Limbic System PDF - BSN 1101 2024-2025

A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO Cerebrospinal f...

A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO Cerebrospinal fluid and blood vessels are found in the LIMBIC SYSTEM AND FUNCTIONS subarachnoid space. The olfactory cortex and certain deep cortical regions The third meningeal membrane, the pia mater, is and nuclei of the cerebrum and the diencephalon are very tightly bound to the surface of the brain and grouped together under the title limbic system. spinal cord. The limbic system influences long-term declarative memory, emotions, visceral responses to emotions, motivation, and mood. A major source of sensory input to the limbic system are the olfactory nerves. The limbic system is connected to, and functionally associated with, the hypothalamus. Lesions in the limbic system can result in voracious appetite, increased (often perverse) sexual activity, and docility (including loss of normal fear and anger responses). LIMBIC SYSTEM AND EMOTIONS MENINGES The meninges are three connective tissue layers that surround the brain and spinal cord. The outermost (most superficial) meningeal layer is the dura mater, which is the toughest of all the meninges. The dura mater forms two layers around the brain and only one layer around the spinal cord. The second meningeal membrane is the very thin, wispy arachnoid mater. The space between the dura mater and the arachnoid mater is the subdural space, which is normally only a potential space containing a very small amount of serous fluid. BSN 1101: ANAPHY LESSON 7 1 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO CEREBROSPINAL FLUID Cerebrospinal Fluid (CSF) bathes the brain and spinal cord, providing a protective cushion around the CNS. The ependymal cells located in the choroid plexuses of the ventricles produced the CSF. (a) Anterior superior view of the head to show the meninges. CSF fills the brain ventricles, the central canal of the (b) Meningeal membranes surrounding the spinal cord. (c) spinal cord, and the subarachnoid space. Cross section of a vertebra and the spinal cord. The CSF flows from the lateral ventricles into the third ventricle and then through the cerebral VENTRICLES aqueduct into the fourth ventricle. The CNS contains fluid-filled cavities, called A small amount of CSF enters the central canal of the ventricles. spinal cord. Each cerebral hemisphere contains a relatively large The CSF exits the fourth ventricle through small cavity called the lateral ventricle. openings in its walls and roof and enters the The third ventricle is a smaller, midline cavity subarachnoid space. located in the center of the diencephalon between the Masses of arachnoid tissue, called arachnoid two halves of the thalamus and connected by granulations, penetrate the superior sagittal sinus, a foramina (holes) to the lateral ventricles. dural venous sinus in the longitudinal fissure, and The fourth ventricle is located at the base of the CSF passes from the subarachnoid space into the cerebellum and connected to the third ventricle by a blood through these granulations. narrow canal, called the cerebral aqueduct. The fourth ventricle is continuous with the central canal of the spinal cord. The fourth ventricle also opens into the subarachnoid space through foramina in its walls and roof. BSN 1101: ANAPHY LESSON 7 2 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO Cranial Nerve VII (Facial) is both a sensory and motor nerve. It is sensory for taste and motor for facial expression. Cranial Nerve VIII (Vestibulocochlear) is a pure sensory nerve for hearing and equilibrium Cranial Nerve IX (Glossopharyngeal) is both a motor and sensory nerve. It is sensory for taste and motor for swallowing. Cranial Nerve X (Vagus) is both a motor and sensory nerve. It is a sensory and motor for organs in the thoracic and abdominal cavities. Cranial Nerve XI (Accessory) is a pure motor nerve for the trapezius, sternocleidomastoid, and muscles of the larynx. Cranial Nerve XII (Hypoglossal) is a pure motor nerve for the tongue CRANIAL NERVES 12 pair of cranial nerves Named by roman numerals 2 categories of functions: sensory and motor Cranial Nerve I (Olfactory) is a pure sensory nerve for smell Cranial Nerve II (Optic) is a pure sensory nerve for vision Cranial Nerve III (Oculomotor) is a pure motor nerve for eye movement SPINAL CORD Cranial Nerve IV (Trochlear) is a pure motor nerve Extends from foramen magnum to 2nd lumbar for eye movement vertebra Cranial Nerve V (Trigeminal) is both a motor and Protected by vertebral column sensory nerve. It is sensory for pain, touch, and Spinal nerves allow movement temperature for the eye and lower and upper jaws. It is If damaged paralysis can occur a motor for the muscles of chewing. Cranial Nerve VI (Abducens) is a pure motor nerve for eye movement BSN 1101: ANAPHY LESSON 7 3 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO Posterior horns: contain axons which synapse with interneurons Anterior horns: contain somatic neurons Lateral horns: contain autonomic neurons Central canal: fluid filled space in center of cord GRAY MATTER AND WHITE MARKER Gray Matter: center of spinal cord looks like letter H or a butterfly White Matter: REFLEXES outside of spinal cord an involuntary reaction in response to a stimulus contains myelinated fibers applied to the periphery and transmitted to the CNS. The simplest reflex is the stretch reflex. WHITE MATTER IN SPINAL CORD A stretch reflex occurs when muscles contract in Located in the white matter of the CNS are three columns: response to a stretching force applied to them. dorsal, ventral, and lateral. The knee-jerk reflex, or patellar reflex is a classic Columns: example of a stretch reflex. Ascending tracts The withdrawal reflex, or flexor reflex, is to remove axons that conduct action potentials toward the brain a limb or another body part from a painful stimulus. Descending tracts The sensory receptors are pain receptors, and axons that conduct action potentials away from the stimulation of these receptors initiates the reflex. brain The gray matter has a letter H shape with horns. BSN 1101: ANAPHY LESSON 7 4 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO WITHDRAWAL REFLEX LUMBOSACRAL PLEXUS 1. Pain receptors detect a painful stimulus. Originates from spinal nerves L1 to S4 2. Sensory neurons conduct action potentials to the Supply nerves lower limbs spinal cord. 3. Sensory neurons synapse with interneurons that synapse with motor neurons. 4. Excitation of the motor neurons results in contraction of the flexor muscles and withdrawal of the limb from the painful stimulus. SPINAL NERVES Arise along spinal cord from union of dorsal roots and ventral roots Contain axons sensory and somatic neurons Located between vertebrae Categorized by region of vertebral column from which it emerges (C for cervical) 31 pairs Organized in 3 plexuses CERVICAL PLEXUS DERMATOME Spinal nerves C1-4 The nerves arising from each region of the spinal Innervates muscles attached to hyoid bone and neck cord and vertebral column supply specific regions of Contains phrenic nerve which innervates diaphragm the body. A dermatome is the area of skin supplied with BRACHIAL PLEXUS sensory innervation by a pair of spinal nerves. Originates from spinal nerves C5-T1 Each of the spinal nerves except C1 has a specific Supply nerves to upper limb, shoulder, hand cutaneous sensory distribution. BSN 1101: ANAPHY LESSON 7 5 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO SYMPATHETIC DIVISION The sympathetic division cell bodies of sympathetic preganglionic neurons are in the lateral horn of the spinal cord gray matter between the first thoracic (T1) and the second lumbar (L2) segments. The axons of the preganglionic neurons exit through ventral roots and project to either sympathetic chain ganglia or collateral ganglia. PARASYMPATHETIC DIVISION Some preganglionic cell bodies of the parasympathetic division are located within the lateral part of the central gray matter of the spinal cord in the regions that give rise to spinal nerves S2 through S4. Other preganglionic cell bodies of the parasympathetic division are located within brainstem nuclei of the oculomotor, facial, AUTONOMIC NERVOUS SYSTEM glossopharyngeal, and vagus nerves. The autonomic neurons innervate smooth muscle, Axons of the preganglionic neurons extend through cardiac muscle, and glands. spinal nerves or cranial nerves to terminal ganglia Autonomic functions are largely controlled either located near effector organs in the head or unconsciously. embedded in the walls of effector organs in the The autonomic nervous system is composed of the thorax, abdomen, and pelvis. sympathetic division and the parasympathetic Most of the thoracic and abdominal organs are division. supplied by preganglionic neurons of the vagus nerve Increased activity in sympathetic neurons generally extending from the brainstem. prepares the individual for physical activity, whereas parasympathetic stimulation generally activates involuntary functions, such as digestion, that are normally associated with the body at rest. In the autonomic nervous system, two neurons in series extend from the CNS to the effector organs. The first neuron is called the preganglionic neuron; the second neuron is the postganglionic neuron. The neurons are so named because preganglionic neurons synapse with postganglionic neurons in autonomic ganglia within the PNS. BSN 1101: ANAPHY LESSON 7 6 A LESSON 7: LIMBIC SYSTEM BSN 1101 1ST SEMESTER |2024 - 2025 | PROF. JEMWEL SICO SOMATIC AND AUTONOMIC NERVOUS SYSTEM SOMATIC AND AUTONOMIC NERVOUS SYSTEM BSN 1101: ANAPHY LESSON 7 7