ANAT 321 Lecture Notes - Lecture 3: Lumbar Vertebrae, Spinal Cord, Subarachnoid Cisterns

• School: McGill University
• Department: Anatomy & Cell Biology
• Course: ANAT 321
• Professor: David Ragsdale

Document Summary

Spinal reflexes: the spinal cord is much more than a conduit connection brain & periphery; has highly complex internal circuitry, the simplest goal-directed movements are spinal reflexes. The stretch reflex circuitry: muscle gets stretched, sensors send ap that synapses with motor neurons (excitatory) or onto inhibitory interneuron, causes that muscle to contract and antagonist to relax. Complexity: alternative view is that sensory-motor function hierarchically organized around behavioral goals, reflexes are simplest examples of goal-oriented responses --tap into same spinal cord circuitry used for more complex responses. Facial expressions: circuitry contained within the spinal cord --nuclei in brainstem; cranial nerves, emotional states elicit appropriate facial expression, smile looks fake when asked to since activate muscles through different pathway. Fiber locations: two branches in autonomic nervous system; parasympathetic & sympathetic, preganglionic parasympathetic preganglionic fibers emerge from the brainstem (cranial nerves iii, vii, ix & x) and sacral spinal cord.