SUGER Anatomy 🍦🍧🍨🍩🍪🎂🍭🍬🍫

Question 1

Outline the adrenal glands

Answer 1

The terms ‘adrenal’ and ‘suprarenal’ are often used interchangeably to refer to the adrenal glands. They lie close to the upper pole of each kidney. The right adrenal gland lies behind the liver and inferior vena cava. The left adrenal gland lies behind the stomach and pancreas

Question 2

What are the 3 arteries that supply the adrenal glands?

Answer 2

• Superior adrenal artery - a branch of the inferior phrenic artery
• Middle adrenal artery - a branch of the abdominal aorta
• Inferior adrenal artery - a branch of the renal artery.

Question 3

Describe the venous drainage of the adrenal glands

Answer 3

They are drained by a single vein on each side. The right adrenal vein drains directly into the inferior vena cava, but the left adrenal vein drains first into the left renal vein, which then joins the inferior vena cava.

Question 4

What are the different parts of the adrenal glands and what do they produce?

Answer 4

The adrenal gland is composed of a cortex (outer part) and medulla (inner part). The cortex produces steroid hormones including cortisol, aldosterone, and testosterone. The medulla produces adrenaline.

Question 5

Outline the size, shape and placement of the kidneys

Answer 5

The two bean-shaped kidneys are about 11cm long, 7cm wide and 3cm thick. The kidneys are located outside the peritoneum so are extra-peritoneal structures. The term retro-peritoneal is also often used to further distinguish that they are behind the peritoneum, rather than above or below it. There is one on either side of the upper lumbar vertebrae. Each kidney is embedded in perinephric fat and this fatty layer is covered by renal fascia. A further layer of paranephric fat lies outside the renal fascia.

Question 6

What is the renal hilum and where do the vessels in it originate from?

Answer 6

On the medial border of the kidney is the renal hilum, where the renal vessels, nerves, lymphatics, and ureter enter or leave the kidney. The left and right renal arteries are branches of the abdominal aorta, and the left and right renal veins both drain directly into the inferior vena cava

Question 7

Outline the basic structure of the kidneys

Answer 7

The internal aspect of the kidney is composed of the cortex, medulla, and the calyces. The cortex is the outer part. The medulla is the inner part and is arranged into pyramids.

Question 8

What are the nephrons?

Answer 8

The functional units of the kidneys – nephrons - are responsible for filtering blood, reabsorbing water and solutes, and secreting and excreting waste products as urine. The glomeruli, glomerular capsules (‘Bowman’s capsule’), proximal and distal tubules, and part of the collecting ducts are in the cortex of the kidney, while the nephron loop (of Henle) and the rest of the collecting ducts are in the renal pyramids.

Question 9

What happens after the collecting duct?

Answer 9

From the collecting ducts, urine travels down the pyramid towards the renal papilla (the apex of the pyramid) where it enters a minor calyx

Question 10

What happens to the minor calyx?

Answer 10

Minor calyces merge with other minor calyces to form a major calyx

Question 11

What do major calyces merge to form?

Answer 11

Major calyces merge to form the renal pelvis which is continuous with the ureter.

Question 12

Outline ureters

Answer 12

The ureters carry urine to the urinary bladder. They are narrow tubes with muscular walls which transport urine by peristalsis. They run anterior to psoas major on the posterior abdominal wall and cross the pelvic brim to enter the pelvis.

Question 13

What is the urinary bladder and where is it?

Answer 13

The urinary bladder is a hollow muscular organ located in the pelvis below the peritoneum, therefore, it is classified as an infra-peritoneal organ. It is located posterior to the pubic symphysis, and anterior to the vagina and rectum

Question 14

What does the bladder do and how does the structure help it to do this?

Answer 14

It stores urine and helps to squeeze urine out during micturition. The bladder wall contains smooth muscle known as the detrusor which contracts to forcibly expel urine.

Question 15

Where do the ureters enter the bladder and what is special about this area?

Answer 15

The ureters join the posterior aspect of the bladder near the base. This triangular area of the bladder has a smooth internal wall and is called the trigone. The ureters enter the trigone of the bladder at an angle, forming a rudimentary valve which prevents reflux of urine into the ureters when the bladder is full.

Question 16

What is most of the bladder wall covered in?

Answer 16

The rest of the inside wall of the bladder is corrugated with folds of mucosa called rugae which allow the bladder to stretch without tearing when it fills

Question 17

How much space does the bladder take up and how much liquid can it hold?

Answer 17

When empty, the bladder may squash down completely, but when full, its superior aspect may extend above the pubic symphysis. It can accommodate approximately 400-600ml of urine in an adult.

Question 18

Describe the vasculature of the bladder

Answer 18

The bladder is supplied by the vesical arteries which are branches of the internal iliac artery. Similarly, vesical veins drain into the internal iliac vein.

Question 19

What controls the release of urine?

Answer 19

The release of urine is controlled by two sphincters: the internal and external urethral sphincters

Question 20

Outline the internal urethral sphincter

Answer 20

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

Question 21

Outline the external urethral sphincter

Answer 21

The external urethral sphincter is located just inferior to the prostate in males, and in the deep perineal pouch in females. This sphincter is composed of skeletal muscle and is under voluntary control.

Question 22

Describe the somatic innervation of the bladder and urethral sphincters

Answer 22

• Via branches of the pudendal nerve (S2-S4)
• Allows conscious control of the external urethral sphincter.

Question 23

Describe the sympathetic innervation of the bladder and urethral sphincters

Answer 23

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

Question 24

Describe the parasympathetic innervation of the bladder and urethral sphincters

Answer 24

• Via the pelvic splanchnic nerves (S2-S4)
• Causes contraction of the detrusor and relaxation of the internal urethral sphincter, allowing initiation of micturition.

Question 25

Describe the urethra

Answer 25

The urethra carries urine from the internal urethral orifice of the bladder to the external urethral orifice (located at the tip of the penis in males and in the vestibule in females). The female urethra is relatively short (approximately 3-4cm). For descriptive purposes, the longer male urethra is conventionally subdivided into pre-prostatic, prostatic, membranous, and penile parts. The male urethra also carries semen.

Question 26

What is the posterior abdominal wall

Answer 26

The posterior abdominal wall is the region behind the abdominal cavity and extends from the attachments of the diaphragm superiorly, to the pelvic brim inferiorly. It consists of the lumbar spine together with the psoas and quadratus lumborum muscles.

Question 27

What are some structures associated with the posterior abdominal wall?

Answer 27

Structures associated with the posterior abdominal wall include the aorta (with its associated autonomic plexuses and lymph nodes), inferior vena cava, and the sympathetic trunks on either side of the lumbar spine. More laterally, the ureters descend from the kidneys towards the pelvis on the surface of the psoas muscle and the gonadal vessels descend over the ureters to supply the gonads (testes or ovaries).

Question 28

Describe the lumbar plexus

Answer 28

Lumbar spinal nerves L1 - L4 form the lumbar plexus (with a contribution from the T12 nerve) as they leave the spinal cord. This plexus gives rise to several branches that innervate the skin and muscles of the abdominal wall and thigh

Question 29

What are the notable branches of the posterior abdominal wall?

Answer 29

• Iliohypogastric and ilioinguinal nerves
• Genitofemoral nerve
• Lateral femoral cutaneous nerve
• Femoral nerve
• Obturator nerve

Question 30

What do the Iliohypogastric and ilioinguinal nerves supply?

Answer 30

Supply the anterior abdominal wall muscles and skin of the external genitalia.

Question 31

What does the genitofemoral nerve supply?

Answer 31

Supplies the skin of the external genitalia.

Question 32

Where does the lateral femoral cutaneous nerve supply?

Answer 32

Also known as the ‘lateral cutaneous nerve of the thigh’, this nerve unsurprisingly supplies the skin over the lateral thigh

Question 33

Where does the femoral nerve supply and why is this useful?

Answer 33

This large nerve supplies the muscles and skin of the anterior thigh and is often a target for nerve blocks to provide pain relief for lower limb fractures or surgery. It is relatively easy to locate in the inguinal region using ultrasound.

Question 34

Where does the obturator nerve supply?

Answer 34

This nerve supplies the muscles and skin of the medial thigh.

Question 35

Describe the abdominal aorta

Answer 35

The thoracic aorta pierces the diaphragm at the level of the T12 vertebra and descends through the abdomen as the abdominal aorta. It descends on the posterior abdominal wall just to the left of the midline and terminates by bifurcating into the left and right common iliac arteries at approximately the level of L4. The abdominal aorta gives rise to several unpaired and paired branches.

Question 36

What are the unpaired branches of the abdominal aorta?

Answer 36

Recall that the coeliac trunk, superior mesenteric artery, and inferior mesenteric artery are unpaired branches.

Question 37

What are the paired branches of the abdominal aorta?

Answer 37

Paired branches include the renal, adrenal, gonadal, and lumbar arteries (the latter supply the posterior abdominal wall).

Question 38

What forms the inferior vena cava?

Answer 38

The inferior vena cava is formed by the union of the left and right common iliac veins at approximately the level of L5. It ascends on the posterior abdominal wall just to the right of the midline. Veins which correspond to the paired arterial branches from the abdominal aorta drain into the inferior vena cava. The inferior vena cava also receives the hepatic veins before passing through the diaphragm at the level of T8.

Question 39

Where does the left gonadal vein typically drain into?

Answer 39

Left gonadal vein typically drains into the left renal vein

Question 40

Outline urinary tract infections (UTIs)

Answer 40

UTIs are almost always caused by bacteria (most commonly E. Coli) entering the urinary bladder via the urethra. They are more common in females than males as the female urethra is much shorter. Infection of the urinary bladder is called cystitis and symptoms include burning pain on passing urine (dysuria) and the sensation of needing to pass urine much more frequently. Infection may spread superiorly to the kidney - this is called pyelonephritis. Pyelonephritis is a more serious infection and often requires intravenous antibiotics. Symptoms include fever, flank pain, and nausea and vomiting in addition to the symptoms of cystitis.

Question 41

Outline renal cancer

Answer 41

Cancer of the kidneys can be divided into three main types, based on their histological origin. Renal cell carcinomas (RCC) originate from the lining of the nephron, transitional cell carcinomas (TCC) arise from the epithelial lining inside the kidney, and Wilms’ tumours originate from renal stem cells. Renal cancers may present with a triad of symptoms: pain in the flank, a palpable mass in the abdomen and haematuria (blood in the urine). As the kidneys are encased in a renal capsule, perinephric fat, renal fascia and paranephric fat, a renal cancer must grow very large and penetrate these layers before it is able to invade adjacent organs and structures.

Question 42

Outline abdominal aortic aneurysm (AAA)

Answer 42

An aneurysm is the bulging of a blood vessel caused by a weak point in the blood vessel wall. Risk factors for development of an abdominal aortic aneurysm (AAA) include smoking, alcohol, hypertension, and atherosclerosis. AAAs are diagnosed if the diameter of the aorta is wider than 3cm. If a AAA ruptures, significant intra-abdominal bleeding occurs rapidly, and mortality is high. If a small AAA is found incidentally (unexpectedly found during examination or imaging for another reason), they are monitored to see if they increase in size, and treatment, including surgery or stenting, may be offered if they become too large.

Question 43

Outline kidney stones (calculi)

Answer 43

Hard stones (calculi) can form in the kidneys and pass into the ureter. Kidney stones are most often composed of calcium oxalate and risk factors for developing them include high urine-calcium levels, dehydration, obesity, and certain medications. Smaller stones can pass into the ureter and out of the body via the bladder and urethra without causing any problems, but larger stones can obstruct the ureter. The typical presentation of an obstructing stone in the ureter is excruciating, pulsatile pain felt from ‘loin to groin’. This is because the pain fibres supplying the ureters originate from the T12 to L2 nerves, so pain is referred and felt in the T12 - L2 dermatomes. If the flow of urine from the kidney is obstructed, the kidney will fill with urine and swell (hydronephrosis). This can injure the kidney and may also lead to infection.

Question 44

What are the 3 places where kidney stones are most likely to get stuck?

Answer 44

1. Pelvi-ureteric junction (PUJ) – between the renal pelvis and ureter.
2. Pelvic brim - where the ureter runs over the pelvic brim, anterior to the iliac artery.
3. Vesico-ureteric junction (VUJ) - where the ureter joins the bladder.

Question 45

Outline phaeochromocytoma

Answer 45

This is a rare hormone-producing tumour of the adrenal medulla. Secretion of excess adrenaline causes symptoms and signs related to hyperactivity of the sympathetic nervous system which are typically hypertension, tachycardia, and excessive sweating.

Question 46

How is urination stimulated?

Answer 46

Urination is controlled by centres in the cerebral cortex, brainstem and sacral spinal cord. The sacral spinal cord contains the sacral micturition centre. 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 these fibres synapse directly onto motor neurons.

Question 47

Outline the reflex arc involved in spinal cord emptying

Answer 47

The motor neurons (via parasympathetic fibres in the pelvic splanchnic nerves) stimulate bladder contraction. This simple relay through the spinal cord, where bladder filling initiates bladder emptying, is a type of stretch reflex and is referred to as a reflex arc.

Question 48

How is the reflex arc different in younger children?

Answer 48

In older children and adults, the reflex arc is inhibited by inputs from the cerebral cortex meaning older children and adults are aware of bladder filling and can consciously control when and where they urinate. This is achieved through ‘potty-training’ in early childhood, during which infants learn to consciously recognise bladder filling and develop descending pathways that inhibit the reflex when it is not convenient to urinate.

Question 49

How do the different spinal cord injuries affect bladder function

Answer 49

Injuries of the spinal cord produce different patterns of bladder dysfunction, depending on the level of the injury. If a patient suffers an injury to their spinal cord above the sacral level (e.g. a spinal cord transection at the level of T10), two important pathways are interrupted:
1. ascending pathways conveying the sensation of bladder filling to the brain (so the patient is no longer aware of bladder filling).
2. descending pathways that exert voluntary, inhibitory control over the external urethral sphincter (so the external sphincter is permanently relaxed).

Question 50

How is the function of the reflex arc altered below the level of the injury?

Answer 50

The reflex arc still functions below the injury, but the patient does not have any inhibitory control over it. The patient does not realise they need to pass urine and the bladder automatically empties as it fills, so the patient is incontinent of urine.

Question 51

Outline overflow incontinence

Answer 51

If a patient suffers an injury to the spinal cord or cauda equina at or below the level of the sacral micturition centre, the reflex arc itself is disrupted and the bladder fills with urine without emptying. The internal urethral sphincter is permanently contracted. As the bladder continues to fill, the pressure in the bladder eventually exceeds the strength of the internal urethral sphincter and urination will occur

Question 52

What is urinary retention caused by in patients with overflow incontinence?

Answer 52

This type of incontinence is ‘overflow incontinence’. If the pressure inside the bladder does not overcome the sphincter, the patient develops urinary retention. Eventually urine may back up to the ureters and kidneys if a urinary catheter is not placed.

Question 53

What are the functions of the bony pelvis and what is it made up of?

Answer 53

The bony pelvis has numerous functions including supporting the spine, torso, and upper body; locomotion; and housing and protecting the pelvic viscera. It is made up of three bones: the sacrum and the left and right hip bones. The hip bone is composed of three smaller bones that fuse together: the ilium, ischium and pubis.

Question 54

What are the 5 articulations of the bony pelvis?

Answer 54

Hip joint
Sacroiliac joint
Pubic symphysis
Lumbosacral joint
Sacrococcygeal joint

Question 55

Where is the hip joint?

Answer 55

Between the head of the femur and the acetabulum (socket) of the pelvis. The ilium, ischium, and pubis of the hip bone fuse at the acetabulum.

Question 56

Where is the sacroiliac joint?

Answer 56

Between the sacrum and the ilium of the hip bone. This joint is very stable and strong and is supported by many ligaments.

Question 57

Where is the pubic symphysis?

Answer 57

Between the two pubic bones at the front of the pelvis. Very little movement is permitted at the pubic symphysis.

Question 58

Where is the lumbosacral joint?

Answer 58

Between the 5th lumbar vertebra and the sacrum (an intervertebral disc lies between the two

Question 59

Where is the sacrococcygeal joint?

Answer 59

Between the sacrum and the coccyx.

Question 60

What are some useful surface landmarks of the pelvis?

Answer 60

Iliac crest
Anterior superior iliac spine
Iliac tubercle
Pubic tubercle
Inguinal ligament
Mid-inguinal point

Question 61

Iliac crest as a surface landmark

Answer 61

When palpating the iliac crests from the back, a line drawn between them at their highest point (the intercristal line) marks the level of the L4/L5 disc space. This is useful as this is a position where a lumbar puncture can be performed, or an epidural injection given.

Question 62

Anterior superior iliac spine as a surface landmark

Answer 62

This is the most anterior point of the ilium and is palpable in almost all patients.

Question 63

Iliac tubercle as a surface landmark

Answer 63

This is the most lateral point of the ilium. A line drawn between the iliac tubercles (the ‘intertubercular line’) marks the division of the lower third of the abdomen from the middle third, thereby delineating the suprapubic region from the umbilical, and the iliac fossae from the flanks.

Question 64

Pubic tubercle as a surface landmark

Answer 64

Again palpable in most people, this is the most medial point of the pubic bone.

Question 65

Inguinal ligament as a surface landmark

Answer 65

Runs from the anterior superior iliac spine to the pubic tubercle.

Question 66

Mid-inguinal point as a surface landmark

Answer 66

The mid-point of a line drawn from the anterior superior iliac spine to the pubic symphysis (not the pubic tubercle). The femoral artery is palpable here.

Question 67

Differences between male and female pelves

Answer 67

There are several differences between male and female pelves that you may be able to identify on specimens or models in the MTU:
* Wider, circular pelvic inlet in females (for childbirth) and narrower, heart-shaped pelvic inlet in males.
* Obtuse (>90˚) angle formed by the inferior pubic rami in females, acute angle (<90˚) in males.
* Wider and shorter sacrum in females; a narrower, longer sacrum in males.

Question 68

Contents of the pelvis

Answer 68

The pelvis contains organs of the gastrointestinal and genitourinary systems, including the bladder and rectum in both males and females, the uterus, ovaries and vagina in females and the prostate and seminal vesicles in males. It also contains numerous arteries, veins and nerves that supply the pelvic organs.

Question 69

Outline the pelvic floor

Answer 69

The pelvic floor is the collective name for several muscles that support the pelvic organs from below. The muscles of the pelvic floor separate the pelvis from the perineum. The pelvic floor muscles are shaped like a bowl or funnel

Question 70

What are the 3 primary functions?

Answer 70

1. Prevent herniation of the pelvic organs inferiorly, out of the pelvis.
2. Control continence of urine and faeces by providing a sphincter action on the urethra and rectum respectively.
3. Aid in increasing intra-abdominal pressure.

Question 71

What are the muscles of the pelvic floor?

Answer 71

Levator ani and coccygeus

Question 72

What are the three smaller paired muscles of the levator ani?

Answer 72

Puborectalis
Pubococcygeus
Iliococcygeus

Question 73

Outline the puborectalis

Answer 73

This U-shaped muscle attaches to the pubic bones anteriorly and forms a sling around the rectum. When it contracts it pulls on the rectum so that a sharp angle is formed between the rectum and anal canal, preventing defecation. When it relaxes, the path from the rectum to the anal canal straightens and faeces can pass through. It contributes to control of micturition in a similar fashion. Puborectalis is the most anterior levator ani muscle.

Question 74

Outline the pubococcygeus muscle

Answer 74

This muscle lies posterior and lateral to puborectalis. It attaches to the pubic bone anteriorly, and the coccyx and sacrum posteriorly

Question 75

Outline the iliococcygeus muscle

Answer 75

This muscle lies lateral to pubococcygeus. Its name is slightly misleading, as it attaches to the spines of the ischium (not the ilium) and the coccyx.

Question 76

Arterial supply to the pelvis

Answer 76

The arterial supply to the pelvis is via the left and right internal iliac arteries. The internal iliac arteries give rise to several branches in the pelvis that supply the pelvic viscera. Some branches of the internal iliac arteries exit the pelvis to supply the perineum and gluteal region.

Question 77

Key branches of the iliac arteries

Answer 77

• Vesical arteries - supply the bladder in both sexes, and the prostate and seminal vesicles in males.
• Uterine and vaginal arteries in females.
• Middle rectal artery - supplies the rectum.
• Internal pudendal artery - exits the pelvis to supply the perineum.
• Superior and inferior gluteal arteries - exit the pelvis to supply the gluteal region.
• Obturator artery – exits the pelvis to supply the lower limb.

Question 78

Veins of the pelvis

Answer 78

The pelvis contains several venous plexuses which drain the pelvic organs. These plexuses unite and mostly drain into the internal iliac veins.

Question 79

Nerves of the pelvis

Answer 79

The nerves of the pelvis are complex. Structures in the pelvis are supplied by somatic, parasympathetic, and sympathetic nerves. In the pelvis, the sacral spinal nerves come together to form the sacral plexus.

Question 80

Key nerves of the sacral plexus

Answer 80

• Sciatic nerve - formed by the lower lumbar and sacral spinal nerves L4 - S3. It exits the pelvis and supplies the lower limb. We’ll come back to it when we study the lower limb.
• Pudendal nerve – this somatic nerve is derived from spinal nerves S2 - S4. It exits the pelvis and is the major nerve of the perineum.
• Superior and inferior gluteal nerves - these nerves exit the pelvis and innervate the gluteal region.
• Pelvic splanchnic nerves – these nerves carry parasympathetic fibres from the S2 - S4 spinal cord segments to the pelvic viscera.

Question 81

What originates from the lumbar splanchnic nerves?

Answer 81

Sympathetic fibres that innervate the pelvic viscera

Question 82

What is the rectum and how long is it

Answer 82

The rectum is the terminal part of the large intestine. Its name derives from Latin for ‘straight intestine’. The rectum is approximately 12cm long in an adult and its primary purpose is the storage of faeces prior to defecation.

Question 83

What are the notable flexures of the rectum?

Answer 83

This is misleading as the rectum has two notable flexures: the sacral flexure anteriorly and the anorectal flexure posteriorly.

Question 84

Describe the arterial blood supply of the rectum

Answer 84

The rectum is supplied by superior, middle, and inferior rectal arteries. The superior rectal artery is a branch of the inferior mesenteric artery, the middle rectal artery is a branch of the internal iliac artery, and the inferior rectal artery is a branch of the internal pudendal artery (itself a branch of the internal iliac artery).

Question 85

Describe venous drainage from the rectum

Answer 85

Venous blood from the rectum enters the superior, middle, and inferior rectal veins. Branches of these veins anastomose with each other to form a venous plexus around the rectum and anus, making this a site of portosystemic anastomoses. In portal hypertension, these veins may become varicose.

Question 86

Outline the perineum and what are the two triangles

Answer 86

Immediately superficial and inferior to the pelvic floor is the perineum, the superficial region between the pubic symphysis and the coccyx, and between the medial surfaces of the thighs. Viewed from below, the perineum is roughly diamond-shaped and can be split into two triangles by drawing an imaginary line between the ischial tuberosities:
* The urogenital triangle (anteriorly) - this area is complicated and has several layers.
* The anal triangle (posteriorly) - contains the anus and the external anal sphincter.

Question 87

What does the urogenital triangle contain?

Answer 87

The urogenital triangle contains the urethral and vaginal openings, the erectile tissues that unite to form the clitoris or penis, and the muscles overlying them.

Question 88

What are the layers of the urogenital triangle

Answer 88

• Skin
• Peritoneal fascia
• Superficial perineal
• Perineal membrane

Question 89

Outline the skin of the urogenital triangle

Answer 89

The urethra and vagina open out through the skin.

Question 90

Outline the perineal fascia of the urogenital triangle

Answer 90

A continuation of the fascia overlying the abdominal wall muscles.

Question 91

Outline the superficial perineal pouch of the urogenital triangle

Answer 91

A potential space that contains the erectile tissues of the penis or clitoris and three muscles: ischiocavernosus, bulbospongiosus and the superficial transverse perineal muscles.

Question 92

Outline the perineal membrane of the urogenital triangle

Answer 92

• A strong fibrous membrane that provides support for the attachment of ischiocavernosus and bulbospongiosus muscles.
• The urethra and vagina pass through it.

Question 93

Describe the anal canal

Answer 93

The anal triangle contains the anal canal and anus. The anal canal is the most distal part of the gastrointestinal tract and is approximately 4cm long in the adult. It extends from the distal rectum to the anus. The pectinate (dentate) line divides the anal canal into superior and inferior parts.

Question 94

Outline the anal sphincters

Answer 94

Two anal sphincters control defecation. The internal anal sphincter is composed of smooth muscle and is involuntarily controlled, whilst the external anal sphincter is composed of skeletal muscle and is voluntarily controlled.

Question 95

Describe the superior part of the anal canal

Answer 95

The superior part of the anal canal, above the pectinate line, is part of the hindgut and derived from endoderm. Columnar epithelium (i.e. intestinal mucosa) lines the lumen. It is supplied by the inferior mesenteric artery via the superior rectal artery. Venous drainage is via the portal venous system towards the liver. It is encircled by the internal anal sphincter which is innervated by sympathetic fibres (originating from the sympathetic trunk) and parasympathetic fibres (via the pelvic splanchnic nerves).

Question 96

Outline the inferior part of the anal canal

Answer 96

The inferior part of the anal canal, below the pectinate line, is derived from ectoderm. Stratified squamous epithelium lines the lumen. It is supplied by the middle and inferior rectal arteries which originate from the internal iliac arteries. Venous blood enters the systemic venous system and does not pass through the portal system. The inferior anal canal is encircled by the external (voluntary) anal sphincter which is innervated by the pudendal nerve (a somatic nerve).

Question 97

What is the perineal body?

Answer 97

Between the two triangles of the perineum sits the perineal body. This dense mass of fibrous tissue and muscle sits in the centre of the perineum and acts as an attachment for almost all the perineal and pelvic floor muscles, including levator ani, the external anal sphincter, the external urethral sphincter, and muscles associated with the erectile tissues of the perineum.

Question 98

Outline pelvic floor weakness

Answer 98

The pelvic floor muscles support the pelvic organs, but they can be stretched, damaged, or weakened by childbirth, ageing, straining or obesity. Pelvic floor weakness can lead to incontinence of urine or faeces. It can also lead to pelvic organ prolapse where the uterus prolapses into the vagina, or the rectum prolapses out of the anus, because they are no longer supported.

Question 99

What is an episiotomy?

Answer 99

During childbirth, the perineal body may be damaged due to stretching or tearing of perineal tissues. This can lead to incontinence or pelvic floor weakness. During labour, a pre-emptive incision - an episiotomy - can be made just lateral to the perineal body. This avoids injury to the perineal body or an uncontrolled tear through the anal sphincter.

Question 100

Outline haemorroids

Answer 100

The walls of the anal canal are lined with an abundance of veins that form ‘cushions’ which aid faecal continence. These cushions are known as haemorrhoids, or ‘piles’. They can become swollen and inflamed and, depending on whether they become inflamed above or below the pectinate line, they may be painless (above the pectinate line) or painful (below pectinate line). Increased intra-abdominal pressure, for example, in excessive straining, constipation, squatting or pregnancy, increases pressure in the pelvic veins and can lead to haemorrhoids becoming swollen and problematic.

Question 101

What happens when haemorrhoids turn pathological?

Answer 101

If they are pathological, they often bleed when passing stool. If they are painless haemorrhoids, the presence of blood on wiping or blood dripping into the toilet after defecation may be the first sign that they are present.

Question 102

3 components of the barrier of the glomerulus

Answer 102

Podocytes (visceral epithelium)
Glomerular basement membrane
Fenestrated capillary epithelium

Question 103

Key parts of the glomerulus

Answer 103

Hilum of every glomerulus
Juxtaglomerular cells + macula densa

Modified muscular layer of the afferent arteriole
Increased number of smooth muscle cells
Less actin/myosin but many granules (renin)

Low BP → less distended walls → renin release

Question 104

Blood supply of kidneys

Answer 104

Abd aorta -> Renal artery -> Interlobar artery -> Arcuate artery -> Interlobular artery -> Afferent arteriole -> Glomerular capillary -> Efferent arteriole -> Peritubular capillaries -> Vasa recta -> Interlobular veins -> Arcuate veins -> Interlobar veins -> Renal vein -> IVC

Question 105

Up to slide 8

Question 106

Outline the primitive sex cords in females

Answer 106

Primitive sex cords regress
Cortical cords develop
Cortical cords divide into groups of cells that surround germ cells
Germ cell + surrounding cells > primordial follicle

Question 107

Outline the indifferent gonad

Answer 107

Sex determined at fertilization
But the gonad is identical until the 7th week of development
Two pairs of ducts: mesonephric - Wolffian (male) and paramesonephric- Mullerian (female)
Begin to differentiate at week 7

Question 108

Differentiation in male genital development

Answer 108

SRY = development of testes
Anti-mullerian hormone = paramesonephric (Mullerian) ducts regress
Testosterone > male differentiation, stabilization of Wolffian ducts

Question 109

Differentiation of female genital development

Answer 109

Absence of SRY
WNT4 required for ovarian development > but less well understood
Oestrogen > female differentiation, paramesonephric ducts develop

Question 110

Describe the genital ducts (Mullerian and wolffian)

Answer 110

Paramesonephric (Mullerian)
opens into the abdominal cavity at its rostral end
caudal ends meet in the midline
Project into the urogenital sinus

Mesonephric (Wolffian)
open into the urogenital sinus

Question 112

Outline the first stage of development of the mesonephric ducts

Answer 112

Males = ducts develop under influence of testosterone
Form the vas deferens
Distal end opens into urogenital sinus, is absorbed into the bladder wall so ureter and duct enter separately

Question 113

What happens next in the development of the mesonephric ducts

Answer 113

Duct opens into part that will become prostatic urethra – forms the ejaculatory duct.
Prostate develops around the ejaculatory ducts
Seminal vesicle develops from the vas deferens
Sertoli cells produce anti-Mullerian hormone = paramesonephric ducts regress

Question 114

Outline the development of the paramesonephric ducts

Answer 114

Females = ducts develop under influence of oestrogen

Upper parts > uterine tubes
Caudal parts fuse with each other > uterus, cervix, upper vagina (upper 1/3)
Mesonephric ducts regress

Question 115

Outline the development of the vagina

Answer 115

Upper = paramesonephric ducts
Lower = urogenital sinus
Paramesonephric duct meets the urogenital sinus
Growth of the sinovaginal bulbs
Lumen develops

Question 116

When do you get atresia (absence) of the lower vagina?

Answer 116

Results if the sinovaginal bulbs don’t develop

Question 117

What are some uterine anomalies?

Answer 117

Duplication (didelphys)= paramesonephric ducts don’t fuse

Bicornuate = partial fusion of paramesonephric ducts

Unicornuate = one of the paramesonephric ducts doesn’t develop

Septate = uterine septum doesn’t regress

Question 118

Can you differentiate between male and female genitalia in the indifferent stage?

Answer 118

No

Question 119

Key structures of the external genitalia

Answer 119

Genital tubercle
Urethral (genital) folds
Urethral groove
Genital swellings

Question 120

When does differentiation of the external genitalia occur?

Answer 120

Week 5-7??

Question 121

Outline the development of female external genitalia

Answer 121

Influence of oestrogen:
Genital tubercle = clitoris
Urethral folds = labia minora
Urethral groove = vestibule
Genital swellings = labia majora

Question 122

Outline the development of male external genitalia

Answer 122

Influence of Dihydrotestosterone (DHT):

Genital tubercle = elongates > penis
Urethral folds = fuse > penile urethra
Genital swellings = scrotum

Question 123

Anomalies of the male genitalia

Answer 123

Hypospadias
Urethral folds do not fuse properly
Urethral opening(s) on the ventral surface of the penis

Epispadias
Urethra opens on the dorsum of the penis
Rare

Question 124

Ambiguous/atypical genitalia

Answer 124

External genitalia aren’t clearly or typically male or female
Development may be characteristically male or female but with anomalies
E.g. female with large clitoris
male with small penis
Or infant may have features of both sexes

Arise due to conditions called Disorder/ Differences of Sex Development (DSDs)

Question 125

What is the inguinal canal?

Answer 125

The inguinal canal is an oblique passageway through the muscles of the anterior abdominal wall and lies superior to the medial half of the inguinal ligament. It passes through each layer of the abdominal wall as it travels medially and inferiorly. The canal is about 5 cm long in the adult. It extends from the deep inguinal ring laterally (an aperture in the transversalis fascia) to the superficial inguinal ring medially (an aperture in the external oblique aponeurosis).

Question 126

Anterior border of the inguinal canal

Answer 126

● External oblique aponeurosis
● Laterally only: internal oblique aponeurosis

Question 127

Posterior border of the inguinal canal

Answer 127

● Transversalis fascia
● Medially only: medial fibres of the aponeuroses of the internal oblique and transversus abdominis (which are together known as the conjoint tendon).

Question 128

Roof of the inguinal canal

Answer 128

● Transversalis fascia
● Arching fibres of the internal oblique and transversus abdominis

Question 129

Floor of the inguinal canal

Answer 129

● Inguinal ligament (the lower border of the external oblique aponeurosis).

Question 130

Contents of the female inguinal canal

Answer 130

The contents of the inguinal canal are different in males and females. In females it contains three structures:
1. Round ligament of the uterus
2. Ilioinguinal nerve
3. Genital branch of the genitofemoral nerve.

Question 131

What is in the inguinal canal in males?

Answer 131

In males, the contents of the inguinal canal are all contained within the spermatic cord, except for the ilioinguinal nerve, which runs in the canal but lies outside the spermatic cord. The contents of the spermatic cord can be divided in into two nerves, three arteries, three fascial layers and four other structures-
Two nerves, three arteries, three fascial layers and four other structures

Question 132

What are the 2 nerves found in the male inguinal canal?

Answer 132

• Genital branch of the genitofemoral nerve
• Sympathetic nerve fibres

Question 133

What are the 3 arteries of the male inguinal canal?

Answer 133

• Testicular artery
• Cremasteric artery
• Artery to the vas deferens

Question 134

What are the 3 fascial layers of the male inguinal canal?

Answer 134

• External spermatic fascia (derived from the external oblique aponeurosis)
• Cremaster muscle and fascia (derived from the internal oblique muscle)
• Internal spermatic fascia (derived from the transversalis fascia)

Question 135

What are four other structures of the male inguinal canal?

Answer 135

• Pampiniform venous plexus
• Lymphatics
• Vas deferens (plural: vasa deferentia)
• Processus vaginalis (derived from the peritoneum).

Question 136

Outline the testes and scrotum

Answer 136

The testes are located within the scrotum. Scrotal skin is thin, wrinkled and more darkly pigmented than skin elsewhere. Beneath the skin is a thin layer of superficial fascia and a thin, involuntary muscle called the dartos. The superficial fascia extends between the testes to form a septum dividing the scrotum into right and left halves. Each half of the scrotum contains a testis, epididymis and distal part of the spermatic cord.

Question 137

What do testes do

Answer 137

The testes produce sperm and secrete testosterone. They are ovoid structures.

Question 138

Describe the covering of the testes

Answer 138

Covered by the same three layers of spermatic fascia that cover the spermatic cord. The testes are also partially surrounded by a sac derived from the peritoneum called the tunica vaginalis.

Question 139

What is the epidymis?

Answer 139

The epididymis is a coiled tube lying along the posterior border of each testis, which has an expanded head superiorly, a body and a pointed tail lying at the lower pole of the testis. Spermatozoa are formed in the testis and stored in the epididymis. The vas deferens carries sperm from the epididymis and travels with the testicular vessels in the spermatic cord.

Question 140

Outline the testicular arteries

Answer 140

The testicular arteries are direct branches of the abdominal aorta

Question 141

Outline the venous drainage of the testes

Answer 141

Venous blood from the testis and epididymis enters the pampiniform venous plexus. The pampiniform venous plexus forms the testicular vein. The right testicular vein enters the inferior vena cava. The left testicular vein joins the left renal vein.

Question 142

Outline the penis

Answer 142

The penis is composed of three cylinders of erectile tissue: two corpora cavernosa dorsally (along the ‘top’ of the penis) and one corpus spongiosum ventrally (along the ‘bottom’ of the penis).

Question 143

What is Buck’s fascia?

Answer 143

The corpora cavernosa and corpus spongiosum are enclosed within the deep fascia of the penis

Question 144

What is the glans and what is the circular base of it called?

Answer 144

The end of the penis is called the glans and is an expansion of the corpus spongiosum. The circular base of the glans is called the corona

Question 145

Outline the foreskin

Answer 145

The skin of the shaft of the penis extends over the glans and is called the foreskin. The foreskin may be removed for religious, social, or medical reasons in a procedure called circumcision.

Question 146

Outline the corpora cavernosa

Answer 146

The corpora cavernosa are symmetrical and originate along the left and right ischial rami to converge in the midline. Distally, the corpora cavernosa contribute to the body of the penis.

Question 147

What are the crura of the penis?

Answer 147

The parts of the corpora cavernosa that are attached to the ischial rami are known as ‘crura’ (singular: crus), which means ‘legs’, so ‘crura of the penis’ simply refer to the parts of the corpora cavernosa that are attached to the ischial rami.

Question 148

Outline the corpus spongiosum

Answer 148

The corpus spongiosum sits in the midline. In the male, it has an expanded part proximally which rests on the perineal membrane - the ‘bulb’ of the penis (the bulb is just the name of the part of the corpus spongiosum that is attached to the perineal membrane).

Question 149

Outline the penile urethra

Answer 149

The penile urethra (which carries urine and semen) lies within the corpus spongiosum. As the urethra approaches the end of the penis, it opens via the external urethral meatus.

Question 150

Outline the muscle covering of the different parts of the penis

Answer 150

The corpora cavernosa are covered by the ischiocavernosus muscles, and the corpus spongiosum is covered by the bulbospongiosus muscle

Question 151

What do the ischiocavernous muscles do?

Answer 151

Ischiocavernosus forces blood into the body of the penis from the crura.

Question 152

What does the bulbospongius muscle do?

Answer 152

Bulbospongiosus forces blood into the glans penis, assists in maintaining erection by compressing the veins that drain erectile tissues and it contracts to squeeze any remaining urine or semen from the urethra

Question 153

Describe the arterial supply of the penis

Answer 153

The arterial supply to the penis is via the internal pudendal arteries, which themselves branch from the internal iliac arteries. Branches of the internal pudendal include the deep artery of the penis and the artery of the bulb of the penis.

Question 154

Outline nerve supply of the penis

Answer 154

The nerve supply to the penis is from the S2-S4 nerves. Ischiocavernosus and bulbospongiosus are innervated by the pudendal nerve (S2-S4).

Question 155

Where does sensation and sympathetic stimulation of the penis come from?

Answer 155

Both general sensation and sympathetic innervation are carried by the dorsal nerve of the penis, which is a branch of the pudendal nerve.

Question 156

Outline parasympathetic stimulation of the penis

Answer 156

Parasympathetic nerve fibres (responsible for causing erection by dilating the arteries of the corpora) arise from the peri-prostatic nerve plexus.

Question 157

What happens in penile erection?

Answer 157

The corpora cavernosa are primarily responsible for the increase in size and rigidity of the penis during an erection. During sexual arousal, arterial blood flow into the corpora of the penis increases, so the corpora become engorged with blood. Although the corpus spongiosum becomes engorged as well, it does not do so to the same extent as the corpora cavernosa. The main role of the corpus spongiosum during erection is to prevent the urethra from being compressed, which would prevent ejaculation.

Question 158

What are the male pelvic organs?

Answer 158

The male pelvic organs include the intra-abdominal parts of the paired vasa deferentia, the seminal vesicles, ejaculatory ducts, bulbo-urethral glands, prostate gland, bladder and rectum

Question 159

What is the vans deferens?

Answer 159

this tube (also referred to as ‘ductus deferens’) carries sperm from the epididymis up the spermatic cord and through the inguinal canal into the pelvis. From the deep inguinal ring, the vas deferens passes across the side wall of the pelvis, then turns medially onto the back of the bladder. Here it has a dilated portion, the ampulla, which lies medial to the seminal vesicle. The vas deferens terminates by joining the duct of the seminal vesicle to form the ejaculatory duct.

Question 160

What is the seminal vesicle?

Answer 160

Each seminal vesicle is a lobulated sac, about 4cm long, lying lateral to the ampulla of the vas deferens. They secrete a thick alkaline fluid which forms the bulk of seminal fluid (also known as 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 161

Outline the prostate

Answer 161

The prostate gland is a roughly spherical fibromuscular gland about the size of a 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 162

What supplies the vans deferens, seminal vesicle and prostate?

Answer 162

internal iliac artery

Question 163

Outline hydrocoele

Answer 163

This is a painless scrotal swelling caused by accumulation of peritoneal fluid between the layers of the tunica vaginalis around the testis. When a light is shone through a hydrocoele, it can be seen from the other side. This is called ‘transillumination’ and is often used in diagnosis of scrotal swellings.

Question 164

Outline Varicocele

Answer 164

This is an abnormal dilation of the pampiniform venous plexus which causes a scrotal swelling. Varicoceles are often described as feeling like a ‘bag of worms’ on palpation, due to the dilated veins. They are much more common on the left side because the left testicular vein drains into the left renal vein before it drains into the inferior vena cava. Because of this, development of a left-sided varicocele may be caused by obstruction of the left renal vein

Question 165

Outline epididymo-orchitis

Answer 165

This condition is a painful inflammation of the epididymis and testis. Epididymo-orchitis in sexually active patients is very often caused by a sexually transmitted infection such as chlamydia or gonorrhoea. It may also be caused by a urinary tract infection.

Question 166

Outline testicular torsion

Answer 166

This is caused by twisting of the testis on the spermatic cord, which can lead to ischaemia of the testis and represents a surgical emergency. Patient’s often present suddenly with a very painful and tender testis which may be positioned higher or at an unusual angle. If left untreated, it can lead to necrosis and loss of the affected testis

Question 167

Outline cryptorchidism (undescended testis)

Answer 167

During foetal development, the testes form in the abdomen and descend through the inguinal canal to reach the scrotum before birth. If this fails to occur, the infant is born with one or both testes absent from the scrotum, and the affected testis will be stuck somewhere along the path of descent. As spermatogenesis is optimal just below core body temperature, the testes will only function correctly if they are in the scrotum. Additionally, there is an increased risk of testicular cancer if the undescended testis is left inside the abdomen. For these reasons, undescended testes are often brought into the scrotum surgically.

Question 168

Outline testicular cancer

Answer 168

Cancer of the testis is an important diagnosis to consider in any scrotal lump or swelling. The prognosis is excellent if detected and treated early, usually with surgery to remove the testis and part of the spermatic cord (orchidectomy) plus chemotherapy or radiotherapy if required. In the same way that females are advised to examine their breasts for lumps on a regular basis, males should regularly examine their testes for lumps and seek medical advice from their GP if they are concerned about a new lump.

Question 169

Outline the metastisisation of testicular cancer

Answer 169

If a testicular cancer metastasises, it will likely follow the lymphatic drainage which follows the testicular arteries back to lymph nodes around the aorta. For this reason, testicular cancer metastasises first to the para-aortic or retroperitoneal lymph nodes.

Question 170

Outline vasectomy

Answer 170

Vasectomy is a means of male sterilisation (permanent male contraception). It is considered a relatively straightforward surgical procedure where the scrotum is incised and the vasa deferentia are located on each side. They are then ligated, cauterised or clamped to prevent the passage of sperm from the testes.

Question 171

Outline erectile dysfunction

Answer 171

Historically referred to as impotence, erectile dysfunction describes the inability to achieve or maintain an erection during sexual activity. It is common and will affect most males at some point. As achieving and maintaining an erection relies on intact nerve pathways and reflexes, controlled blood flow in and out of the corpora of the penis, and psychological arousal, a problem with any of these may lead to erectile dysfunction. Management includes identifying the cause and treating that or using medications such as sildenafil (Viagra) which increase blood flow into the corpora of the penis.

Question 172

Outline benign prostate hyperplasia

Answer 172

The prostate gland completely encircles the urethra. With progressing age, benign
enlargement of the prostate is common and is called ‘benign prostatic hyperplasia’ (BPH) or ‘benign prostatic enlargement’ (BPE). This may lead to compression of the urethra and the inability to pass any urine - called urinary retention - which requires catheterisation (insertion of a catheter into the bladder) to drain the urine.

Question 173

Outline prostate cancer

Answer 173

Prostate cancer is common. Venous blood from the prostate passes into a plexus of veins which lie anterior to the sacrum and communicate with veins which run up to the azygos vein in the chest. These veins communicate with veins in the vertebral bodies which explains why prostate cancer commonly metastasises to the vertebrae.

Question 174

How can you examine the prostate?

Answer 174

The prostate can be examined during a digital rectal exam (DRE), also known as a ‘per rectum’ exam (PR). This involves pushing a gloved and lubricated finger into the rectum via the anus and flexing it anteriorly to palpate the prostate which sits immediately anterior to the anal canal and rectum. A clinician can feel the size, contour and firmness of the prostate during this examination, and this can help guide diagnosis. A hard, craggy prostate is concerning for malignancy.

Question 175

Outline the vulva

Answer 175

This is the collective term for all parts of the female external genitalia. There are many named parts of the vulva: Mons pubis, labia majora, labia minora, clitoris, vestibule, vaginal opening, hymen, urinary meatus, vestibular glands

Question 176

Outline the mons pubis

Answer 176

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

Question 177

Outline the labia majora

Answer 177

Prominent hair-bearing folds of skin that meet at the mons pubis anteriorly.

Question 178

Outline the labia minora

Answer 178

• Smaller, hairless folds of skin located medial to the labia majora.
• Fuse together anteriorly to form the hood of the clitoris.
• Form the boundaries of the vestibule.

Question 179

Outline the clitoris

Answer 179

• Pea-sized, highly sensitive tissue comprised of the erectile corpora cavernosa and corpus spongiosum.
• Becomes engorged during sexual arousal.

Question 180

Outline the vestibule of the vulva

Answer 180

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

Question 181

Outline the vaginal opening

Answer 181

Entrance to the vagina. Also known as the vaginal introitus.

Question 182

Outline the hymen

Answer 182

• Thin membrane that partially covers the vaginal opening.
• Often ruptures during the first episode of sexual intercourse and historically its presence was taken as proof of virginity. However, it can rupture spontaneously, during exercise, by using tampons or menstrual cups, or it may simply be absent altogether.

Question 183

Outline the urinary meatus

Answer 183

• Opening of the urethra.
• Located posterior to the clitoris, but anterior to the vaginal opening.

Question 184

Outline the vestibular glands

Answer 184

• Greater vestibular glands - also known as Bartholin’s glands - they are located just posterior to the vaginal opening and secrete a lubricant into the vagina during sexual arousal.
• Lesser vestibular glands - also known as Skene’s glands - they lie near the urethral opening. The function of the fluid they secrete is debated but it may lubricate the vaginal opening or urethra, or have an antimicrobial effect.

Question 185

What is the clitoris?

Answer 185

The clitoris is formed of two corpora cavernosa and the glans clitoris. As in males, the corpora cavernosa are symmetrical and run along the left and right ischial rami to converge in the midline. The ‘crura of the clitoris’ refers to the parts of the corpora cavernosa that are attached to the ischial rami. The body of the clitoris is formed by the distal parts of the corpora cavernosa.

Question 186

Where is the corpus spongiosum in females and what are the bulbs of the vestibule?

Answer 186

In females, the corpus spongiosum lies in the midline on the perineal membrane, but it is split into two parts that flank the vaginal opening. These parts of the corpus spongiosum in females are named the bulbs of the vestibule (or the bulb of the clitoris). The anterior parts of the bulbs form the glans clitoris in the midline.

Question 187

Outline the musculature of the female external area

Answer 187

As in males, the corpora cavernosa are covered by the ischiocavernosus muscles, and the corpus spongiosum is covered by the bulbospongiosus muscle.

Question 188

What does the ischiocavernosus muscle do in females?

Answer 188

Ischiocavernosus forces blood from the crura to the body of the clitoris.

Question 189

What does the bulbospongiosus muscle do in females?

Answer 189

Bulbospongiosus forces blood into the glans clitoris. It helps to maintain clitoral erection and constricts around the vaginal orifice which can help expression of fluid from the greater vestibular glands

Question 190

Outline the blood supply of the clitoris

Answer 190

The blood supply to the clitoris is via the internal pudendal arteries (from the internal iliac arteries) – branches include the deep arteries of the clitoris and the arteries of the bulb of the vestibule.

Question 191

Outline the innervation of the clitoris

Answer 191

The erectile tissues of the clitoris are innervated by parasympathetic nerves. Ischiocavernosus and bulbospongiosus are innervated by the pudendal nerve (S2-S4).

Question 192

Outline the innervation of the vulva

Answer 192

The vulva is innervated via four nerves: the ilioinguinal nerve, the genital branch of the genitofemoral nerve, the pudendal nerve and the posterior cutaneous nerve of the thigh.

Question 193

What are the female pelvic organs?

Answer 193

The female pelvis contains the ovaries, uterus, uterine tubes, cervix, part of the vagina, the bladder and rectum.

Question 194

Outline the ovaries

Answer 194

The ovaries are almond-shaped organs about 4cm long and 2cm wide. They are attached to the posterior aspect of the broad ligament by a short mesentery; the mesovarium. The position of the ovary is not fixed, but it frequently lies in the ovarian fossa, formed by the angle between the internal and external iliac arteries. The ureter and the obturator nerve and vessels are close relations of the ovarian fossa.

Question 195

Outline the uterus

Answer 195

The pear-shaped uterus is a hollow muscular organ about 8cm long. It communicates laterally with the uterine tubes and inferiorly with the vagina. The uterus has a fundus (above the uterine tubes), a body and a cervix.

Question 196

Outline the position of the uterus

Answer 196

The body of the uterus is typically angled anteriorly (ante-flexed) and rests on the superior surface of the bladder. The junction between the body and cervix may be tilted anteriorly (anteverted) or posteriorly (retro-verted). The uterus is covered in a fold of peritoneum which adheres to itself at the sides of the uterus to form the broad ligament.

Question 197

Outline the retrouterine pouch

Answer 197

The space behind the uterus but anterior to the rectum is called the rectouterine pouch (pouch of Douglas) and is lined with peritoneum. It is the deepest point in the peritoneal cavity, so it is a common site for the accumulation of intraperitoneal fluid or pus.

Question 198

Outline the uterine (fallopian) tubes

Answer 198

These paired tubes carry ova from the ovary towards the uterine cavity. They are about 10cm long and run in the upper border of the broad ligament. Near the uterus, the tubes have a narrow isthmus. Laterally, the uterine tubes have a dilated ampulla, leading into a funnel-shaped infundibulum. The free edge of the infundibulum is broken up into finger-like projections, the fimbriae, which are draped over the ovary.

Question 199

Outline the cervix

Answer 199

The cervix has a narrow lumen, the cervical canal, which communicates with the uterine cavity via the internal os and with the vagina via the external os. The lower part of the cervix lies inside the vagina creating a recess, the vaginal fornices, around the cervix. 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.

Question 200

Outline the vagina

Answer 200

The vagina is the excretory duct of the uterus. It is approximately 10cm long. It is bordered superiorly by the cervix and terminates below at the introitus by opening into the vestibule (space) between the labia minora. The vagina passes through the pelvic floor; the upper two thirds of the vagina lie in the pelvic cavity and the lower one third in the perineum. The vagina is closely related to the bladder anteriorly and the urethra is often embedded in the anterior wall of the lower third of the vagina.

Question 201

Outline the blood supply of the female pelvic organs

Answer 201

All these structures receive arterial blood via branches of the internal iliac artery, except the ovary which is supplied by the ovarian artery. The ovarian artery is a direct branch of the abdominal aorta and also contributes to the blood supply of the uterine tubes.

Question 202

Outline endometriosis

Answer 202

Endometriosis is a condition in which endometrial tissue, which lines the inside of the uterus, is found outside the uterus. Most commonly these endometrial deposits affect the ovaries, uterine tubes, uterine ligaments and rectouterine pouch. Rarely, endometrial tissue is found outside the pelvis, even in distant sites such as the thorax. The cause is not fully understood but it can lead to painful periods, heavy bleeding during periods, chronic pelvic pain, and pain during intercourse. Endometriosis can make it difficult to conceive. It is formally diagnosed by taking biopsies during surgical exploration of the pelvis (diagnostic laparoscopy).

Question 203

Outline fibroids

Answer 203

These are benign growths of the uterus which may be asymptomatic or cause varied symptoms, including painful and heavy periods. They vary in size and may grow very large. They may grow into the lumen of the uterus and make it difficult to conceive.

Question 204

Outline gynaecological cancers

Answer 204

Cancer can affect the ovaries, uterus, cervix, vagina, and vulva. Symptoms may include pelvic pain, abnormal vaginal discharge, abnormal vaginal bleeding (bleeding between periods, after intercourse or after the menopause), urinary disturbance, abdominal swelling, and more non-specific symptoms of malignancy such as fatigue and weight loss.

Question 205

Outline ovarian cancer

Answer 205

Often diagnosed late as symptoms tend to be non-specific, including abdominal bloating, pelvic pain, loss of appetite and weight loss. Uterine cancer typically presents with abnormal vaginal bleeding, for example, bleeding between periods, heavier periods than usual or bleeding after the menopause.

Question 206

Outline cervical cancer

Answer 206

Also typically presents with abnormal vaginal bleeding, including bleeding between periods, after the menopause or after intercourse. Most cases of cervical cancer are caused by infection with specific types of human papillomavirus (HPV). In the UK, females aged 25-64 are regularly invited for a cervical screening (cervical smear test) as part of the cervical cancer screening programme. This involves taking a sample of cells from the cervix to see if these specific types of human papillomavirus (HPV) are present. Children in the UK are offered the HPV vaccine to prevent against these viruses and the chances of developing cervical cancer

Question 207

Outline ectopic pregnancy

Answer 207

Fertilisation usually occurs in one of the uterine tubes and the zygote is swept down the tube by ciliated cells, towards the body of the uterus where it implants as a blastocyst in the endometrium. An ectopic pregnancy occurs when the blastocyst implants outside the body of the uterus. The uterine tube is the most common place for an ectopic pregnancy to implant. The uterine tube cannot stretch to accommodate a growing embryo and so may rupture as the pregnancy progresses in the weeks after conception. This can cause significant pain and internal bleeding and may be life-threatening. A tubal pregnancy cannot progress, and surgery is often required to remove the pregnancy from the uterine tube.

Question 208

Outline female sterilisation

Answer 208

Female sterilisation involves interrupting the uterine tubes so that the sperm and egg cannot meet. It is usually performed laparoscopically and is achieved either by using devices to clamp the tubes shut or by removing a small segment of tube.

Question 209

Outline female genital mutilation (FGM)

Answer 209

This takes many forms, and may include removal of the clitoris, removal of the labia minora, and/or narrowing the entrance to the vagina. FGM can cause serious problems including chronic pain, infections, painful intercourse, complications in labour, emotional trauma, and mental health problems. In the UK, it is illegal to perform FGM or to take a girl to another country for FGM to be performed.

Question 210

Outline the embryology of the pancreas

Answer 210

• At junction of foregut and midgut 2 pancreatic buds (dorsal and ventral) are generated and eventually fuse to form pancreas
• Exocrine functions begins after birth
• Endocrine (hormone) functions from 10-15 weeks

Question 211

Outline the anatomy of the pancreas

Answer 211

• Retroperitoneal, posterior to greater curvature of stomach
• 12-15cm long, head is near C-portion of duodenum
• Secretions pass into small ducts, then 2 larger ducts

Question 212

What does the metanephric tissue form?

Answer 212

Nephrons

Question 213

Describe the ascent and the role of the foetal kidney

Answer 213

Kidney ascends in utero
During ascent, new vessels are derived from more proximal parts of the aorta and lower vessels regress
Kidney starts to function in week 12 (12/40)
Urine is formed and excreted into the amniotic fluid

Question 214

Outline renal agenesis

Answer 214

• Nephrons and collecting ducts don’t develop
• Can result if signaling between ureteric bud and metanephric tissue fails
• Unilateral or bilateral – bilateral is rare but incompatible with life
• Seen in many genetic conditions

Question 215

Outline horseshoe kidney

Answer 215

1/600
Lower poles of the kidneys fuse
Ascent obstructed by the IMA
Usually asymptomatic and found incidentally

Question 216

Outline a pancake kidney

Answer 216

Fusion of the upper and lower poles of the kidney.

Question 217

Accessory renal vessels

Answer 217

As the kidneys ascend,
lower vessels do not regress

Question 218

Outline the development of the bladder

Answer 218

Cloaca = common cavity for urogenital system and the gut

Urorectal septum divides cloaca:
urogenital sinus
anal canal

Question 219

What are the parts of the urogenital sinus?

Answer 219

Gives rise to 3 parts:

Upper part = bladder
Middle / pelvic part = part of the male urethra
Phallic part = develops differently in males and females

Question 220

Outline exstrophy of the bladder

Answer 220

Rare
Failure of anterior abdominal wall to close
Bladder is exposed

Question 221

Outline the development of the ureter

Answer 221

Develops from the ureteric bud
Ureter directly enters the bladder after the distal part of the mesonephric duct merges into the bladder wall.

Question 222

Outline double ureter

Answer 222

Ureteric bud splits early in development

Question 223

Outline ectopic ureter

Answer 223

• Development of two ureteric buds
• One enters bladder
• Other enters bladder, urethra, vagina or epididymal region

Question 224

Thyroid

Answer 224

Located in neck
Brownish-red
25-30 g
Thin fibrous capsule of connective tissue
Right and left lobes united by a narrow isthmus