Lecture (3) NERVOUS SYSTEM .pdf
- 1. NERVOUS SYSTEM Foundation block - Anatomy - Lecture 3
- 2. Objectives At the end of the lecture, the students should be able to: ● List the subdivisions of the nervous system. ● Define the terms: grey matter, white matter, nucleus,ganglion, tract and nerve. ● List the parts of the brain. ● Identify the external and internal features of spinal cord. ● Enumerate the cranial nerves. ● Describe the parts and distribution of the spinal nerve. ● Define the term ‘dermatome’. ● List the structures protecting the central nervous system. Color guide : Only in boys slides in Green Only in girls slides in Purple important and doctors note in Red Extra information in Blue
- 3. Functions of The Nervous system 1-Collection of sensory input: (PNS) Identifies changes (also called stimuli) occurring inside and outside the body using sensory receptors. 2-Integration(واﻟﻤﻌﺎﻟﺠﺔ )اﻟﺘﻨﺴﯿﻖ: (CNS) processes, analyses and interprets changes, then makes decisions. 3-Effects a response: (PNS) by activating muscles or glands via motor output.
- 4. Structural organization -Central nervous system (CNS): Brain & spinal cord -Peripheral nervous system (PNS): Nerves & Ganglia -Cranial nerves -Spinal nerves
- 5. Functional Organization -Sensory division (afferent) -Motor division (Efferent) ● autonomic(visceral) ● Somatic SNS ANS CNS PNS
- 6. Axon (nerve fiber) Nervous Tissue Nervous Tissue consists of: Nerve cells (neurons) + Supporting cells (neuroglia). Which are organised into white matter and grey matter. Myelin sheath
- 7. Always remember that .. ● Nucleui: Is a group of neurons within the CNS. ● Ganglia: Is a group of neurons outside the CNS. ● Tract: Is a group of nerve fibers (axons) within the CNS. ● Nerve: Is a group of nerve fibers (axons) outside the CNS.
- 8. The Brain The brain is a large mass of nervous tissue located in the cranial cavity. It has four major regions: Cerebrum: Has 2 cerebral hemispheres Diencephalon: - Thalamus - Hypothalamus - Subthalamus - Epithalamus Cerebellum Brainstem: - Midbrain - Pons - Medulla oblongata
- 9. Cerebrum ○ The largest part of the brain, has two hemispheres. ○ The cerebral hemispheres are connected by a thick bundle of nerve fibers called corpus callosum. ○ The surface shows ridges of tissue, called gyri, separated by grooves called sulci. Divided (each hemisphere) by deeper sulci, into 4 lobes: 1. Frontal 2. Parietal 3. Temporal 4. Occipital Note: the cerebrum is folded in order to give more surface space and increase the number of neurons. Corpus Callosum Left Hemisphere Right Hemisphere Guyrus Sulcus
- 10. Tissue of The Cerebral Hemispheres ● Outermost layer is called gray matter or cortex. ● Deeper located is the white matter, composed of fiber tracts (bundles of nerve fibers), carrying impulses to and from the cortex. ● Located deep within the white matter are masses of grey matter called the basal nuclei . They help the motor cortex in the regulation of voluntary motor activities. Important note :(Basal nuclei) can called also (Basal ganglia)
- 11. Cerebellum The cerebellum has 2 hemispheres and a convoluted surface. It has an outer cortex made from gray matter and an inner region of white matter. It provides precise coordination for body movements and helps maintain equilibrium.
- 12. Spinal cord ● It is a two-way conduction pathway to the brain & a major reflex center. ● 42-45 cm long, cylindrical shape(اﺳﻄﻮاﻧﻲ ), lies within the vertebral canal. ● Extends from foramen magnum (اﻟﺠﻤﺠﻤﺔ أﺳﻔﻞ )ﻓﺘﺤﺔ to L2 vertebra Note : The spinal cord is extended to L2 vertebra but in children it extends to L3 vertebra because their vertebral column is smaller/shorter. ● Continuous above with medulla oblongata. ● Caudal tapering end is called conus medullaris. It’s in the (CNS) if it’s damaged, it’s never regenerated ● Has 2 enlargements: cervical and lumbosacral (اﻷطﺮاف ﻣﻨﻄﻘﺔ ﻋﺸﺎن ). ● Gives rise to 31 pairs of spinal nerves. ● Group of spinal nerves at the end of the spinal cord is called cauda equina. (اﻟﺤﺼﺎن ذﯾﻞ )ﺗﺸﺒﮫ It’s in the (PNS) if it’s damaged, it can be regentrat Helpful video https://youtu.be/qB6WPr5Jhc4 conus medullaris اﻟﺸﻮﻛﻲ اﻟﺤﺒﻞ ﻧﮭﺎﯾﺔ cauda equina ﺑﻌﺪ اﻷﻋﺼﺎب اﻣﺘﺪاد اﻟﺸﻮﻛﻲ اﻟﺤﺒﻞ ﻧﮭﺎﯾﺔ
- 13. Cross Section of Spinal Cord It is incompletely divided into two equal parts: ● anteriorly by a short, shallow median fissure. ● posteriorly by a deep, narrow median septum. It is composed of grey matter in the center surrounded by white matter. (cerebrum و cerebellum ال ﻋﻜﺲ ) The grey matter resembles the letter H having two posterior, two anterior and two lateral horns/columns.
- 14. Protection of CNS: Pia mater (innermost)
- 15. Cerebrospinal Fluid (CSF) Helpful video https://www.youtube.com/watch?v=7B1w6lDw-yM
- 16. Peripheral Nerves - May be sensory, motor or mixed. - Two types: Cranial Spinal 12 pairs 31 pairs Attached to the brain Attached to the spinal cord Named & numbered from 1-12 Named & numbered according to the region of the spinal cord
- 17. Cranial Nerves - 12 pairs: 3 pairs are sensory, 5 pairs are motor, and 4 pairs are both. Note: functions are extra information.
- 18. (EXTRA) Mnemonics to memorise cranial nerves
- 19. Made up of 31 pairs, each spinal nerve is attached to two roots: dorsal (sensory) and ventral (motor). ● Dorsal roots bear a sensory ganglion (DRG). ● Each spinal nerve exits from the intervertebral foramen which is then divided into dorsal and ventral ramus. ● The rami (single = ramus) contain both sensory and motor fibers, roots have pure nerves, but trunks have mixed nerves. ● The dorsal rami are distributed individually supply the skin and muscles of the back. ● The ventral rami form plexuses ( )ﺿﻔﺎﺋﺮ (except in thoracic region where they form intercostal nerves), which supply the anterior part of the body. Spinal Nerves and Nerve Plexuses
- 20. Dermatomes: The segment of skin supplied by a segmental spinal nerve is called “Dermatome” ﻛﻞ اﻟﺠﻠﺪ ﻣﻦ ﻣﺤﺪد ﺑﺠﺰء ﻣﺨﺘﺺ اﻟﺸﻮﻛﻲ اﻟﺤﺒﻞ ﻣﻦ ﺟﺰء ﻛﻞ اﻟﺠﻠﺪ ﻣﻦ (اﻷﻟﻢ ذﻟﻚ ﻓﻲ )ﺑﻤﺎ اﻹﺣﺴﺎس ﯾﻨﻘﻞ اﻷﻋﺼﺎب ھﺬه ﻣﻦ اﻟﺪﻣﺎغ إﻟﻰ
- 21. Test Yourself… (True or False) 1. Nucleus is a group of neurons within the PNS 2. In the Brain, grey matter located in the centre and surrounded by white matter. 3. CSF is drained into the dural sinuses through the arachnoid villi. 4. Cerebrum provides precise coordination for body movements and helps maintain equilibrium. 5. Each spinal nerve exits from the intervertebral foramen and divides into a dorsal and ventral ramus. 6. The dorsal rami form plexuses . 7. Dermatome is a segment of skin supplied by one spinal nerve. 8. CSF is produced by the choroid plexuses inside the ventricles of brain. 9. The rami contain only sensory fibers. Answers : 1-F(CNS) 2-F(spinal cord) 3-T 4-F(Cerebellum) 5-T 6-F(ventral) 7-T 8-T 9-F(both sensory and motor )
- 22. ● Abdulrahman Shadid ● Ateen Almutairi Contact us: Twitter : @Anatomy438 Boys team: ● Khalid AL-Dossari ● Naif Al-Dossari ● Faisal Alqifari ● Salman Alagla ● Ziyad Al-jofan ● Suhail Basuhail ● Ali Aldawood ● Khalid Nagshabandi Girls team : ● Ajeed AlRashoud ● Taif Alotaibi ● Noura Alturki ● Amirah Al-zahrani ● Alhanouf Al-haluli ● Sara Al-Abdulkarim ● Rawan Alzayed ● Reema Almasoud ● Renad Alhaqbani ● Nouf Alhumaidhi ● Fay AlBuqami ● Jude Alkhalifah ● Nouf Alhussaini Team members Team leaders Good luck to you all A special thanks to the 436 anatomy team, who inspired our work.