Lumbar spine and pelvis

Question 1

Pelvis rotation affecting overall spinal mechanics

Answer 1

Anterior rotation of pelvis- increase lumbar spine lordosis (increased extension of the lumbar spine)
– increased extension on facets, approximating them

Posterior rotation of the pelvis- decreased lumbar spine lordosis, increased flexion of lumbar spine

Question 2

form closure

Answer 2

When structures have congruent shapes and by the shapes coming together, they make a congruent structure

– the sacrum and ilium each have one flat surface and one rigid surface which interlock with each other, promoting stability

– there is a keystone like shape that is created as the sacrum has a wider side superiorly, which allows the sacrum to be wedged in between the 2 inominates

Question 3

Force closure

Answer 3

When the soft tissue structures around the bony structures (muscles, ligaments and capsules), hold the pelvis together

Their contraction holds the bone of the pelvis together and keep it stable

Question 4

Intervertebral discs

Answer 4

separate the vertebrae to form part of a functional segmental unit

Nerve supply:
– usually has no nerve supply, apart from the peripheral posterior aspect (innervated by the sinuvertebral nerve)
– lateral aspect innervated peripherally by the anterior and posterior grey rami

Pain sensitive structures are ALL, PLL, vertebral body, nerve root and cartilage of facet joints

Features:
- contains water:
– non compressive- allows a state of ‘preloading’ and greater resistance to compressive forces
– fluid nature o water allows for resistance to lateral flexion

• layering of annulus:
  — allows for resistance to asymmetrical loading, especially torsion
  —- the annulus and nucleus become a functional couple reliant on the structural integrity of each other
  ——– this becomes a mechanism for self-stabilisation

3 layers:
- nucleus pulposus- 77% water, 14% proteoglycan, 4% collagen

• annulus fibrosus- 70% water, 5% proteoglycan, 15% collagen

Cartilage endplate- 55% water, 25% collagen, 8% proteoglycan

Function:
– shock absorbing
– separate the vertebra as part of a functional segmental unit
– They help protect the nerves that run down the spine

Question 5

The process of spondylosis

Answer 5

Definition:
– spine degeneration

Structures involved:
– vertebrae, discs, facets, capsules, muscles and ligaments

Initial phase:
– degeneration of disc leading to reduced disc height
– this leads to approximation of facets and ligamentous laxity as the vertebrae are closer together
– resulting in acute episodes of pain and muscle spasm

Middle stage:
– segment instability due to ligamentous laxity
– chronic muscle fatigue, hypoxia and micro trauma due to increased stabilising effort from muscles
– resulting in constant low grade ache

Late stage:
– osteophyte formation around facets and vertebral bodies leads to more episodes of acute pain along with constant ache from overuse of paraspinal muscles

Question 6

Force coupling of the pelvis

Answer 6

Force coupling- forces rotating around a pivot

This pivot in the pelvis is the acetabular socket

There are multiple forces at any given moment

They can be equal or unequal depending on the function required

Force coupling is seen during activities like walking up the stairs etc

Moving elements such as muscles and stabilising elements such as ligaments can affect the rotation of the sacrum due to force coupling

Force coupling muscles:
– looks at the relationship between the anterior and posterior pelvic musculature

• anterior superior pelvic muscles:
  — abdominal muscles (can be involved with the posterior rotation of the pelvis)
• anterior inferior pelvic muscles:
  — hip flexors (psoas and rem fem), can be involved with the anterior rotation of the pelvis
• posterior superior pelvic musculature:
  – erector spinae
  – QL (attaches to the posterior iliac crest)
  – Latissimus dorsi (connected to the iliac crest)
• posterior inferior pelvic musculature:
  — hamstrings (connect to ischial tuberosity)

Question 7

Pelvis’ role in locomotion

Answer 7

Locomotion- movement or the ability to move from one place to another

Pelvis takes all the weight and diffuses it equally across the whole pelvic ring and then down the 2 legs
Also takes the forces coming from the ground reaction forces up through the legs and absorbs it and dissipates it equally around the pelvic girdle so it doesn’t just hit the lumbar spine full on.

Question 8

How cough can cause lower back pain

Answer 8

Attachments of the left and right crus of the diaphragm, connect to the lumbar vertebrae

QL attaches to the last 3 ribs (10,11 and 12) and also to the lumbar vertebrae L1-L4

There is a central tendon that runs up to the pericardium. it may also be that the pericardium is innervated by the phrenic nerve (C3,C4,C5) just like the diaphragm