Understanding Nervous System Anatomy and Functions: Lecture Summary

1. Lecture 11 Nervous System Anatomy JPHubbard Hartnell College – Bio11

2. CNS • Enclosed in cranial cavity & vertebral canal • Covered by Meninges – 3 layers: • Outer: _____________________ • Folds create dural sinuses • Middle: _____________________ • Subarachnoid space contains: CSF • Inner: ______________________

5. Spinal Cord Anatomy • Extends from brain to L1 • Tapered at caudal end – conus medullaris • Cauda equinae – extends into sacrum • Spinal Nerves: • Between each vertebrae • Include dorsal + ventral roots • Cross Section • White matter – towards outside • Gray matter – H pattern inside • Central canal – contains cerebrospinal fluid

8. Functions of Spinal Cord • Tracts: Transmission of messages to and from brain • In white matter (myelinated nerves) • Ascending – to brain • Descending – motor information transmitted to spinal nerves • Serves as reflex center – by playing a part in reflex arcs – spinal reflexes

9. Brain • Encased and protected in: skull/menenges/cerebrospinal fluid • Regions: Major Functions: • Cerebrum _______________ • Diencephalon _______________ • Cerebellum _______________ • Brain stem _______________ • 4 ventricles

10. Cerebrum • Gyri and sulci form surface convolutions • Two hemispheres • Longitudinal fissure divides • Corpus callosum – connecting tracts • Five lobes • Frontal • Parietal • Temporal • Occipital • Insula • Cortex = gray matter

11. Longitudinal fissure (green) Frontal lobe Central sulcus (yellow) precentral & postcentral gyrus Parietal lobe Parieto-occipital sulcus Occipital lobe Lateral sulcus (blue) Temporal lobe Insula Lobes and Fissures

13. Functional Areas of Cerebrum • Motor areas • Basal Nuclei • Modify motor action • Sensory areas • Association areas

14. Ventricles Hollow spaces within brain – 4 2 lateral ventricles Third ventricle: within diencephalon Interventricular foramen connects to lateral ventricles Forth ventricle: in brain stem Cerebral aqueduct = aqueduct of midbrain connects to 3rd ventricle Contain cerebrospinal fluid (CSF) Communicate with each other, central canal of spinal cord and with subarachnoid space CSF – produced at Choroid plexuses Cushions Removal of wastes

17. Memory and the Limbic System • Learning – retention and utilization of past memories • Memory – ability to hold a thought or information • Short term – lack association • Long term – contextual development for facts • Semantic • Episodic • Skill association with motor activity

18. Diencephalon • Maintenance of homeostatic function • Centers for control of • Body temp, heart rate/bp/thirst and electrolyte balance, glandular secretions … • Close ties with endocrine system • Regions: • Thalamus • hypothalamus

19. Hypothalamus • Dozen or so nuclei in 4 major regions • mammillary bodies are relay station for olfactory reflexes;infundibulum suspends the pituitary gland • Major regulator of homeostasis • receives somatic and visceral input, taste, smell & hearing information; monitors osmotic pressure, temperature of blood

20. Cerebellum • Acts as an integration/reflex center for sensory input from the eyes, ears, joints, and muscles that relates to body position. • Sends motor impulses to skeletal muscles that maintain posture and balance. • Communicates via cerebral peduncles (3 pairs)

21. Cerebellum • 2 cerebellar hemispheres and vermis (central area) • Function • correct voluntary muscle contraction and posture based on sensory data from body about actual movements • sense of equilibrium

22. Cerebellum • Transverse fissure between cerebellum & cerebrum • Cerebellar cortex (folia) & central nuclei are grey matter • Arbor vitae = tree of life = white matter

23. Brain Stem • Medulla oblongata • Pons (‘bridge’) • Midbrain (= mesencephalon) • Functional: • Reticular formation • Reticular activating system (RAS) • Centers for control of vital functions • Cardiac center • Vasomotor center • Respiratory centers

25. Peripheral Nervous System Afferent: Sensory Efferent: Motor Starts with cranial nerves: 12 pairs spinal nerves: 31 pairs

27. Spinal nerves – 31 pairs – numbering: • 8 cervical • Numbers above corresponding vertebrae • C1 superior to Atlas • C2 superior to Axis … • C8 superior to 1st thoracic vert. • C1C4 cervical plexus • C4 T1  brachial plexus • 12 thoracic • T12  S4  lumbosacral plexus

29. Spinal nerves begin as roots • Dorsal or posterior root is incoming sensory fibers • dorsal root ganglion (swelling) = cell bodies of sensory nerves • Ventral or anterior root carries outgoing motor fibers

30. Output in Two Divisions of Peripheral Nervous System • Somatic: • What would this division control? • Autonomic System • 2 aspects: Fight or flight responses associated with: _____________________ Rest and repose – the SLUDD activities with: _____________________

32. Neurotransmitters of the ANS • Acetylcholine: • All preganglonic fibers – both aspects • All Post ganglionic fibers in parasympathetic and few in the sympathetic aspect • = cholinergic fibers • Norepinephrine: • most sympathetic fibers • Dual innervation