body is a nucleus , which controls the cell’s activities and contains the cell’s genetic material.  axon the longest process of the cell body that carries nerve impulses away from the nerve cell body; (looks like a long tail) neurons can have only 1 axon  Dendrites the short processes of the cell body that carries nerve impulses toward the nerve cell body (look like the branches of a tree) neurons may have multiple dendrites;  Neurons communicate with each other by sending chemicals, called neurotransmitters, across a tiny space, called a synapse, between the axons and dendrites of adjacent neurons. Glial cells (neuroglia). (Supporting Cells) work to support, nourish, insulate neurons and remove waste products. In the central nervous system, there are four types of supporting cells: Astrocytes, Oligodendrocytes, Microglia and Ependymal cells. In the peripheral nervous system, there is one type of supporting cell: the Schwann cell  Nervous System Terminology A nerve fiber is an axon or dendrite. A nerve is a bundle of nerve fibers in the PNS A nerve tract is a bundle of nerve fibers in the CNS. Nuclei are clusters of cell bodies in The CNS Ganglia are clusters of cell bodies in the PNS (except the basal ganglia, which are more appropriately called basal nuclei).  central nervous system is organized into gray and white matter. Gray matter consists of nerve cells embedded in neuroglia. White matter consists of nerve fibers (axons) embedded in neuroglia.  Peripheral Nervous System The peripheral nervous system consists of the cranial and spinal nerves and their associated ganglia. On dissection, the cranial and spinal nerves are seen as grayish white cords. They are made up of bundles of nerve fibers (axons) supported by delicate areolar tissue. Cranial Nerves There are 12 pairs of cranial nerves that leave the brain and pass through foramina in the skull. All the nerves are distributed in the head and neck except the Xth (vagus), which also supplies structures in the thorax and abdomen. The cranial nerves are named as follows: I. Olfactory nerve – sensory for smell II. Optic nerve – sensory for vision III. Oculomotor nerve – motor fibers to eye muscles IV. Trochlear nerve – motor fibers to eye muscles V. Trigeminal nerve – sensory for the face; motor fibers to chewing muscles VI. Abducent nerve – motor fibers to eye muscles VII. Facial nerve – sensory for taste; motor fibers to the face VIII. Vestibulocochlear nerve – sensory for balance and hearing IX. Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx X. Vagus nerve – sensory and motor fibers for pharynx, larynx, and viscera XI. Accessory nerve – motor fibers to neck and upper back XII. Hypoglossal nerve – motor fibers to tongue  The olfactory, optic, and vestibulocochlear nerves are entirely sensory;  the oculomotor, trochlear, abducent, accessory, and hypoglossal nerves are entirely motor;  the remaining nerves are mixed. Note: each cranial nerve (CN) has its specific number (No.) e.g. CN I is Olfactory nerve.  Spinal Nerves A total of 31 pairs of spinal nerves leave the spinal cord and pass through intervertebral foramina in the vertebral column. The spinal nerves are named according to the region of the vertebral column with which they are associated: 8 cervical (C1-C8), 12thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), 1coccygeal (Co).  Autonomic Nervous System The autonomic nervous system is the part of the nervous system concerned with the innervation of involuntary structures such as the heart, smooth muscle, and glands throughout the body and is distributed throughout the central and peripheral nervous system. The autonomic system may be divided into two parts— the sympathetic and the parasympathetic—and both parts have afferent and efferent nerve fibers. The hypothalamus of the brain controls the autonomic nervous system and integrates the activities of the autonomic and neuroendocrine systems, thus preserving homeostasis in the body.  Sympathetic System The activities of the sympathetic part of the autonomic system prepares the body for action and an emergency—as in the “fight or flight” response— by increasing heart rate, respiration, blood pressure (by constriction of the peripheral blood vessels), and also increase blood flow to the brain, heart, and skeletal muscles; dilating the pupils; and it inhibits peristalsis of the intestinal tract “shutting down” visceral activity and closes the sphincters.  Parasympathetic System The activities of the parasympathetic part of the autonomic system aim at conserving and restoring energy and functions to calm the body— as in “rest or digest“— by decreasing heart rate, respiration,and blood pressure; constricting the pupils; and increase peristalsis of the intestine “increasing visceral activity” and glandular activity, and open the sphincters. Neurons of the parasympathetic system originate either in the brain in certain nuclei of cranial nerves III, VII, IX, and X(cranial outflow) or in the sacral spinal cord from the intermediolateral cell column of spinal nerves S2–S4 (sacral outflow).Together, this system is known as the craniosacral outflow. Both systems (sympathetic and para sympathetic) innervate many organs of the body where their antagonistic actions serve to balance functioning to maintain homeostasis  Organization of the Nervous System The Nervous System supplies the body wall and limbs (Somatic) and the Viscera (autonomic). The CNS(Brain and Spinal Cord) send and receive information through the PNS in form of impulses. The sending impulses is called Efferent Impulses. The Cerebral Cortex of the brain is the final area of the afferent impulses The Efferent Impulses (Movement) are send to and the Afferent Impulses (Sensation) are received from the Body by the Spinal nerves Nervous System The nervous system is divided into two main parts: 1-the central nervous system, which consists of the brain and spinal cord 2-peripheral nervous system, which consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves and their associated ganglia. Functionally, the nervous system can be further divided into the  somatic nervous system, which controls voluntary activities,  autonomic nervous system, which controls involuntary activities. The nervous system, together with the endocrine system, controls and integrates the activities of the different parts of the body  The Brain The brain is a part of the CNS & composed of 3 main structural divisions: Cerebrum, Brainstem Cerebellum. The cerebrum is the largest part of the human brain. The brain stem is between the spinal cord and the rest of the brain. The cerebellum is at the base and the back of the brain. The brain controls thoughts, memory and speech, body movements and the function of many organs within the body The Brain: The basic components of the CNS include the: Cerebrum Diencephalon Cerebellum Brain stem (midbrain, pons, and medulla) Spinal cord  The Cerebrum Externally, the cerebrum has a highly convoluted appearance and it is divided into 2 halves: the right and left cerebral hemispheres. The hemispheres are joined at the bottom by the corpus callosum. The corpus callosum connects the two halves of the brain and delivers messages from one half of the brain to the other. The cortex is the outermost layer of the brain and consists mainly of neuron cell bodies, it appears grayish brown brown in color and is called the “gray matter.” The cerebral cortex has sulci (small grooves), fissures (larger grooves) and bulges between the grooves called gyri. A fissure that separates the two hemispheres is called the Interhemispheric fissure. The falx cerebri descends vertically to fill this fissure. Each hemisphere can be divided into four lobes: the frontal lobe, temporal lobe, occipital lobe, and parietal lobe. The lobes are functional segments The corpus callosum is the most important landmark in the brain. It is a bridge of axons that joins the two hemispheres and allows communication between them. Corpus Callosum  Nowadays MRI enables us to see a histology-like picture in the living brain. Stained post-mortem Living Cerebral Hemispheres (Cerebrum) Account for 83% of brain mass Paired (left and right) superior parts of the brain Include more than half of the brain mass Gray matter Outer layer Composed mostly of neuron cell bodies White matter Fiber tracts inside the gray matter Example: corpus callosum connects hemispheres  Deeper sulci divide cerebrum into lobes Lobes are named for the skull bones overlying them Central sulcus separates frontal and parietal lobes Bordered by two gyri Precentral gyrus Postcentral gyrus  Fissures – deep grooves –  separate major regions of the brain  Transverse fissure – separates cerebrum and cerebellum  Longitudinal fissure –  separates cerebral hemispheres  The Brain: Cerebrum (lobes) Cerebrum divided into 4 lobes: Frontal: motor function, motivation, aggression, smell and mood Parietal: reception and evaluation of sensory info. Temporal: smell, hearing, memory and abstract thought Occipital: visual processing  Functions of Cerebrum Lobes Frontal contains voluntary motor functions and areas for planning, mood, smell and social judgement Parietal contains areas for sensory reception & integration of sensory information Occipital is visual center of brain Temporal contains areas for hearing, smell, learning, memory, emotional behavior Can make a drawing on your hand THANK YOU