Unit 8 - 1 Anatomy

Front 1

Back 1

nervous system review

Front 2

innervation to the urinary system

Back 2

Axons of neurons in
the intermediolateral
cell column pass
through the ventral
root through the
ventral ramus into
the mixed spinal nerve.
They then pass through
the white ramus
communicans into
a paravertebral
sympathetic ganglion,
where they do NOT
synapse. They continue
into the abdomino-pelvic splanchnic nerves to synapse in a prevertebral ganglion by means of a N2 (N G) synapse.
Acetylcholine is the neurotransmitter for the first-order (primary) neuron, whereas norepi-
nephrine is the neurotransmitter for the second-order (secondary) neuron. The only exception is
the sympathetic supply to the sweat glands, where acetylcholine is the neurotransmitter for both
neurons.

Front 3

loin and groin pain

Back 3

characteristic of ureitic pain; ureteric stone produces colicky pain

Front 4

Referred renal pain

Back 4

Primarily to the back and flank

Front 5

Back 5

When empty, the urinary bladder Is located in the lesser pelvis,
posterior to the pubic symphysis. It rises higher when full. Its body has an apex, a superior surface, two inferolateral surfaces, and a base. The base is located posteriorly, and contains the trigone.

Front 6

Back 6

PNS -> pelvic plexus (synapse) -> supply destusor and sphincter muscles of bladder

sensory fibers follow this path backwards

Front 7

Back 7

Coronal section through bladder;

Note bladder is infraperitoneal, note ureteric orifices, trigone located in fundus of bladder, note neck of bladder passes through prostate gland

Front 8

Back 8

IML T10 to L2 -> ventral root -> ventral ramus -> white ramus communicans -> paravertebral ganglion (no synapse) -> lesser, least, lumbar splanchnic nerves -> aortic and hypogastric plexuses -> postganglionic fibers pass w vesical arteries to supply the bladder

Front 9

Back 9

The first neuronal cell bodies lie within the sacral parasympathetic nucleus of the spinal cord at S2-S4. Axons pass out the
ventral rami to join the pelvic splanchnic nerves which feed the pelvic plexus. Synapse occurs on second-order neurons via a N2 nicotinic cholinergic receptor. Postganglionic
neurons then send their processes through the plexus to innervate the bladder. Red =
preganglionic sympathetics and somatic motor fibers. Purple = postganglionic sympathetic fibers. Orange = preganglionic parasympathetic fibers. Green = postganglionic sympathetic fibers. Blue = somatic sensory fibers.

Front 10

motor supply to the sphincter urethrae (external)

Back 10

This
sphincter lies within the urogenital diaphragm. It is composed of striated muscle. Its
motor supply arises from the nucleus of Onuf in the sacral spinal cord from S2-S4. The axons of these neurons pass via the ventral roots to the ventral rami to enter the pudendal nerve. They pass with the pudendal nerve to innervate the sphincter urethrae
(external urethral sphincter). Note that this system is under voluntary control, unlike the
sphincter vesicae (internal urethral sphincter).

Front 11

Back 11

At the lower tip of the bladder trigone, the
bladder neck opens into the prostatic
urethra (dark blue arrow). At this point the
smooth muscle fibers are interspersed with
elastic tissue to form the sphincter vesicae*,
also termed the internal urethral sphincter or
Involuntary urethral sphincter (red arrow). The
parasympathetic fibers innervate the smooth
muscle cells via M3 muscarinic cholinergic
Receptors. Thus, drugs that inhibit muscarinic cholinergic receptors (such as tolterodine, trospium, darifenacin, and solifenacin) can be used
to treat urinary incontinence due to bladder hyperactivity.

Front 12

Parasympathetic effects on bladder

Back 12

stimulates detrusor smooth muscle contraction

postganglionic symps also reelase ATP which can stimulate purinergic receptors

Front 13

NO on bladder

Back 13

Relaxes smooth msucle cells in bladder

note that the preganglionic para-
sympathetics in the pelvic splanchnic
nerves cause the detrusor muscle to
contract, and the sphincter vesicae
(dark blue arrow) to relax, promoting
emptying of the bladder in a coordin-
ated manner.

Front 14

Sympatheic stimulus of bladder

Back 14

Increased sphincter vesicae tone (NE) -> alpha 1 adrenergic receptors

NE can also relax detrusor muscle in the wall of bladdder by stimulating B3 adrenergic receptors

Front 15

Back 15

peripheral innervation of the bladder

Front 16

normal micturition reflex involves a supraspinal pathway

Back 16

The reflex is
coordinated by the pontine
micturition center. This region,
activated by input from the
bladder, contains neurons that
stimulate sacral preganglionic
parasympathetic neurons and
inhibit a lateral pontine area
that activates neurons In Onuf’s
nucleus. Thus, activation of the
pontine micturition center leads
to coordinated contraction of
the detrusor muscle of the
bladder and relaxation of the
external urethral sphincter
muscle required for normal
micturition. The excitability of
the pontine micturitioncenter is controlled by inhibitory input from the medial frontal lobe, which is the basis for voluntary control of micturition.

Front 17

COMBINED AFFERENT AND EFFERENT LESIONS

Back 17

Severing both afferent and efferent
nerves initially causes the bladder to become distended and flaccid. In the chronic
state of “decentralized bladder”, many small contractions of the progressively
hypertrophied bladder muscles replace the coordinated events of micturition.
Although small amounts of urine can be expelled, a residual volume of urine remains
In the bladder after urination.

Front 18

afferent lesions

Back 18

When only the sacral dorsal nerve roots containing the sensory
fibers are interrupted, reflex contractions of the bladder, in response to the stimulation
of the stretch receptors are totally abolished. The bladder frequently becomes distended,
the wall thins, and bladder tone decreases. However, some residual contractions remain
because of the intrinsic contractile response of smooth muscle to stretch. As a rule,
residual volume is present after urination. Incontinence is present, and urinary retention
occurs. Perianal sensation, and the anal and bulbocavernous reflexes are abolished. Bladder
volume is increased, but bladder pressure is decreased. The lesion is localized typically in
the conus medullaris or cauda equina.

Front 19

Spinal cord lesions

Back 19

The effects of spinal cord transection (e.g., in paraplegic patients)
include the initial state of spinal shock in which the bladder becomes overfilled and
exhibits sporadic voiding (“overflow incontinence”). With time, the voiding reflex is
re-established, but no voluntary control of urination is possible. Bladder volume is often
reduced and reflex hyperactivity may lead to a state of spastic neurogenic bladder,
in which the bladder fills to a set point, and then spontaneously empties whether it is
convenient for the patient or not. Perianal sensation is preserved, and the anal and bulbo-
cavernous reflexes are normal. Bladder intravesical pressure is increased but bladder volume is decreased.

The bladder cannot empty completely, resulting in the presence of significant amounts
of residual urine. Urinary tract infections (UTIs) are common, because the residual volume of urine in the bladder serves as an incubator for bacteria. In addition, during the
period of overflow incontinence before the voiding reflex is re-established, these patients
must be catheterized frequently, further predisposing them to urinary tract infections.
The level of the lesion is between the lower brainstem or spinal cord above the level of the conus medullaris.

Front 20

Uninhibited neurogenic bladder

Back 20

This condition is produced by a lesion between the medial frontal cortex and the pontine
micturition center. Incontinence occurs, but retention does not. Perianal sensation and
the anal and bulbocavernous reflexes are preserved. Bladder volume and intravesical
pressure are normal. The lesion is typically localized in the medial frontal lobes.
CLINICAL EXAMPLES: HYDROCEPHALUS, MENINGIOMA, OTHER TUMORS OF THE BRAIN.

Front 21

bulbocaavernous reflex

Back 21

tapping the dorsal portion of the penis causes the bulbocavernous portion to contract (measures integrity of S2,3 and 4)

Front 22

Relative height of kidneys

Back 22

Right kidney is lower than the left due to the large right lobe of the liver

Front 23

Kidney location in abdomen

Back 23

Retroperitoneal (posterior to the parietal peritoneum)

Thus they are retro-peritoneal in location, and are associated with the
musculature of the posterior abdominal wall (psoas, quadratus lumborum).

Front 24

Where would a ruptured renal cyst drain to?

Back 24

Due to the fascial capsule of Gerota (fascial sac which contains the kidney and perirenal fat) it would not cross the midline or mix with other contents of retroperitoneal space but pass with the ureter within the fascial capsule into the pelvis

Front 25

blood supply of kidney

Back 25

Front 26

where does the gonal vein enter the IVC?

Back 26

gonadal veins joins the left renal vein

Front 27

Hallmark of renal pain

Back 27

Pain elicited or increased by pressure on the costovertebral angle

Front 28

Urter pain

Back 28

T12 and L1; pain is felt in back, over lateral side of hip (loin) and L1 (groin); ureteric pain is colicky

Front 29

Testicular pain

Back 29

Can be a symptom of ureteric colic;

Paravertebral ganglia 0> least thoracic splanchnic nerve -> white ramus communicans of L1

Front 30

Kidney pain dermatone

Back 30

T8-L1, referred to back; T12 and L1 involve only when proximal ureter is involved (loin and groin)

Front 31

Common sites of stones

Back 31

Front 32

differential for upper lumbar pain

Back 32

erector spinae contraction (herniation)
kidney pain (full blown dermatone)
ureteric pain (more localized)

Front 33

supravenal vein

Back 33

only one; receive blood from adrenal glands; the right goes straigh tinto the IVC while the left drains into the left renal vein

Front 34

nutcracker renal pelvis

Back 34

superior mesenteric artery compresses left renal vein

Front 35

Where do the two ureters enter the bladder?

Back 35

Trigone?

Front 36

detrusor muscle

Back 36

smooth muscle which surrounds the entire bladder

Front 37

Parasympathetic innervation of the bladder

Back 37

Terminate on ganglion cells located in wall of bladder -< short postganglionics innervate detrusor muscle

Also innervated bladder neck (posterior urethra)

Front 38

Sympathetic Innervation of Bladder

Back 38

Sympathetic chain -> hypogastric nerves via L2

Front 39

Voluntary innveration of bladder

Back 39

Pudendal nerve to external bladder sphincter (S2-S3)