Renal anatomy 3

Question 1

What are the functions of the bony pelvis?

Answer 1

Supporting the spine, torso and upper body
Locomotion
Housing and protecting the pelvic viscera

Question 2

What are the bones that make up the bony pelvis?

Answer 2

The sacrum and the left and right innominate/hip bones

Question 3

What is the innominate/hip bone made up of?

Answer 3

The ilium, ischium and pubis (more medial- yellow)

Question 4

What are the 5 articulations of the bony pelvis?

Answer 4

Hip joint- between the head of the femur and the acetabulum of the pelvis
Sacroiliac joint- Between the sacrum and ilium of the hip bone. (stable and strong and supported by many ligaments)
Pubic symphysis- between 2 pubic bones (almost no movement permitted)
Lumbosacral joint- Between the 5th lumbar vertebrae and the sacrum
Sacrococcygeal joint- Between the sacrum and coccyx

Question 5

What is the acetabulum?

Answer 5

It is the socket where the head of the femur articulates with the bony pelvis

It is also the point where the ilium, ischium and pubis of the hip bone fuse.

Question 6

What is the surface landmark for the iliac crest? What is its clinical significance?

Answer 6

The intercristal line (highest point of iliac crests) marks the level of L4/L5 disc space – useful for lumbar puncture or epidural injection.

Question 7

What is the surface landmark for the anterior superior iliac spine?

Answer 7

It is the most anterior point of the ilium

Question 8

What is the surface landmark for the iliac tubercles?

Answer 8

The intertubercular line marks the division of the lower third of the abdomen from the middle third, thus delineating the suprapubic region from the umbilical region.

Question 9

What are the surface landmarks for the pubic tubercle and inguinal ligament?

Answer 9

Pubic tubercle- the most medial point of the pubic bone (palpable in most people)
Inguinal ligament- running from the anterior superior iliac spine to the pubic tubercle

Question 10

What are the surface landmarks for the mid-inguinal point and mcburney’s point?

Answer 10

Mid inguinal point- Midpoint of a line drawn from the ASIS to the pubic symphysis. (femoral artery is palpable here)

Mcburney’s point- ⅔ the way on a line drawn from the umbilicus to the ASIS. - approximate location of base of appendix.

Question 11

What are the pelvic organs in both males and females?

Answer 11

Males
Rectum, bladder, prostate and seminal vesicles

Females
Rectum, bladder, uterus, ovaries and vagina

Question 12

What is the arterial supply to the pelvis? What are some of its branches?

Answer 12

Arterial supply is from the left and right internal iliac arteries
Key branches include:
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- supplying the rectum
Internal pudendal artery- exits the pelvis to supply the perineum (protecting the pelvic floor muscle and blood vessels that supply the genitals and urinary tract.
Superior and inferior gluteal arteries- exit pelvis to supply the gluteal region

Take note that the pelvis has several venous plexuses which drain the pelvic organs. They unite and mostly drain into the internal iliac vein.

Question 13

What are the key nerves of the sacral plexus?

Answer 13

Sciatic nerve- L4-S3. It exits the pelvis to supply the lower limb
Pudendal nerve- S2-S4 (somatic nerve- sensory and motor) - Major nerve of the perineum
Superior and inferior gluteal nerves- innervate the gluteal region
Pelvic splanchnic nerve- carrying parasympathetic fibres from S2-S4 to the pelvic viscera

Sympathetic fibres innervating the pelvic viscera arise from the lumbar splanchnic nerves and so are not included.

Question 14

What are the functions of the pelvic floor?

Answer 14

They prevent herniation of the pelvic organs inferiorly (and out of the pelvis)
They control the continence of urine and faeces (continence means you can control when you want to pee basically) by providing a sphincter action on the urethra and rectum respectively.
They increase intraabdominal pressure

Question 15

What is the pelvic floor made up of?

Answer 15

2 muscles: the levator ani and coccygeus.

Question 16

What is the levator ani composed of? (all muscles)

Answer 16

Puborectalis- most anterior muscle of levator ani. U shaped muscle attaching to the pubic bones anteriorly and forms a sling around the rectum. 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 between the rectum and anal canal straightens allowing faeces to pass through). It also contributes to control of micturition.
Pubococcygeus- Lies posterior and lateral to puborectalis. It attaches to the pubic bone (pubis) anteriorly and the coccyx and sacrum posteriorly
Iliococcygeus- Lies lateral to the pubococcygeus. It attaches to the spines of the ischium and coccyx

Question 17

What is the levator ani innervated by?

Answer 17

A branch of the S4 nerve and branches of the pudendal nerve (S2-S4)

Question 18

What is the perineum and where is it located?

Answer 18

The perineum protects the pelvic floor muscles and the blood vessels that supply the genitals and urinary tract.
It is located (in a diamond shape) immediately superficial and inferior to the pelvic floor. Between the pubic symphysis and the coccyx, and in between the medial surfaces of the thighs.

Question 19

What is the perineum split into and where is it split?

Answer 19

The anterior urogenital and posterior anal triangles. A horizontal line is drawn between the ischial tuberosities

Question 20

Where and what is the perineal body?

Where exactly is it situated in both male and female bodies?

Answer 20

It is located in the middle of the two triangles of perineum.
It is a dense mass of fibrous tissue and muscles that sits in the centre of the perineum to act as an attachment for almost all the perineal and pelvic floor muscles (levator ani, external anal sphincter, external urethral sphincter, superficial and deep transverse perineal muscles and bulbospongiosus.

Males- between the bulb of penis and the anus
Females- between vagina and external anal sphincter

Question 21

What do the corpora cavernosa do in the superficial perineal pouch?

Answer 21

The corpora cavernosa are symmetrical and run along the ischial rami to converge in the midline, to form a strong foundation for the clitoris or penis.
The crura of the clitoris/penis refers to the parts of the corpora cavernosa that are attached to the ischial rami.

Question 22

What is the difference between corpus spongiosum in males and females?

Answer 22

In males, the corpus spongiosum sits in the midline, it expands proximally and rests on the perineal membrane. This is the bulb of the penis.
In females, the corpus spongiosum sits in the midline, splits into 2 parts that flank the vaginal opening and rests on the perineal membrane (either side of the vaginal opening). This is the bulb of the vestibule/clitoris

Question 23

What are the corpora cavernosa and corpus spongiosum covered by and what are the functions of that?

Answer 23

Corpora cavernosa is covered by ischiocavernosus muscles and the corpus spongiosum is covered by the bulbospongiosus muscle.
The ischiocavernosus helps to stabilise the erect penis and clitoris
In males, the bulbospongiosus 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
In females, it helps maintain clitorial erection and constricts around the vaginal orifice which can help expression of fluid from the greater vestibular glands.

Question 24

What is the arterial supply and innervation of the perineum?

Answer 24

The internal pudendal artery, a branch of the internal iliac artery.
The main nerve of the perineum is the pudendal nerve (S2-S4) also by autonomic nerves

Question 25

How do the internal pudendal artery and pudendal nerve enter the pelvis?

Answer 25

They travel through the greater and lesser sciatic foramina of the pelvis

Question 26

What are the differences between the male and female pelvis?

Answer 26

Wider, circular pelvic inlet in females (for childbirth) and narrower, heart-shaped pelvic inlet in males
Obtuse angle formed by the inferior pubic rami in females and acute angle in males
Wider and shorter sacrum in females, and narrower and longer

Question 27

What does the pubic bone consist of?

Answer 27

The superior pubic ramus
The pubic tubercle
Body of the pubis
First ⅓ of the inferior pubic ramus

Question 28

What does the ischium consist of?

Answer 28

The bottom ⅔ of the inferior pubic ramus

Question 29

What are the borders of the perineum?

Answer 29

Anterior- Pubic symphysis
Posterior- tip of coccyx
Laterally- Inferior pubic rami, inferior ischial rami, sacrotuberous ligament
Roof- Pelvic floor
Base- skin and fascia

Question 29

What does the anterior urogenital triangle contain?

Answer 29

The urogenital triangle (anteriorly) has 5 layers:
Deep perineal pouch- (space between perineal membrane and pelvic floor muscles) - contains parts of the vagina, urethra and the external urethral sphincter

Perineal membrane- A strong fibrous membrane that provides support for the attachment of ischiocavernosus and bulbospongiosus - it has specific holes in it for the urethra and vagina.

Superficial perineal pouch- Space containing erectile tissues of the penis or clitoris and has 3 muscles: ischiocavernosus, bulbospongiosus and the superficial transverse perineal muscles

Perineal fascia- Continuation of fascia overlying the abdominal wall muscles

Skin- The urethra and vagina open out through the skin.

Question 30

What does the posterior anal triangle contain?

Answer 30

The anal triangle (posteriorly)- contains the opening of the anus (anal aperture) and the external anal sphincter

Question 31

What muscles is the sacral plexus anterior to?

Answer 31

The piriformis muscle