Lecture 4c (Sexual Function) Flashcards
What causes a male erection?
- vasodilation of the arteries supplying penis and relaxing of smooth muscle of corpus cavernosum and spongiosum
- blood fills vascular space of cavernosum (Top of penis) and spongiosum (Bottom of penis)
- engorgement of cavernosum and spongiosum (Erectile tissue)
The vasodilation of arteries and smooth muscle relaxation is under neural control
What causes female arousal
- vaginal lubrication caused by secretions of greater vestibular glands (Side of opening)
- Vascular engorgement (Erection) of clitoris (Erectile tissue - corpus cavernosum no spongiosum)
Under neural control
What is emission
Pushing something along with wave like pattern (Sperm NOT semen)
Male
- peristaltic contractions in vas deferens transports sperm from testis to vas deferens
- secretions from prostate added to sperm to form semen
- contractions of vas deferens transports semen to posterior of urethra
Female:
- Peristaltic contractions of fallopian tubes
- Further contractions of uterus (Propelling egg from ovaries)
Under control of sympathetic NS
What is ejaculation - NOT orgasm
Male:
- Propulsion of semen from posterior urethra
- Contractions of muscles of pelvic floor
- Closure of bladder neck (to prevent retrograde ejaculation (Going into bladder)
Female:
- Also pelvic floor muscle contraction
Somatic motor neurons
- Lower parasympathetic, not vagus
What are the 2 erection centers and what do they do
Areas in spinal cord that initiate erection and lubrication
- outflow from either one can initiate, but maintenance of erection requires outflow from both
T11-L2 - Thoracolumbar
S2-S4 - Sacral
Reflexogenic vs psychogenic erection/lubrication
Reflexo:
- higher quality
- response to touch
- sensory afferents
- afferent TO sacral erection center
- Efferent FROM parasymp to erection
Psycho:
- Lower quality
- brain thinking/psycho arousal
- message from brain to thoracolumbar center
- para release of NE to initiate
- symp nobody knows, but is necissary
Is erection and lubrication possible after SCI
Not during spinal shock
- could take year to recover
Incomplete injuries is very likely may need assistance like Viagra or lube
Complete above T11
- no psychogenic since no message can travel to erection centers
- Can have reflexogenic since the reflex remains
- maintenance is an issue since needs both centers to do so
-Cannot feel area, so not sexually initiated fully reflexive
Complete between L2-S2
- preservation of reflexo and psycho since two centers can function
- Maintenance is issue since no communication between the two centers since injury is in between them
Complete between T11-L2 or S2-S4 (At the erection centers)
- varying degree of either reflexo or psycho
- maintenance is issue
- total damage to centers or LMN will eliminate that type of erection or lubrication
How is neural control of emission done
thoracolumbar and sacral centers involved, thoraco has more influence
- sensory info from genitals to sacral erection center
- either to brain or straight to thoracolumbar ec
- from brain goes to thoracolumbar ec
- From thoraco goes to vas deferens and seminal vesicles
How is neural control of ejaculation done
- emission occurs
- semen in post urethra - afferents to sacral erection center
- somatic motor reflex to pelvic floor and neck of bladder muscles
- rhythmic patterns form ejaculation
is ejaculation after SCI possible
Rare since
- complete sci above sacral ec has pathway for emission is impaired
- Complete sci at sacral ec has somatic ejaculation reflex impaired
Incomplete injuries may result in preservation of ejaculation since brain has ability to communicate with centers
Is orgasm possible after sci
fairly common since can touch and not feel things
- mainly cerebral event not necissarily due to genital stim
- might be achieved by stim above level of sci
- even in complete some deep sensation percieved in vagina for example
- other ways to make use of erroneous zones above injury like eargasm
- spasticity may occur just before or after orgasm but subsides after
Fertility rates after SCI
Male:
- spontaneous paternity rates 5% or lower
- due to impaired ejaculation
- due to lower quality sperm (low motility and malformation)
Female:
- No permanent threat, menstrual cycle may stop after injury but resumes after 5-12 months
- SCI pregnancies will mostly be delivered vaginally
Other issues from male infertility?
Infection, antibiotic use, elevated scrotal temp due to prolonged sitting stress, non-drainage due to impaired ejac.
- to produce sperm , testicles need to have lower temp, sitting in chairs can make sperm production occur higher up, meaning elevation of scrotal temp (Not good)
So what is possible with sex in sci?
Sex is very possible although males have trouble maintaining erection and females need lube
Fertility no issue for female, males likely have ejaculation issues due to sci and sperm quality
-Both of these male issues can be helped
Orgasm possible for both male and female even after complete but more likely for female and will be different experience than pre sci
Other methods of helping males maintain erection
- pump and tourniquet
- Penile implants hydraulics
- injection of vasodilator medication
- viagra (Could be some issues conflicting with other vasodilating medications for heart issues, cannot take two)
