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The patellar reflex, also called the knee reflex or knee-jerk, is a stretch reflex which tests the L2, L3, and L4 segments of the spinal cord. Many animals, most significantly humans, have been seen to have the patellar reflex, including dogs, cats, horses, and other mammalian species.
A list of reflexes in humans. Abdominal reflex; Accommodation reflex — coordinated changes in the vergence, lens shape and pupil size when looking at a distant object after a near object. Acoustic reflex or attenuation reflex — contraction of the stapedius and tensor tympani muscles in the middle ear in response to high sound intensities.
Westphal's sign is the clinical correlate of the absence or decrease of patellar reflex or knee jerk. Patellar reflex or knee jerk is a kind of deep or stretch reflex where an application of a stimulus to the patellar tendon such as strike by a solid object or hammer caused the leg to extend due to such stimulus causes the quadriceps femoris muscle to contract.
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 ]
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.
Tendon reflex (or T-reflex) may refer to: The stretch reflex or muscle stretch reflex (MSR), when the stretch is created by a blow upon a muscle tendon. This is the commonly used definition of the term. [1] [2] Albeit a misnomer, in this sense a common example is the standard patellar reflex or knee-jerk response. [3]
The deep tendon reflexes are also diminished or absent; for example, the "knee jerk" or patellar reflex may be lacking (Westphal's sign). A complication of tabes dorsalis can be transient neuralgic paroxysmal pain affecting the eyes and the ophthalmic areas, previously called "Pel's crises" after Dutch physician P.K. Pel .
The patellar is an example of a sesamoid bone that develops within the tendon itself. Grays refers to it as the Patellar Tendon (Gray's Anatomy, 39th edition, 2005, page 1472, 1474, Fig 113.25), but often with (patellar ligament) in brackets.JeffBagust 11:04, 4 November 2009 (UTC)