The urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus.
The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra. The typical adult human bladder will hold between 300 and 500 ml before the urge to empty occurs, but can hold considerably more.
The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra.
The pudendal nerve is the main nerve of the perineum. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well as the motor supply to various pelvic muscles, including the male or female external urethral sphincter and the external anal sphincter. If damaged, most commonly by childbirth, lesions may cause sensory loss or fecal incontinence. The nerve may be temporarily blocked as part of an anaesthetic procedure.
Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geriatric health care. The term enuresis is often used to refer to urinary incontinence primarily in children, such as nocturnal enuresis. UI is an example of a stigmatized medical condition, which creates barriers to successful management and makes the problem worse. People may be too embarrassed to seek medical help, and attempt to self-manage the symptom in secrecy from others.
Kegel exercise, also known as pelvic-floor exercise, involves repeatedly contracting and relaxing the muscles that form part of the pelvic floor, now sometimes colloquially referred to as the "Kegel muscles". The exercise can be performed many times a day, for several minutes at a time but takes one to three months to begin to have an effect.
The Bulbospongiosus muscle is one of the superficial muscles of the perineum. It has a slightly different origin, insertion and function in males and females. In males, it covers the bulb of the penis. In females, it covers the vestibular bulb.
The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the levatores ani and coccygei, with which may be included the parietal pelvic fascia on their upper and lower aspects. The pelvic floor separates the pelvic cavity above from the perineal region below. Both males and females have a pelvic floor. To accommodate the birth canal, a female's pelvic cavity is larger than a male's.
Onuf's nucleus is a distinct group of neurons located in the ventral part of the anterior horn of the sacral region of the human spinal cord involved in the maintenance of micturition and defecatory continence, as well as muscular contraction during orgasm. It contains motor neurons, and is the origin of the pudendal nerve. The sacral region of the spinal cord is the fourth segment of vertebrae in the spinal cord which consists of the vertebrae 26-30. While working in New York City in 1899, Bronislaw Onuf-Onufrowicz discovered this group of unique cells and originally identified it as “Group X.” “Group X” was considered distinct by Onufrowicz because the cells were different in size from the surrounding neurons in the anterolateral group, suggesting that they were independent.
Older texts have asserted the existence of a urogenital diaphragm, also called the triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of the urogenital diaphragm and superior fascia of the urogenital diaphragm.
The external sphincter muscle of male urethra, also sphincter urethrae membranaceae, sphincter urethrae externus, surrounds the whole length of the membranous urethra, and is enclosed in the fascia of the urogenital diaphragm.
Stress incontinence, also known as stress urinary incontinence (SUI) or effort incontinence is a form of urinary incontinence. It is due to inadequate closure of the bladder outlet by the urethral sphincter.
The transverse perineal muscles are the superficial and the deep transverse perineal muscles.
The deep perineal pouch is the anatomic space enclosed in part by the perineum, and located superior to the perineal membrane.
Neurogenic bladder dysfunction, or neurogenic bladder, refers to urinary bladder problems due to disease or injury of the central nervous system or peripheral nerves involved in the control of urination. There are multiple types of neurogenic bladder depending on the underlying cause and the symptoms. Symptoms include overactive bladder, urinary urgency, frequency, incontinence or difficulty passing urine. A range of diseases or conditions can cause neurogenic bladder including spinal cord injury, multiple sclerosis, stroke, brain injury, spina bifida, peripheral nerve damage, Parkinson's disease, or other neurodegenerative diseases. Neurogenic bladder can be diagnosed through a history and physical as well as imaging and more specialized testing. Treatment depends on underlying disease as well as symptoms and can be managed with behavioral changes, medications, surgeries, or other procedures. The symptoms of neurogenic bladder, especially incontinence, can have a significant impact on quality of life.
The detrusor muscle, also detrusor urinae muscle, muscularis propria of the urinary bladder and muscularis propria, is smooth muscle found in the wall of the bladder. The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine. Related are the urethral sphincter muscles which envelop the urethra to control the flow of urine when they contract.
The internal urethral sphincter is a urethral sphincter muscle which constricts the internal urethral orifice. It is located at the junction of the urethra with the urinary bladder and is continuous with the detrusor muscle, but anatomically and functionally fully independent from it. It is composed of smooth muscle, so it is under the control of the autonomic nervous system, specifically the sympathetic nervous system.
The external sphincter muscle of female urethra is a muscle which controls urination in females. The muscle fibers arise on either side from the margin of the inferior ramus of the pubis. They are directed across the pubic arch in front of the urethra, and pass around it to blend with the muscular fibers of the opposite side, between the urethra and vagina.
A urethral bulking injection is a gynecological procedure and medical treatment used to treat involuntary leakage of urine: urinary incontinence in women. Injectional materials are used to control stress incontinence. Bulking agents are injected into the mucosa surrounding the bladder neck and proximal urethra. This reduces the diameter of the urethra and creates resistance to urine leakage. After the procedure, the pressure forcing the urine from the bladder through the urethra is resisted by the addition of the bulking agent in the tissue surrounding the proximal urethra. Most of the time this procedure prevents urinary stress incontinence in women.
The vaginal support structures are those muscles, bones, ligaments, tendons, membranes and fascia, of the pelvic floor that maintain the position of the vagina within the pelvic cavity and allow the normal functioning of the vagina and other reproductive structures in the female. Defects or injuries to these support structures in the pelvic floor leads to pelvic organ prolapse. Anatomical and congenital variations of vaginal support structures can predispose a woman to further dysfunction and prolapse later in life. The urethra is part of the anterior wall of the vagina and damage to the support structures there can lead to incontinence and urinary retention.
