Muscle tone. Definition. noun. (1) The muscle in a steady partially contracted state caused by the successive flow of nerve impulses. (2) The amount of tension or resistance to movement in a muscle. Supplement. Muscle tone or tonus helps in maintaining body posture.
Hydronephrosis is the distention of the pelvis and calyces of one or both kidneys, resulting in thinning of the renal tubules because of obstructed urinary flow. When the obstruction is a stone or kink in one of the ureters, only one kidney is damaged.
Ureters are the two funnel-shaped tubes that carry urine from the kidneys to the bladder. A ureter that does not connect properly to the bladder and drains somewhere outside of the bladder is called an ectopic ureter. In boys the ectopic ureter usually drains into the urethra closer to the prostate.ost commonly, as seen here, the ectopic ureter drains to the urethra. 1  Hydronephrosis: When the ectopic ureter connects outside the bladder, the insertion is usually narrow, creating a level of obstruction. 2  The urine that is draining from the kidneys backs up and causes the kidney and ureter to dilate (hydronephrosis).