BIOM20002 Lecture Notes - Lecture 18: Stretch Reflex, Intrafusal Muscle Fiber, Reciprocal Inhibition

• School: University of Melbourne
• Department: Biomedicine
• Course: BIOM20002
• Professor: All

Document Summary

Synapses from motor cortex to the skeletal muscle system can be divided into monosynaptic reflexes or polysynaptic reflexes. Monosynaptic: the direct and excitatory transmission of signals between afferent and efferent neurons. Polysynaptic: have two or more neurons the presence of interneurons can adjust either. Epsps or ipsps going to the efferent neurons. Muscle spindles: designed to sense the length of the muscle fibres during contraction (by contracting/shortening themselves) Small, elongated structures scattered among and arranged parallel to the contractile extrafusal muscle fibres. Each muscle spindle consists of a connective tissue capsule that encloses a group of small muscle fibers known as intrafusal fibers. At their resting lengths, spindles are stretched enough to activate the sensory fibres, creating a constant stream of action potentials from tonically active sensory neurons to the spinal cord. As a result, even at rest muscles maintains a certain level of tension known as muscle tone.