Sacral Spine
ROM at SIJ
1-4 degrees rotation, 1-2mm of translation
Pubis makes up ______- of acetabulum
1/5th
The iliac makes up _____ of acetabulum
2/5ths
The sacrum have how many foramina
4 pairs, anterior and posterior primary rami of sacral nerves
Bony landmarks of innominates
ASIS, AIIS, PSIS, Iliac crest, coccyx (muscle and ligament attachment)
The innominate bone is considered an __________ of the lower extremity
An extension of the lower extremity
What is SIJ nutation
Anterior Sacral on ilial rotation, posterior iliac on sacral rotation or both performed simultaneous
Articular surfaces of sacroiliac joint and joint capsule
Change from smooth to rough which enhances resistance against vertical shear forces, joint capsule becomes more fibrotic and less mobile with age
The structure of the pelvis is a ________. Components are 4 bones and 3 joints ________
Closed osteoarticular ring Bones- Sacrum, coccyx, 2 innominates (ilium, ischium) Joints- 2 Sacroiliac joints, pubic symphysis
Posterior layer of thoracolumbar fascia
Covers posterior surface of muscles including erector spinae, multifidi and lats attaches to SP's L1-5, sacrum and ilium
Short and long posterior sacroiliac ligaments
Cross posterior SIJ, many short fibers blend with interosseous ligament
Sacrospinous ligament
Deep to sacrotuberous ligament
Abdominal muscles that affect SIJ
Diaphragm, pelvic floor, rectus abdominis, obliquus abdominis internus and externus, transverse abdominis
Back muscles that reinforce SIJ
Erector spinae and Lumbar multifidus
Ischium is the ___ of acetablum
Floor, 2/5ths of acetablum
Thoracolumbar fascia role
Functional stability
Leg and arm muscles affecting SIJ
Hip extensor muscles (Biceps femoris and glute), lats, Iliacus and piriformis
Which inominate bone articulates with sacrum
Ilium
Laxity
Increased ROM of joint
What innominate bone do you sit on
Ischium
Sacrotuberous ligament
Large, blends with biceps femoris tendon (lateral hamstring)
Men and Sacrum
Larger Sacroiliac joint surfaces, increased congruency (stability), taller and more narrow pelvis
Coccyx purpose
Muscle and ligament attachment
Rotation of SIJ occurs ________
Near sagittal plane, around near medial-lateral axis of rotation (transverses the interosseous ligament)
The sulcus is _______
Near the PSIS and look like dimples in low back area
Nutation SIJ kinematics
Nutation increases articular stability Close packed position is full nutation Nutation torque created by (gravity, ligaments(passive when stretched), and muscle activation)
What is counternutation
Posterior sacral on ilial rotation, anterior iliac on sacral rotation or both performed simultaneously
The base of the Sacrum is ______ and is the most ______ and has what facets
S1, cephalad (superior), has 2 facets (face posterior) articulate with L5
The inferior lateral angles of the sacrum are ________
S3-S5 area, muscle and ligament attachments
The apex of the sacrum is _______ and articulates with
S5, most caudal, articulates with coccyx
Sacroiliac vs iliosacral joint
Sacrum moving on iliac- sacroiliac Iliac moving on sacrum- iliosacral
Sacroiliac joint innervation
Sensory nerve fibers, dorsal rami of L5-S3 spinal nerve roots, less often ventral rami of L4-S2
Women and sacrum
Smaller Sacroiliac joint surfaces, increased mobility, shorter and wider pelvis
Iliolumbar ligament
Stabilizer of lumbosacral joint, blends with parts of anterior sacroiliac ligament, reinforces anterior SIJ
Function of sacrum
Support abdomen and spinal column (within pelvic ring), link vertebral column to lower extremities
The sacroiliac joint is a _____ joint
Synovial/diarthrodial joint, freely mobile joint in childhood, becomes modified synarthrodial joint in puberty and adulthood
Anterior sacroiliac ligament
Thickening of anterior and inferior capsule, reinforces anterior SIJ
Interosseous ligament
Very dense and short, fills gape between posterior and superior SIJ
Movment of SIJ occurs during
Walking, labor and delivery and during pregnancy (weight gain, lordsis and hormone induced ligamentous laxity)
Sacrum is part of vertebral column and describe dimensions
Wider superior vs inferior, wider anterior vs posterior, has 5 fused vertebrae
Anterior and middle layers of thoracolumbar fascia
named according to position relative to quadratus lumborum, attach to TP's of L-spine and to iliac crests