15 - Muscles and Movements of the Back Flashcards
Part of spine where flexion mostly occurs
Lumbar
Which movement increases stress on spinal facet joints?
Hyperextension
What limits mobility of T spine?
Ribs
Things that influence spinal movement
1)
2)
1) Shape of IV discs. Wedge-shaped
2) Orientation of articular facets
Movements allowed by lumbar articular facets
Flexion/extension in sagittal plane
Movements allowed by thoracic articular facets
Permit rotation in coronal plane (but limited by ribs)
Movements allowed by sacral articular facets
Limit movement in sagittal plane
Superficial back muscles 1) 2) 3) 4)
1) trapezius
2) latissimus dorsi
3 rhomboids
4) levator scapulae
Where do superficial muscles of the back originate from (except trapezius)
From cervical myotomes
What innervates superficial back muscles (except trapezius)
Anterior rami
Do posterior rami innervate superficial back muscles?
No. They pass through superficial back muscles on their way to innervate the skin
Intermediate muscles of the back
Serratus posterior superior and inferior
Innervated by anterior rami
Division of the deep muscles of the back
1)
2)
1) Erector spinae (run medial to lateral)
2) Transversospinalis (run lateral to medial)
Most common site of rib fracture
Lateral border of erector spinae, which runs along rib angle
Erector spinae functions
Prime movers of back extension
Concentrically return flexed back to extended position
Eccentrically control back flexion
When are erector spinae electrically silent?
When back is fully flexed
Transversospinalis function
Segmental stabilisers
Form ‘corset’ with deep abdominal muscles (EG: transversus abdominus) around lumbar region with lumbar fascia
Muscles that waste quickly following back injury
Transversospinalis
Where does lymph from the back drain?
Anteriorally, as there are no lymph nodes on the back.
Path taken from arteries from spinal cord
Penetrate through muscles with posterior rami to skin
What do posterior rami innervate?
1)
2)
3)
1) facet joints
2) deep back muscles
3) overlying skin
Two broad types of back pain
1) Mechanical pain (EG: muscular pain)
2) Compressive pain (occurs when nerve roots are pinched or irritated)
Common causes of compressive back pain
Spinal stenosis or herniated IV disc
Stenosis
Abnormally narrow space
Why do IV discs herniate posterolaterally?
Because of posterior longitudinal ligament (lies along mid-posterior back)
Most-commonly impinged nerve root
Between L5/S1.
This is where the largest IV disc is, largest nerve root and narrowest foramen
Contributors to disc prolapse 1) 2) 3) 4) 5) 6)
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
Spondylosis
Bones lose water with ageing, become less dense.
How might spondylosis lead to nerve root compression?
Spondylosis can lead to osteophyte growth, which narrow IV foramen (stenosis)
Non-compressive causes of back pain
Cardiovascular (eg. aortic aneurism) Neoplasia (particularly in older person) Tumour metastasis (from lung, breast, thyroid, kidney, prostate) Infection
