The use of âholidayâ to mean âa missed spotâ appears to be that rarity in English etymology, a word or phrase that actually has a nautical origin. The original use of âholidayâ in the âmissed a spotâ sense, back in the 18th century, was in reference to crew members painting the decks of a ship or âpayingâ (sealing seams with tar or pitch) its hull.
The knee jerk reflex is when a tendon above the kneecap is tapped with a reflex hammer, which causes the whole leg to involuntarily jerk.
A knee jerk is a spinal reflex. In a spinal reflex, a sensation is relayed to neurons in the spinal cord via a sensory pathway. Neurons in the spinal cord create reflexes that occur independent of the brain.The spinal nerves, which carry signals to and from the brain, make most of the body's functions, such as movement, and senses, possible.A spinal reflex will bypass the brain and is an action only by the cells in the spinal cord. spinal reflex will bypass the brain and is an action only by the cells in the spinal cord.