15 - Muscles and Movements of the Back

Question 1

Part of spine where flexion mostly occurs

Answer 1

Lumbar

Question 2

Which movement increases stress on spinal facet joints?

Answer 2

Hyperextension

Question 3

What limits mobility of T spine?

Answer 3

Ribs

Question 4

Things that influence spinal movement
1)
2)

Answer 4

1) Shape of IV discs. Wedge-shaped

2) Orientation of articular facets

Question 5

Movements allowed by lumbar articular facets

Answer 5

Flexion/extension in sagittal plane

Question 6

Movements allowed by thoracic articular facets

Answer 6

Permit rotation in coronal plane (but limited by ribs)

Question 7

Movements allowed by sacral articular facets

Answer 7

Limit movement in sagittal plane

Question 8

Superficial back muscles 
1)
2)
3)
4)

Answer 8

1) trapezius
2) latissimus dorsi
3 rhomboids
4) levator scapulae

Question 9

Where do superficial muscles of the back originate from (except trapezius)

Answer 9

From cervical myotomes

Question 10

What innervates superficial back muscles (except trapezius)

Answer 10

Anterior rami

Question 11

Do posterior rami innervate superficial back muscles?

Answer 11

No. They pass through superficial back muscles on their way to innervate the skin

Question 12

Intermediate muscles of the back

Answer 12

Serratus posterior superior and inferior

Innervated by anterior rami

Question 13

Division of the deep muscles of the back
1)
2)

Answer 13

1) Erector spinae (run medial to lateral)

2) Transversospinalis (run lateral to medial)

Question 14

Most common site of rib fracture

Answer 14

Lateral border of erector spinae, which runs along rib angle

Question 15

Erector spinae functions

Answer 15

Prime movers of back extension
Concentrically return flexed back to extended position
Eccentrically control back flexion

Question 16

When are erector spinae electrically silent?

Answer 16

When back is fully flexed

Question 17

Transversospinalis function

Answer 17

Segmental stabilisers

Form ‘corset’ with deep abdominal muscles (EG: transversus abdominus) around lumbar region with lumbar fascia

Question 18

Muscles that waste quickly following back injury

Answer 18

Transversospinalis

Question 19

Where does lymph from the back drain?

Answer 19

Anteriorally, as there are no lymph nodes on the back.

Question 20

Path taken from arteries from spinal cord

Answer 20

Penetrate through muscles with posterior rami to skin

Question 21

What do posterior rami innervate?
1)
2)
3)

Answer 21

1) facet joints
2) deep back muscles
3) overlying skin

Question 22

Two broad types of back pain

Answer 22

1) Mechanical pain (EG: muscular pain)

2) Compressive pain (occurs when nerve roots are pinched or irritated)

Question 23

Common causes of compressive back pain

Answer 23

Spinal stenosis or herniated IV disc

Question 24

Stenosis

Answer 24

Abnormally narrow space

Question 25

Why do IV discs herniate posterolaterally?

Answer 25

Because of posterior longitudinal ligament (lies along mid-posterior back)

Question 26

Most-commonly impinged nerve root

Answer 26

Between L5/S1.

This is where the largest IV disc is, largest nerve root and narrowest foramen

Question 27

Contributors to disc prolapse
1)
2)
3)
4)
5)
6)

Answer 27

1) 15 deg lumbar flexion – forces
nucleus posteriorly
2) 15 deg rotation – max torsion in
annulus, only 50% fibres resist force
3) slight LF forces nucleus posterolaterally

4) be overweight or fat
5) keep lower limbs fully extended
6) pick up heavy object near opposite
foot

Question 28

Spondylosis

Answer 28

Bones lose water with ageing, become less dense.

Question 29

How might spondylosis lead to nerve root compression?

Answer 29

Spondylosis can lead to osteophyte growth, which narrow IV foramen (stenosis)

Question 30

Non-compressive causes of back pain

Answer 30

Cardiovascular (eg. aortic aneurism)
Neoplasia (particularly in older person)
Tumour metastasis (from lung, breast,
thyroid, kidney, prostate)
Infection