WordNet

an automatic instinctive unlearned reaction to a stimulus (同)reflex response, reflex action, instinctive reflex, innate reflex, inborn reflex, unconditioned_reflex, physiological reaction
a small flat triangular bone in front of the knee that protects the knee joint (同)kneecap, kneepan
near or relating to the patella or kneecap; "patellar tendon"
(of leaves) bent downward and outward more than 90 degrees

PrepTutorEJDIC

反射(刺激に対する無意識の反応) / 《複数形で》反射的な動き / (光などの)反射,反射光;映像 / 反射性の / (カメラが)レフ鋼の,反射型の
=kneecap

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/08/22 11:51:58」(JST)

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Patellar reflex.

The patellar reflex or knee-jerk is a deep tendon reflex and is a myotatic reflex.

Mechanism[edit source | edit]

Striking the patellar ligament with a reflex hammer just below the patella stretches the muscle spindle in the quadriceps muscle. This produces a signal which travels back to the spinal cord and synapses (without interneurons) at the level of L4 in the spinal cord, completely independent of higher centres. From there, an alpha-motor neuron conducts an efferent impulse back to the quadriceps femoris muscle, triggering contraction. This contraction, coordinated with the relaxation of the antagonistic flexor hamstring muscle causes the leg to kick. This reflex is a reflex of proprioception which helps maintain posture and balance, allowing to keep one's balance with little effort or conscious thought.

The patellar reflex is a clinical and classic example of the monosynaptic reflex arc. There is no interneuron in the pathway leading to contraction of the quadriceps muscle. Instead the bipolar sensory neuron synapses directly on a motor neuron in the spinal cord. However, there is an inhibitory interneuron used to relax the antagonistic hamstring muscle.

It tests L2, L3, and L4.^[1]

Purpose of Testing[edit source | edit]

After the tap of a hammer, the leg is normally extended once and comes to rest. The absence or decrease of this reflex is known as Westphal's sign. On the other hand, multiple oscillation of the leg following the tap may be a sign of a cerebellar disease. The test itself assesses the nervous tissue between and including the L2 and L4 segments.

History[edit source | edit]

The term knee-jerk was recorded by Sir Michael Foster in his Textbook of physiology in 1877: "Striking the tendon below the patella gives rise to a sudden extension of the leg, known as the knee-jerk."^[2]

Popular culture[edit source | edit]

The term began to be used figuratively from the early 20th century onwards. O. O. McIntyre, in his New York Day-By-Day column in The Coshocton Tribune, October 1921, wrote: "Itinerant preacher stemming Broadway on a soap box. And gets only an occasional knee-jerk."^[2]

Notes[edit source | edit]

^ William J. Weiner (30 July 2010). Neurology for the Non-Neurologist. Lippincott Williams & Wilkins. pp. 499–. ISBN 978-1-60547-239-3. Retrieved 4 July 2011.
^ ^a ^b Knee-jerk reaction

References[edit source | edit]

Gurfinkel' VS, Lipshits MI, Popov KE (1974). "Is the stretch reflex a basic mechanism in the system of regulation of human vertical posture?". Biofizika (in Russian) 19 (4): 744–8. PMID 4425696.
Pinnock CA, Lin ES, Smith T (2003). "9". Fundamentals of Anaesthesia, 2nd Edition (2 ed.). Greenwich Medical Media Ltd.

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English Journal

The patellar reflex: does activity of quadriceps femoris muscles reflect leg movement?

Dafkin C, Green A, Kerr S, McKinon W.AbstractOBJECTIVES: The assessment of spinal reflexes has traditionally been performed by clinicians with minimal need for recording equipment, where doctors rely on their training and may use established subjective reflex rating scales. With advances in technology, it is now possible to assess reflexes objectively. This study compared two objective methods of assessing patellar reflex magnitude, duration, and latency, namely electromyography (EMG) of the quadriceps muscles and kinematic assessment of the leg movement around the knee joint.
Neurological research.Neurol Res.2012 Mar 20. [Epub ahead of print]
OBJECTIVES: The assessment of spinal reflexes has traditionally been performed by clinicians with minimal need for recording equipment, where doctors rely on their training and may use established subjective reflex rating scales. With advances in technology, it is now possible to assess reflexes obj
PMID 22449943

Allograft closure of lateral release after revision total knee arthroplasty.

Sahai V, Bono JV, Talmo CT.SourceDepartment of Orthopedic Surgery, New England Baptist Hospital, Boston, Massachusetts 02120, USA.
The Journal of arthroplasty.J Arthroplasty.2012 Mar;27(3):494.e9-12. Epub 2011 Aug 9.
Lateral patellar retinacular release (lateral release) is a common technique for resolving patellar tracking issues during total knee arthroplasty. Complications such as hemarthrosis, wound healing complications, patellar fracture, reflex sympathetic dystrophy, and medial subluxation of the patella
PMID 21831578

Japanese Journal

TuD-2-3 Characterization of Patellar Tendon Reflex Utilizing Portable Instrument

Proceedings of ... JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment : IIP/ISPS joint MIPE 2015, "TuD-2-3-1"-"TuD-2-3-3", 2015-06-14
NAID 110010044108