Brain, spinal cord and spinal tracts Definitions to bring home Nerve Ganglion Neuron Nucleus Tract Collection neurons Collection of nerve A single cell Collection of Collection of axons that transmits cell bodies in the transmitting nerve cell bodies in traveling up or sensation or motor PNS, typically linked electrical impluses. the CNS, typically down the spinal impulses depending by synapses. linked by synapses. cord, depending on the function and Location: both on function destination. Location: PNS Location: CNS and destination. Location: PNS Location: CNS ANS Characteristic Sympathetic Parasympathetic Nuclei of CNIII, VII, IX, X Origin of Preganglionic Nerve Nuclei of Spinal Cord segs T1-T12, L1-L3 Spinal Cord S2-S4 Length of Preganglionic n. Axon Short Long Receptor type in ganglion Nicotinic Nicotinic Neurotransmitter in ganglion Acetylcholine Acetylcholine Length of Postganglionic nerve axon Long Short Effector Organs Smooth + cardiac muscle, glands Smooth + cardiac muscle, glands Neurotransmitter in effector organs Norepinephrine (ACh in glands) Acetylcholine Receptor types in effector organs A1, A2, B1, B2, B3 M1, M2, M3 BRAIN 1. CEREBRUM • Higher brain functions 2. CEREBELLUM • Little brain • Posture and balance • Coordinate movement 3. BRAIN STEM • Connects cerebrum/cerebellum and spinal cord • CN III – XII nuclei • 3 parts: • Midbrain / Mesencephalon • Pons • Medulla oblongata CEREBRUM • Left and right hemisphere • 4 lobes: • Frontal = motor + speech • Parietal = sensory (homunculus) • Temporal = memory + understanding • Occipital = vision SPINAL CORD • Signal to and from the brain • Grey matter = cell bodies + unmyelinated axons • White matter = myelinated axons • Central canal = CSF • Bell-Magendie Law • Ventral = motor • Ventral horn • Dorsal = sensory • Dorsal root ganglia Spinal cord terminations • Spinal cord: lower border of L1-L3 • Subarachnoid space (with CSF): lower border of S2 • Cauda equina: L3 (adult age) • Filum terminale: fibrous string 3 main functions of the spinal cord: 1. Motor conduction FROM the brain (to the muscles) 2. Sensory conduction TO the brain (from receptors) 3. Reflexes SPINAL TRACTS Tract - highway to pass anatomy exam? • Highway = Tract • Lane = Axons • Car = Signal 4 IMPORTANT TRACTS MOTOR TRACTS 1. PYRAMIDAL TRACTS = CORTICOSPINAL + CORTICOBULBAR TRACTS 2. EKSTRAPYRAMIDAL TRACTS SENSORY TRACTS 1. SPINOTHALAMIC TRACT 2. DORSAL COLUMN / MEDIAL LEMNISCUS .