Urethra

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Urethra

In anatomy

Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, the urethra (from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
??????a - ourethra) is a tube which connects the urinary bladder

Urinary bladder

In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
to the outside of the body. The urethra has an excretory function in both sexes to pass urine

Urine

Urine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra....
to the outside, and also a reproductive function in the male, as a passage for semen

Semen

Semen is an organic fluid, also known as seminal fluid, that usually contains spermatozoon....
.

The external urethral sphincter

Urethral sphincter

The urethral sphincter is a collective name for the muscles used to control the flow of urine from the urinary bladder. These muscles envelop the urethra, so that when they contract, the urethra is sealed shut....
is a striated muscle that allows voluntary control over urination

Urination

Urination, also known as micturition, voiding, and, more rarely, emiction, is the process of disposing urine from the urinary bladder through the urethra to the outside of the body....
.

he human female, the urethra is about 1 1/2-2 inches (3-5 cm) long and opens between the clitoris

Clitoris

The clitoris is a sex organ that is present only in female mammals. In humans, the visible button-like portion is located near the anterior junction of the labia minora, above the opening of the urethra and vagina....
and the vagina

Vagina

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Anatomy

Female urethra

In the human female, the urethra is about 1 1/2-2 inches (3-5 cm) long and opens between the clitoris

Clitoris

Vagina

The vagina is a fibromuscular cylinder tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles....
l opening, extending from the internal to the external urethral orifice. It is placed behind the symphysis pubis, embedded in the anterior wall of the vagina, and its direction is obliquely downward and forward; it is slightly curved with the concavity directed forward. Its lining is composed of stratified squamous epithelium, which becomes transitional near the bladder. The urethra consists of three coats: muscular, erectile, and mucous, the muscular layer being a continuation of that of the bladder. Between the superior and inferior fascia of the urogenital diaphragm, the female urethra is surrounded by the Sphincter urethae. Somatic innervation of the external urethral sphincter is supplied by the pudendal nerve. The uro-genital sinus may be divided into three component parts. The first of these is the cranial portion which is continuous with the allantois and forms the bladder proper. The pelvic part of the sinus forms the prostatic urethra and epithelium as well as the membranous urethra and bulbo urethral glands in the male and the membranous urethra and part of the vagina in females. The area above and on both sides of the female urethra is thought by some to be sexually sensitive and is sometimes referred to as the U-spot or Urethral Erogenous Zone.

Male urethra

In the human male, the urethra is about 8 inches (17.5 cm) long and opens at the end of the penis

Penis

The penis is an external sex organ of certain biologically male organisms, in both vertebrates and invertebrates.The penis is a reproductive organ, technically an intromittent organ, and for Eutheria, additionally serves as the external organ of urination....
. The inside of the urethra has a spiral groove (like rifling

Rifling

Rifling is the helix-shaped pattern in the Gun barrel of a gun or firearm, which imparts a spin to a projectile around its long axis. This spin serves to gyroscope stabilize the projectile, improving its Aerodynamics stability and accuracy....
in a gun barrel), which makes the urine flow in a wide stream.

The urethra is divided into four parts in men, named after the location:

prostatic urethra

Prostatic urethra

The prostatic urethra, the widest and most dilatable part of the urethra canal, is about 3 cm. long.It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form of the canal is spindle-shaped, being wider in the middle than at either extremity, and narrowest below,...
>

Region	Description	Epithelium Epithelium In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body.... \|- \| pre-prostatic urethra Pre-prostatic urethra The pre-prostatic urethra is one of the four parts of the male urethra. The pre-prostatic urethra is also known as the intramural urethra, as it is the portion of the urethra which passes almost vertically through the wall of the urinary bladder, before it enters the prostate gland....	This is the intramural part of the urethra and varies between 0.5 and 1.5 cm in length depending the fullness of the bladder.	Transitional
Crosses through the prostate gland. There are several openings: (1) the ejaculatory duct Ejaculatory duct The Ejaculatory ducts are paired structures in male anatomy, about 2 cm in length.Each ejaculatory duct is formed by the union of the vas deferens with the Excretory duct of seminal gland.... receives sperm Spermatozoon A sperm, from the ancient Greek word sp???a and and more commonly known as a sperm cell, is the ploidy cell that is the male gamete. It Fertilization an ovum to form a zygote.... from the vas deferens Vas deferens The vas deferens , also called ductus deferens, is part of the male anatomy of some species; they transport sperm from the epididymis in anticipation of ejaculation.... and ejaculate fluid from the seminal vesicle Seminal vesicle The seminal vesicles are a pair of simple tubular glands posteroinferior to the urinary bladder of males.... , (2) several prostatic ducts Prostatic ducts The prostatic ducts open into the floor of the prostatic portion of the urethra, and are lined by two layers of epithelium, the inner layer consisting of columnar and the outer of small cubical cells.... where fluid from the prostate Prostate The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. Females do not have a prostate gland, although females do have tiny paraurethral Skene's glands connected to the distal third of the urethra in the prevaginal space that are homologous to the prostate.... enters and contributes to the ejaculate, (3) the prostatic utricle Prostatic utricle The prostatic utricle is a small indentation located in the prostatic urethra, at the apex of the urethral crest, on the seminal colliculus, laterally flanked by openings of the ejaculatory ducts.... , which is merely an indentation. These openings are collectively called the verumontanum.	Transitional Transitional Transitional was a post punk Band with riot grrrl and New Wave music influences.They released one album called The People Vs Transitional on Sound on Sound in 1999 and an EP called Not even the Most Condescending Form of Noblesse Oblige on Pehr in 2000.... \|- \| membranous urethra Membranous urethra The intermediate part of male urethra is the shortest, least dilatable, and, with the exception of the external orifice, the narrowest part of the canal....	A small (1 or 2 cm) portion passing through the external urethral sphincter. This is the narrowest part of the urethra. It is located in the deep perineal pouch Deep perineal pouch The deep perineal pouch is an anatomical term that refers to the space enclosed in part by the perineum, and located superior to the perineal membrane.... . The ducts of the bulbourethral glands (Cowper's gland) enter here.	Pseudostratified columnar \|- \| spongy urethra Spongy urethra The spongy urethra is the longest part of the male urethra, and is contained in the corpus spongiosum urethrae?.It is about 15 cm long, and extends from the termination of the membranous portion to the external urethral orifice.... (or penile urethra)	Runs along the length of the penis on its ventral (underneath) surface. It is about 15-16 cm in length, and travels through the corpus spongiosum Corpus spongiosum Corpus spongiosum is the mass of spongy biological tissue surrounding the male urethra within the penis.... . The ducts from the urethral gland Urethral gland The term urethral or periurethral gland is used to refer to any of the many glands that branch off the wall of the urethra of male mammals.The glands secrete mucus, which is incorporated into the semen, and are most numerous in the section of the urethra that runs through the penis.... (gland of Littre) enter here. Some textbooks will subdivide the spongy urethra into two parts, the bulbous and pendulous urethra.	Pseudostratified columnar - proximally, Stratified squamous - distally

The length of a male's urethra, and the fact it contains a prominent bend, makes catheter

Catheter

In medicine a catheter is a tubing that can be inserted into a body cavity, duct or vessel. Catheters thereby allow drainage or injection of fluids or access by surgical instruments....
ization more difficult.

Histology

The epithelium

Epithelium

In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are stratified columnar cells, then stratified squamous cells near the external meatus (exit hole).

There are small mucus

Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. It is a viscous colloid containing antiseptic enzymes and immunoglobulins that serves to protect Epithelium in the respiratory,...
-secreting urethral glands, that help protect the epithelium from the corrosive urine.

Medical problems of the urethra

Hypospadias
Hypospadias

Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urinary meatus . Instead of opening at the tip of the glans penis of the penis, a hypospadic urethra opens anywhere along a line running from the tip along the underside of the shaft to the junction of the penis and scrotum or perineum....
and epispadias
Epispadias

An epispadias is a rare type of congenital malformation of the penis in which the urethra ends in an opening on the upper aspect of the penis....
are forms of abnormal development of the urethra in the male, where the meatus
Urinary meatus

The urinary meatus is the external orifice of the urethra, from which urine is ejected during urination and semen is ejected during ejaculation....
is not located at the distal end of the penis (it occurs lower than normal with hypospadias, and higher with epispadias). In a severe chordee
Chordee

Chordee is a condition in which the head of the penis curves downward or upward, at the junction of the head and shaft of the penis. The curvature is usually most obvious during erection, but resistance to straightening is often apparent in the flaccid state as well....
, the urethra can develop between the penis and the scrotum
Scrotum

In some male mammals the scrotum is a protuberance of skin and muscle containing the testicles. It is an extension of the abdomen, and is located between the penis and anus....
.
Infection of the urethra is urethritis
Urethritis

Urethritis is inflammation of the urethra. The main symptom is dysuria, which is painful or difficult urination....
, said to be more common in females than males. Urethritis is a common cause of dysuria
Dysuria

In medicine, specifically urology, dysuria refers to painful urination. This is typically described to be a burning or stinging sensation. It is most often a result of a urinary tract infection....
(pain when urinating).
Related to urethritis is so called urethral syndrome
Urethral syndrome

Urethral syndrome is defined as symptoms suggestive of a lower urinary tract infection but in the absence of significant bacteruria with a conventional pathogen....
Passage of kidney stone
Kidney stone

Kidney stones, also called renal Calculus , are solid concretions of dissolved dietary mineral in urine; calculi typically form inside the kidneys or bladder....
s through the urethra can be painful and subsequently it can lead to urethral stricture
Urethral stricture

A urethral stricture is a narrowing of the urethra caused by injury or disease such as urinary tract infections or other forms of urethritis....
s.

Endoscopy of the bladder via the urethra is called cystoscopy

Cystoscopy

Endoscopy of the urinary bladder via the urethra is called cystoscopy.Diagnostic cystoscopy is usually carried out with local anaesthesia. General anaesthesia is sometimes used for operative cystoscopic procedures....
.

Foreign bodies in the urethra are uncommon, but there have been medical case reports of self-inflicted injuries a result of insertion of foreign bodies into the urethra such as an electrical wire .

Sexual physiology

The male urethra is the conduit for semen during sexual intercourse

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which the Penis enters the Vagina. The two entities may be of opposite sexes or not, or they may be hermaphrodite, as is the case with snails....
. It also serves as a passage for urine to flow.

Additional images

External links

"Male Urethra"

Urethra

Anatomy

Female urethra

Male urethra

Histology

Medical problems of the urethra

Sexual physiology

See also

Additional images

External links