Pelvis I Flashcards by Kaelyn Garner

What forms the pelvic girdle?

Pelvic girdle

2 os coxae (hip bones)
sacrum
coccyx

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Os coxae (hip bones)

Formed by?
What are the two features of the lateral side?

Os coxae (hip bones)

Formed by the fusion of:
- ilium
- pubis
- ischium
Acetabulum
- lateral aspect
- formed by the ilium, pubis, and ishium
- head of femur articulates here, forming the hip joint
Obturator foramen
- formed by the ischium and pubis
- big hole

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Ilium

What does the iliac crest connect?
What is the concave medial surface?

Ilium

The iliac crest connects the anterior superior iliac spine (ASIS) and posterior iliac spine (PSIS)
The concave medial surface is the iliac fossa

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Pubis

What are the features of the pubis?
- Four rami
- Two rami form what
- Arch and angle

Pubis

Pubic tubercles
Pubic bones articulate at the midline to form the pubic symphysis
Superior pubic ramus - unites with the ilium and ischium superiorly
Inferior pubic ramus - unites with the ischial ramus inferiorly, which forms the ischiopubic ramus
Pubic arch - formed by the two ischiopubic rami
Subpubic angle - formed by the inferior borders of the two ischiopubic rami

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Ischium

What joins to form the ischiopubic ramus?
What are the two notches?
What is for muscle attachment?

Ischium

Ischiopubic ramus - formed by the ischial ramus and inferior pubic ramus
Ischial spine - parrot peak projection
Greater sciatic notch - large concavity superior to the ischial spine
Lesser sciatic notch - small concavity inferior to the ischial spine (and superior to ischial tuberosity)
Ischial tuberosity - for muscle attachment

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Sacrum

Base, apex
SI joint
Anterior projection
Foramina

Sacrum

5 fused vertebrae
Base - articulates with L5 / S1 intervertebral disk and L5 vertebrae
Apex - articulates with coccyx
Sacroiliac (SI) joint - formed by the lateral surfaces articulating with the ilium on each side (very stable, this joint holds a lot of weight)
Sacral promontory - anterior projection of S1 vertebrae (obstetrical landmark - limits about of space baby has to come out)
Sacral foramina - 4 pairs of anterior and posterior sacral foramina
- Anterior foramina - ventral rami of sacral spinal nerves
- Posterior foramina - dorsal rami of sacral spinal nerves

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Coccyx

How many vertebrae?
Articulates with sacrum where?

Coccyx

4 fused vertebrae
Articulates with sacrum at the sacrococcygeal joint

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Pelvic inlet

Divides the pelvis into what?
How is it tilted?

Pelvic inlet

The pelvic inlet divides the pelvis into:
- Greater (false) pelvis
  - Superior to pelvic inlet
  - Occupied by abdominal viscera (hence “false”)
- Lesser (true) pelvis
  - Inferior to pelvic inlet
  - Occupied by pelvic viscera
The pelvic inlet is tilted 55 degrees from the horizontal plane
ASIS and anterior border of the pubic symphysis are in the same coronal plane

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Pelvic outlet

Boundaries?
What is in the pelvic outlet?
How does it tilt?

Pelvic outlet

Boundaries:
- Coccyx and sacrum
- Sacrotuberous ligaments
- Ischial tuberosities
- Ischiopubic rami / pubic arch
- Pubic symphysis
The pelvic outlet is closed by the pelvic diaphragm
The pelvic outlet is tilted 15 degrees from the horizontal plane
ASIS and anterior border of the pubic symphysis are in the same coronal plane

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What are the sex differences in the pelvis?

(There are three)

Features different in the female and male pelvis shape (so babies can pass through)

Females have:

Larger, more round / oval shaped pelvic inlet
Ischial tuberosities and ischial spines are farther apart
Subpubic angle is wider

Pelvic inlet

Females: larger, round / oval shaped
Males: heart shaped

Ischial tuberosities and ischial spines

Females: farther apart

Subpubic angle:

Females: wider, greater than 80 degrees
Males: acute, less than 70 degrees

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What are the three sacroiliac ligaments?

Sacroiliac ligaments

Anterior sacroiliac ligaments
Posterior sacroiliac ligaments
Interosseous sacroiliac ligaments (deep)

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Sacrotuberous and sacrospinous ligaments

Location of each?
What do these ligaments do?

Sacrotuberous ligaments

Extend from the sacrum / coccyx to the ischial tuberosity

Sacrospinous ligaments

Extend from the sacrum / coccyx to the ischial spine
Located anterior to the sacrotuberous ligament

Together, these resist the influence of body weight that rotates the sacrum / coccyx posteriorly and superiorly

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Foramen and canals of the pelvis

The sacrotuberous and sacrospinous ligaments form what foramen?
Obturator membrane? Canal? ?
What do all foramen / canal form passageways to

Foramen and canals of the pelvis

The sacrotuberous and sacrospinous ligaments form the:
- Greater sciatic foramen
  - Superior to ischial spine
  - Passageway to the gluteal region
- Lesser sciatic foramen
  - Inferior to ischial spine
  - Passageway to perineum
Obturator membrane
- Fills the obturator foramen, except for a small opening, the obturator canal
- Obturator canal forms passageway to the medial compartment of the thigh

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What are the three major muscles of the lesser pelvis?

What part of pelvis does each form?

Muscles of the lesser pelvis:

Piriformis (forms wall)
Obturator internus (forms wall)
Pelvic diaphragm (forms floor)
- Coccygeus
- Levator ani

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Piriformis

Forms what wall of lesser pelvis?
Originates from? Courses through? Inserts on?
What nerves pass through this muscle?
Innervation?

Piriformis

Helps form the posterior wall of the lesser pelvis
Originates from the anterior surface of the sacrum
Courses through the greater sciatic foramen
Inserts on the femur
Ventral rami of the sacral spinal nerves emerge from the anterior sacral foramina and pass through piriformis, and meet with the lumbosacral trunk to form the sacral plexus on its internal surface
Innervation: sacral plexus

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Obturator internus

Forms what wall of lesser pelvis?
Originates from? Courses through? Inserts on?
What covers the medial (internal) surface? Thickens to form?
Innervation?

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Obturator internus

Helps form the lateral walls of the lesser pelvis
Originates from the obturator membrane and the margin of the obturator foramen
Courses throught the lesser sciatic foramen
Inserts on the femur
Obturator fascia covers medial (internal) surface
- Obturator fascia thickens centrally as a tendinous arch for attachment of levator ani (muscle of pelvic diaphragm)
Innervation: sacral plexus

Pelvic diaphragm

Composed of what two muscles?
Shaped like?
Fuse at center to form?
Fills the? Forms what of the pelvis?
What is superior and inferior?
What structures pass through it?
Weakness of pelvic diaphragm can cause what?
Innervation?

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Pelvic diaphragm

Shaped like a bowl / hammock
Composed of:
- Coccygeus
- Levator ani
Right and left muscles fuse at midline, forming a median raphe
Fills the inferior pelvic aperture and forms the pelvic floor
Supports the pelvic viscera on superior surface (peritoneum is inferior to pelvic diaphragm)
Pelvic structures that pass through to reach perineum:
- Urethra
- Vagina
- Rectum
Weakness of the pelvis diaphragm (coccygeus and levator ani) can result in:
- Urinary stress incontinence
- Bowel incontinence
- Prolapse of pelvic viscera (more common in females due to childbirth)
Innervation: branches of the sacral and coccygeal plexuses

Coccygeus muscle of the pelvic diaphragm

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Coccygeus muscle of the pelvic diaphragm

Extends from the ischial spine to the coccyx and inferior sacrum
Lies on the internal surface of the sacrospinous ligament

Levator ani muscle of the pelvic diaphragm

Extends from what to what?
What are the two openings?
What are the two portions?
Portion subdivided into?
How does the puborectalis work?

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Levator ani muscle of the pelvic diaphragm

Extends from the pubis, the tendinous arch (thickening in the oburator fascia), and the ischial spine TO the coccyx and levator ani of the opposite side, along the median raphe
Two openings:
- Posterior anal aperture
- Anterior urogenital hiatus (passageway for urethra and in females, vagina)
Portions of the levator ani:
- Iliococcygeus
- Pubococcygeus
  - Pubovaginalis (females)
  - Puboprostaticus (males)
  - Puborectalis
Puborectalis
- Fibers surrounding the rectum
- Forms a sling around the anorectal junction, maintaining the anorectal flexure and preventing defecation
- This relaxes during defecation, while the rest of the levator ani contracts to prevent pelvic viscer from herniating inferiorly during the increase in intra abdominal pressure

Pelvic arteries

Gonadal arteries branch off?
Where do the testicular and ovarian arteries travel?
How does the abdominal aorta divde? At what vertebral level?
What does the external iliac artery supply?

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Pelvic arteries

Gonadal (ovarian or testicular) arteries are branches of the abdominal aorta
- Testicular arteries travel within the spermatic cords inferiorly
- Ovarian arteries travel within the suspensory ligaments of the ovaries
- In addition to supplying the gonads, the ovarian arteries also supply the uterine tubes and the uterus
Abdominal aorta divides into the common iliac arteries at the L4 vertebral level
- In the pelvis, the common iliac arteries divide into the external and internal iliac arteries
- The external iliac artery supplies the anterolateral abdominal wall and the lower extremity

Internal iliac artery

What does it supply?
What are the branches?

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Internal iliac artery

Primary blood supply to the pelvis, perineum, and gluteal region
Branching pattern varies greatly!
Major branches (paired)
- Superior gluteal artery
- Inferior gluteal artery
- Internal pudendal artery
- Umbilical artery
- Obturator artery
- Inferior vesicle artery
- Middle rectal artery
- Uterine artery (females)
- Vaginal artery (females)

What is the location of the superior and inferior gluteal arteries of the internal iliac artery?

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Superior gluteal artery

Exits greater sciatic foramen superior to piriformis to supply the gluteal region

Inferior gluteal artery

Exites greater sciatic foramen inferior to piriformis to supply the gluteal region

Internal pudendal artery of the internal iliac artery

Location?
Travels to?
Gives rise to?

Umbilical artery of the internal iliac artery

Gives rise to? Which supplies?
Obliterated portion continues on where as the what?

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Internal pudendal artery

Exits the greater sciatic foramen inferior to the piriformis to enter the gluteal region
Then travels to the perineum via the lesser sciatic foramen
Eventually gives rise to the inferior rectal artery

Umbilical artery

Gives rise to the superior vesical arteries supplying the superior aspect of the bladder (and ductus deferens in males)
Obliterated portion continues on the internal surface of the anterior abdominal wall as the medial umbilical ligaments

Obturator artery of the internal iliac artery

Where does it course?
Where does it exit and go to?

Aberrant obturator artery

Where does it rise from and course over?
Clinical significance?

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Obturator artery

Courses along the lateral wall of the pelvis with the obturator vein and nerve
Exits the pelvis via the obturator canal to enter the medial compartment of the thigh
In 20% of the population, there is an aberrant obturator artery arising from the inferior epigastric artery (instead of the internal iliac artery)
- The aberrant obrturator artery courses over the superior pubic ramus to exit via the obturator canal
- This artery can be accidently damaged during inguinal hernia repairs

Inferior vesical artery of the internal iliac artery * What does it supply? Middle rectal artery of the internal iliac artery * What does it anastomose with?

**Inferior vesicle artery** * Direct branch of the internal iliac artery in males only * Supplies the inferior bladder, urethra, seminal vesicles, and prostate **Middle rectal artery** * Anastomoses with the superior and inferior rectal arteries

Uterine artery of the internal iliac artery * Location? Vaginal artery of the internal iliac artery? * Supplies? * Anastomoses with?

**Uterine artery** * Passes superior to the ureter **Vaginal artery** * Supplies the vagina, inferior bladder (via the inferior vesicle branch), and urethra * Anastomoses with the uterine arteries, which anastomose with the ovarian arteries

Pelvic veins * Pattern * Names * Plexuses

**Pelvic veins** * Venous pattern is similar to the arterial pattern * Share same names as arteries * In addition, there are numerous venous plexuses around the pelvic organs (e.g. prostatic, uterine, vaginal, rectal, and vesical plexuses)

Pelvic lymphatics * Drainage pattern? * Exceptions?

**Pelvic lymphatics** * Most of the lymph from structures within the pelvic cavity drains to internal iliac nodes * Drainage pattern: * Internal iliac nodes * Common iliac nodes * Lumbar nodes (along the aorta) * Chyle cistern * Thoracic duct * Exceptions: Lymph from the ovaries and testes follows the ovarian and testicular vessels, and then drains directly into the lumbar lymph nodes

Pelvis I Flashcards

(28 cards)