Seeley's Anatomy and Physiology 11th Edition PDF

Seeley’s Anatomy and Physiology commands from the CNS to other body tissues that alter body movements. 11th Edition...

Seeley’s Anatomy and Physiology commands from the CNS to other body tissues that alter body movements. 11th Edition - 12 pairs Cranial Nerves - 31 pairs Spinal Nerves Blue – Heading Dark Orange – Topic Light Orange – Subtopic Light Green – Terms The PNS can be subdivided into two parts: 8.1 Functions of the Nervous System a. Sensory division / Afferent Division. - Towards the CNS. Nervous System - Conducts action potentials from sensory receptors to the CNS. o A communication system, receiving signals from and - Sensory Neurons – neurons that transmit sending commands to different areas of the body. action potentials from the periphery to the o Helps coordinate the body functions to maintain CNS. homeostasis. b. Motor division Major functions of the Nervous System: - Away from the CNS. - Conducts action potentials from the CNS to 1. Receiving sensory input effector organs. - Sensory receptors monitor numerous external - Motor Neurons – neurons that transmit and internal stimuli. action potentials from the CNS towards the periphery. Note: Internal stimuli are not easily felt unless they become - The effectors controlled by the motor division abnormal. They are picked up by sensory receptors. include muscle tissue and glands. 2. Integrating information Note: Muscle tissue includes skeletal muscle = voluntarily - Combining all processed stimuli and in return controlled, cardiac and smooth muscle = involuntarily controlled. initiates a response. Glands are also involuntarily controlled. - The brain and spinal cord are responsible for integration. The motor division can be further subdivided into two - The input may produce an immediate components: response, be stored as memory, or ignored. 3. Controlling muscles and glands o Somatic Nervous System - When stimulated, the skeletal muscles - Soma = body (Greek) controls bodily movements. - Transmits action potentials from the CNS to - Controls the major movements of the body. skeletal muscles. - Also participates in controlling cardiac muscle, o Autonomic Nervous System smooth muscle, and many glands. - Self-governing / involuntary 4. Maintaining Homeostasis - Transmits action potentials from the CNS to - Homeostasis (balance) depends on the cardiac muscles, smooth muscles, and nervous system’s ability to detect, interpret, glands. and respond to changes in internal and - Divided into sympathetic (for physical activity external conditions. – fight or flight response) and - In response, the nervous system can simulate parasympathetic (involuntary – rest and or inhibit the activities of other systems to help digest) division. maintain a constant environment. - Preganglionic neuron connects to the - Too much or too little of anything disrupts the postganglionic neuron in the structure called balance which can make an individual sick. autonomic ganglion (PNS). 5. Establishing and maintaining mental activity - The brain is the center of mental activity. 8.2 Divisions of the Nervous System a. Central Nervous system - Consists of the brain and spinal cord. b. Peripheral Nervous System - Away from the CNS. - The stemming of the CNS. - Consists of all the nervous tissue outside the CNS. - The connection link between the CNS and the various parts of the body. o Enteric Nervous System - Carries information about the different tissues - has both sensory and motor neurons of the body to the CNS and delivers contained wholly within the digestive tract. MARY ANNE QUIAOIT 01NU08  - Has plexuses within the wall of the digestive 3. Pseudo-unipolar Neurons tract including sensory neurons to the CNS - Single process extending from the cell body. and para/sympathetic motor neurons to the - Divides into two processes: one extends to digestive tracts. the periphery, and the other extends to the - Also has enteric neurons to the enteric CNS. plexuses. - Axon receives sensory information at the - It can function without an input coming from periphery (acts like a dendrite) and transmits the CNS or PNS. (Very independent) that information in the form of action potentials - How does it work independently? – through to the CNS. reflexes. Glial Cells - Neuroglia = nerve glue 8.3 Cells of the Nervous System - The supportive cells of the CNS and PNS. - These cells do not conduct action potentials. The two types of cells that make up the nervous system are: - Carry out different activities that enhance neuron function and maintain normal conditions within nervous a. Neurons tissue. - Receive stimuli, conduct action potentials, - Can divide = more numerous than neuron cells. and transmit signals to other neurons or effector organs. In the CNS, there are four types of glial cells: - Three parts: Cell body – contains a single o Astrocytes nucleus (source of information for - Major supporting cells in the CNS. gene expression). - Can stimulate or inhabit the signaling activity Dendrites – short, often highly of nearby neurons. branching cytoplasmic extensions - Participate with the blood vessel endothelium that are tapered from the bases at to form a permeability barrier (blood-brain the neuron cell body to their tips. barrier) between the blood and the CNS. Also, it usually receives - Help limit damage to neural tissue, however, information from other neurons or the repair process can form a scar that blocks from sensory receptors and regeneration of damaged axons. transmit the information toward o Ependymal Cells the neuron cell body. - Line the fluid-filled cavities within the CNS. Axon – a single long cell process - Some produces cerebrospinal fluid, and that leaves the cell body at the others with cilia, help move cerebrospinal fluid axon hillock and conducts sensory through the CNS. signals to the CNS and motor - CSF – fluids made by the cells that helps signals from the CNS. protect the brain and spinal cord from sudden 1. Axon Hillock – area where impact and removes waste products form the the axon leaves the neuron brain. cell body. o Microglia 2. Collateral Axons – formed - Act as immune cells of the CNS. by a branched or - Help protect the brain by removing bacteria unbranched axon. and cell debris. o Oligodendrocytes Note: When a neuron does it cannot be replaced because it - Provide an insulating material (myelin) that does not divide nor multiply. surrounds axons. Note: Axons of sensory neurons conduct action potentials In the PNS, there are two types of glial cells: towards the CNS, and axons of motor neurons conduct action potentials away from the CNS. o Schwann Cells - Provide insulating material around axons. Action Potential – a change of the resting membrane potential. o Satellite Cells - Found around the cell bodies of certain Types of Neurons neurons of the PNS. 1. Multipolar neurons - Provide support and nutrition to the neurons - Have many dendrites and a single axon. and protect the neurons from heavy-metal - Most neurons in the CNS and motor neurons poisons. are multipolar. Myelin Sheaths 2. Bipolar Neurons - One dendrite and one axon. - Specialized layers that wrap around the axons of some - Located in some sensory organs (retina and neurons. nasal cavity). MARY ANNE QUIAOIT 01NU08  - Formed by the cell process of oligodendrocytes in the - Chemically gated channels – opened by CNS and Schwann cells in the PNS. neurotransmitters or other chemicals. - Myelinated Axons – axons myelin sheaths. - Voltage gated channels – opened by a - An excellent insulator that prevents almost all ion change in membrane potential movements across that cell membrane. (depolarization). - Nodes of Ranvier – gaps in myelin sheaths. ▪ Opening voltage gated channels - Unmyelinated axons – lack the myelin sheaths but starts an action potential. these axons rest in indentation of the oligodendrocytes - Depolarization – change in the membrane in the CNS and Schwann cells in the PNS. potential (the difference decreases). Note: Myelination of an axon increases the speed and efficiency How does depolarization happen? of action potential generation along the axon. a) Sodium has more potential to go inside the cell than Note: A typical small nerve which consists of axons of multiple back out the cell because it goes from higher neurons, usually contain more unmyelinated axons than concentration ton lower concentration. myelinated axons. b) The inside of the cell is originally more negative as opposed on the outside. (Opposite charges attract). - Multiple sclerosis – an autoimmune disease of the - The more sodium goes inside, the inside of myelin sheath that causes the loss of muscle function. the cell becomes more positive than usual. - Leak Channels Organization of Nervous Tissue - The resting membrane potential is Gray Matter established because it is always open. - Substances tend to go from higher - Consists of group of neuron cell bodies and their concentration to lower concentration. dendrites, where there is very little myelin. - Potassium contributes the most to the RMP - Located outside the brain. because there are 50-100x more potassium - Nuclei – clusters of gray matter are also located deep leak channels than sodium which makes it within the brain. easier to go in and out the cell. White Matter Note: The reason why the inside of the cell is negative is because there are more negatively charged molecules. They are - Consists of bundles of parallel axons with their myelin impermeable (not able to pass through) in the membrane. sheaths which are whitish in color. - In the CNS, it forms nerve tracts are conduction Sodium-Potassium Pump pathways propagating action potentials from one area of the CNS to another. - In the PNS, forms nerves. 8.4 Electrical Signals and Neural Pathways Resting Membrane Potentials - Differences in concentrations of ions across the membrane, membrane channels, and the sodium- potassium pump. - Inside of the cell is negative and the outside of the cell is positive. - The unstimulated and unevenly distributed charge. - The time when the cell membrane is polarized (divided - Due to variety of potassium leakage channels the into two opposing groups). positively charged potassium goes outside the cell - Potential – a small voltage difference. because it has a lower concentration. - The inside becomes more negative, however, since the 3 Factors that generate the RMP: opposite charges attract the potassium has no choice a. A higher concentration of potassium inside the cell. but to move back inside the cell. (Potassium goes in b. A higher concentration of sodium outside the cell. and out the leakage gate). c. Cell membrane permeability preference to the - The membrane should ensure that there is a greater potassium as compared to sodium (due to ion concentration of sodium outside and potassium inside channels). (needs to be maintained). - In every 2 potassium ions pumps back in the cell, it Membrane Channels: pumps out back 3 potassium ions. This compensate and helps sodium ions to go back outside the cell - Gated Channels where it has higher concentration. - Only opens via a specific signal. MARY ANNE QUIAOIT 01NU08 Note: S-PP only works when there is ATP (energy), especially Unmyelinated Axons in neurons which requires 70% ATP. EVEN IF A PERSON IS JUST SITTING AND DOES NOT MOVE AROUND, AN INDIVIDUAL MAY FEEL TIRED THAN USUAL BECAUSE THE BRAIN CONSUMES A LOT OF ENERGY WHEN IT IS WORKING! Action Potential - Allows conductivity along nerve or muscle membrane, similar to electricity going along an electric wire. - The muscle and nerve cells are excitable cells. Therefore, as long as there is a stimuli the resting membrane potential can change via the gated channels. It allows permeability of some substances which were previously impermeable and then 1. The cell membrane stimulates local currents in the eventually produces an action potential because of adjacent part of the cell membrane. (1 – orange area). depolarized cells. 2. The depolarized produces and action potential. - When the cell is stimulated, upon stimulus of the nerve 3. The new part stimulates local currents into the next part cell or the muscle cell with the neurotransmitter, it and depolarizes it. (Continuous conduction) briefly opens the sodium channels, and some sodium Myelinated Axons diffuses quickly into the cell. - Local current – when the door only opens for a while. Also causes the depolarization. - Local potential – caused by depolarization. Usually occurs in dendrites or soma. - If the depolarization is not strong enough, the sodium channels close, the local potential disappears. - Sodium channels are open until it reaches a threshold value (most often reached at the axon hillock). - Hyperpolarization – at the end of repolarization, the charge on the cell membrane briefly becomes more negative than the resting membrane potential. Note: A stronger stimulus does not produce a stronger action potential, but it produces more action potentials. - The myelin sheath acts as an insulator and it does not have ion channels which means depolarization cannot occur in the certain area. - Node of Ranvier – produces an action potential because it does not have any myelin. - The sodium ions bumps other positive ions until the wave depolarizes the next node due to the action potential that happened in the node of Ranvier. - Saltatory Conduction – jumps from one node to another. It also increases conduction velocity. - Pure ions are conducted along the cell membrane just to produce an action potential. Synapse Propagation of Action Potentials Neuronal Synapse - Conducted slowly in unmyelinated axons and rapidly in - A junction where the axon of one neuron interacts with myelinated axons another neuron or effector organ. - Presynaptic Terminal – end of an axon. - Postsynaptic Membrane – formed by the membrane of the next neuron with a synaptic cleft in between. - Vesicles – the round substances located in the presynaptic terminals (neurotransmitters). - Action potentials are being conducted along axons. - Once the potential actions reach the presynaptic terminal the voltage gated channels of calcium opens. MARY ANNE QUIAOIT 01NU08 Note: Neurotransmitters does not activate an action potential all Neuronal Pathway (Diverging) the time. It depends on what type of neurotransmitter it is and what type of receptor it is. - An axon from one neuron divides and synapses with more than one other postsynaptic neuron. Extracellular ions (outside of the cell) – Sodium, Calcium, and - Allows information transmitted in one neuronal Chloride pathway to diverge into two or more pathways. - From sensory neuron to the ascending tracts. Intracellular ions (inside of the cell) – Potassium, a little bit of - e.g., For the muscle contraction to occur a stimulus Sodium, and a little bit of Chloride. must be present. This stimulus is picked up by the pain receptors and activates the sensory fibers and the Note: Neurotransmitters do not stay on the synaptic cleft sensory neurons that carries the action potential indefinitely. Thus, their effects on the postsynaptic membrane towards the spine. The axons of the sensory neuron are short in duration. These substances are either rapidly broken branches within the spinal cord. down by enzymes or they are transported back to the - One branch produces the reflex by synapsing with the presynaptic terminal. interneuron and the interneuron synapses to the motor Acetylcholinesterase – an enzyme that breaks down the neuron without any stimulus coming from the brain. acetylcholine and the products go back to the presynaptic These produces a jerking movement away from the terminal for recycling. stimulus. - The other branch carrying an action potential synapses Norepinephrine – can also be actively transported back to the with the ascending neuron where it ascends towards presynaptic terminal. the brain and the pain is received. Note: These transfers of neurotransmitters happen as rapidly Summation and as countless times per second and these are affected by numerous diseases and drug - Many presynaptic action potentials are needed. - A single presynaptic action potential usually does not Reflex cause a sufficient postsynaptic local potential to reach a threshold and cannot produce an action potential. - Involuntary reaction in response to a stimulus applied - Spatial Summation – occurs from the local potentials to the periphery and transmitted to the CNS. that came from different locations of the postsynaptic - Allows reaction faster than conscious thought. neuron (converging pathways). - Occur in the spinal cord or the brain stem rather than - Temporal Summation – occurs when the local the higher brain centers. potential overlap (briefly) in time. Reflex Arc Spinal Cord - The neuronal pathway by which a reflex occurs. - Extends from the foramen magnum located at the base - The basic functional unit of the nervous system of the skull to the second lumbar vertebra (Conus because it is the smallest and also the simplest Medullaris). pathway capable of receiving a stimulus and giving a - Filum Terminale – long strand (tail) located after the response. second lumbar vertebra. - When the interneuron synapses with the motor neuron - Spinal nerves exit as the cauda equina (looks like a to produce an action from the muscle. horse tail). - Components: - Protected by the vertebral column and communicates - Sensory receptor with the body through the spinal nerves. - Sensory neuron - Spinal nerve – allow movements and causes paralysis - Interneurons when damaged. - Motor neuron - Effector organ Spinal Cord Cross Section Neuronal Pathway (Converging) - Simple pathway in which two or more neurons synapse with the same postsynaptic neuron. - Allows information transmitted in more than one neuronal pathway to converge into a single pathway. - From the brain towards the motor neuron. - The interneuron synapses with the motor neuron to produce an action from the muscle (Reflex Arc). There are also signal coming from the cerebral cortex. These neurons also synapses with the same motor neuron which came from the axons from the descending tracts. - The motor neuron in the converging pathway can be stimulated either by the conscious thought or reflex arc. MARY ANNE QUIAOIT 01NU08  - The white matter is superficial, and the gray matter is Reflexes the deeper portion. White Matter - When divided in half, it has three columns: dorsal (posterior), ventral (anterior), and lateral column. - The lateral column contains the ascending (going up the brain) and descending (going away the brain) tracts (pathways). - Tracts – axons in the CNS. Gray Matter - Looks like an “H” or a butterfly. - It has three horns: - Posterior – contains axons with sensory neurons that synapse with interneurons. - Anterior – contains somatic or motor neuron. - Lateral – responsible for the autonomic nervous system. - Central Canal – hole in the middle of the gray matter. It is also where the cerebrospinal fluid flows from the brain. Spinal Nerve - Arise from the numerous rootlets which forms the root Quadriceps femoris muscle – anterior thigh muscle where they are located. - The dorsal root and the ventral root forms the spinal Flexor muscles – posterior thigh muscle. (Biceps femoris) nerve. - Once the patella ligament is tapped with a hammer, the - Dorsal root ganglion – the blub (swelling) in the anterior muscles and its tendon is stretched which also dorsal which contains cell bodies or pseudo-unipolar triggers the sensory motors to stretch. sensory neurons. - Since the quadriceps femoris contracts it becomes - The pseudo-unipolar axons in the dorsal root shorter and lifts the lower leg forward (Knee-jerk ganglion have a peripheral branch and a Reflex / Patellar Reflex). central branch. ▪ Originated from the periphery and Stretch Reflex passes through the spinal nerves up to the sensory neuron to the dorsal - Occurs when muscles contract in response to a root and to the posterior horn which stretching force applied to them. synapses with the interneuron. ▪ The interneuron synapses with the Spinal Nerves motor neuron which passes through - Arises along spinal cord from union of dorsal roots and the ventral root and goes out through ventral roots. the spinal nerve towards the effector - Contains axons sensory and somatic neurons (Mixed organ (reflex arc). Nerves). Some have para-sympathetic and ▪ If the pseudo-unipolar axons passes sympathetic axons. through the white matter, it either - Located between the vertebra. descends or ascends in the spinal - Cervical roots exits at the top of the vertebral column cord. with the same number. - The dorsal area picks up the external stimulus (sensory - Thoracic and Lumbar exits below the vertebra. neurons). - There are 8 pair of cervical roots. 12 pairs of thoracic - The motor neuron is located on the ventral / anterior roots. 5 pairs of lumbar roots. 5 pairs of sacral roots. 1 portion of the horn. pair of coccygeal roots. Cerebral Cortex – controls the conscious movement. Dermatomes - These nerves supply specific regions in the body. - The area of the skin supplied by sensory innovation by the spinal nerves. - C1 is the only spinal nerve that does not have sensory distribution to the skin. MARY ANNE QUIAOIT 01NU08  - Radial Nerve – sensory innervation: is for the posterior arm, forearm, and hand, motor innervation: is for the posterior arm and forearm only. Lies very close to the proximal and the medial side of the humerus. - Ulnar nerve – innervates two anterior forearm muscles in most of the intrinsic hand muscles in the skin on the ulnar side. When it passes the exterior of the medial side of the elbow, there will be a tingling sensation when bumped (funny bone). - Median nerve – innervates most of the anterior forearm muscles and some of the extrinsic hand muscles and the skin on the Note: The spinal nerves are organized in 3 plexuses (braid). radial side. Spinal Plexuses - Musculocutaneous nerve – innervates the anterior muscles of the arm in the skin over - Neurons from different spinal nerves and segments the radial surface of the forearm. intermingle like a braid. - Sensory Neuron – provide sensory innervation to the skin. - Motor Neuron – innervate the muscles in the certain area. - Lumbosacral plexus – originates from the spinal nerves L1 – S4 – supply the lower limbs. - Cervical plexus – originated from the spinal nerves C1 – C4 – innervates the muscles attached to the hyoid bone and the sensations on the neck and the posterior part of the head. - Phrenic Nerve – innervates the diaphragm. - Brachial plexus – originates from the spinal nerves C5 – T1 – supply the nerve to the upper limbs, shoulders, and the hands. - The obturator nerve innervates the muscles and the skin located in the medial side (sensory). - The femoral nerve innervate the anterior thigh muscle and its skin; also, the skin of the medial leg (sensory). - The tibial nerve innervates the posterior thigh, the anterior and posterior leg muscles, as well as the skin over the sole (motor). - The common fibular nerve innervates the - Axillary Nerves (armpit) – innervates the skin muscle of the lateral thigh as well as the and muscles of the shoulders on both sides. lateral leg. Also has some innervation in the intrinsic floor muscles (motor). MARY ANNE QUIAOIT 01NU08  - The common fibular (peroneal) nerve The major regions of the brain are the brainstem, cerebellum, innervates the skin over the anterior leg and diencephalon, and cerebrum. the lateral leg; as well as the dorsal surface of the foot (sensory). Brainstem - The sciatic nerve is the combination of the - The connection of the spinal cord to the rest of the brain. tibial and common fibular nerves bounded - Responsible for the vital bodily function (BP, HR, RR). together by a connective tissue sheath. - If there is damage in this area, the patient would most Humerus – long bone of the upper arm. likely die. - Three components (have ascending and tracts going Medial – towards the center. to and from the cerebrum): - Medulla oblongata Lateral – away the center. - Pons - Midbrain Proximal – near the point of origin. Distal – away from the point of origin. Crutch Paralysis – it impinges on the radial nerve which causes the paralysis of the posterior arm and forearm muscles which also causes numbness on the back of the forearm and some parts of the hand. Note: T2 – T11 spinal nerves does not form a plexus but they extend around the chest in between the ribs to supply the skin in that area and to help other muscles of respiration in that same area. Note: Whenever there is a presence of phrenic nerves on both sides of the lungs; when the right phrenic nerve, the diaphragm from on the right side will lose its function. It will not be able to contract, and an individual will have a hard time breathing. Medulla oblongata - Extends from the level of the foramen magnum. Then goes to the pons upwards and to the midbrain. - Functions as a regulator of the heart rate and blood vessel diameter (vomiting, swallowing, coughing, breathing, sneezing, balance, and coordination). - The pyramids found in the anterior portion of the Medulla oblongata consists of descending tracts which is responsible for the conscious control of the skeletal muscle. - Coccygeal plexus that supply the skin over the coccyx Pons and muscles of the pelvic floor. - Some of the nuclei found in the area where the pons is rely information between the cerebellum and cerebrum. - The lower pons is responsible for breathing, Brain swallowing, and balance because some of the nuclei from the Medulla extends to this area. - The rest of the area is for salivation and chewing. Midbrain - Located above the pons. - On the dorsal, four mounts can be seen which are called the colliculi. - Inferior colliculi – major relay centers for the auditory nerve pathways. - Superior colliculi – for touch and some auditory input. It is also responsible for the visual reflexes, coordinated eye movements, pupil diameter, lens and shape, and turning the head. MARY ANNE QUIAOIT 01NU08  - Substantia Nigra – can be seen when the Cerebrum midbrain is cut into cross section. It is a black mass of nuclei which regulates the general body movement. - Largest part of the brain. - Its surface is composed of gray matter and is divided into two hemispheres (left and right) which is divided by Reticular Formation – functions to regulate cyclical motor the longitudinal fissure. functions (respiration, walking, chewing, sleep-wake cycle). - The right hemisphere controls the left side of the body which is responsible for music, art, and abstract ideas. Diencephalon - The left hemisphere controls the right side of the body which is responsible for math, analytics, and speech. - Anatomically connects the brainstem and the cerebrum. - Divided into thalamus, epithalamus, hypothalamus. Note: The sensory signals crosses over the other side of the - Thalamus – biggest part made up of cluster spinal cord or the brainstem before it ascends to the cerebrum. of nuclei. There are two lateral parts connected by interthalamic adhesion. - Corpus callosum – the connection between the two hemispheres. - Gyri (circular) – snake-like folds found in the brain. It increases the surface area of the brain. - Sulci (furrows / ditch) – the grooves between the gyri. - The cerebrum controls thinking, communicating, memory, understanding, and initiates involuntary movements. Note: Each hemisphere is divided into five lobes. a. Frontal Lobe - For olfactory and voluntary motor functions. - Responsible for motivation, aggression, mood, and olfactory reception. ▪ From the ascending neurons, the b. Parietal Lobe thalamic neurons send signals to the - For receiving sensory information (touch, cerebrum which influences the mood. pressure, pain, temperature, taste, and - Epithalamus – located superiorly and sometimes balance) posteriorly to the thalamus. Its function is for the emotional and visceral response to others. Note: The frontal lobe and parietal lobe is divided by the Central It is also where the penial gland is found. sulcus / Central fissure. ▪ Penial Gland – influences the onset of puberty and circadian rhythm c. Temporal Lobe which is responsible for knowing - Perceives the olfactory and auditory when to sleep and when to wake up. sensation (on the side). - Hypothalamus – located below the thalamus. - Also plays a role in memory. It maintains homeostasis and controls the - The anterior and inferior part of the temporal body temperature, hunger, thirst, fear, rage, lobe are for abstract thought and judgement and even sexual emotions. called psychic cortex. ▪ Infundibulum – a funnel shape - Separated from the others by the lateral stock that controls hormone fissure. secretion from the pituitary gland. o Insula (fifth lobe) – can be seen ▪ Mammillary bodies – swellings on deep in the lateral fissure (taste). the posterior hypothalamus which d. Occipital Lobe are responsible for the emotional - For visual input. response to odors and memory. MARY ANNE QUIAOIT 01NU08 Sulcus vs. Fissure Motor Functions - Responsible of any movement (voluntary and involuntary). - Details of most voluntary movements occur automatically. o Due to neural circuits in the reticular formation and the spinal cord automatically control the limbs. o e.g. walking, talking, typing, playing piano, breath - Upper Motor Neuron (cerebrum) – a part of a neural circuit. The cell bodies of these neurons are in the cerebral cortex which form descending tracts that connects to the lower motor neuron (cell bodies are found in the anterior horn of the gray matter). Sensory Function - Lower Motor Neuron (spinal cord) – can be found in - CNS constantly receives sensory inputs, and ‘we’ are un- the spinal cord or in the cranial nerve nuclei and its aware of it (perception). axon extends to the skeletal muscles. - The sensory input to the brainstem in the diencephalon helps maintain homeostasis while the cerebrum and the cerebellum keeps us informed about the environment and allows us to control motor functions as a reaction. - The ascending and descending tracts usually course through the white matter of the spinal cord. - Spinothalamic tract – originates from the spinal cord and end in the thalamus. Deals with pain and temperature. - Dorsal Column – deals with touch, position, and pressure. - Spinocerebellar Tract (posterior and anterior) – comes from the spinal cord towards the cerebellum. It transmits signals for body position and proprioception which Primary Motor Cortex makes it responsible for balance. - Posterior portion of the frontal lobe. Note: Majority of the neurons terminate in the thalamus that is - Directly anterior to the central sulcus. why it is usually called “relay center”. - Controls voluntary movements of the skeletal muscle. Primary Sensory Areas Prefrontal Area - Where sensations are perceived from the ascending - Located in front of the brain. tracts. - Plays an important role in higher level cognitive - Primary somatosensory cortex – located in the functions (planning, critical thinking, understanding parietal lobe. Posterior to the central sulcus. Where the consequences of behaviors). sensory fibers from specific parts of the body projects in different parts of the cortex. Premotor Area Association Areas - Located anterior to the primary motor cortex and posterior to the prefrontal area. - Beside the primary areas. - Organizes motor functions and make decisions about - Responsible for the process of recognition. which action an individual shall take before they are initiated in the primary motor cortex. Corticospinal Tract - Begins in the cerebral cortex and end in the spinal cord. - Direct tracts. - Extend directly from the upper motor neuron from the cerebrum to the lower motor neuron in the spinal cord. Note: Indirect tracts originates from the brainstem. However, they are indirectly controlled by the cerebrum, cerebellum, and basal nuclei. MARY ANNE QUIAOIT 01NU08 Spinal Cord - Lateral columns which controls goal directed limb movements (reaching, writing). Lateral corticospinal Tract - Focuses on speed and precision (direct skilled movements). Reticulospinal - Located in the ventral column. - Contains nerve tracts that share sensory information - For posture, balance, and limb position. with each other. Therefore, both hemispheres are able to share sensory information however, not all Basal Nuclei information are shared. - Group of functionally related nuclei. Speech - Plan, organize, coordinate motor movements, and posture. - The speech area in most people is located in the left - Linked together with the thalamus in the cerebrum by cerebral cortex. complex neuro circuits. - Two major cortical areas are: - Either inhibit or excite muscles. o Wernicke area (sensory speech) - 2 primary nuclei: ▪ Located in the parietal lobe. o Corpus striatum – located deep within the ▪ Important for understanding and cerebrum. comprehending. o Substantia nigra – located in the midbrain. ▪ Receives input / stimulation. o Broca area (motor speech). Note: When the basal nuclei gets damaged, an individual loses ▪ Located in the frontal area. control on their muscle movements (Diseases: Parkinson’s, ▪ Controls movement of the mouth Huntington’s, and Cerebral Palsy) – manifests with resting and tongue for speech. tremors. ▪ Determines what to reply. Therefore, it send it to the prefrontal area which Cerebellum (little brain) sends it to the – premotor area that - Attached to the brainstem by the cerebellar peduncles recognizes and initiates the (stalk). movement – to the primary motor - Cortex is composed of gyri, sulci, and gray matter. cortex – cerebellum – sends signals - Has a gray nuclei with white nerve tracts. to the muscles of the mouth. - It controls balance and coordinates fine motor - Aphasia – absent or defective speech / language movements. comprehension. - Main function: to compare data from the motor cortex o Wernicke Aphasia – when an individual (cerebrum) and peripheral structures. cannot understand what is being said and - “like a boss that checks the quality control” start responding unrelated to the question. o Broca Aphasia – an individual can Note: When the cerebellum is damaged, it becomes a concern understand the question but cannot put the to people with an occupation that requires fine motor answer into words. movements. Note: When the cerebrum send signal to the spinal cord, its collateral branches also send signals to the cerebellum about the intended movement. While it happens the proprioceptive neurons from the joints, tendons, and muscles, also send signals to the cerebellum (PNS). Result: the cerebellum compares both sensory and motor signals if they are appropriate. If there is a difference, it sends signals to the motor neurons and corrects the intended movement (for a smooth and coordinated movement). Corpus Callosum - Commissure that connects the right and left hemisphere. MARY ANNE QUIAOIT 01NU08 Touch receptors - Touch receptors in the skin sends signals to the Limbic System and Emotions sensory neurons and to the dorsal horn of the spinal cord and eventually sent to the brain. - The Limbic system comprises of Olfactory cortex, - Perceived by the primary somatic sensory cortex. certain deep cortical regions and nuclei of the - It is recognized as something that has been touched cerebrum and Diencephalon. before. This information is then sent to the sensory - It influences long-term declarative memory, emotions, speech area and is given a name; it travels to the motor visceral responses to emptions, motivations, and mood. speech area where the spoken word is initiated. Note: Mamillary bodies (posterior to the hypothalamus) is part Brain waves and Consciousness of the diencephalon – functions as emotional response to odor and memory. Electroencephalogram (EEG) - Olfaction plays a large role – it stimulates survival - Used to diagnose and determine treatment for brain instinct. disorders. - Lesions in the limbic system can result in voracious - Electrodes placed on scalp to record brain’s electrical appetite and increased sexual activity. activity by detecting simultaneous action potentials. o These action potentials are detected in large Meninges number of neurons and not individually. - Are three connective tissue layers that surround the o A normal pattern is irregular since action brain and spinal cord. potentials do not really work simultaneously. a. Dura mater o Can detect a person’s level of consciousness. ▪ Outermost and toughest o Beta waves – can be seen when one is ▪ The fold extends to the longitudinal problematic or thinking of a solution. fissure and help keep the brain in o Alpha waves – can be seen when one is place. awake but resting with eyes closed. ▪ Dural venous sinus – collects o Delta waves – can be seen when one is in blood from the small veins of the deep sleep. brain and lead towards the heart. o Theta waves – can be seen when one is frustrated or have brain disorder. Note: If the Dural venous sinus ruptures (trauma, aneurism, hemorrhagic stroke due to hypertension) the leak can lead to Memory subdural (below the dura) hematoma (blood clot formation). Staged of Memory Storage: Note: The subdural space usually just contains controlled 1. Working Memory serous fluid. When uncontrolled, it will increase intracranial o For immediate tasks performance pressure which can cause loss of function on a certain side. o Usually found in the frontal cortex Worst case scenario: losing of consciousness. o Only lasts for a few seconds to two minutes Note: In the spinal cord there is only one layer of dura mater. In o Stored one time only the vertebral canal the dura mater and the vertebra is separated 2. Short-term Memory by an epidural space. o Stored via increased synaptic transmission o Usually lasts for a few days o Susceptible to brain trauma, decreased oxygen, or when exposed to anesthesia 3. Long-term Memory o To occur: one need to consolidate the learning – a gradual process involving the information of new and stronger synaptic connections depending on how often it is retrieved or used. o Declarative / Explicit Memory – about facts (names, dates, places) – emotionally related. o Procedural / Reflexive Memory – motor skills. Memory engrams / Memory traces b. Arachnoid mater - Neurons involved in retention of information (thoughts ▪ Very thin and wispy or ideas). ▪ Subarachnoid space – seen - Repeating the information and associating it with underneath the arachnoid. It existing memories helps an individual transfer contains cerebrospinal fluid and information from short-term to long-term. blood vessels. It goes beyond the spinal cord down the vertebral MARY ANNE QUIAOIT 01NU08  column. It is also where the anesthesia called spinal block be injected. c. Pia mater ▪ Very tightly bound to the surface of the brain and spinal cord. Ventricles - CSF is made with fluid-filled cavities called ventricles by specialized ependymomas called choroid plexuses. - The ventricles are located in the ff: o Lateral Ventricle – found in each cerebral hemisphere. o Third Ventricle – found in the center of the diencephalon between the two thalamus. Connected to the lateral ventricle via the o Foramen of Monro – an interventricular foramina that connects the third ventricle and the lateral ventricle. o Cerebral aqueduct – connects the fourth ventricle to the third ventricle. o Fourth ventricle – found in the base of the cerebellum and it is continuous with the central canal of the spinal cord. It also has connection with the subarachnoid space through the Foramen of Lushcka and Cranial Nerves Foramen of Magendie. - Have two categories of function: o Sensory o Motor ▪ Somatic Motor – skeletal muscles ▪ Parasympathetic Motor – glands and cardiac muscles (involuntary muscles) - Some are exclusive for sensory and some are exclusive for motor and some are mixed. - Cranial nerves 1, 2, and 8 are purely sensory. - Cranial nerves 4, 6, 11, and 12 are purely somatic motor. - Cranial nerve 5 is mixed. - Cranial nerve 3 have somatic and parasympathetic motor. - Cranial nerve 7, 9, and 10 all have the three functions (sensory, motor, and parasympathetic. - Arachnoid granulations penetrate the Dural venous sinus where CSF transfers from the subarachnoid space into the blood stream. It is important because when the intracranial pressure (pressure in brain) is increased it needs to release CSF into the blood to decreases the pressure. Any blockage of these canals can cause accumulation in the ventricles leading to the hydrocephalus (only appears in infants). LR6 (Lateral Rectus) – Cranial 6 SO4 (Superior oblique) – Cranial 4 Mandibular Nerve – one branch of the trigeminal. It is also the target for anesthesia when having a tooth extraction. MARY ANNE QUIAOIT 01NU08 Autonomic Nervous System Sympathetic Division (fight or flight) - Prepares an individual for any physical activity. - Preganglionic neurons are found in the lateral gray horn of the spinal cord between the T1 – L2. - Exits through the vertebral roots and goes either to the sympathetic chain ganglia or the collateral ganglia. - Sympathetic Chain Ganglia – form a chain along both sides of the spinal cord where preganglionic fibers synapse with the postganglionic fibers which in return forms synaptic nerve that innervate with the effector organs of the thoracic cavity. Note: When the preganglionic nerves bypass the sympathetic chain ganglia, they become the splanchnic nerves which extend to either of the three collateral ganglia (celiac, superior mesenteric, and inferior mesenteric – innervates abdominal and pelvic organs) Parasympathetic Division (rest and digest) - The preganglionic cell bodies are located within the brainstem nuclei of the cranial nerve 3, 7, 9, and 10; also within the lateral part of the central gray mater of the spinal cord. - Happens at the level of S2 – S4. - The preganglionic axon extends to other spinal or cranial nerve to the terminal ganglia (near effector organs – found in the head or embedded in the walls of the organs in the thorax, abdomen, and pelvis). - Cranial nerve 10 is the only one that supplies parasympathetic innovation to most of the organs in the thorax and the abdomen. - 2 major neurotransmitters: o Acetylcholine – secreted by all preganglionic neurons of both division and postganglionic fibers for only the parasympathetic because most of the postganglionic of the sympathetic division secrete norepinephrine (drugs that are made to mimic the effect of neurotransmitters). Dual innervation – when an organ both has sympathetic and parasympathetic innervation. MARY ANNE QUIAOIT 01NU08