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The stretch reflex (myotatic reflex), or more accurately "muscle stretch reflex", is a muscle contraction in response to stretching a muscle. The function of the reflex is generally thought to be maintaining the muscle at a constant length but the response is often coordinated across multiple muscles and even joints. [ 1 ]
For example, if the intended movement direction is associated with stretch of the spindle-bearing muscle, Ia afferent and stretch reflex sensitivity from this muscle is reduced. Gamma fusimotor control therefore allows for the independent preparatory tuning of muscle stiffness according to task goals.
Knee jerk or patellar reflex — a kick caused by striking the patellar tendon with a tendon hammer just below the patella, stimulating the L4 and L3 reflex arcs. Moro reflex , a primitive reflex — only in all infants up to 4 or 5 months of age: a sudden symmetric spreading of the arms, then unspreading and crying, caused by an unexpected ...
Stretch reflex tests are used to determine the integrity of the spinal cord and peripheral nervous system, and they can be used to determine the presence of a neuromuscular disease. [4] The term "deep tendon reflex", if it refers to the muscle stretch reflex, is a misnomer. "Tendons have little to do with the response, other than being ...
The sensory receptors for this reflex are called tendon Golgi receptors, which lie within a tendon near its junction with a muscle. In contrast to muscle spindles , which are sensitive to changes in muscle length, tendon organs detect and respond to changes in muscle tension that are caused by muscular contraction, but not passive stretch.
A muscle spindle, with γ motor and Ia sensory fibers. A type Ia sensory fiber, or a primary afferent fiber, is a type of afferent nerve fiber. [1] It is the sensory fiber of a stretch receptor called the muscle spindle found in muscles, which constantly monitors the rate at which a muscle stretch changes.
Examples include stretch receptors in the arm and leg muscles and tendons, in the heart, in the colon wall, and in the lungs. Stretch receptors are also found around the carotid artery, where they monitor blood pressure and stimulate the release of antidiuretic hormone from the posterior pituitary gland. Types include: Golgi organ
The Bainbridge reflex is attenuated by both anticholinergics and beta-adrenergic receptor antagonists in innervated hearts (as one or the other afferent part of the reflex arc mediating the Bainbridge reflex is blocked), [15] and can be entirely abolished by bilateral vagotomy (as the afferent portion of the reflex arc is entirely destroyed). [13]