Chapter 3 Part 2 The Thalamus =LGN, MGN and so on ascending - PDF document

Chapter 3 Part 2

The Thalamus =LGN, MGN and so on — ascending information relay station — projecting to all cortical regions

Hypothalamus • Controls many functions including hunger, thirst, pain, pleasure and the sex drive. • Regulate the pituitary gland, which in turn, regulates hormonal levels in the body. • Important in homeostasis, reproduction, and various behaviors • Two pathways, anterior and posterior

Midbrain= tectum + tegmentum Midbrain acts as a relay station, as a point of integration for sensory input (=tectum), and in perception of pain 1) Overlapping maps for visual, auditory, and somatosensory input 2) Multisensory neurons integrate more than one sensory input

Hindbrain=cerebellum + pons + medulla

Cerebellum • A. Functional organization – 1) Vestibulocerebellum (important in balance and eye/ head movements) – 2) Spinocerebellum (adjustment of voluntary behaviors, such as walking) – 3) Cerebrocerebellum (voluntary behavior; assists in planned movements via the premotor cortex; behaviors that work or don't work) • B. Arbitrator of motor events • C. A general topographic map exists for control of motor events 1) Homunculi exist in the cerebellum

Brainstem • Brainstem (Midbrain, Pons, and Medulla oblongata) • Site of Reticular Activating System (RAS) • Affects state of arousal (sleep- wake cycle, hibernation cycle)

Spinal Chord Cross-Section

Spinal Cord • General organization: An extension of the brain • Spinal root: a bundle of axons surrounded by connective tissue that occurs in pairs, which fuse and form a spinal nerve. • Gray matter/ white matter • 2. Functions • a. Relays information to and from brain (more on this later) • Ascending and descending paths in the spinal cord—dorsal and ventral root • b. Spinal cord is also involved in various reflexes without going through the brain, eg, stretch reflex

Divisions of nervous system • Central nervous system – Brain – spinal cord • Peripheral nervous system – By location: 31 pairs of spinal nerves + 12 pairs of cranial nerves – By function: somatic (motor function) + autonomic (visceral function) • Autonomic = Sympathetic + parasympathetic • Afferent/ efferent axon – An axons directed toward the central nervous system conveying sensory information – An axon directly away from the central nervous system, conveying motor commands to muscles and glands.

Difference of Somatic and autonomic nervous system • Function: somatic receives sensory information from the sensory organs and controls movements of the skeletal muscles, consciously controlled; autonomic regulates smooth muscle, cardiac muscle, and glands, self-governing. • Structure: somatic involves only one efferent neurons; autonomic involves two (preganglionic and postganglionic)

Column Spinal

Cranial Nerves Cranial Nerve: a peripheral nerve attached directly to the brain The tenth, vagus nerve: the largest of the cranial nerves, conveying efferent fibers of the parasympathetic division of the autonomic nervous system to organs of the thoracic and abdominal cavities.

Common Autonomic Anatomy Spinal Cord Ganglion Target Organ Preganglionic Fiber Postganglionic Fiber Neurtransmitter: Ach, Nicotinic, Excitatory

Compare the Two Systems

Compare the Two Systems Differences: 1. Structure 2. Function