Neuroanatomy Lecture: Brainstem, Spinal Cord - PDF

Neuroanatomy: Brainstem, Spinal Cord, and General Features CNS vs. PNS Central Nervous System (CNS): Comprises the brain and the spinal cord Interpret sensory information and issue commands based on experience Peripheral Nervous System (PNS): Includes sensory neu...

Neuroanatomy: Brainstem, Spinal Cord, and General Features CNS vs. PNS Central Nervous System (CNS): Comprises the brain and the spinal cord Interpret sensory information and issue commands based on experience Peripheral Nervous System (PNS): Includes sensory neuros that link receptors on the body surface with processing from the CNS Cranial and Spinal Nerves Division of the PNS Somatic Nervous System (SNS) Control of body movements Division of the PNS Somatic Nervous System (SNS) Control of body movements Autonomic Nervous System (ANS) Influences function of internal organs Division of the PNS PNS: Cranial Nerves Twelve pairs of nerves at the base Olfactory and optic are CNS 10 axons of PNS Single nerve = multiple function PNS: Cranial Nerves Twelve pairs of nerves at the base Olfactory and optic are CNS 10 axons of PNS Single nerve = multiple function Used for identification of Neurological disorders Cranial nerves have nuclei associated with midbrain, pons, and medulla Covering of the brain CNS encased in bone does not make direct contact Three membrane layer called meninges Dura mater, arachnoid membrane, and pia mater Meninges Dura Mater is the outermost Tough, leather like inelastic bag Arachnoid membrane is just under the Dura Mater Spider web consistency No space between Dura and Arachnoid; subdural hematoma Pia Mater thin membrane near surface Many blood vessels Sub area has CSF Meninges and CSF Dura Mater is the outermost Tough, leather like inelastic bag Arachnoid membrane is just under the Dura Mater Spider web consistency No space between Dura and Arachnoid; subdural hematoma Pia Mater thin membrane near surface Many blood vessels Sub area has CSF Brainstem - Midbrain Serves as a conduit for information coming from spinal cord and forebrain Contains neurons associated with sensory, movement, and others Red nucleus is also associated with motor control Periaqueductal gray – somatic pain sensation Superior colliculus: direct input from the eye (optic tectum); control of eye movements Inferior colliculus: sensory input from the eye (auditory information to thalamus Core of the midbrain is the cerebral aqueduct Connects the third and fourth ventricle Brainstem - Medulla Process sensory information, control voluntary movement, and regulate autonomic system Medullary pyramids – bundle of axons descending to the spinal cord Very bottom of the medulla Name for shape Contain Corticospinal tracts; voluntary movement Nuclear clusters associated with hearing Dorsal and ventral cochlear nuclei and superior olive Inferior Olive: role in motor control Raphe nucleus: modulation of pain, mood, and wakefulness Medulla-Spinal Cord Fourth Ventricle disappears; beginning of the spinal cord Dorsal column nuclei – somatic sensory information Axons from Dorsal Column cross to the other side (decussate) to the thalamus The Spinal Cord Spinal cord situated within vertebral column Vertebrate described by location Neck - Cervical C1 – C7 Ribs – Thoracic T1 – T12 Lower back – Lumbar L1 – L5 Pelvic – Sacral S1 – S5 The Spinal Cord Major conduit of information from skin, joints, and muscles Transection of the spinal cord Anesthesia, lack of feeling, in skin Paralysis of muscles caudal to cut Muscles cannot be controlled by the brain The Spinal Cord Spinal nerves communicate with the cord Somatic PNS Spinal nerves adopt the names of vertebrae 8 cervical nerves for 7 cervical vertebrae Spinal Cord ends at L3 Does not grow after birth; column does Cauda equina – Bundle of nerves down the lumbar and sacral column  Ventral-Lateral Surface Organization of spinal nerves attached to the spinal cord (with meninges) Nerves split into two roots at the vertebral notch  Ventral-Lateral Surface Butterfly shape core is Gray matter is divided into 3 gray matter while the groups outside is white mater Dorsal, lateral, and ventral horns How does this compare to White matter is divided into 3 the brain? What does it columns mean? Dorsal, lateral, ventral columns  Ventral-Lateral Surface Organization of spinal nerves attached to the spinal cord (with meninges) Nerves split into two roots at the vertebral notch White vs. Gray Dorsal root carries axon within the dorsal root ganglia Ventral root carries motor axons from the ventral gray matter Cross-Sectional Anatomy Cross-Sectional Anatomy Major ascending sensory pathway Dorsal column consists of sensory axons to the brain Conscious appreciation of touch Spinothalamic tract Painful stimuli and temperature Cross-Sectional Anatomy Major ascending sensory pathway Dorsal column consists of sensory axons to the brain Conscious appreciation of touch Spinothalamic tract Painful stimuli and temperature Cross-Sectional Anatomy Descending tracts for control of movement Names of tracts describes their origins and terminations Dorsal column consists of sensory axons to the brain Conscious appreciation of touch Two descending tract pathways Lateral – Controls muscle tone and antigravity Ventromedial – Maintain orientation in space and equilibrium Autonomic PNS Regulation of internal organs, glands, and vasculature Regulation occurs automatically  Autonomic PNS Regulation of internal organs, glands, and vasculature Regulation occurs automatically ANS divisions Sympathetic - Stimulate fight-or-flight response Parasympathetic - Stimulate rest-and-digest or feed and breed Sympathetic ANS Sympathetic Ganglia form a chain Begins at the Thoracic to lumbar Thoracolumar outflow Runs along the vertebral column Spinal nerves emerging from the column Chemical signaling – Acetylcholine Nicotinic receptor and norepinephrine  Sympathetic ANS Signaling Chemical signaling – Postsynaptic neuron – Acetylcholine Norepinephrine What type of neurons? What type of neurons? Parasympathetic ANS Nerves arise from the CNS Carniosacral outflow Cranial Nerves – preganglionic parasympathetic nerves Trigeminal branches Opthalmic nerve, maxillary nerve, mandibular nerve Parasympathetic ANS Nerves arise from the CNS Carniosacral outflow Cranial Nerves – preganglionic parasympathetic nerves Vagus Nerve Paired but normally referred to as singular Supplies motor fibers to all organs from the neck down to the colon Heart rate, sweating, and muscle movements Parasympathetic ANS Nerves arise from the CNS Carniosacral outflow Cranial Nerves – preganglionic parasympathetic nerves Vagus Nerve Pelvic Splanchnic Innervation to hindgut Regulates bladder, sphincter, and sexual functions Parasympathetic ANS Signaling Nicotinic receptors are channels while Muscarinic are G- Proteins Main end-receptor stimulated from postganglionic fibers Enteric Nervous System (ENS) Division of the ANS Located in the lining of the esophagus, stomach, intestines, pancreas, and gallbladder Controls processes associated with transport and digestion of food 500 million neurons Makes use of 30 different neurotransmitters 90% of serotonin and 50% of dopamine Lecture Overview CNS vs. PNS Somatic and Autonomic Cranial Nerves and Arteries Meninges Brainstem Spinal Cord: Sensory vs. Motor; Tracts Divisions of the PNS Sympathetic and Parasympathetic Enteric Nervous System