Spinal and StretchReflexes. A reflex is an involuntary neural response to a specific sensory stimulus that threatens the survival or homeostatic state of an organism. Reflexes exist in the most primitive of species, usually with a protective function for animals when they encounter external and internal stimuli. A primitive example of this protective reflex is the gill withdrawal reflex of the sea slug Aplysia. In humans and other vertebrates, protective reflexes have been maintained and expanded in number.
http://www.dgward.com/physo101/web_pages/section_5/lab_stretch_reflexes.htm
[ne] the area around the knee joint, a hinge joint that is one of the largest joints of the body, sustaining great pressure. The knee is formed by the proximal portion of the tibia, the distal end of the femur, and the patella, or kneecap.
http://medical-dictionary.thefreedictionary.com/knee+jerk
triceps surae jerk ankle jerk. knee. the area around the knee joint, a hinge joint that is one of the largest joints of the body, sustaining great pressure. The knee is formed by the proximal portion of the tibia, the distal end of the femur, and the patella, or kneecap. The bones are joined by ligaments, and the patella is secured to the adjacent bones by powerful tendons. The fibula is attached at the side of the knee to the tibia.
http://medical-dictionary.thefreedictionary.com/knee+jerk
Definition of Knee jerk. Knee jerk: The reflex that is tested by tapping just below the bent knee on the patellar tendon. Normally this causes the quadriceps muscle to contract and bring the lower leg forward. It has given rise to the saying 'a knee-jerk reaction.' Also known as patellar reflex. Last Editorial Review: 5/13/2016.
http://www.medicinenet.com/script/main/art.asp?articlekey=4116
The reality is, outside forces are stimulating our muscles every time we move, run, jump, walk, throw, catch, get out of bed, or hold our head up, and our reflexes govern our reactions to those forces. Reflexes are ultimately responsible for the action of our muscles and, so, govern the way we move. Reflexes are, by definition, actions that occur before the brain is aware of what is happening. Reaction to a stimulus is processed in the spinal cord, bypassing brain control. Naturally, if movement results, the brain will become aware of such movement and can regulate it somewhat, but the brain cannot control it.
http://www.positivehealth.com/article/chiropractic/reflex-reactions-our-body-s-rapid-defence-mechanism
knee jerk (knee reflex) a kick reflex produced by sharply tapping the patellar ligament. To test this reflex, the lower part of the leg is allowed to hang relaxed (such as by crossing the legs at the knees) and the examiner taps the ligament below the patella with a small rubber hammer.
http://medical-dictionary.thefreedictionary.com/knee+reflex
[ne] the area around the knee joint, a hinge joint that is one of the largest joints of the body, sustaining great pressure. The knee is formed by the proximal portion of the tibia, the distal end of the femur, and the patella, or kneecap. The bones are joined by ligaments, and the patella is secured to the adjacent bones by powerful tendons. The fibula is attached at the side of the knee to the tibia.
http://medical-dictionary.thefreedictionary.com/knee+reflex
The knee-jerk and other tendon reflexes differ significantly from other types of reflexes in that no central nervous system interneurons are involved in the knee-jerk reflex. Under normal circumstances, brain pathways descend onto the same motor neurons, constantly modulating the strength of stretch reflexes.
http://www.dgward.com/physo101/web_pages/section_5/lab_stretch_reflexes.htm
The stretch reflex or myotatic reflex (sometimes myotactic reflex) is probably our body's most unrecognised and unappreciated defence mechanism. Forget about the immune system. When it comes to making it safely through the day, nothing comes close to the myotatic reflex.
http://www.positivehealth.com/article/chiropractic/reflex-reactions-our-body-s-rapid-defence-mechanism
knee jerk (knee reflex) a kick reflex produced by sharply tapping the patellar ligament. To test this reflex, the lower part of the leg is allowed to hang relaxed (such as by crossing the legs at the knees) and the examiner taps the ligament below the patella with a small rubber hammer.
http://medical-dictionary.thefreedictionary.com/knee+jerk
what is the knee jerk protecting
Knee-jerk protecting is a kick reflex produced by sharply tapping the patellar ligament.