Part 1 stretch Reflex
Part 1 Stretch Reflex
1 Anatomy of Muscle Spindle (A)Muscle spindle a motor neuron o 3-10 intrafusal muscle fibers Extrafusal detect change in the length fibers of the muscle neuron stretch receptors that report Spindle afferent the stretching of the muscle to (a afferent th le spine o The central region and Intrafusal peripheral region of the fibers intrafusal fibers
1 Anatomy of Muscle Spindle ⚫ 3-10 intrafusal muscle fibers ⚫ detect change in the length of the muscle -- stretch receptors that report the stretching of the muscle to the spine. ⚫ The central region and peripheral region of the intrafusal fibers
Anatomy of Muscle Spindle o Intrafusal fibers are wrapped by two types of afferent endings Primary sensory endings Ty ype la fiber Innervate the center of the spindle Secondary sensory endings Type Il fiber Associated with the ends of the nuclear chain fiber la primary from nuclear bag fiber 2 阝 efferent fusal fibers afferent Nuclear chain fiber Trail ending Flower-spray ending
Anatomy of Muscle Spindle ⚫ Intrafusal fibers are wrapped by two types of afferent endings – Primary sensory endings ⚫ Type Ia fibers ⚫ Innervate the center of the spindle – Secondary sensory endings ⚫ Type II fibers ⚫ Associated with the ends of the nuclear chain fiber
Components of muscle spindle Primary Afferent la ending axons Secondary ending uclear Bag Nuclear chain Fiber Fiber
Components of muscle spindle Afferent axons Ia II Primary ending Secondary ending } } Nuclear Bag Fiber Nuclear Chain Fiber
Anatomy of Muscle Spindle o Primary sensory endings Type la fibers o Stimulated by both the rate and amount of stretch(dynamic response B ynamic response 4 St 早adY state 200 response 5 mm/sec 15 mm/sec 30 mm/sec sec
Anatomy of Muscle Spindle ⚫ Primary sensory endings – Type Ia fibers ⚫ Stimulated by both the rate and amount of stretch (dynamic response)