Pelvis

Question 1

Form closure

Answer 1

When two congruent shapes come together, they are able to create a stable structure. Sacrum is the keystone in the arch adding stability to SI joints.
Boney surface of Sacrum & Ilium come together to create a close + congruent fit.

Question 2

Force closure

Answer 2

Sacroiliac ligaments and the interosseous ligament help maintain the integrity of the joint, preventing excessive movement and maintaining form closure.

Question 3

Force coupling

Answer 3

Pivot point where two or more opposing forces pull in opposite directions, so the structure rotates. Occurs at the acetabulum (pivot point), the two ilia and the sacrum.
Lumbar erector spinae, Hamstrings, QL, Psoas and hip flexors.

Question 4

The impact altered angulation of pelvis has on spinal mechanics and curves.

Answer 4

Increased anterior rotation of pelvis can lead to increased lumbar lordosis (increased extension of lsp).
Increased extension on facets, posterior compression on discs.
Can lead to increased stretch on hamstrings, leading to muscle hypoxia and micro trauma.
Increased posterior rotation of pelvis will lead to reduced lumbar lordosis (increased flexion of lsp)

Question 5

The impact altered angulation of pelvis has on spinal mechanics and curves. Weight bearing:

Answer 5

Weight bearing in bilateral stance.
* In standing / upright weight bearing (WB) activities, at least half the weight of head, arms, trunk (HAT) passes down through the pelvis to the femoral head.
* Whereas the ground reaction force (GRF) travels up the shaft of the femur before it reaches the pelvis.
* Gravity passes through the L Shaped SI joint
* Trabeculae follow the directions of forces

Question 6

Importance of Trabeculae

Answer 6

A hierarchical, spongy, and porous material composed of hard and soft tissue components which can be found at the epiphyses and metaphyses of long bones and in the vertebral bodies

Tensile strength
* Prime location for fractures
* Ability to cope with stretching and rotating forces going through a structure

Question 7

Lumbar sacral Angle

Answer 7

Determined by drawing a line between the midpoint of the superior endplate of the first sacral vertebra (S1) and the midpoint of the superior endplate of the fifth lumbar vertebra (L5). Another line is drawn parallel to the horizontal line passing through the midpoint of the L5 endplate. The angle formed between these two lines is the lumbar sacral angle.

typically ranges between 30 and 60 degrees. This angle represents the natural lordotic curvature of the lumbar spine, which is important for distributing forces during weight-bearing activities and maintaining the stability of the spine.

Adding gravity to the concave curve, anteriorly rotates the pelvis, increasing the lumbar sacral angle and increasing the chances of an anterior slippage of L4/L5 or L5/S1.

Question 8

Illio lumbar ligament

Answer 8

• Connects L4/5 to sacrum and iliac crest (pelvis)
• Ant and post portion

Question 9

Nerve supply to the facet capsule and disc

Answer 9

The dorsal rami from segment above and segment below
Nerve supply to the discs o Sinuvertebral nerve
Facets have a much bigger nerve supply – why pain can be worse quicker