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Anatomy IV > Bony Pelvis and Pelvic Diaphragm > Flashcards

Bony Pelvis and Pelvic Diaphragm Flashcards

1
Q

What is the bony pelvis defined by? (4 bones)

A

The pelvic bones (2), sacrum, and coccyx

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2
Q

The pelvic bone (innominate bone) is comprised of what 3 fused bones?

A

Ilium, ischium, and pubis

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3
Q

Where does the fusion of the 3 pelvic bones occur?

A

In the region of the acetabulum (socket for the head of the femur)

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4
Q

Name the 9 features of the ilium:

A
  1. Body
  2. Crest
  3. Anterior superior and anterior inferior iliac spines
  4. Posterior superior and posterior inferior iliac spines
  5. Arcuate line (part of Linea terminalis)
  6. Articular surface
  7. Iliac fossa
  8. Acetabulum
  9. Greater sciatic notch
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5
Q

Name the 6 features of the ischium:

A
  1. Body
  2. Ischial tuberosity
  3. Ischial spine - Greater sciatic notch (superior to the spine, ilium) and Lesser sciatic notch (inferior to the spine, ischium)
  4. Ramus of ischium (makes up half of the ischiopubic rami)
  5. Acetabulum
  6. Obturator foramen (forms half)
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6
Q

Name the 9 features of the pubis:

A
  1. Body
  2. Pubic symphysis
  3. Pubic crest (part of Linea terminalis)
  4. Pectineal line (part of Linea terminalis)
  5. Pubic tubercle
  6. Inferior pubic ramus (makes up half of the ischiopubic rami)
  7. Superior pubic ramus
  8. Acetabulum
  9. Obturator foramen (forms half)
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7
Q

5 features of the sacrum/coccyx:

A
  1. Articular surface
  2. Ala
  3. Promontory (part of Linea terminalis)
  4. Margin of ala (part of LT)
  5. Anterior and posterior sacral foramen
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8
Q

What is the linea terminalis?

A

Terminal line - is a sharp marginal line that defines the boundary of the true pelvis from the false pelvis. It also defines the pelvic inlet

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9
Q

Linea terminalis also forms the pelvic inlet. Formed by what boundaries? (Anterior to posterior)

A

Pubic crest (pubis), pectineal line (pubis), arcuate line (ilium), margin of ala (sacrum) and the promontory (sacrum)

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10
Q

What is the false pelvis?

A

Part of the abdominal cavity and defined as the region contained by the pelvic bones that lies superior to the linea terminalis

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11
Q

What is the true pelvis?

A

The region contained by the pelvic bones that lies inferior to the linea terminalis

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12
Q

The pelvic inlet is defined by:

A

The linea terminalis and is the transition from the abdominalcavity (false pelvis) into the pelvis (true pelvis)

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13
Q

The pelvic outlet is defined by:

A

The circular dimension measured from the inferior aspect of the pubic symphysis and the tip of the coccyx.

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14
Q

What are the borders of the pelvic outlet?

A

Bordered by the coccyx, medial boundary of the sacrotuberous ligament, ischial tuberosity, ischiopubic rami and pubic symphysis

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15
Q

What are gynecological conjugates?

A

Use to determine dimensions of the birth canal prior to delivery. There are several methods to determine this but all measure the ant/post dimensions for the pelvic inlet and outlet.

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16
Q

How is the pelvic inlet measured?

A

From the superior surface of the pubic symphysis to the promontory of the sacrum

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17
Q

How is the pelvic outlet measured?

A

Determined by measuring from the inferior aspect of the pubic symphysis to the tip of the cocyx

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18
Q

Describe the orientation of the pelvis:

A

The pelvis is orientated so the anterior-superior iliac spines lie in the same vertical plane as the pubic tubercles

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19
Q

Gender differences: describe the female pelvis:

A
  • The pelvic inlet and outlet are wider in the female and usually circular/oval (gynocoid)
  • Sacral ala is wider
  • Promontory is not as pronounced
  • Pubic angle is 80-85 degrees
  • Acetabulum is displaced laterally, which positions the alignment of the neck of the femur to be almost parallel with the frontal plane (horizontal plane) of the body (move the lower limbs away from the birth canal)
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20
Q

Gender differences: describe the male pelvis:

A
  • Pelvic outlet is heart-shaped (android)
  • More pronounced promontory
  • Pubic angle is less in males 50-60 degrees
  • Orientation of the neck of the femur is 15-20 degrees anterior to the female
  • Pelvic bone is much denser and taller than female
  • More pronouned sacral promontory and ischial spine
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21
Q

Ligaments of the bony pelvis:

A
  1. Iliolumbar
  2. Anterior and posterior sacroiliac ligaments
  3. Superior and inferior pubic ligaments (maintain integrity of the R and L pelvic bones)
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22
Q

What is occupying the majority of the obturator foramen?

A

Obturator membrane

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23
Q

What is the space that is left open in the obturator foramen for?

A

does not fully enclose the foramen and has a small opening at its superior margin - accommodates the passage of the obturator nerve, a, and v from the pelvis into the adductor compartment)

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24
Q

What does the sacrotuberous ligament attach to?

A

The posterior aspect of the sacrum and inserts onto the ischial tuberosity

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25
Q

Where does the sacrospinous ligament attach?

A

It is positioned anterior to the sacrotuberous ligament and attaches from the ischial spine to the lower lateral margin of the sacrum.

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26
Q

The sacrospinous ligament divides into?

A

The greater sciatic foramen (superior to sacrospinous ligament) and the lesser sciatic foramen (inferior to sacrospinous ligament)

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27
Q

Greater sciatic foramen allows for communication between:

A

The pelvis and gluteal region, foramen allows for the outflow of blood vessels, nerves, and a muscle

28
Q

What blood vessels flow through the greater sciatic foramen?

A
  • Superior and inferior gluteal

- Internal pudendal artery and v

29
Q

What nerves pass through the greater sciatic foramen?

A
  • Sciatic
  • Pudendal
  • Superior and inferior gluteal nn
  • N to obturator internus
  • Quadratus femoris
  • Posterior cutaneous
  • Perforating cutaneous n
30
Q

What muscle passes thru the greater sciatic foramen from the pelvis into the gluteal region?

A

Piriformis m.

31
Q

The Lesser sciatic foramen communicates between?

A

The gluteal region and the perineum and allows for passage of n, a, & v.

32
Q

What nerve passes through lesser?

A

Pudendal n. Also the nerve to the obturator internus from the gluteal region enter the perineum thru the pudendal canal

33
Q

What vessels pass through lesser?

A

Internal pudendal vessels

34
Q

The only structure from the pelvis that exits out thru the lesser sciatic foramen is the:

A

Tendon of the obturator internus m. The obturator internus m occupies the wall of both the pelvis and perineum and it is in the perineum, where its tendon exits thru this foramen

35
Q

What are the 2 paired muscles of the pelvic wall?

A

Obturator internus and piriformis

36
Q

Where does the obturator internus attach?

A

Broad muscle that firmly attaches to the internal suraface of the obturator membrane an to the superior pubic and inferior ischiopubic rami. Its tendon exits the perineum by making a 90 degree bend, around the lesser sciatic notch, and then passing out thru the lesser sciatic foramen into the gluteal region

37
Q

Where does the obturator internus insert?

A

Greater trochanter of the femur

38
Q

What does the obturator internus gives rise to?

A

2 specialized fascial thickenings - one in the pelvis (tendinous arch) and one in the perineum that makes up the pudendal canal

39
Q

What innervates the obturator internus?

A

Nerve to the obturator internus (L5, S1)

40
Q

Where does the piriformis m originate?

A

Pelvic (anterior) surface of the sacrum

41
Q

Where does the piriformis insert?

A

Exits out the greater sciatic foramen and attaches to the greater trochanter of the femur

42
Q

What is the action of the piriformis?

A

Both piriformis and obturator internus muscles laterally rotate the femur

43
Q

What is piriformis innervated by?

A

Ventral rami (L5, S1, S2)

44
Q

What is the tendinous arch?

A

Thickened caliginous structure that is derived from the obturator internus fascia and its purpose is the suspend part of the levator ani muscles off the pelvic wall to form the pelvic diaphragm

45
Q

Where does the tendinous arch attach?

A

From the superior pubic rami (just lateral to the pubic tubercle) and extends, in an arc on the surface of the obturator internus m, to the ischial spine. The arch bisects the obturator internus m and with its attachment to the pelvic diaphragm forms the division between the true pelvis above and the perineum below. So the obturator internus m can be seen in both the true pelvis (sup to tendinous arch) and in the perineum (inf to tendinous arch)

46
Q

What is the pelvic diaphragm comprised of?

A

Two paired muscle groups, the levator ani (made up of 3 distinct muscles) and the coccygeus m.

47
Q

The R and L halves of the pelvic diaphragm are fused at midline posterior to the anal canal, with each half attaching to:

A

Anococcygeal ligament, a central ligament that suspends the anal canal to the tip of the coccyx

48
Q

The fusion of the two halves of the pelvic diaphragm forms the:

A

Median raphe

49
Q

What is the urogenital hiatus?

A

Anterior to the anal canal, the pelvic diaphragm splits with each side sweeping laterally to allow midline passage of the urethra in the male and the urethra and vagina in the female

50
Q

The pelvic diaphragm defines the boundary between:

A

The region of the true pelvis (superior to diaphragm) and the perineum (inferior to diaphragm)

51
Q

With the aid of the __________, these 2 diaphragms form the inferior physical boundary of the peritoneal cavity which prevents:

A

Urogenital diaphragm; abdominal and pelvic viscera from escaping the pelvis into the perineum

52
Q

What are the pelvic diaphragm muscles?

A
  • Levator ani muscles - puborectalis, pubococcygeus, and iliococcygeus
  • Coccygeus m
53
Q

Describe the levator ani:

A

Comprised of 3 separate muscles (per side) that have their origin from the body and superior rami of the pubis and along the tendinous arch. They are: puborectalis, pubococcygeus, and iliococcygeus

54
Q

Describe the puborectalis:

A
  • It is paired, can be seen best from the perineum
  • Consists of a thin strap m, located inferior to the pubcoccygeus m.
  • Attaches to the pubis (just lateral to the pubic symphysis) and wraps around the rectum posteriorly, where it fuses with its partner to form a sling
55
Q

The sling of the puborectalis m. is important in maintaining the:

A

Anorectal flexure at the anorectal junction. The puborectalis m. is normally in a contracted state, which places an 80 degree bend in the alignment of the rectum with the anal canal. This flexure maintains fecal continence

56
Q

Describe the pubococcygeus m:

A

It is paired, Suspended off of the anterior half of the tendinous arch and forms the lateral margins of the urogenital hiatus. Posterior to the anal canal, the R and L muscles fuse at midline superior surface of the anococcygeal ligament to form part of the median raphe.

57
Q

Describe the iliococcygeus m:

A

Paired, It has its origin from the posterior half of the tendinous arch and the ischial spine and inserts onto the posterior portion of the anococcygeal ligament and tip of the coccyx

58
Q

Describe the coccygeus m:

A

It is paired, a thin triangular m that has its origin from the ischial spine and attaches to the coccyx and to the lateral margin of the sacrum at S5. It attaches onto the anterior surface of the sacrospinous ligament

59
Q

What is the coccygeus m. innervated by?

A

Ventral rami from S4-5

60
Q

What forms the pelvic diaphragm?

A

The 2 coccygeus muscles together with the R and L levator ani muscles

61
Q

Innervation of the pelvic diaphragm (levator ani and cocygeus) is provided by:

A

Ventral pelvic rami S3-5 (located on the floor of the pelvis) and from inferior rectal n (a branch of the pudendal n - S2-4)

62
Q

What is the Urogenital diaphragm?

A

Occupies the space between the 2 ischiopubic rami (IPR) up to the ischial tuberosities. It anchors the foundations of the urethra in the male and the urethra and vagine in the female and forms a physical boundary to close off the opening made by the urogenital hiatus of the levator ani.

63
Q

The fascia of the levator ani fuses with:

A

The superior fascia of the UG diaphragm (on its superior surface) along the margin of the urogenital hiatus to prevent abdominal and pelvic cavity contents from gaining access to the perineum

64
Q

What is the anterior recess?

A

Lateral to the fusion of the fascia (inferior to the levator ani, and superior to the UG diaphragm) is a potential space of the ischianal fossa. It is occupied by ischioanal fat. Removing the fat pad creates a space where the relationship of the UG diaphregm with the levator ani (pelvic diaphragm) can be seen

65
Q

In the anterior recess, what are the boundaries?

A
  • Positioned medially - levator ani
  • Inferiorly - UG diaphragm
  • Laterally - obturator internus m and ishciopubic rami
  • *The pelvic diaphragm and the UG diaphragm are 2 separate structures - pelvic diaphragm is positioned superior to the UG diaphragm

Anatomy IV (4 decks)

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