Lumbar Spine Ligaments and Muscles

Question 1

Anterior Longitudinal Ligament

Answer 1

• Well developed along lumbar lordosis
• Tensile strength is greatest in lumbar region
  
  • Supports weight of lumbar spine, especially at L/S junction (sling)
  • 2x stronger than PLL

-Superficial fibers span multiple levels, Deep fibers span single level (deep blend with AF to reinforce disk)

Question 2

Role of Anterior Longitudinal Ligament

Answer 2

Resists:

• *Anterior shear/ translation
• *Extension
• Axial rotation
• Distraction

Slacks with flexion
Proprioception with extension

Question 3

Posterior Longitudinal Ligament

Answer 3

Ventral surface of vertebral canal
Very thin in lumbar region (thicker in C spine)
Resistance to axial tension is 1/6 that of ALL

Superficial span multiple levels, deep attach adjacent vertebrae and interlace with outer AF

Question 4

Role of Posterior Longitudinal Ligament

Answer 4

Resist:

• Posterior translation
• Flexion (minimally)

Slacks with extension
Proprioception with flexion

Question 5

Ligamentum Flavum

Answer 5

• Postero-lateral surface of vertebral canal
• Connect lamina to lamina
• Highly elastic and thick
• Includes slips to anterior facet joint capsule

With aging: Stretches out – can buckle in spinal canal

Question 6

Role of Ligamentum Flavum

Answer 6

• Resists flexion
• Slacks with extension
• May assist with return to extension
• Elasticity –> constant tension, creating compressive force on disk –> Increase disk stiffness

Question 7

Interspinous ligament

Answer 7

• Spinous process to spinous process

- Well developed in lumbar region

Question 8

Supraspinous ligament

Answer 8

• Runs along tips of spinous processes from C7 to L3 (some individuals to L4)

**Absent at L5-S1

In lumbar region, blends with thoracolumbar fascia and multifidus

Question 9

Role of supraspinous ligament

Answer 9

Resists:

• Flexion
• Separation of spinous processes
• Rotation (to a lesser degree)

Slacks with extension

Dense with mechanoreceptors –> Proprioception

Question 10

Intertransverse ligament

Answer 10

• Bilateral transverse process to transverse process
• Blend with thoracolumbar fascia, TA, EO, lats
• Thickest in lumbar region
• Alternately stretched and compressed during lateral bending
• *Absent at L4 and L5

Question 11

Role of intertransverse ligament

Answer 11

Resists:

• Lateral bending on contralateral side
• Rotation

Slack with lateral bending to ipsilateral side
Proprioception during lateral bending and rotation

Question 12

Iliolumbar ligaments

Answer 12

• Ventral band and dorsal band: L4/5 Transverse process –> Iliac crest
• Sacral band: L4/5 TP and sacral ala –> Iliac crest (AKA lumbosacral ligament)

Question 13

Role of iliolumbar ligaments

Answer 13

Prevent anterior displacement of L5 on sacrum (sliding off)

Resists motion in all planes

Question 14

Lumbar mobilizers

Answer 14

Rectus abdominus
abdominal obliques
psoas major (ant fibers)
iliocostalis
longissimus
quadratus lumborum

Question 15

Lumbar stabilizers

Answer 15

Multifidus
Transversus abdominus
Psoas major (post fibers)
Muscular attachments to thoracolumbar fascia

Question 16

Muscle function: Lumbar flexors

Answer 16

• Attachments on ribs, sternum, pelvis
• Rectus abdominus, psoas, obliques
• Other functions: Increasing intra-abdominal pressure (decrease stress on lumbar spine)

Question 17

Muscle function: Lumbar extensors

Answer 17

Acting bilaterally: Dorsal muscles are extensors

Acting unilaterally: Dorsal muscles are lateral rotators and lateral flexors

Question 18

Multifidus

Answer 18

Transverse process (and adjacent facet jt/ capsule) –> Spinous process 2-3 levels superior

From sacrum

To activate: Contralateral rotation

Question 19

Multifidus action

Answer 19

1. Increases spine stiffness (stabilization)**
2. Avoid painful nipping of capsule by facet joint (approximates facets)
3. Secondary:
   - Extension (bilateral)
   - Ipsilateral side bend
   - Contralateral rotation

Question 20

Transverse Abdominus

Answer 20

Ribs, iliac crest, thoracolumbar fascia –> Linea alba

Question 21

Action of TA

Answer 21

1. Stabilizes spine
2. Narrows waist
3. Generates tension on thoracolumbar fascia

Question 22

Psoas major (posterior)

Answer 22

Transverse process (T12-L5), anterolateral vertebral bodies, intervertebral disks –> Lesser trochanter

Question 23

Action of psoas major (posterior)

Answer 23

1. Stabilizes spine (axial compression)
2. Can generate anterior sheer
3. Assist with trunk flexion

Question 24

Thoracolumbar Fascia

Answer 24

1. Superficial and deep
2. Multiple muscular attachments of superficial and deep muscles
3. Compressive “corset” to stabilize spine

Question 25

Spinal Cord

Answer 25

Ends L1-L2 Cauda Equina Nerve roots L2-S5 continue to run through central canal

Question 26

What structures are innervated?

Answer 26

Lumbar disk PLL and ALL Interspinous ligament Facet joints

Question 27

What structure is not innervated?

Answer 27

Main ligamentous substance of ligamentum flavum (superficial surface is innervated)