anatomy of urinary incontinence and renal system pain

Question 1

what type of sensory nerve fibres are there?

Answer 1

• visceral afferent nerve fibres which detect sensation from our organs
• somatic sensory nerve fibres which detect sensations from the body wall

Question 2

what are the different motor nerve fibres called?

Answer 2

• ‘somatic motor’ nerve fibres which give responses to our body wall
• ‘parasympathetic’ nerve fibres and ‘sympathetic’ nerve fibres which give motor responses to our organs

Question 3

what type of nerve fibres are responsible for steric peristalsis and bladder contraction?

Answer 3

sympathetic/parasympathetic motor nerve fibres

Question 4

what type of nerve fibres are responsible for urethral sphincter control?

Answer 4

• somatic motor as it is voluntary for the external sphincter and levetar ani (both males and females)
• sympathetic/parasympathetic for the internal sphincter as it is involuntary (only in males)

Question 5

what type of nerve fibres control sensing pain from the kidneys?

Answer 5

visceral afferent

Question 6

what type of nerve fibres control sensing pain from the ureters?

Answer 6

visceral afferent

Question 7

what type of nerve fibres control sensing pain from the bladder?

Answer 7

visceral afferent

Question 8

what type of nerve fibres control sensing pain from the urethra?

Answer 8

• visceral afferent in the pelvis

- somatic sensory in perineum

Question 9

what type of nerve fibres control sensing pain from the testis?

Answer 9

visceral afferent (but it can also have somatic presentation due to close relationship of testis to scrotum)

Question 10

what type of nerve fibres control motor and sensory for urinary continence?

Answer 10

-the voluntary control of the elimination of urine from the bladder is controlled by sympathetic, parasympathetic, somatic motor and visceral afferent nerve fibres

Question 11

what type of nerve fibres control motor and sensory for lumbar and sacral plexus?

Answer 11

this is the perineum and lower limbs

-somatic sensory and somatic motor

Question 12

where do the sympathetic nerve fibres leave the CNS?

Answer 12

only within the spinal nerves between spinal cord levels T1-L2

Question 13

how do sympathetic nerve fibres reach the smooth muscle/glands of the body wall (other than the head)

Answer 13

-as they travel within spinal nerves

Question 14

how do sympathetic fibres reach the smooth muscle/glands of the body (other than the body wall)?

Answer 14

within nerves called splanchnic nerves

there are cardiopulmonary splanchnic nerves and abdominopelvic splanchnic nerves

Question 15

how do sympathetic nerve fibres rach the smooth muscles/glands of the head?

Answer 15

essentially hitch a ride

-follow the arteries which supply the same structures

Question 16

where do sympathetic nerve fibres leave to reach the abdomen?

Answer 16

• leave spinal cord between levels T10 and L2
• enter the sympathetic chain (bilaterally) but do not synapse
• leave the sympathetic chain within abdominopelvic and splanchnic nerves
• synapse at the abdominal sympathetic ganglia which are located around the abdominal aorta
• the fibres are then known as post synaptic sympathetic fibres and pass from the ganglia onto the surface of the arteries which are heading towards the organs they are needing to innervate

Question 17

what is a periarterial plexus?

Answer 17

• a collection of nerve fibres found on the outside of the arteries
• sympathetic, parasympathetic and visceral afferent nerve fibres take part in this

Question 18

where do parasympathetic nerves leave the CNS?

Answer 18

• only within 4 cranial nerves and the sacral spinal nerves (‘craniosacral outflow’)
• CN II, VII, IX and X

Question 19

do parasympathetic fibres innervate the smooth muscle/glands of the body wall?

Answer 19

no

Question 20

how do parasympathetic fibres reach the smooth muscle/glands of the head and body?

Answer 20

via the cranial nerves

Question 21

how do parasympathetic fibres reach the smooth muscle/glands of the hind gut and pelvis organs?

Answer 21

-via splanchnic nerves (pelvic splanchnic nerves which are different than the abdominopelvic splanchnic nerves which the sympathetic nerve fibres use)

Question 22

what are parasympathetic nerve fibres which innervate the kidneys and ureter carried in?

Answer 22

the vagus nerve (CNX)

Question 23

what are parasympathetic nerves which innervate the bladder carried in?

Answer 23

-pelvis splanchnic nerves

Question 24

where do the pelvic spinal nerves leave the spine?

Answer 24

S2, S3, S4

Question 25

where do somatic motor nerve fibres go to?

Answer 25

• only go to body wall
• do not go to visceral structures
• only parts of the renal system they go to are those within the perineum so the distal urethra and its sphincter (external urethral sphincter and levator ani muscle)

Question 26

where is pain from the kidney felt and described?

Answer 26

• posterior aspect of the flank region

- dull, achy, type pain

Question 27

where is pain from a calculus obstructing the ureter felt?

Answer 27

-radiating from loin to groin on the affected side

Question 28

where is pain from the bladder usually felt and described?

Answer 28

• in the suprapubic region

- usually dull, achy pain

Question 29

where is pain from the perineal part of the urethra usually felt and described?

Answer 29

• quite localised in the perineum as it is somatic sensory fibres that are responsible for the sensation of this area
• usually quite a sharp pain

Question 30

how do visceral afferent nerve fibres get from the kidneys to the CNS?

Answer 30

• visceral afferent from the kidneys run alongside sympathetic nerve fibres back to the spinal cord
• they enter the spinal cord between T11 and L1
• the patient feels this pain in these dermatomes posteriorly

Question 31

how do visceral afferent nerve fibres get from the ureters to the CNS?

Answer 31

• visceral afferents from the ureters run alongside the sympathetic fibres back to the spinal cord
• they enter the spinal cord between levels T11 and L2
• pain from these structures tends to be perceived by the patient anywhere along this path

(groin pain)

Question 32

How do visceral afferent nerve fibres get from the bladder to the CNS?

Answer 32

• visceral afferents carrying pain from that part of the bladder which touches the peritoneum (superior part) run alongside sympathetic fibres back to the spinal cord
• they enter the spinal cord between levels T11-L2 and the pain is perceived by the patient as suprapubic pain (midline)

-for the remainder of the bladder (not touching peritoneum): visceral afferent fibres run alongside the parasympathetic nerve fibres back to spinal cord levels S2,S3 and S4

Question 33

how do visceral afferent nerve fibres get from the urethra to the CNS?

Answer 33

-visceral afferents from the proximal urethra (i.e. above the levator ani and in the pelvis) run alongside the parasympathetic nerve fibres back to spinal cords levels S2, S3, S4

Question 34

how do somatic sensory nerve fibres get from the urethra to the CNS?

Answer 34

• somatic sensory nerve fibres (from the distal urethra) are carried within the pudendal nerve also back to spinal cord levels S2,S3 and S4
• pain from this part of the urethra will present as a localised pain within the perineum

Question 35

how do pain fibres get from the testis to the CNS?

Answer 35

• due to its embryological descent, visceral afferents run alongside sympathetic fibres back to the spinal cord levels T10-11
• however, due to its close relationship to scrotal wall (body wall), pain from the testis can also present to the scrotum and/or groin (L1 region)

Question 35

how do pain fibres get from the testis to the CNS?

Answer 35

• due to its embryological descent, visceral afferents run alongside sympathetic fibres back to the spinal cord levels T10-11
• however, due to its close relationship to scrotal wall (body wall), pain from the testis can also present to the scrotum and/or groin (L1 region)

Question 36

what spinal nerves are key in urine flow?

Answer 36

S2-S4

Question 37

what is the role of visceral afferent and where do they enter the spinal cord for control of micturition (urine control)?

Answer 37

• they feel the bladder stretching as it fills

- they enter the spinal cord at levels S2-S4

Question 38

what are the roles of the parasympathetic fibres in micturition (urine flow) and where do they leave the CNS?

Answer 38

• contract the detruser muscle and relaxation of the internal urethral sphnicter
• leave the CNS in pelvis splanchnic nerves at S2, S3 and S4

Question 39

what forms the pudendal nerve and what is its role in micturition (urine flow)?

Answer 39

S2, S3, S4 and carries somatic sensory and somatic motor nerve fibres

-somatic motor nerve fibres are responsible for the voluntary relaxation of the external urethral sphincter

Question 40

explain the science behind needing to pee and going to the toilet when appropriate

Answer 40

• as the bladder fills, this is sensed by stretch receptors at the end of visceral afferent nerve fibres
• this information is relayed to the CNS via S2, S3 and S4
• there is a reflex at this point to empty the bladder by stimulation of the detrusor muscle and inhibition of the internal (only in males) sphincter muscle

-however in those infants who have been potty trained and adults the brain overrides this reflex, action potentials within inhibitory nerve fibres from the cortex pass inferiorly and inhibit this reflex. We can also voluntarily contract the external sphincter and levator ani muscles

Once it is appropriate to micturate:

• the cerebral inhibition of this reflex is lifted and there is co ordinated contraction/ relaxation of various muscles:
• the detruser muscle contracts (parasympathetic innervation)
• the internal urethral sphincter relaxes (parasympathetic control)
• external urethral sphincter and levator ani muscles relax (somatic motor control)
• the anterolateral abdominal wall muscles contract to increase intra abdominal pressure and force urine out of the external urethral orifice (somatic motor nerve fibres)