Renal anatomy 4

Question 1

Describe what seminal vesicles are

Answer 1

Lobulated sacs each 4 cm long that lie lateral to the ampulla of the vas deferens.
They secrete a thick alkaline fluid which forms the bulk of seminal fluid (semen)
The duct of the seminal vesicle joins the vas deferens to become the ejaculatory duct which pierces the back of the prostate gland to enter the prostatic urethra.

Question 2

Describe the prostate gland

Answer 2

It is a roughly spherical fibromuscular gland (size of walnut)
It lies against the neck of the bladder and is pierced by the urethra and ejaculatory ducts.
Secretions of the prostate are added to the seminal fluid during ejaculation

Question 3

What artery supplies the prostate, vas deferens and seminal vesicles?

Answer 3

Branches of the internal iliac artery

Question 4

What are some male pelvic organs?

Answer 4

Testes
Epididymis
Vas deferens
Seminal vesicles
Prostate gland
Ejaculatory ducts
Penis
Rectum and bladders

Question 5

What are some female pelvic organs?

Answer 5

Uterus, cervix, vagina, uterine tubes, ovaries, rectum and bladder

Question 6

Describe the uterus. Explain what happens during conception.

Answer 6

Pear shaped muscular organ about 8cm long
Communicates laterally with uterine tubes and inferiorly with vagina
Has a fundus, body and a cervix
Body- angled anteriorly and lies on the superior surface of the bladder
(angle between body and cervix may be tilted anteriorly or posteriorly)
If conception occurs, the blastocyst implants into the endometrium in the body of the uterus. The myometrium (middle muscular layer) becomes distended as pregnancy continues.
A broad ligament (double layer fold of peritoneum) which attaches the lateral portions of the uterus to the pelvic sidewalls is formed.
(the space in between the uterus and rectum is called the rectouterine pouch)

Question 7

What is the significance of the rectouterine pouch?

Answer 7

It is the deepest point in the peritoneal cavity, so it is a common site for the accumulation of the intraperitoneal fluid or pus. (it is lines with peritoneum)

Question 8

Describe the cervix. What is its position stabilised by?

Answer 8

It has a narrow lumen (cervical canal)
The cervical canal communicates with the uterine cavity via the internal os and with the vagina via the external os.
The lower part of the cervix lies in the vagina, creating a recess- the vaginal fornices
The position of the cervix is stabilised by the tone of the levator ani muscle and ligaments which run from the lateral wall of the cervix to the lateral pelvic wall at the base of the broad ligament. (use teach me anatomy 3D model– but essentially the levator ani muscles are at the base of the broad ligament)

Question 9

Describe the fallopian tubes (uterine tubes)

Answer 9

Paired tubes carrying ova from the ovary towards the cervix
Fertilisation occurs inside the uterine tubes
About 10cm long and are found running in the upper border of the broad ligament
Near the uterus there is a narrow isthmus and laterally, they have a dilated ampulla leading to a funnel shaped infundibulum. The free-edge of the infundibulum is broken up into finger-like projectings known as fimbriae which drape over the ovary.
(uterine tubes may be clipped surgically as a means of sterilisation)

Question 10

Describe the ovaries

Answer 10

Almond shaped organs 4cm long and 2cm wide
Attached to the posterior aspect (superiorly) of the broad ligament via the mesovarium (short mesentery)
Although the position of the ovary is not fixed, it frequently lies in the ovarian fossa (formed by the angle between internal and external iliac arteries) (the ureter and obturator nerve and vessels are closely related to the ovarian fossa)

Question 11

Describe the ovaries

Answer 11

Almond shaped organs 4cm long and 2cm wide
Attached to the posterior aspect (superiorly) of the broad ligament via the mesovarium (short mesentery)
Although the position of the ovary is not fixed, it frequently lies in the ovarian fossa (formed by the angle between internal and external iliac arteries) (the ureter and obturator nerve and vessels are closely related to the ovarian fossa)

Question 12

Describe the vagina

Answer 12

Female organ of sexual intercourse and excretory duct of the uterus
About 10cm long
Terminates at the introitus by opening into the vestibule between the labia minora
The upper ⅔ of the vagina lies in the pelvic cavity while lower ⅓ lies in the perineum (where urethra is usually embedded)

Question 13

What artery supplies the cervix, uterine tubes, ovary and vagina?

Answer 13

The cervix, uterine tubes and vagina are supplied by branches of the internal iliac artery
The ovary is supplied by the ovarian artery, a direct branch of the abdominal aorta (contributes to uterine tube blood supply)

Question 14

Describe the vulva including blood supply and innervation

Answer 14

It is the collective term for the external part of the female genitals. It comprises of the: opening of the vagina, labia majora, labia minora clitoris, etc.
Blood supply is mainly via the internal pudendal arteries
It is innervated by 4 nerves: the pudendal nerve, genital branch of genitofemoral nerve, ilioinguinal nerve, and posterior cutaneous nerve of the thigh

Question 15

Name some parts of the vulva

Answer 15

Mons pubis, labia majora, labia minora, clitoris, vestibule, vaginal opening, hymen, urinary meatus, vestibular glands
Ladies make cookies very unusually when valuable urges happen
(labia x2) (mons) (clitoris) (vaginal opening) (urinary meatus) (vestibule and vestibular glands) (hymen)

Question 16

What is the mons pubis?

Answer 16

Mound of fatty tissue located in front of the pubic symphysis causing an elevation of the hair bearing skin

Question 17

What is the labia majora and labia minora?

Answer 17

Labia majora- prominent hair bearing folds of skin that meet at the mons pubis anteriorly
Labia minora- smaller hairless folds of skin located medial to the labia majora - they fuse anteriorly to form the hood of the clitoris and form the boundaries of the vestibule

Question 18

What is the clitoris?

Answer 18

Pea-sized, highly sensitive tissue comprised of the corpus spongiosum
It becomes engorged during sexual arousal

Question 19

What is the vestibule?

Answer 19

Area between the labia minora
Contains the vaginal opening, urinary meatus and vestibular glands

Question 20

What is the vaginal opening?

Answer 20

The entrance to the vagina also known as the vaginal introitus

Question 21

What is the hymen?

Answer 21

A thin membrane that partially converse the vaginal opening. It often ruptures during the first episode of sexual intercourse. (but can rupture spontaneously during exercise, by using tampons or may be absent altogether.

Question 22

What is the urinary meatus?

Answer 22

The opening of the urethra
It lies in between the clitoris and vaginal opening

Question 23

What are the vestibular glands?

Answer 23

Greater vestibular glands- Bartholin’s glands- lie posterior (below) the vaginal opening and secrete a lubricant into the vagina during sexual arousal
Lesser vestibular glands- Skene’s glands- lie near the urethral opening. The fluid they secrete might lubricate the vaginal opening or urethra, or have an antimicrobial effect (unsure function)

Question 24

Describe the urinary bladder

Answer 24

It is a hollow muscular organ located in the pelvis below the peritoneum.
It is located posterior to the pubic symphysis and anterior to the vagina and rectum
It is supplies by vesical arteries, branches of the internal iliac arteries (vesical veins drain into the internal iliac vein)
It stores urine and helps to squeeze urine out during micturition/urination
It can accommodate approx 400-600ml of urine (when full, its superior aspect may extend above the pubic symphysis)
The rest of the inside of the bladder wall has folds of mucosa called rugae which allow the bladder to stretch without tearing when it fills.
The bladder wall contains smooth muscle- the detrusor which contracts forcibly to expel urine.

Question 25

Where does the bladder fill and drain?

Answer 25

The ureters enter the trigone (triangular smooth wall) of the bladder at an angle which forms a rudimentary valve to prevent reflux of urine into the ureters when the bladder is full.
The ureters fill the bladder with urine which drains into the posterior aspect of the bladder near the base.
The rest of the inside of the bladder wall has folds of mucosa called rugae which allow the bladder to stretch without tearing when it fills.

Question 26

What are the 2 sphincters controlling the release of urine? Where are they located?

Answer 26

Internal urethral sphincter- located at the base of the bladder where it opens into the urethra. It is composed of smooth muscle and is under involuntary control

External urethral sphincter- located just after the prostate gland in males and in the deep perineal pouch in females. It is composed of skeletal muscle and is under voluntary control.

Question 27

What is the innervation of the urinary bladder and urethral sphincter?

Answer 27

Somatic- Via branches of the pudendal nerve (S2-S4) → this allows for conscious control of the external urethral sphincter

Sympathetic- Via branches of the hypogastric nerve (T12-L2- sympathetic chain) → it causes relaxation of the detrusor and contraction of the internal urethral sphincter, allowing storage of urine.

Parasympathetic- Via the pelvic splanchnic nerves (S2-S4) → It causes contraction of the detrusor and relaxation of the internal urethral sphincter, allowing initiation of micturition

Question 28

Describe the urethra

Answer 28

It carries urine from the internal urethral orifice (medial to internal urethral sphincter) to the external urethral orifice (tip of penis in males and vestibule in females)
The male urethra also carries semen
The female urethra is relatively short
The male urethra has 4 parts (preprostatic, prostatic, membranous and penile parts)

Question 29

What is the bladder stretch reflex

Answer 29

As the bladder fills, stretch of the bladder wall is detected and this is relayed to the sacral spinal cord via visceral afferent fibres. In the sacral spinal cord, they synapse directly onto motor neurons which via parasympathetic fibres of the pelvic splanchnic nerves, cause bladder contraction. Referred to as the reflex arc
After ‘potty training’ this reflex arc can be inhibited by inputs from the cerebral cortex (in older children and adults)– we learn to consciously recognise bladder filling and develop descending pathways that inhibit the reflex when it is not convenient to urinate.

Question 30

What bladder dysfunction happens when a patient suffers an injury to their spinal cord above the sacral level (at the level of T10)?

Answer 30

2 pathways are interrupted
Ascending pathways conveying the sensation of bladder filling to the brain (patient no longer aware of bladder filling)
Descending pathways that exert voluntary, inhibitory control over the external urethral sphincter (so external sphincter is permanently relaxed)
So the reflex arc still functions below the injury but the patient no longer has control over it. (the patient does not realise they need to pass urine and the bladder automatically empties as it fills - the patient is incontinent of urine)

Question 31

What bladder dysfunction happens when a patient suffers an injury to the spinal cord or cauda equina at or below the level of sacral micturition centres?

Answer 31

The reflex arc is disrupted and the bladder fills with urine without emptying. The internal urethral sphincter is permanently contracted
So as the bladder continues to fill, the pressure in the bladder eventually exceeds the strength of the internal urethral sphincter and urination will occur. Referred to as overflow incontinence
However if the pressure in the bladder does not overcome the strength of the internal sphincter, the patient develops urinary retention→ eventually urine may back up to the ureters and kidneys if a urinary catheter is not placed.

Question 32

Describe the rectum

Answer 32

The terminal part of the large intestine
Approximately 12cm long in an adult
Its primary purpose is to store faeces prior to defecation
Has 2 flexures; the sacral flexure anteriorly and the anorectal flexure posteriorly

Question 33

Describe the anal canal

Answer 33

Most distal part of the GI tract- approx 4cm long in an adult
Extends from the distal rectum to the anus and lies in the anal triangle of the perineum
Has 2 anal sphincters that control defecation- the internal anal canal is made of smooth muscle and is involuntarily controlled and the external anal canal is made of skeletal muscle and is voluntarily controlled.

Question 34

What is the pectinate/dentate line?

Answer 34

It divides the superior and inferior part of the anal canal.
The superior part is derived from the endoderm whilst the inferior part is derived from the ectoderm.

Question 35

the difference between the superior and inferior part of the anal canal?

Answer 35

Superior anal canal
Inferior anal canal
Part of the hindgut and supplied by inferior mesenteric artery (via superior rectal artery)
Supplied by the middle and inferior rectal arteries which originate from the internal iliac arteries
Venous drainage is via the portal venous system towards the liver
Venous blood enters the systemic venous system and does not pass through the portal system
Encircled by the internal anal sphincter which is innervated by sympathetic fibres from the sympathetic trunk and parasympathetic fibres from the pelvic splanchnic nerves
Encircled by the external (voluntary) anal sphincter which is innervated by the pudendal nerve (somatic)
Lined by columnar epithelium
Lined by stratified squamous epithelium