Case 14- anatomy Flashcards
Pelvic girdle
The bony pelvis. Made from the Sacrum, Coccyx and left and right pelvic bones
Pelvic bone
Made up of the ileum, ischium and pubis which are separate before puberty but fuse as adults. When they fuse they are connected by cartilage in the area of the Acetabulum.
Function of pelvic girdle
- Weight bearing
- Muscle attachment
- Attachment point for the erectile bodies and external genitalia
- Protect pelvic viscera and inferior abdominal viscera
- Support abdominopelvic viscera and gravid uterus
How is the pelvic girdle divided
Between the abdominal and pelvic cavity.
1) The superior region of pelvis is the false pelvis (greater pelvis) and is part of the abdomen.
2) The true pelvis (lesser pelvis) is related to the inferior parts of the pelvic bones, sacrum, and coccyx, and has an inlet and an outlet.
The pelvic cavity
The pelvic cavity is enclosed by the true pelvis and consists of the pelvis inlet, walls and floor. Continuous with abdominal cavity and contains parts of the urinary, gastrointestinal and reproductive system.
Sacrum
- Fusion of 5 sacral vertebrae
- Articulates with L5 vertebra – via superior articular facet
- Articulates with the Ilium – via articular facet on lateral surface
- The Sacral cornua on the sacrum articulates with the Coccygeal cornua on the Coccyx
Sacral ala
The expanded transverse process
Sacral canal
Continuation of the vertebral canal, nerves pass through it
Sacral promontory
Sticks out from the sacrum and projects anteriorly
Nerves associated with the sacrum
The posterior and anterior rami of spinal nerves S1 to S4 emerge from the sacrum through separate foramina. 4 pairs of nerves on each side
The Ileums articulate line
The Ileum articulates with the Sacrum. The articulate line separates the upper and lower parts of the ileum, it forms part of the pelvic brim. The upper part is the greater/false pelvis, the lower part is the lesser/true pelvis.
Iliac fossa
Where the cecum and appendix are located.
Iliac crest
Superior arch of the pelvis
Landmarks in the Ileum
Anterior to the Iliac crest is the Anterior superior iliac spine (ASIS). Inferior to this is the Anterior inferior iliac spine (AIIS). Posterior to the Iliac crest is the Posterior superior iliac spine. Inferior to this is the Posterior inferior iliac spine. The Iliac tuberosity is a large outgrowth on the posterior region of the pelvis.
The greater sciatic notch
A notch in the Ileum, it is below the posterior inferior iliac spine.
Pectineal line
The pelvic inlet. In the pubis
Ramus of ischium
In the pubis. Continuation of the inferior ramus
Pubis structures
Both pubic bones come to together and articulate at the Pubic symphysis. The joining of the two pubic bones is the pubic arch. There is a bump on the pubic bones called the pubic tubercle. The superior pubic ramus and inferior pubic ramus make up the shape of the pubic bone. Together they form the body of the pubis at the front. The articulate line continues at the Pectineal line on the pubic bone.
Obturator foramen
In the Ischium. Covered by the Obturator membrane, some things do pass through it i.e. the obturator nerve
Structures in the Ischium
The ischial ramus is a continuation of the inferior pubic ramus. Together they are the Ischiopubic ramus. The Obturator foramen is a gap in the pelvic bone. The ischial tuberosity are the bones you sit on. The ischial spine are superior and point out. The lesser sciatic notch is inferior to the greater sciatic notch.
Ligaments in the Sacroiliac joint
Between the sacrum and Ilium. The strongest ligament is the Interosseous ligament, on the posterior aspect of the joint. The posterior Sacroiliac ligament runs over the top of the Interosseous ligament. The anterior Sacroiliac ligament is along the top of the joint.
1) Interosseous
2) Posterior Sacroiliac
3) Anterior Sacroiliac
Ligaments between the pubic symphysis
The anterior and superior pubic ligament
The Sacrotuberous and Sacrospinous ligament
Form part of the pelvic wall. The Sacrospinous and Sacrotuberous ligament splits the greater and lesser sciatic notches into foramen. Foramen are enclosed spaces.
Pelvic inlet
Bordered by the Sacrum posteriorly and the pubic symphysis anteriorly, the pelvic brim is made of the arcuate and pectineal lines. Sacrum promontory is part of it.
Pelvic outlet
Bordered by the coccyx posteriorly, the lateral tuberosities laterally and the pubic arch anteriorly. Pubic symphysis is superior, the sacrotuberous ligament also forms the lateral border
Male adaptions of the pelvis
False pelvis- deep
True pelvis- narrow and deep
Angle of pubic arch- narrow <70
Pelvic outlet- small
Female adaptions of the pelvis
False pelvis- narrow
True pelvis- wide and shallow
Angle of pubic arch- wide >80
Pelvic outlet- relatively large
Function of pelvic wall and muscles
Stops organs from falling out the pelvis. It resists increasing abdominal pressure when defecating and lifting heavy objects, helps maintain urinary/ faecal continence. The shape of the pelvic floor helps guide the fetal skull through birth canal (partition).
Pelvic floor
Inner lining of the pelvic cavity and trunk, separates pelvic cavity above the perineum below. Made of the pelvic floor muscles, known as the pelvic diaphragm. Made of Levator ani and (Ischio)Coccygeus. Paired levator ani and coccygeus muscles. Bowl shaped. Coccygeus – overlie sacrospinous ligaments. Attached to tips of ischial spines and to coccyx/sacrum
Pelvic wall
Made of muscles (Piriformis, Obturator infernus). The obturator internus lies over the internal surface of the obturator foramen. Both muscles insert on the femur soare involved in moving the hip joint.
Levator ani
3 muscles which make up the pelvic floor. The Iliococcygeus, Pubococcygeus and the Puborectalis. The Iliococcygeus is from the Ischial spine and the Ischeum. It is above the Sacrospinous ligament. The Pubococcygeus originates from the pubic bone and connects to the coccyx.
The Obturator infernos and piriformis
Originates in the pelvic cavity, and inserts on the femur outside the pelvic cavity.
1) The Obturator infernus through the LSF (lesser sciatic foramen). It originates on the fascia overlying the foramen and turns 90 degrees.
2) The Piriformis attaches to the femur through the GSF (greater sciatic foramen) and is pear shaped.
Number of muscles in the pelvic wall and floor
They are paired muscles with one on each side
Tendinous arch
A thickened band in the fascia over the obturator internus (tendinous arch)
Anal aperture
A hole in the levator ani which the anal canal passes through
Urogenital hiatus
Where the urethra passes through and where the vagina is
Where do the paired levator ani muscles join
At the midline, the muscles blend together posterior to the urogenital hiatus and around the anal aperture
The iliococcygeus muscle
Arises from the lateral wall of the pelvis and inserts into the midline raphe behind the rectum
Puborectalis
Controls movement of faeces from rectum to anal canal. The puborectalis originates in the pubococcygeus muscle, on each side to form a sling around the anorectal junction. This muscular sling maintains an angle, called the perineal flexure, at the anorectal junction. This angle keeps the end of the gastrointestinal system closed. Originates from the pubis and passes inferiorly, two on each side which meet in the middle. Part of levator ani.
Somatic innervation of the pelvic floor
Controls contraction/relaxation of your pelvic floor muscles. Helps control defecation. Innervated by the pudendal nerve, the anterior rami S4 and a direct branch of the lumbosacral plexus.
Most common cause of damage to the pelvic floor
Childbirth
Peritoneum in the pelvis
1) The peritoneum goes into the pelvis but does not reach the pelvic floor. It is separated from the pelvic floor by the pelvic viscera and reflect onto the pelvic viscera.
2) Pelvic viscera is mostly sub peritoneal- only the superior/superolateral surfaces are covered by peritoneum. The exception is the uterine tubes and ovaries (intraperitoneal).
3) The Peritoneum forms pouches (peritoneal recesses) between adjacent viscera and folds. Peritoneal folds or ligaments form between viscera and the pelvic wall.
Peritoneum on the bladder
In both males and females its subperitoneal with peritoneum only on the superior side
Peritoneum on the rectum
Same in males and females
• Upper 1/3- Peritoneum drapes over the anterior and lateral aspects
• Middle 1/3- Anterior only
• Lower 1/3- not covered by peritoneum
Male peritoneal recesses
The rectovesical pouch is between the bladder and the rectum
Female Peritoneal recesses
- Vesico-uterine pouch= anterior, between bladder and uterus (shallow)
- Recto-uterine pouch (of douglas)= posterior, between uterus and rectum.
Female ligaments
1) Broad ligament
2) Suspensory ligament of the ovary
3) Ligament of the ovary (ovarian ligament)
4) Round ligament
Broad ligament
Large sheet of peritoneum that reflects over the uterus and extends to the lateral pelvic wall. The uterine tube is enclosed in the superior margin and the ovary is attached posteriorly. It’s a double layer of peritoneum that goes from the pelvic wall to the uterus, it’s a type of mesentery. The Broad ligament is subdivided into different types of mesentery.
Suspensory ligament of the ovary, Ovarian ligament and the round ligament
- Suspensory ligament of the ovary- part of broad ligament. Contains ovarian nerves and vessels, supplies the ovary.
- Ligament of ovary (ovarian ligament)- between the ovary and the uterus, joins the uterus at uterotubal junction (where the uterine tube joins the uterus). Suspending the ovary and holding it in place.
- Round ligament- from the utero tubal junction through the inguinal canal to the labia majora.
Types of mesentery in the broad ligament
- Mesovarium- posterior extension of the broad ligament, which attaches to the ovary.
- Mesosalpinx- most superior part of the broad ligament, which suspends the uterine tube in the pelvic cavity.
- Mesometrium- largest part of the broad ligament, between the lateral pelvic walls and the body of the uterus.
- Perimetrium- the Peritoneum overlying the uterus (outermost layer of the uterus)
Connection between round ligament and the ovarian ligament
The round ligament and the ovarian ligament are continuous. Together the ligaments extends from the ovary to the uterine corpus and ends in the labia majora. They are embryological remnants of the Gubernaculum which guides the gonads into the pelvic cavity during development. So, there is connection between the labia majora and the ovaries/uterus.
Course of the round ligament
Leaves the pelvic cavity via the deep inguinal ring, travels through the inguinal canal, leaves through the superficial inguinal ring and inserts on the labia majora. It helps maintain the position of the uterus in pregnancy. Some pregnant women report a pulling sensation on the labia majora.
What makes up the vulva
The vulva is the superficial pouch of the urogenital triangle
• External part of the clitoris (glans)
• Labia majora and minora- the labia majora fuses to form the posterior and anterior commissure. The labia minora converges anteriorly to form the prepuce (hood) and frenulum. The frenulum is a fibrous structure inferior to the Glans clitoris.
• Various skin folds
• Mons pubis- not part of vulva, fleshy mound normally covered by pubic hair
The labia minora fuses posteriorly to form the fourchette
What is contained within the vestibule
- External urethral meatus
- Vaginal orifice
- Openings of the vestibular (Bartholin’s) and paraurethral (Skene’s) glands. Skene’s glands open either side of the external urethral orifice and the greater vestibule gland opens either side of the lateral wall of the vaginal opening. They produce lubricating fluid during sexual arousal.
What does the abdominal aorta split into
The abdominal Aorta splits into the Gonadal arteries, inferior mesenteric arteries and the 2 common iliac arteries. The common iliac arteries split into the External iliac artery and the Internal iliac arteries. The external iliac artery goes to the lower limbs whilst the internal iliac artery helps supply the pelvic viscera.22
Gonadal arteries
Paired structures with one on the left and right. They are direct branches of the abdominal aorta which descend with the ureters retroperitoneally.
Testicular artery
The male gonadal artery, it travels within the spermatic cord and passes through the inguinal canal to enter the scrotum. Supplies the abdominal ureter, testis and epididymis on the corresponding side.
Ovarian artery
Crosses the pelvic brim and descends into the suspensory ligament of the ovary. Supplies the ureter, ovary and the ampullary end of the uterine tube on the corresponding side.
Rectal arteries
1) Superior rectal artery- terminal branch of the inferior mesenteric artery. Supplies the rectum which is within the pelvic cavity.
• Middle rectal artery- branch of the anterior division od the internal iliac artery
• Inferior rectal artery- branch of the internal pudendal artery
Rectal arteries
1) Superior rectal artery- terminal branch of the inferior mesenteric artery. Supplies the rectum which is within the pelvic cavity.
• Middle rectal artery- branch of the anterior division od the internal iliac artery
• Inferior rectal artery- branch of the internal pudendal artery
Internal Iliac arteries
Has a posterior and anterior division. The anterior division of the internal Iliac artery supplies the majority of the pelvic viscera. Typically there are 7 or 8 branches but there is lots of variation.
Branches of the anterior division of the Internal Iliac artery
1) Umbilical artery
2) Obturator artery- in males and females, supplies blood to muscles in the pelvic region. It leaves the pelvis via the obturator foramen
3) Inferior vesical artery (male)- supplies the inferior bladder, prostate, seminal vesicles and the pelvic ureter.
4) Uterine artery (female)- supplies the uterus, ligaments of the uterus, medial part of the uterine tube, ovary and superior vagina
5) Vaginal artery (female)- vagina, vestibular bulb, adjacent rectum and fundus/base of bladder. The vaginal artery can be a branch of the uterine artery, its highly variable.
6) Middle rectal artery- supplies the inferior rectum
7) Internal Pudendal artery
8) Inferior Gluteal artery- Supplies muscles of the pelvic diaphragm, piriformis, and muscles of the hip and lower limb.
Umbilical artery
In males and females, supplies the placenta in fetal development. After birth the distal portion is obliterated and becomes the medial umbilical ligament (no blood passes through). The umbilical artery branches into the superior vesicle branch which supplies the bladder and the Deferential artery supplies the vas deferens.
Internal pudendal artery
Gives off the inferior rectal artery which supplies the rectum. Gives off branches that supply the structures of the Perineum, so the muscles and skin of the anal and urogenital triangle and erectile tissue. Leaves the pelvis via the greater sciatic foramen.
Uterine arteries
- Ascending branch- Uterine body
* Descending branch- Cervix and vagina, can be known as the vaginal branch. Different from vaginal artery
Anastomoses to the blood supply of the pelvic organs
There is an anastomoses between the ascending branch of the uterine artery and ovarian artery. They both contribute to the blood supply of the uterine tube and they anastomose within the broad ligament. The Ovarian vessels travel within the suspensory ligament.
Blood supply to the vulva
- Internal pudendal artery- branch of the anterior division of the internal iliac artery. It supplies the skin, external genitalia and perineal muscles. The branches come of in the pudendal canal. Branches into the Deep artery of the clitoris, the Dorsal artery of the clitoris, the Posterior labial artery (branch of the perineal artery) and the Artery of the bulb of the vestibule
- External pudendal artery (branch of the femoral artery)- supplies the labial skin
Blood supply to the penis
- Internal pudendal artery- supplies the skin, external genitalia and the perineal muscles. Branch of the anterior division of the internal iliac artery. Its branches; Dorsal artery of the penis, Deep artery of the penis, the Bulbourethral artery and the Posterior scrotal artery.
- External pudendal artery (branch of the femoral artery)- branches into the anterior scrotal artery which supplies the scrotal skin.
