Urinary System

Question 1

Quadratus lumborum attachments, actions and innervation

Answer 1

Attachments: Originates from the iliac crest and iliolumbar ligament. The fibres travel superomedially, inserting onto the transverse processes of L1 – L4 and the inferior border of the 12th rib.

Actions: Extension and lateral flexion of the vertebral column. It also fixes the 12th rib during inspiration, so that the contraction of diaphragm is more efficient.

Innervation: Anterior rami of T12 – L4 nerves.

Question 2

Psoas major attachments, actions and innervation

Answer 2

Attachments: Originates from the transverse processes and vertebral bodies of T12 – L5. It then moves inferiorly and laterally, running deep to the inguinal ligament, and attaching to the lesser trochanter of the femur.

Actions: Flexion of the thigh at the hip and lateral flexion of the vertebral column.

Innervation: Anterior rami of L1 – L3 nerves.

Question 3

Psoas minor attachments, actions and innervation

Answer 3

**Attachments: **Originates from the vertebral bodies of T12 and L1 and attaches to a ridge on the superior ramus of the pubic bone, known as the pectineal line.

Actions: Flexion of the vertebral column.

Innervation: Anterior rami of the L1 spinal nerve.

Question 4

Iliacus attachments, actions and innervation

Answer 4

Attachments: Originates from the surface of the iliac fossa and anterior inferior iliac spine. Its fibres combine with the tendon of the psoas major, inserting into the lesser trochanter of the femur.

Actions: Flexion and lateral rotation of the thigh at the hip joint.

Innervation: Femoral nerve (L2 – L4).

Question 5

Fascia of the posterior abdominal wall

Answer 5

A layer of fascia (sheet of connective tissue) lies between the parietal peritoneum and the muscles of the posterior abdominal wall. This fascia is continuous with the transversalis fascia of the anterolateral abdominal wall.

Psoas Fascia- covers the psoas major muscle. It is attached to the lumbar vertebrae medially, continuous with the thoracolumbar fascia laterally and continuous with the iliac fascia inferiorly

Thoracolumbar fascia- The thoracolumbar fascia consists of the three layers; posterior, middle and anterior. Muscles are enclosed between these layers:
- Quadratus lumborum – between the anterior and middle layers.
- Deep back muscles – between the middle and posterior layers.
The posterior layer extends between the 12th rib and the iliac crest posteriorly. Laterally the fascia meets the internal oblique and transversus abdominis muscles, but not the external oblique. As it forms these attachments it covers the latissimus dorsi. The anterior layer attaches to the anterior aspect of the transverse processes of the lumbar vertebrae, the 12th rib and the iliac crest. Laterally the fascia is continuous with the aponeurotic origin of the transversus abdominis muscle. Superiorly the fascia thickens to become the lateral arcuate ligament, which joins the iliolumbar ligaments inferiorly.

Question 6

Abdominal aorta superior to inferior

Answer 6

Canned- celiac trunk
Soup- superior mesenteric
Really- renal
Good- gonadal
In- inferior mesenteric
Cans- common iliac

Question 7

Layers of kidney deep to superficial

Answer 7

• Medulla
• Cortex
• Renal capsule – tough fibrous capsule.
• Perirenal fat – collection of extraperitoneal fat.
• Renal fascia (also known as Gerota’s fascia or perirenal fascia) – encloses the kidneys and the suprarenal glands.
• Pararenal fat – mainly located on the posterolateral aspect of the kidney.

Question 8

Components of Retroperitoneum

Answer 8

Question 9

What is the flow of blood through the kidney?

Answer 9

Abdominal aorta
Renal artery
Segmental artery
Lobar artery
Interlobar artery
Arcuate artery
Interlobular artery
Afferent glomerular arteriole
Efferent glomerular arteriole
Straight arteriole (vasa recta)
Interlobular vein
Arcuate vein
Interlobar vein
Segmental vein
Renal vein
Inferior venal cava

Question 10

Where do kidney stones most commonly occur?

Answer 10

•The renal calyces.
•The renal pelvis.
•The ureteric constrictions. (Junction of renal pelvis and ureter, pelvic inlet and entrance to bladder)

Question 11

What are the urethral sphincters?

Answer 11

• Internal urethral sphincter:
  
  • Male –consists of circular smooth fibres, which are under autonomic control. It is thought to prevent seminal regurgitation during ejaculation.
  • Females – thought to be a functional sphincter (i.e. no sphincteric muscle present). It is formed by the anatomy of the bladder neck and proximal urethra.
• Externalurethralsphincter– has the same structure in both sexes. It is skeletal muscle, and under voluntary control. However, in males the external sphincteric mechanism is more complex, as it correlates with fibres of the rectourethralis muscle and the levator ani muscle.

Question 12

What is the innervation of the bladder?

Answer 12

Nerve supply-

• Sympathetic– hypogastric nerve (T12 – L2). It causes relaxation of the detrusor muscle, promoting urine retention.
• Parasympathetic– pelvic nerve (S2-S4). Increased signals from this nerve causes contraction of the detrusor muscle, stimulating micturition.
• Somatic–pudendal nerve(S2-4). It innervates the external urethral sphincter, providing voluntary control over micturition.

In addition to the efferent nerves supplying the bladder, there aresensory (afferent) nervesthat report to the brain. They are found in the bladder wall and signal the need to urinate when the bladder becomes full.

Question 13

What is the process of micturition?

Answer 13

The Bladder Stretch Reflex-

The bladder stretch reflex is aprimitive spinal reflex, in which micturition is stimulated in response to stretch of the bladder wall. It is analogous to a muscle spinal reflex, such as the patella reflex.

During toilet training in infants, this spinal reflex isoverriddenby the higher centres of the brain, to give voluntary control over micturition.

The reflex arc:

• Bladder fillswith urine, and the bladder wallsstretch. Sensory nerves detect stretch and transmit this information to thespinal cord.
• Interneurons within the spinal cord relay the signal to theparasympathetic efferents(the pelvic nerve).
• The pelvic nerve acts tocontract the detrusor muscle, and stimulate micturition.

Question 14

Female vs male urethra

Answer 14

Female-

• Shorter in length than biological males
• Length of 4cm (predisposal to urinary tract infections)
• Passes through the pelvic floor and the deep perineal pouch to become surrounded by the external urethral sphincter
• Urine is expelled through the external urethral orifice between the right and left labia minora, anterior to the vaginal orifice

Male-

• The pre-prostatic urethra is around 1cm long and extends from the bladder to the prostate.
• The prostatic urethra is between 3 and 4cm long and is surrounded by the prostate.
• The membranous urethra passes through the deep perineal pouch. This is the location of the EUS in both men and women.
• The spongy/penile urethra is surrounded by the corpus spongiosum of the penis.