Module 3 Unit 3 Flashcards
How many sacral segments are fused in adulthood?
5 sacral segments
Is the posterior surface of the sacrum concave or convex? What curve is this? Where does it articulate?
Convex; kyphosis
It articulate with the lateral edges of the ilium
What is the shape of the sacral base? Where does it face?
Oval/round
anterior/superior
What is the clinical importance of sacral promontory?
Osteophytes with spondyolisthesis of L5
What are the portions of the posterior sacrum?
Pedicles
Laminae
Tubercles
Sacral canal
Is the superior articular process of the sacrum concave or convex? What directions do they face?
Concave
Faces posterior and medial
What are the ‘wings’ of the sacral called? This is a common diagnosis for what?
Ala
Common location for stress fractures in osteoporotic patients
What are the typical sacral insufficiency fracture pattern? How are they classified?
Occurs when the quality of the sacral bone has become insufficient to handle the stress of weight bearing
They are classified into 3 zones.
What are the portions of the anterior surface of the sacrum?
4 osseous ridges
4 pair of sacral foramina
- ventral rami of sacral nerves
Apex of sacrum articulates w/ coccyx
- oval facet
What are the portions of the posterior surface of the sacrum?
Convex top to bottom
Rough
- Median sacral crest (3-4 tubercles)
- Intermediate sacral crest
- Lateral sacral crest
Sacral hiatus
- No fusion of 5th laminae
4 dorsal sacral foramina
- dorsal rami
Sacral cornu
Sacral groove
- Fused lamina
Lateral sacral crest
- Remnant TP’s fused together
What are the portions of the lateral surface of the sacrum?
Wide superiorly
Transverse and costal remnants fuse
Large articular surface
- Auricular surface
- From S1-S2
- Thick hyaline cartilage
— 3x that of ilium
What are the shape of the sacral canal? What directions does it open to?
Triangular shaped
Opens superiorly and inferiorly
How many segments of the coccyx? What are the shape of the facets? What are the horns of the coccyx called?
4 segments
Oval facets
The horns are called cornu
What are the 3 portions of the pelvic girdle?
Ilium, Ischium, Pubic bones
What are is the Y-shaped epiphyseal plate called? What are the junctions that make up the Y-shaped epiphyseal plate?
Triradiate Cartilage is made up of ischium, ilium, and pubis
When does the triradiate cartilage close in males and females?
Closure/ fusion for males at 15-16 years old and females at 13-14 years old
What are the difference between a male and female pelvis?
Male pelvis:
- Taller
- Narrower
- V-shaped/conical
Female pelvis:
- Shorter
- Wider
- Cylindrical
— Sacrum/coccyx don’t curve forward as much
— Ischial spines
What are the anterior borders of the ilium? What are they attachment sites for? What part of the acetabulum?
Anterior superior iliac spine (ASIS) attachment for sartoius
Anterior inferior iliac spine (AIIS) attachment for rectus femoris
Top of the acetabulum
What are the posterior borders of the ilium? What are the notches? Where does it merge on the posterior side?
Posterior superior iliac spine
Greater sciatic notch
- Merges with the ischium
How much of the medial surface of the ilium is the anterior and the posterior portions?
Iliac fossa - Anterior 2/3
Sacropelvic area - Posterior 1/3
What does the sacropelvic area of the ilium?
Articular surface - fits in the surface of the sacrum
Iliac tuberosity - sacroiliac ligaments attach
Pelvic surface - bends into the iliopectinal line
What is the pelvic brim?
A line from the sacral promontory to the upper part of the pubic symphysis
What is the false pelvis?
Lies above the pelvic brim - contains the ASIS and AIIS
What is the true pelvis?
Lies below the pelvic brim - contains the PSIS and most ischium and pubis
What is the pelvic axis?
Path of baby during birth - between the false pelvis and true pelvis
What are the directions are the anterior aspect and posterior aspect and size (convex or concave) (large or small)? What is it an attachment to?
Anterior aspect - convex and small
Posterior aspect - concave and large
Attachment for the iliacus muscle
What are the gluteal surfaces and what muscles attach there?
Inferior gluteal line - Rectus femoris attaches below AIIS
Anterior gluteal line (middle line) - gluteus minimus attaches below; gluteus medius attaches above
Posterior gluteal line - Gluteus Maximus attaches behind
What are the major landmarks on the ischium?
Body & ramus
Ischial spine - separates greater/lesser sciatic notch
What is considered the sit bone? What attaches to it?
Ischial tuberosity
Muscles: biceps femoris
Semimembranosis
Semitendinosis
What is the ramus of the ischium?
The ramus curves forward and connects with the pubis
What connects the two pubis bones?
Symphysis
What ligament attaches from the ASIS and pubic tubercle?
Inguinal ligament
What is the hip socket called? What 3 bones make it?
Acetabulum
Inferior portion of the Ilium, Posterior portion of the pubis, anterior portion of the ischium
What is the obturator foramen? How do the shapes differ in males vs females?
Ischium and pubis
Females: Smaller/triangular
Males: Larger/oval
Describe the Obturator canal. What runs through the canal?
Blood vessels & obturator nerve exit pelvis, into thigh
- Obturator nerve = L2-4 nerve roots
This nerve innervates
- Obturator externus
- Adductor magus, longus, brevis
- Gracilis
Where does the iliolumbar continue?
Upper band - attaches to the posterior portion of iliac crest
Lower band (limbo sacral ligament) - attaches to the anterior lateral portion of the sacral ala
Why is the iliolumbar ligament and lumbosacral ligament clinically significant?
If there is asymmetry can cause deviation from normal biomechanical forces.
What are the attachment points of the anterior sacroiliac ligament?
Thickening of the anterior and inferior portions of the SI joint capsule
Where does the inguinal ligament attach? What does it protect?
Connects ASIS to pubic tubercle
Protects soft tissues underneath
- nerve
- artery
- vein
- lymphatics
(NAVL)
What does the anterior sacrococcygeal ligament resemble?
Anterior Longitudinal Ligament
Where are the pubic ligaments located?
Superior - across the top of the pubic symphysis
Inferior - Bottom of pubic symphysis (AKA: arcuate ligament)
Where does the Mamillo-Accessory Ligament (MAL) attach? What runs through the foramen?
From the maxillary process to accessory process
medial branch of the posterior ramus
- Innervation: facet joints and some fibers of multifidus
Where do the long and short posterior sacroiliac ligaments run? What directions are the fibers in the long and short ligaments?
Long - vertical fibers
- Connects: S3-4 tubercles; intermediate & lateral crests, PSIS, Sacrotuberous ligament
Short - horizontal fibers
- Connects: S1-2 tubercles, iliac tuberosity, PSIS
What is the strongest ligament? Where does it attach?
Interosseous sacroiliac ligament attaches at the sacrual and iliac tuberosities
What does the articular ligament hold together?
Margins of the auricular surfaces of the sacrum and ilium
What does the sacrotuberous ligament attach to?
What tendon does it blend with?
Connects to inferolateral sacrum and ischial tuberosity; also connects to PIIS/PSIS
Blends with tendon of the long head of the biceps femoris
What shape is the sacrospinous ligament? Where does it connect? Where does it limit movement?
Triangular shape
Connects:
- lateral portion of sacrum and coccyx to ischial spine
Limits movement between the sacrum and ilium/ischium
What muscle and nerve passes through the great sciatic foramen?
Piriformis
- O: anterior sacrum
- I: greater trochanter
- A: external rotation of hip
Sciatic nerve
- Deep/inferior to piriformis
What makes up the lesser sciatic foramen? What muscle and nerve passes through?
Anterior border: body of ischium
Posterior border: sacrotuberous ligament
Superior border: Sacrospinous ligament & ischial spine
Muscle and nerve passing though:
- Obturator internus
- Obturator nerve
What are the posterior sacrococcygeal ligaments? What does the more superficial ligament protect?
Superficial: Continuation of the ligamentum flavum
- Protects the S5 and coccygeal nerves
Deep: Continuation of the PLL
- From the posterior ‘body’ of S5
- To the surface of coccyx
Where does the lateral sacrococcygeal ligament connect? What does it form?
Connects to the inferior/lateral sacrum to transverse process of coccyx
Forms the foramen for S5 nerve root
Where does the intercornual ligament attach?
Between sacral cornu and coccygeal cornu on same side (fibers run vertically)
