1 - Pelvic Walls (Add Pictures)

Question 1

Pelvic Girdle:

Overview / Anatomical Function

Bony Components

Answer 1

• Attachment of lower extremities
• Transmits weight to lower extremities
• Protects pelvic organs
• Outlet for GI, Urinary, Reproductive systems
• Bones:
  
  • R / L Pelvic Bones
  • Sacrum
  • Coccyx

Question 2

Pelvic Girdle: Sacrum

Primary Body

Sacral Pomontory

Sacral Canal

Sacral Hiatus

Answer 2

• Primary Body
  
  • Five rudimentary vertebrae which are fused together; articulates with L5 above, and coccyx below
• Sacral Promontory
  
  • Anterior-Superior margin of vertebra S1 that projects forward
• Sacral Canal
  
  • Continuation of vertebral canal; contains the cauda equina
• Sacral Hiatus
  
  • Inferior opening of sacal canal; site of entry of needle for caudal injection/epidural

Question 3

Pelvic Girdle: Coccyx

Body

Purpose

Canals

Answer 3

• Body:
  
  • Formed from 4 coccygeal vertebrae fused
• Purpose:
  
  • Site for muscle and ligament attachment
• Canals:
  
  • None present

Question 4

Pelvic Girdle: Pelvic Bones

Bone Components

Landmark of Intersection

Clinical Juvenile Structural Difference?

Answer 4

• Bone Components: Fusion of -
  
  • Ilium
  • Ischium
  • Pubis
• Intersect at acetabulum
• Juvenile Difference:
  
  • Three bones joined only by cartilage; thus gaps on x-ray in young patients could be confused for fractures

Question 5

Landmarks of Ilium

Iliac Crest

Iliac Fossa

Anterior Superior Iliac Spine

Anterior Inferior Iliac Spine

Answer 5

Question 6

Pelvic Girdle: Landmarks of Ischium

Ischial Tuberosity - What attaches here?

Ischial Spine - What attaches here? (2x)

Ischial Ramus

Greater Sciatic Notch

Lesser Sciatic Notch

Answer 6

• Ischial Tuberosity
  
  • Roughened, posterior, inferior part of ischium
  • Attachment site for sacrotuberous ligament
• Ischial Spine
  
  • Pointed process from posterior border of ischium; lies between greater and lesser sciatic notches
  • Attachment site for sacrospinous ligament and coccygeus muscle
• Ischial Ramus
  
  • Inferior border of ischium; inferior to obturator foramen
• Greater Sciatic Notch
  
  • Deep indention in posterior border of innominate bone superior to ischial spine
• Lesser Sciatic Notch
  
  • Deep indentation in posterior border of ischium inferior to ischial spine

Question 7

Pelvic Girdle: Landmarks of Pubis

Answer 7

N2K:

Pubic Symphysis

Body of Pubis

Obturator Foramen

Superior Pubic Ramus

Inferior Pubic Ramus

Pubic Arch

Question 8

Pelvic Girdle: Pelvic Brim

Overview/Location

Components

Answer 8

• Overview:
  
  • Bondy ridge surrounding and defining pelvic inlet
• Components:
  
  • Promontory and Ala of Sacrum
  • Right and Left Linea Terminalis
    
    • Arcuate Line of Ilium
    • Pecten Pubis
    • Pubic Crest

Question 9

Pelvic Girdle: Divisions of Pelvis in Relation to Pelvic Brim

False Pelvis (Greater Pelvis)

True Pelvis + Boundaries (Lesser Pelvis)

Answer 9

• False Pelvis
  
  • Located above pelvic brim
  • Part of posterior wall of abdominal cavity
• True Pelvis
  
  • Located below pelvic brim
  • Lower part of GI tract and urogenital organs
  • Boundaries:
    
    • ​Pelvic Inlet (superior opening)
    • Pelvic Outlet (inferior opening)

Question 10

Pelvic Girdle: Fracture of Pelvis and Mortality

What organs must you assume damage to?

Answer 10

Fractures of pelvis are associated with high mortality due to pelvic organ damage and hemorrhage; one must assume damage to urinary bladder and urethra

Question 11

Pelvic Girdle - Joints and Ligaments of Pelvis

Vertebral Joints (Vertebrae to Sacrum, Sacrum to Coccyx)

Sacroiliac Joint (Sacrrum to Iliac)

Answer 11

• Joints of Vertebral Column
  
  • Lumbosacral / Sacrococcygeal Joints
• Sacroiliac Joint
  
  • Transmits weight of most of body to hip bones
  • Held together by strong, interosseuous ligaments and anterior and posterior sacro-iliac ligaments

Question 12

Pelvic Girdle - Joints and Ligaments of Pelvis

Sacrotuberous Ligament

What is this ligaments relation to the sacrospinous ligament?

Answer 12

Broad attachment to sacrum and narrows inferiorly to attch to ischial tuberosity

Is located posterior to the sacrospinous ligament

Question 13

Pelvic Girdle - Joints and Ligaments of Pelvis

Sacrospinous Ligament

What is its relation to the sacrotuberous ligament?

Answer 13

Triangular

Located anterior to sacrotuberous ligament

Question 14

Pelvic Girdle - Joints and Ligaments of Pelvis

What prevents the upward tilting of sacrum due to the weight of trunk? (2x major ligaments)

What is an additional purpose of these structure?

Answer 14

Sacrotuberous / Sacrospinous Ligaments

Convert greater / lesser sciatic notches in Greater and Lesser Sciatic Foramina, e.g. make a “hole” from 1/2 bone + 1/2 ligament

Question 15

Pelvic Girdle - Joints and Ligaments of Pelvis

Greater Sciatic Foramen - What passes through here?

Lesser Sciatic Foramen - What passes through here?

Answer 15

• Greater Sciatic Foramen
  
  • Window through which neurovascular structures and piriformis pass from true pelvis into gluteal region
• Lesser Sciatic Foramen
  
  • Window through which neurovascular structures and obturator internus pass from gluteal region (buttock) to the perineum (area around anal canal, external genitalia)

Question 16

Measurements for Obstetrics:

Purpose

Methods

Answer 16

Purpose: Used to determine size of birth canal

Methods: Manually during vaginal exam, or with MRI

Question 17

Measurements for Obstetrics:

Obstetric Conjugate

What blocks this measurement during pelvic exam?

Answer 17

• Minimum AP diamete of the lesser pelvis and narrowest fized distance through which baby’s head must pass in vaginal delivery
• From sacral promontory to the thickest margin of pubic symphysis
• Can NOT be measured during pelvic exam due to the bladder

Question 18

Measurements for Obstetrics:

Diagonal Conjugate

What two structures are palpated? (will need both hands)

Answer 18

Measured by palpating the sacral promontory with tip of middle finger while using other hand to mark level of the inferior margin of the pubic symphysis on the examing hand

Question 19

Measurements for Obstetrics:

Interspinous Distance

What structures does this measure between?

What does this represent?

Answer 19

Distance between ischial spines

Narrowest part of pelvic canal

Question 20

Male vs Female Differences of Bony Pelvis

Pelvic Inlet - Shape?

Pelvic Outlet - Size?

Pelvic Cavity - Girth?

Angle of Pubic Arches - Hand mnemonic?

Answer 20

• Pelvic Inlet
  
  • F - Oval
  • M - Kidney (protrusion of sacral promontory)
• Pelvic Outlet
  
  • F - Large
  • M - Small
• Pelvic Cavity
  
  • F - Wide
  • M - Narrow
• Angle of Pubic Arches
  
  • F - Wide (80-85 deg)
  • M - Narrow (50-60 deg)

Question 21

Walls of True Pelvis: What forms the following?

Lateral Wall - Bones? Muscle? Ligaments?

Anterior Wall - Bones? Ligamentous structure?

Posterior Wall - Bones? Muscle?

Answer 21

• Lateral Wall:
  
  • Pelvic Bones
  • Obturator Internus
  • Sacrospinous and Sacrotuberous Ligaments
• Anterior Wall:
  
  • Pubic Symphysis / bodies of pubic bones
• Posterior Wall
  
  • Sacrum, Coccyx, Piriformis

Question 22

Pelvic Diaphragm:

Anatomical Location

Passage of Urethra - Opening name?

Pierce @ midline = Anorectral Junction, what is this?

Answer 22

• Anatomical Location
  
  • Floor of true pelvis
• Passage of Urethra
  
  • Urogenital Hiatus (both sexes) and vagina
• Anorectral Junction
  
  • Jx of anal canal and rectum

Question 23

Pelvic Diaphragm:

Region Above - Major organs?

Region Below - Major organs?

Answer 23

• Region Above
  
  • Main pelvic cavity of true pelvis
  • Urinary bladder, rectum, uterus, etc
• Region Below
  
  • Perineum
  • External genitalia and outlet of gut and urogenital system

Question 24

Pelvic Diaphragm:

What muscles make up the pelvic diaphragm? (2x)

What are they innervated by?

Answer 24

• Insert on midline structures; Innervated by Anterior Rami of Lower Sacral Nerves (S4, S5)
• Levator Ani
• Coccygeus

Question 25

Levator Ani: Origin Insertion Perinal Body & Child Birth clinical implications?

Answer 25

* Origin * Ant - Body of pubis * Mid - Tendinous Arch * Post - Ischial Spine * Insertion (structures located midline) * Coccyx * Anococcygeal Body * Perineal Body * Maintaining support of pelvic viscera * **If torn during childbirth, can compromise integrity of pelvic floor; could result in collapse of organs (prolapse)** * Subdivisions * Puborectalis - Sling around anorectal jc (sphincter-like) * Puboco

Question 26

Levator Ani: Subdivisions (3x) Purpose of puborectalis? Pubococcygeus Illiococcygeus

Answer 26

* Puborectalis * Sling around anorectal junction (**sphincter-like**) * Pubococcygeus * Inserts on anococcygeal body and coccyx * Illiococcygeus * Extends from tendinous arch and ischial spine to insert on coccyx and anococcygeal body

Question 27

Urogenital Gap difference in male / female? (vagina/urethra/perineal body orientation)

Answer 27

Male - Urethra in Urogenital Gap Females - **Vagina** is anterior to perineal body; **Urethra** is **anterior to vagina**

Question 28

Endopelvic Fascia Anatomical Description - What is it continuous with? Parietal Pelvic Fascia Visceral Pelvic Fascia - Continuous with?

Answer 28

* Anatomical Description * Lines pelvic cavity and covers pelvic organs * Continuous with **endoabdominal fascia** * Parietal Pelvic Fascia * Invests muscles of pelvic walls * Condensations of pelvic fascia, holds organs in place * Visceral Pelvic Fascia * Fascia on surface of viscera * Continuous with parietal pelvic fascia

Question 29

Sacral Plexus (Posterior Pelvis Wall) Anatomical Purpose Clinical Correlate and Sciatica?

Answer 29

Provides **motor** nerve supply to most lower limb muscles, pelvic diaphragm, muscles of perineum, pelvic viscera, and **cutaneous sensory fibers** to lower buttock and back of thigh Clinical: Can be compressed by **pelvic tumor (rectal tumor)** or by **head of fetus during childbirth** resulting in **sciatica**

Question 30

Sacral Plexus Componsition Location (in reference to major muscle)

Answer 30

Anterior Rami of **L4, L5 (lumbosacral trunk) and S1 - S4** Located **anterior to piriformis muscle**

Question 31

Sacral Plexus branches which pass through **Greater** Sciatic Foramen: (location in ref. to **piriformis**?) Superior Gluteal Nerves Inferior Gluteal Nerves Sciatic Nerve (composed of?) Posterior Cutaneous Nerve of Thigh

Answer 31

* Superior Gluteal Nerves * Leaves pelvis through greater sciatic foramen **above piriformis muscle** * Supply gluteal muscles of buttock * Inferior Gluteal Nerves * Leaves pelvis through greater sciatic foramen **below piriformis muscle** * Supply gluteal muscles of buttock * Sciatic Nerve * Largest nerve in body * Composed of **L4-L5, S1-S3** * Leaves pelvis through greater sciatic foramen **below piriformis muscle** * Posterior Cutaneous Nerve of Thigh * Innervates back of thigh ; has _perineal branch_ to **posterior scrotum/labium majus**

Question 32

Sacral Plexus Branches which pass through **greater and lesser** sciatic foramina: Pudendal nerve - Somatic and Sensory? Nerve to Obturator Internus Muscle

Answer 32

* **\*\*Pudendal Nerve\*\*** * Branches of Anterior Rami of **S2-S4** * Passes through **greater and lesser sciatic foramina** to innervate _somatic, skeletal muscles of perineum_ * Provides **sensory fibers** to _lower half of anal canal_ and _skin of external genitali_a * Nerve to Obturator internus Muscle

Question 33

Sacral Plexus Branches which **do not leave the true pelvis**: Branches to Pelvic Diaphragm Pelvis Splanchnic Nerves - Nerve type?

Answer 33

* Branches to Pelvic Diaphragm * Pelvis Splanchnic Nerves * Composed of **_parasympathetic_ preganglionic fibers** * Innervates terminal ganglia, which innervate all **hindgut derivatives** * Upper half anal canal, **urinary bladder**