Download Anatomy Lecture 7, additional notes. Dr. Faraj Al

Anatomy Lecture 7, additional notes.
Dr. Faraj Al-Bustami
Slide 29:
The internal urethral sphincter is also known as sphincter vesicae and functions to
prevent the reflux of seminal fluid backwards into the urinary bladder during
ejaculation.
The external urethral sphincter must relax at the beginning of micturition along
with the relaxation of the levator ani muscle; this relaxation allows a couple of
droplets of urine to reach the prostatic urethra and thus will initiate the
micturition reflex (detrusor muscle’s relaxation).
Slide 24:
This huge distention of the bladder by which its anterior surface is no longer covered by
peritoneum usually occurs in old neglected men with BPH. These patients are unable to
urinate that’s why we do one of 2 things:
1- Catheterization: we enter Foley’s catheter into the bladder through the
urethra, which works in about 80-90% of people.
2- If catheterization fails then we do an Extra-peritoneal approach; suprapubic
cystostomy in which a thin tube (canula) is placed through the skin (passes
through the anterior abdominal wall) just above the symphysis pubis into the
bladder.
Slide 13:
The sacroiliac joint is a synovial joint while the symphysis pubis is a secondary
cartilaginous joint.
The pelvis is below and behind the abdominal cavity (with an angle between them) they
are NOT continuous together.
Pelvic Brim = Inlet of true Pelvis = the line that joins between:
1- Sacral Promontory: the anterior edge of S1
2- Ala of sacrum: its opposes (‫ )تقابل‬the transverse processes in the other vertebrae
3- Iliopectineal line: which is part: pubic bone and part: arcuate line “medial border
of ilium” and ends at the pubic tubercle. The point where the pubis and ilium
meet is called iliopectineal eminence.
4- Pubic Crest
The false pelvis is part of the abdominal cavity while the true pelvis is what’s important
in pregnancy and delivery.
Pubic Arch is also known as the ischiopubic ramus which is made up of the inferior pubic
ramus and the ischial ramus.
The perineal membrane extends between the two pubic arches and is always
anatomically in a horizontal position.
Slide 14:
If we look at the outlet of the pelvis from below we see that it is made up of 2 pubic
arches, 2 sacrotuberous ligaments (laterally) and the coccyx posteriorly.
Keep in mind that the widest diameter in the inlet is the transverse and in the outlet is
the anterior-posterior diameter (AP diameter). Thus the head of the baby during
delivery enters through transverse, rotates at mid-pelvis and then exits through the AP
diameter.
Slide 15:
The pelvic cavity is wide anteriorly (pubic bone) and narrows posteriorly (sacrum). The
capacity of the pelvis depends on the shape of the sacrum.
In the female: the sacral curvature causes an increase in the AP diameter of the outlet.
Slide 16:
Subpubic Angle
Articular surfaces
Female
Wider and at a right angle
to help in delivery. It’s
equal to the angle between
the thumb and the index.
Smaller (the smaller the
more the possibility of free
movements)
Male
Narrow (60 degrees) and
equals the angle between
the index and the middle
finger.
Larger (limited movements)
The hip bone articulates
Weight
Muscle Attachment
gluteal muscles)
The hip bone articulates with the sacrum through 3
with the sacrum through 2 sacral vertebrae.
and a half sacral vertebra.
less
more
(of Less visible
More prominent
An increase in the greater sciatic notch angle means an increase in the AP diameter.
Size of the acetabulum means its width.
Differentiation between female and male pelvic bones is important in forensic medicine.
Slide 17:
The true pelvis (between the inlet and outlet) in the female must be shorter in length
with a larger outlet for easy delivery.
Male’s true pelvis is more funnel shaped with a smaller outlet and a longer height.
Heart shaped means that the sacrum is more prominent anteriorly.
Slide 18:
Obstetrical Diameter is in reference to the pelvic cavity (‫(تجويف الحوض‬
Per Vaginal Examination: the doctor enters his/her index and middle fingers through
the vagina, below symphysis pubis, so that s/he can measure the diagonal diameter.
When the middle finger touches the sacral promontory it means that this lady has a
contracted pelvis; a very small pelvis that makes it hard to deliver normally.
If we measure the diagonal diameter, can we measure the obstetrical and the true?
Yes, the doctor could mark his/her middle finger, and then subtract 1-1.5 cm
from its measured length OR s/he could mark the index and measure it.
Why 1-1.5 cm??
Because the obstetrical or true diameters are about 1-1.5 cm shorter than the
diagonal diameter. Keep in mind that these are ROUGH measures.
We have multiple types of female pelvises:
1- Android Pelvis: more funnel shaped with a smaller outlet, just like a male
pelvis
2- Platypelloid Pelvis: the transverse diameter is wider in the outlet while
normally in the outlet the AP diameter must be the widest.
During delivery the doctors give these females some time, maybe their pelvises became
typical in shape, but if not then they are directly transferred for Cesarean Section.
During normal delivery the female is given an epidural (extradural) anesthesia, later if
she is going to undergo C-section she is given an intradural anesthesia (to block the
lower part of the body that wasn’t blocked by epidural anesthesia)
Slide 30:
The vas deferens passes above the ureters in relation to the base of the urinary bladder.
Between the prostate and the pelvic diaphragm (levator ani muscle) lie the prostatic
venous plexus which communicates with the vertebral venous plexus (around the
vertebrae) through valveless veins. So if the patients with prostatic enlargement (who
have urinary retention and sometimes constipation) try to evacuate their bladder or
rectum they would need a lot of pressure. This pressure will cause the blood to travel
from the prostatic plexus to the vertebral plexus to cause early bone metastasis in the
vertebral column or may even reach to the brain.
The cancer may also spread in the case of taking a biopsy or performing an operation on
the prostate very fast and carelessly.
The UG diaphragm lies below the anterior fibers of levator ani muscle.
Slide 32:
Seminiferous Tubules are the sperm factory
The explanation of this diagram is written in the histology part of the male reproductive
system but there are 3 very important points to keep in mind:
1- The efferent ductules coil each on itself forming what’s known as the lobules
of the head of epididymis.
2- Then they JOIN to form on duct that constitutes the body and tail of the
epididymis.
Vas deferens exits from the tail and can be felt as a cord-like texture because it has a
wall made up of 3 muscle layers.
Slide 31:
Vas deferens begins from the tail of epididymis and ends as the ejaculatory duct.
The Pampiniform Plexus: ascends upwards through the superficial inguinal ring then the
inguinal canal the exits through the deep inguinal ring. Near the deep ring the join
together to make the testicular vein that drain:
-
Right one drains into inferior vena cava
Left one opens at a right angle with the left renal vein.
In addition to the previous point (Left testicular vein opens at a right angle with the left
renal vein) there are 3 other reasons for the high probability of getting varicose veins in
the left testis:
1- The left renal vein is at very high pressure
2- The left suprarenal vein also opens at the left renal vein; however it is filled with
catecholamines (EP, NE…) thus cause vasoconstriction leading to even more
pressure.
3- The sigmoid colon also is filled with feces and also presses the testicular vein
Slide 34:
When the testis descends from the abdomen to the pelvis it pushes a tube of
peritoneum with it. This tube passes through all the length of the inguinal canal and
spermatic cord. Then later it gets obliterated posteriorly and forms a thread that is
known as remnants of processus vaginalis. If this stays open it could lead to an
INDIRECT hernia.
The posterior surface of the testis is NOT covered with peritoneum because the
epididymis lies on top of it.
The external Oblique muscle forms the external spermatic fascia at the edges or
beginning of the superficial inguinal ring.
Transverse oblique muscle may or may not be investing in the cremasteric muscle and
fascia (which is formed by the internal oblique muscle).
The inner most layer of the abdomen is the parietal peritoneum (which is very sensitive)
and forms the tunica vaginalis with its 2 parts.
The membranous layer of the superficial fascia in the abdomen is called scarpa
The membranous layer of the superficial fascia in the testis is called Colles fascia.
There is NO deep fascia in the abdomen.
Jumana Abbadi 