ANATOOOMMMY Flashcards
What type of joint is the sacroiliac joint?
Synovial plane joint
What type of joint is the pubic symphysis?
Secondary cartilaginous joint
With regards to the female pelvis and normal vaginal delivery: What is the narrowest diameter of the pelvic inlet?
13cm-Pelvic inlet (Anteroposterior)
With regards to the female pelvis and normal vaginal delivery: What is the narrowest diameter of the pelvic outlet?
11cm-Inferior opening
What are the walls of the pelvic cavity?
Anteroinferior wall
2 x lateral walls
Posterior wall
What is the anteroinferior wall formed by?
Bodies & rami of the pubic bones & pubic symphysis
Which muscle is present in the posterior wall of the pelvis?
PIRIFORMIS
What nerve network lies on the piriformis?
SACRAL PLEXUS
What is the perineal body?
Fibromuscular node that is the anchor point for several muscles
What is the anococcygeal body?
Musculotendinous intersection of the 2 halves of the levator ani muscles
What 2 muscles make up the majority of the pelvic floor?
Coccygeus
Levator ani (3 paired separate muscles)
What are 2 functions of the pelvic diaphragm/floor?
1)Support of abdominopelvic viscera (through their tonic contraction)
2)Urinary & faecal continence
What is the innervation of the pelvic diaphragm/ floor?
Sacral plexus-Pudendal nerve (S2-4)
What is a cystocele?
Cystocele =Prolapsed bladder – into vaginal canal
What is a cystocele?
Cystocele =Prolapsed bladder – into vaginal canal
What is a rectocele?
Rectocele =Posterior vaginal prolapse (tissue between rectum & vagina weakens)
Why is an injury to the pelvic floor (common) during childbirth potentially damaging?
Can get stress incontinence & pelvic prolapse
Why may an episiotomy minimise long term damage?
Can prevent severe perineal tearing/injury & speed up a delivery
Why is a mediolateral episiotomy preferable to a midline episiotomy?
Less risk for anal muscle tears (No midline tear)
What structures can be palpated when performing a DRE (part of the clinical examination of the abdomen)?
Male=Prostate & rectum
Female=Cervix, rectum, uterus & ovaries
Branches of the right & left ..?.. distribute blood to most of the pelvic organs, perineum & gluteal region except the ..?.., ..?.. & upper part of the rectum
Internal iliac artery
Testis
Ovaries
Venous drainage of the pelvic structures is complex & involves interplay between what circulations?
Portal & systemic circulation
This has clinical significance especially in some pathologies e.g. liver cirrhosis, pelvic cancers
There are many ..?.. plexuses formed in relation to pelvic organs (for example: rectal, prostatic) – some of these have clinical significance (e.g. ..?.. venous plexus)
- Venous
- Prostatic
What organ systems are included within the pelvis and perineum?
- The Terminal Portion of the GI tract
- The Urinary System
- Male and Female Reproductive Systems
- The Nerve Supply to the Above Organs from the Sacral Plexus
- Elements of the Musculoskeletal System related to the Bony Pelvis, SI Joints, muscles and ligaments
Pelvis as a ‘region’ the internal cavity of this is continuous with what superiorly?
Abdomen- with organ systems passing from one to another in line with normal physiological activity
In obstetric medicine what dimensions of the pelvis determine whether a baby can be safely delivered vaginally?
Differences in the horizontal & vertical dimensions of the pelvis
Which part(s) of the rectum drain(s) into the portal circulation?
Upper 2/3rds via the superior rectal vein
Which part(s) of the rectum drain(s) into the systemic circulation?
Distal portion (lower 1/3)
What is the significance of understanding the venous drainage of the rectum?
Metastases & infection spread routes/ Portal HT
Why might haemorrhoids be associated with cirrhosis of the liver?
Scarring of liver prevents the free passage of blood-pressure on veins increased as needs to find alternative route
What makes the prostate a very vascular organ?
The veins along the sides and base of the prostate join to form the prostatic venous plexus.
With which venous plexus does the prostatic venous plexus communicate with on its posterior side & why is this important (think about how prostate cancer spreads)?
Vertebral venous plexus
Can affect bones & be route of further spread
Describe the course of:
1) Ilioinguinal nerve
2) Genitofemoral nerve?
1) The ilioinguinal nerve originates from L1 and enters the inguinal canal at the superficial inguinal ring to supply skin at the root of the penis in the male and the labia in the female.
2) The genitofemoral nerve originates at L1-2 and enters at the deep inguinal ring.
What structure(s) in the male are supplied by the genital branch of the genitofemoral nerve & what is the clinical significance of this?
Scrotal skin & cremaster muscle
Clinical significance =Cremaster reflex-assess testicular torsion
Where does the pudendal nerve arise from?
The sacral plexus
From which segmental level(s) does the pudendal nerve arise?
S2-4
What is the course of the pudendal nerve?
Follows the course of the pudendal artery to innervate the skin and the muscles of the perineum.
The pudendal nerve travels from pelvis to perineum, via the gluteal region.
This arrangement is essential to understand in bilateral pudendal nerve block for pain relief during childbirth, particularly for an instrumental (e.g. forceps) assisted vaginal birth.
What bony landmarks are used when performing a pudendal nerve block during labour?
Ischial spines
Where does the autonomic nerve supply to the pelvis originate from?
The pelvic plexus (or inferior hypogastric)
Where do the sympathetic fibres originate from?
The sympathetic fibres originate from L1 and L2 via the hypogastric nerve and terminal aspect of the sympathetic trunk. These fibres hitchhike on the arterial supply to reach their target organs.
Sympathetic fibres (from L1-2) provide what & what do they supply in male compared to female?
They provide sympathetic supply to all internal pelvic organs.
In a male they supply the vas deferens, seminal vesicles, prostate and epididymis.
In a female they supply the ovaries, uterus, fallopian tubes and vagina.
Where do Parasympathetic fibres in the pelvis originate from & what do they supply and innervate?
The pelvic splanchnic nerves (S2 to S4). In addition to providing parasympathetic supply to all the internal pelvic organs, they innervate erectile tissues in both male and female.
What fibres innervate erectile tissues in both male & female?
Parasympathetic fibres from pelvic splanchnic nerves (S2-4)
What is the difference between splanchnic nerves in the thorax & pelvis?
In the thorax the greater, lesser and least splanchnic nerves are sympathetic
In the pelvis the pelvic splanchnic nerves are parasympathetic
After rectal surgery, why are some men unable to ejaculate?
Autonomic nerve damage- Pelvic splanchnic nerves (part of ANS)
Lymphatic drainage of the pelvis tends to follow what?
The arterial supply
There are four primary nodes present in the pelvis receiving the lymphatic drainage of the pelvic organs. (They are variable in number, size and location) What are they?
- External iliac
- Internal iliac
- Sacral
- Common iliac
What 4 categories can the male reproductive organs be grouped into?
1)The External Genitalia
2)The Gonads – Where gametes or sex cells are produced and also the site for the production of male sex hormones
3)The Tube System – For transporting the sperm from the gonads
4)The Accessory Glands – These support the sperm and lubricate the copulatory organs.
What is the role of the accessory glands?
They support the sperm & lubricate the copulatory organs
The gonads (testis) are located where?
Outside the abdomino-pelvic cavity but remain intimately connected to the structures located there.
Where are gametes or sex cells produced in males (also site for the production of male sex hormones)?
The gonads
What are the male reproductive organs?
- Testis
- Vas Deferens or Ductus Deferens
- Seminal glands
- Prostate
- Epididymis
- Bulbourethral glands
During embryological development the testis move from where to where?
The internal abdominal cavity, through the anterior abdominal wall, and lie as part of the external genitalia in the scrotum.
What is the name of the canal that the testis passes through during development?
Inguinal canal
What are the deep and superficial openings of the inguinal canal called?
Inguinal Rings
The inguinal canal carries a group of structures known as what in the male?
Spermatic cord.
What are the main contents of the spermatic cord?
- Ductus deferens
- Testicular artery
- Testicular lymph vessel
- Testicular veins (pampiniform plexus)
- Genital branch of the genitofemoral nerve
- Cremasteric artery
The ovoid testes are suspended in the scrotum by what?
The spermatic cords
What is the tough outer fibrous layer of the testis called?
Tunica Albuginea
What are the two layers of tunica vaginalis?
Visceral tunic (tunica vaginalis propria) and a parietal tunic (tunica vaginalis communis)
What material is present between the two layers of tunica vaginalis?
Serous fluid
What are 2 pathologies associated with the tunica vaginalis & what causes each of these?
Hydroceles
-Type of scrotal swelling that occurs when fluid collects in the thin sheath that surrounds the testical
-Caused by serous fluid collection around testical-injury or inflam
Haematoceles
-Collection of blood in layers
-Caused usually by injury to the testes – rupture or torsion
How is the testis supplied with blood?
Testis is supplied by a branch of the abdominal aorta called the testicular artery.
At what vertebral level do the testicular arteries arise from the abdominal aorta?
L2-3
What route do the testicular arteries take?
These arteries travel retroperitoneally and cross two important structures(Ureter & Genitofemoral nerve) near the pelvic brim before they travel through the inguinal canal.
What structures do the testicular arteries cross?
- Ureter
- Genitofemoral nerve
What is the term used for the 8-12 anastomosing veins associated with the testis & what is the function of these veins?
Pampiniform venous plexus
- They drain testes/epididymis
Into which vein does the right testicular vein drain into?
The right testicular vein drains into IVC
Into which vein does the left testicular vein drain into?
The left testicular vein drains into L Renal vein
What is a varicocele & what causes it?
Enlargement of veins caused by defective valves
Is a pathology specific to the venous drainage of the testis
Is testicular torsion an emergency presentation? If so why?
YES, requires urgent resolution through an operation and internal fixation (orchidopexy) of the testis to the scrotum to prevent this happening in the future
What is happening to cause testicular torsion and what is the risk of this?
Blood supply has been completely cut off from one of the testis, therefore it is at risk of necrosis within a few hours