Fundamentals of the Nervous System
The Major Structures of the Central Nervous System
The Nervous System is the brain, brain stem, spinal cord and nerves that attach to muscle at your head, neck, hands, feet, and extremities. The brain, or cerebral cortex, is a dense and complex, three dimensional matrix of cellular protoplasm compressed into the thickness of one inch. It is convoluted with gyri and sulci (folds & grooves) giving it increased surface area and incorporates the highest level of neural circuitry with many functionally specialized areas of neural tissue.
The brain is naturally subdivided into functional regions and physically divided into longitudinal hemispheres by the longitudinal fissure. The frontal lobe is our personality, planning and tracking mechanisms. It is called neocortex because evolutionarily it is the newest part of our brain. The left and right temporal lobes function to decode and process audition and primarily the left anterior, fronto-temporal cortex delivers our speech (broca's area) while the posterior tempo-parietal cortex resolves written language (wernicke's area). The occipital lobe is almost the entire posterior part of our brains, is responsible for visual processing, and the parietal lobe for spatial awareness and relationships to objects in space and time.
The brainstem is the midbrain, pons, medulla and cranial nerves with their respective nuclei. The midbrain is the thalamus, hypothalamus inferior and superior colliculi, pituitary and pineal glands. The brainstem is structurally and hierarchically below the brain, processing information from and to the cerebral cortex in addition to coordinating homeostasis and audio and visual input. Below the medulla, the brainstem structurally transitions into the spinal cord and descends through the large circular opening at the base of the skull, the foramen magnum.
The spinal cord continues, traversing downward through the center of each vertebrae of the vertebral column to the small of the back. The vertebral column is separated into functional levels; cervical, thoracic, lumbar, sacral and coccygeal. Joint pairs of dorsal and ventral nerve roots (ganglion) emerge at the left and right at thirty-one levels. Each level branches out and develops into an intricate network of nerves, attaching to muscles, organs of the viscera and tissue across the body. The dorsal root ganglion are for processing ascending sensory input from the periphery and carries that information to cortex and ventral root ganglion are for descending muscular control which originates at cortex and carries that information to the head, body and extremities.
The cervical levels consist of the head, neck and upper extremities, from the first through the seventh vertebrae (C1-7) emerge eight pairs of roots (C1-8.) The ventral rootlets converge onto the brachial plexus which traverses the trunk at each shoulder behind each respective clavicle and pectoralis major muscle. Major attachments are made at the trapezius, deltoid, biceps, triceps, brachioradialis, hypothenar and thenar muscles with minor attachments at other fine musculature. The sensory inputs attach to the distal ulnar (C8-T1), median (C5-8) and radial (C5-8) nerves which decode tactile sensation for epicritic touch. Roots C7 & C8 are located at the C7 vertebrae, in respective superior and inferior positions.
The thoracic levels consists of the trunk (T1-12) with the dorsal and ventral roots attaching at the rib cage at the intercostals from (T1-6) with the the remaining pairs joining the abdominals from superior to inferior (T6-12.) The lumbar nerves join at the pelvis, quadriceps and extend to the anterior leg (L1-5,) and sacral nerves attach to the distal lower extremities (S1-5) and one coccygeal level (coccyx.)
The interrelationships between different structures and their function underlie functional localization. The clinician/practitioner can then determine the location of a nervous system lesion in a patient who has a particular neurological or psychiatric impairment typically within a few millimeters.
, a key principle of nervous system organization (structure equals function). By understanding regional anatomy together with with the functions of particular brain structures, an understanding of the functional neural circuitry's underlying behavior develops.
Every second there an enormous number of computations and functional executions by way of its many subdivisions, and unique structures relating to the spatial (space) and temporal (time) relations between them.
The combined knowledge of where structures are located (neuroanatomy) and the structural function (neurophysiology) is essential for a complete understanding of nervous system organization flow. Functional Neuroanatomy examines those parts of the nervous system that work together to accomplish a particular task, whose systems are formed by specific neural connections between different regions that form complex neural circuits. In the study of functional neuroanatomy, structure and function are tightly interwoven, so much so that they should not be separated
The central nervous system consists of the brain, brainstem and spinal cord. The brain is further subdivided into the cerebral hemispheres, diencephalon, and midbrain. The brainstem is further subdivided into the pons, cerebellum and medulla. The cerebral hemispheres of the brain overlie the diencephalon, midbrain and brainstem, which connects with the spinal cord. The cranial nerves originate in nuclei, leave the brainstem and pass through and around the skull to reach regional muscles of the face and neck and nerve roots leave the spinal cord and pass between the bones of the spine to reach distant parts of the body as peripheral nerves, both which contain processes of both sensory and motor neurons.
The gray matter of the spinal cord comprises the region of the cell bodies and interconnections between neurons. The white matter represents the processes of cells (axons) communicating with other parts of the CNS. The white matter is composed of myelin, which surrounds the cell processes making up the tracts (as well as many of the cell processes in peripheral nerves). The function of myelin seems to be to speed transmission of information.
The nervous system consists of separate central and peripheral components. The central nervous system is a complex of nerve tissues that controls activities of the body; the brain and spinal cord. The peripheral nervous system is the nervous system outside of the brain and spinal cord. The peripheral nervous system is further subdivided into different regions. The somatic nervous system is the system relating to the body as distinct from the mind. The autonomic nervous system is the system that is involuntary or unconscious. They sympathetic nervous system is the system consisting of nerves arising from ganglia near the middle part of the spinal cord, supplying the internal organs, blood vessels, and glands, and balancing the action of the parasympathetic nerves. The parasympathetic nervous system compliments the automatic nervous system by counterbalancing the action of the sympathetic nerves. It consists of nerves arising from the brain and the lower end of the spinal cord and supplying the internal organs, blood vessels, and glands. The enteric nervous system is the intestinal nervous system.
The brain is naturally subdivided into functional regions and physically divided into longitudinal hemispheres by the longitudinal fissure. The frontal lobe is our personality, planning and tracking mechanisms. It is called neocortex because evolutionarily it is the newest part of our brain. The left and right temporal lobes function to decode and process audition and primarily the left anterior, fronto-temporal cortex delivers our speech (broca's area) while the posterior tempo-parietal cortex resolves written language (wernicke's area). The occipital lobe is almost the entire posterior part of our brains, is responsible for visual processing, and the parietal lobe for spatial awareness and relationships to objects in space and time.
The brainstem is the midbrain, pons, medulla and cranial nerves with their respective nuclei. The midbrain is the thalamus, hypothalamus inferior and superior colliculi, pituitary and pineal glands. The brainstem is structurally and hierarchically below the brain, processing information from and to the cerebral cortex in addition to coordinating homeostasis and audio and visual input. Below the medulla, the brainstem structurally transitions into the spinal cord and descends through the large circular opening at the base of the skull, the foramen magnum.
The spinal cord continues, traversing downward through the center of each vertebrae of the vertebral column to the small of the back. The vertebral column is separated into functional levels; cervical, thoracic, lumbar, sacral and coccygeal. Joint pairs of dorsal and ventral nerve roots (ganglion) emerge at the left and right at thirty-one levels. Each level branches out and develops into an intricate network of nerves, attaching to muscles, organs of the viscera and tissue across the body. The dorsal root ganglion are for processing ascending sensory input from the periphery and carries that information to cortex and ventral root ganglion are for descending muscular control which originates at cortex and carries that information to the head, body and extremities.
The cervical levels consist of the head, neck and upper extremities, from the first through the seventh vertebrae (C1-7) emerge eight pairs of roots (C1-8.) The ventral rootlets converge onto the brachial plexus which traverses the trunk at each shoulder behind each respective clavicle and pectoralis major muscle. Major attachments are made at the trapezius, deltoid, biceps, triceps, brachioradialis, hypothenar and thenar muscles with minor attachments at other fine musculature. The sensory inputs attach to the distal ulnar (C8-T1), median (C5-8) and radial (C5-8) nerves which decode tactile sensation for epicritic touch. Roots C7 & C8 are located at the C7 vertebrae, in respective superior and inferior positions.
The thoracic levels consists of the trunk (T1-12) with the dorsal and ventral roots attaching at the rib cage at the intercostals from (T1-6) with the the remaining pairs joining the abdominals from superior to inferior (T6-12.) The lumbar nerves join at the pelvis, quadriceps and extend to the anterior leg (L1-5,) and sacral nerves attach to the distal lower extremities (S1-5) and one coccygeal level (coccyx.)
The interrelationships between different structures and their function underlie functional localization. The clinician/practitioner can then determine the location of a nervous system lesion in a patient who has a particular neurological or psychiatric impairment typically within a few millimeters.
, a key principle of nervous system organization (structure equals function). By understanding regional anatomy together with with the functions of particular brain structures, an understanding of the functional neural circuitry's underlying behavior develops.
Every second there an enormous number of computations and functional executions by way of its many subdivisions, and unique structures relating to the spatial (space) and temporal (time) relations between them.
The combined knowledge of where structures are located (neuroanatomy) and the structural function (neurophysiology) is essential for a complete understanding of nervous system organization flow. Functional Neuroanatomy examines those parts of the nervous system that work together to accomplish a particular task, whose systems are formed by specific neural connections between different regions that form complex neural circuits. In the study of functional neuroanatomy, structure and function are tightly interwoven, so much so that they should not be separated
The central nervous system consists of the brain, brainstem and spinal cord. The brain is further subdivided into the cerebral hemispheres, diencephalon, and midbrain. The brainstem is further subdivided into the pons, cerebellum and medulla. The cerebral hemispheres of the brain overlie the diencephalon, midbrain and brainstem, which connects with the spinal cord. The cranial nerves originate in nuclei, leave the brainstem and pass through and around the skull to reach regional muscles of the face and neck and nerve roots leave the spinal cord and pass between the bones of the spine to reach distant parts of the body as peripheral nerves, both which contain processes of both sensory and motor neurons.
The gray matter of the spinal cord comprises the region of the cell bodies and interconnections between neurons. The white matter represents the processes of cells (axons) communicating with other parts of the CNS. The white matter is composed of myelin, which surrounds the cell processes making up the tracts (as well as many of the cell processes in peripheral nerves). The function of myelin seems to be to speed transmission of information.
The nervous system consists of separate central and peripheral components. The central nervous system is a complex of nerve tissues that controls activities of the body; the brain and spinal cord. The peripheral nervous system is the nervous system outside of the brain and spinal cord. The peripheral nervous system is further subdivided into different regions. The somatic nervous system is the system relating to the body as distinct from the mind. The autonomic nervous system is the system that is involuntary or unconscious. They sympathetic nervous system is the system consisting of nerves arising from ganglia near the middle part of the spinal cord, supplying the internal organs, blood vessels, and glands, and balancing the action of the parasympathetic nerves. The parasympathetic nervous system compliments the automatic nervous system by counterbalancing the action of the sympathetic nerves. It consists of nerves arising from the brain and the lower end of the spinal cord and supplying the internal organs, blood vessels, and glands. The enteric nervous system is the intestinal nervous system.
- The Cerebrum/Cerebral Cortex/Telencephalon -The principal and most superior part of the brain in vertebrates, it is encompassed in the skull and consists of two hemispheres, left and right, separated the longitudinal fissure. The cortex is responsible for the processing and integration of complex neural functions and the initiation and coordination of voluntary activity and sensation in the body.
- Diencephalon - The caudal (posterior) part of the forebrain, that contains the epithalamus, thalamus, hypothalamus, ventral thalamus and the third ventricle.
- Thalamus - Two masses of gray matter lying between the cerebral hemispheres on either side of the third ventricle, that processes and relays sensory information and acts as a center for pain perception.
- Mesencephalon/Midbrain - A small central part of the brainstem, developing from the middle of the primitive or embryonic brain.
- The Pons - The part of the brainstem that links the medulla oblongata and the thalamus
- Cerebellum - Small brain at the rear and posterior part of the brain that coordinates and regulates muscular activity.
- Medulla Oblongata - A structure that forms the lowest part of the brainstem that containing control centers for the heart and lungs whose inferior continuation transitions to the spinal cord.
- The Spinal Cord - The cylindrical bundle of cell bodies, nerve fibers, tracts that is enclosed within the vertebral column and connects nearly all parts of the body to the brain, with which it forms the central nervous system.
- Ganglia - A structure containing a number of nerve cell bodies, typically linked by synapses.
- Peripheral Nerves - Bundles of fibers of nervous tissue that transmits impulses of sensation to the brain and spinal cord, and impulses from the brain and spinal cord to the muscles and organs.
- Gray Matter - The darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites.
- White Matter - The paler tissue of the brain and spinal cord, consisting mainly of nerve fibers with their myelin sheaths.
- Nuclei - A dense organelle, typically a single rounded structure bounded by a double membrane, containing the genetic material.
RUNOFF
Three-dimensional organization of the nervous system is key to understanding how the structures function and interact. Brain and spinal cord, peripheral nerves. Head and neck, upper and lower extremities, genitals, hair.
***Do not delete!~!
Each cell is the progeny of another cell and each is separated from others by a boundary; the cell membrane sealed by a phospholipid bilayer. The cell is highly organized inside with macromolecules concerned with the cell's replication, growth, and maintenance (the nucleus), the cell's energy metabolism (the mitochondria), and with any special products that the cell may produce for extrusion or excretion (the endoplasmic reticulum and golgi apparatus). The cell membrane separates the cell's internal and external environments. Outside the cell is extracellular fluid, which is a dilute solution of Na2+/Sodium molecules. Inside the cell (cytoplasm) is the intracellular fluid, which is a concentrated solution of K+/Potassium molecules.
Legendary neuroanatomist and professor at the University of California, Berkeley found that renowned physicist Albert Einstein's brain had a higher concentration of glial cells when compared with others.
Three-dimensional organization of the nervous system is key to understanding how the structures function and interact. Brain and spinal cord, peripheral nerves. Head and neck, upper and lower extremities, genitals, hair.
***Do not delete!~!
Each cell is the progeny of another cell and each is separated from others by a boundary; the cell membrane sealed by a phospholipid bilayer. The cell is highly organized inside with macromolecules concerned with the cell's replication, growth, and maintenance (the nucleus), the cell's energy metabolism (the mitochondria), and with any special products that the cell may produce for extrusion or excretion (the endoplasmic reticulum and golgi apparatus). The cell membrane separates the cell's internal and external environments. Outside the cell is extracellular fluid, which is a dilute solution of Na2+/Sodium molecules. Inside the cell (cytoplasm) is the intracellular fluid, which is a concentrated solution of K+/Potassium molecules.
Legendary neuroanatomist and professor at the University of California, Berkeley found that renowned physicist Albert Einstein's brain had a higher concentration of glial cells when compared with others.