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Anatomy Exam 2 > Pelvis lesson 1 > Flashcards

Pelvis lesson 1 Flashcards

1
Q

Describe the Osteology of the Pelvis

A
  • The pelvic girdle is formed by: 2 hip bones, sacrum, and coccyx
  • The Os coxae (a.k.a. hip bones) are each formed by the fusion of 3 bones: ilium, pubis, and ischium
  • The ilium, pubis, and ischium fuse to form the acetabulum (the head of the femur articulates here, forming the hip joint)
  • The obturator foramen is formed by the ischium and the pubis
  • Sacrum (5 fused vertebra)
  • Coccyx (4 fused vertebrae)
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2
Q

Describe illium features

A
  • The iliac crest connects the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS)
  • The concave medial surface is the iliac fossa
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3
Q

Describe pubis features

A
  • 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 (forming the conjoined ischiopubic ramus)
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4
Q

Describe ischium features

A
  • The ischial ramus unites with the inferior pubic ramus (forming the conjoined ischiopubic ramus)
  • The pubic arch is formed by the two ischiopubic rami and the inferior borders of the two ischiopubic rami define the subpubic angle
  • Greater sciatic notch is the large concavity superior to the ischial spine (and formed in part by the ilium)
  • Lesser sciatic notch is the small concavity between the ischial spine and the ischial tuberosity
  • Ischial tuberosity for muscle attachment
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5
Q

Describe sacrum features

A
  • 5 fused vertebrae
  • Base articulates with L5/S1 intervertebral disc and L5 vertebra
  • Apex articulates with coccyx
  • Lateral surfaces articulate with the ilium on each side to form the sacroiliac (SI) joints
  • The anterior edge of the S1 vertebral body projects to form the sacral promontory, an obstetrical landmark
  • 4 pairs of anterior and 4 pairs of posterior sacral foramina (for the transmission of the ventral and dorsal rami of the sacral spinal nerves)
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6
Q

Describe coccyx features

A
  • 4 fused vertebrae

- Articulates with the sacrum at the sacrococcygeal joint

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7
Q

What does the pelvic inlet do?

A

-The pelvic inlet divides the pelvis into the:
-Greater (false) pelvis
• superior to the pelvic inlet
• occupied by abdominal viscera
-Lesser (true) pelvis
• inferior to the pelvic inlet
• occupied by pelvic viscera
-The pelvic inlet is normally tilted about 55 degrees from horizontal plane (ASIS’s and anterior border of the pubic symphysis are in the same coronal plane)

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8
Q

What are the boundaries of the pelvis?

A
  • coccyx and sacrum
  • sacrotuberous ligaments
  • ischial tuberosities
  • ischiopubic rami (pubic arch)
  • pubic symphysis
  • The pelvic outlet is normally tilted about 15 degrees from horizontal plane (ASIS’s and anterior border of the pubic symphysis are in the same coronal plane)
  • The pelvic outlet is closed by the pelvic diaphragm (muscles separating the pelvis above from the perineum below)
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9
Q

Describe Sex Differences in the Pelvis.

A
  • Compared to the male pelvis, the FEMALE pelvis has:
  • Larger, round or oval-shaped pelvic inlet (heart-shaped in male)
  • Ischial tuberosities and ischial spines farther apart
  • Wider subpubic angle, >80˚ (<70˚ in male)
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10
Q

What are the Ligaments, Foramina, and Canals of the Pelvis?

A
  • Anterior, posterior, and interosseous sacroiliac ligaments
  • Sacrotuberous ligaments
  • Sacrospinous ligaments
  • Obturator membrane
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11
Q

Describe the significance of the sacrotuberous and sacrospinouos ligaments.

A
  • Sacrotuberous ligaments: Extend from the sacrum and coccyx to the ischial tuberosity
  • Sacrospinous ligaments: Located anterior to the sacrotuberous ligament. Extend from the sacrum and coccyx to the ischial spine

They both form the:

  • Greater sciatic foramen (superior to the ischial spine): Forms a passageway to/from the gluteal region
  • Lesser sciatic foramen (inferior to the ischial spine): Forms a passageway to/from the perineum

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

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12
Q

Describe the significance of the Obturator membrane

A
  • Closes the obturator foramen except for a small opening, the obturator canal
  • The obturator canal forms a passageway to the medial compartment of the thigh
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13
Q

What are the Muscles of the Lesser Pelvis?

A
  • Piriformis
  • Obturator internus
  • Pelvic diaphragm
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14
Q

What is the purpose of the piriformis?

A
  • Helps form the posterior wall of the lesser pelvis
  • Originates from the anterior surface of the sacrum, courses through the greater sciatic foramen and inserts on the femur (we will discuss its function in the Gluteal lab)
  • Ventral rami of the sacral spinal nerves emerge from the anterior sacral foramina and pass through piriformis to form the sacral plexus on its internal surface

-Innervation: sacral plexus

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15
Q

What is the purpose of the Obturator internus?

A
  • Helps form the lateral walls of the lesser pelvis
  • Originates from the obturator membrane and the margin of the obturator foramen and courses through the lesser sciatic foramen to insert on the femur (we will discuss its function in the gluteal lab)
  • Covered on its medial (internal) surface by thick obturator fascia
  • Obturator fascia thickens centrally as a tendinous arch for attachment of levator ani (muscles of the pelvic diaphragm)

-Innervation: sacral plexus

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16
Q

What is the purpose of the Pelvic diaphragm?

A
  • Shaped like a bowl or funnel
  • Right and left muscles fuse in midline, forming a median raphe
  • Closes the inferior pelvic aperture and forms the pelvic floor
  • Supports the pelvic viscera on its superior surface, the perineum lies inferior to it
  • Pelvic structures pass through it to reach the perineum (urethra, vagina, rectum)
  • Has two muscles: Coccygeus + Levator ani

-Innervation: branches of the sacral and coccygeal plexuses

17
Q

What are the two muscles in the Pelvic diaphragm? Describe them.

A

1) Coccygeus: Extends from the ischial spine to the coccyx and inferior sacrum. Lies on the internal surface of the sacrospinous ligament
2) Levator ani: Extends from the pubis, a thickening in the obturator fascia (the tendinous arch) and the ischial spine to the coccyx and levator ani of the opposite side, along the median raphe
- There are 2 openings: posterior anal aperture and anterior urogenital hiatus (passageway for the urethra, and in females, the vagina)

18
Q

Describe the two portions of the Levator ani

A

1) Iliococcygeus
2) Pubococcygeus –> further subdivided into parts:
- Pubovaginalis (in female)
- Puboprostaticus (in male)
- Puborectalis (fibers surrounding the rectum)
- Puborectalis: forms a sling around the anorectal junction, maintaining the anorectal flexure (preventing defecation). It relaxes during defecation, while the rest of the levator ani contracts (to prevent pelvic viscera from herniating inferiorly during the increase in intra-abdominal pressure).
- Weakness of the pelvic diaphragm (levator ani + coccygeus) can result in urinary stress incontinence, bowel incontinence, and prolapse of pelvic viscera

19
Q

Describe the gonadal arteries.

A
  • The gonadal arteries (ovarian or testicular) are branches of the abdominal aorta
  • Testicular arteries travel within the spermatic cords inferiorly
  • Ovarian arteries travel within the suspensory ligaments of the ovaries and supply the uterine tubes and the uterus

-The abdominal aorta divides into the common iliac arteries at about the level of L4. 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, and will be discussed in future labs.

20
Q

What are the Internal iliac arteries?

A

-Primary blood supply to the pelvis, perineum and gluteal region (paired, left and right):

  • Superior gluteal artery
  • Inferior gluteal artery
  • Internal pudendal artery
  • Umbilical artery
  • Obturator artery
  • Inferior vesical artery (direct branch of internal iliac in male only)
  • Middle rectal artery
  • Uterine artery (in female only)
  • Vaginal artery (in female only)
21
Q

Details of the Superior gluteal artery

A

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

22
Q

Details of the Inferior gluteal artery

A

-Exits greater sciatic foramen inferior to piriformis to supply the gluteal region

23
Q

Details of the Internal pudendal artery

A
  • Exits greater sciatic foramen inferior to the piriformis to enter the gluteal region
  • It then travels to the perineum via the lesser sciatic foramen
  • Eventually gives rise to inferior rectal artery which supplies the anal canal
24
Q

Details of the Umbilical artery

A
  • Gives off the superior vesical artery (or arteries) supplying the superior aspect of the bladder (and ductus deferens in the male)
  • Obliterated portion continues on the internal surface of the anterior abdominal wall as the medial umbilical ligaments
25
Q

Details of the Obturator artery

A
  • 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% it arises from the inferior epigastric artery
  • Courses over the superior pubic ramus to exit via the obturator canal
  • Can be accidentally damaged during inguinal hernia repairs
26
Q

Details of the Inferior vesical artery

A
  • Direct branch of internal iliac in male only

- Supplies inferior bladder, urethra, seminal vesicles, prostate

27
Q

Details of the Middle rectal artery

A

-Anastomoses with the superior and inferior rectal arteries

28
Q

Details of the Uterine artery

A
  • In female only

- Passes superior to the ureter

29
Q

Details of the Vaginal artery

A
  • In female only
  • Supplies vagina, inferior bladder (via inferior vesical branch), and urethra
  • Anastomoses with the uterine arteries, which anastomose with the ovarian arteries
30
Q

Describe the Pelvic Veins.

A
  • Venous pattern is similar to arterial pattern (share same names)
  • In addition, there are numerous venous plexuses around the pelvic organs (e.g., prostatic, uterine, vaginal, rectal, and vesical plexuses)
31
Q

Describe Pelvic Lymphatics

A
  • 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; also called para-aortic nodes) –> chyle cistern –> thoracic duct

-Exceptions:lymph from theovariesandtestesfollows the ovarian and testicular vessels, and drains directly intolumbar lymph nodes –> chyle cistern –> thoracic duct

Anatomy Exam 2 (10 decks)

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