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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 loud ...
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action [1] and nearly instantaneous response to a stimulus. [2] [3] The simplest reflex is initiated by a stimulus, which activates an afferent nerve. The signal is then passed to a response neuron, which generates a response.
Like the knee jerk reflex, the Lazarus sign is an example of a reflex mediated by a reflex arc—a neural pathway which passes via the spinal column but not through the brain. As a consequence, the movement is possible in brain-dead patients whose organs have been kept functioning by life-support machines , precluding the use of complex ...
Usually the onset of the startle response is a startle reflex reaction. The startle reflex is a brainstem reflectory reaction (reflex) that serves to protect vulnerable parts, such as the back of the neck (whole-body startle) and the eyes (eyeblink) and facilitates escape from sudden stimuli. It is found across many different species ...
The patellar reflex (knee jerk) is an example of the stretch reflex and it is used to determine the sensitivity of the stretch reflex. Reflexes can be tested as part of a neurological examination, often if there is an injury to the central nervous system. To test the reflex, the muscle should be in a neutral position.
The associated term "ideo-dynamic response" (or "reflex") applies to a wider domain, and extends to the description of all bodily reactions (including ideo-motor and ideo-sensory responses) caused in a similar manner by certain ideas, e.g., the salivation often caused by imagining sucking a lemon, which is a secretory response.
A common example of reciprocal innervation, is the effect of the nociceptive (or nocifensive) reflex, or defensive response to pain, otherwise commonly known as the withdrawal reflex; a type of involuntary action of the body to remove the body part from the vicinity of an offending object by contracting the appropriate muscles (usually flexor ...
The acoustic reflex (also known as the stapedius reflex, [1] stapedial reflex, [2] auditory reflex, [3] middle-ear-muscle reflex (MEM reflex, MEMR), [4] attenuation reflex, [5] cochleostapedial reflex [6] or intra-aural reflex [6]) is an involuntary muscle contraction that occurs in the middle ear in response to loud sound stimuli or when the person starts to vocalize.