VERTEBRAL COLUMN 3 Flashcards
Thoracic region
Wedge shaped vertebrae = primary cause of thoracic kyphosis - ANTERIOR HEIGHT OF VB IS LESS THAN POSTERIOR WHICH GIVES A WEDGED SHAPED
Low disc: vertebral body height
Tall, coronal superior articular processes limit flexion - TALL AND VERTICAL IN CORONAL PLANE
Coupling of movements in the thoracic spine:
Upper thoracic: lateral flexion & ipsilateral rotation coupling
When the inferior articular process of the superior vertebrae slides inferiorly it also moves
posteriorly (like mid & lower Csp (C3-7))
Mid & lower thoracic: variable
Rotation refers to the direction that the anterior vertebral body turns toward
C3-7 SIMILAR TO THORACIC
Lumbar vertebral column
Flat superior & inferior ends of vertebral bodies
Almost sagittal orientation of zygapophysial joints
(curved anteriorly)
6. Mammillary process: Located on the superior articular process
1. Accessory process: Located on the dorsal, medial aspect of the transverse process
L1-4 PARALLEL VB
Lumbar vertebral column - 2
Almost sagittal orientation of zygapophysial joints favour movements in the sagittal plane (F/E)
Changes to coronal by L5 to help prevent forward slipping of L5 on S1
L4 TRANSITION STAGE
L5-SUP. ARTICULAR PROCESS IS NOW MAJORITY IN CORONAL PLANE
The lumbar lordosis
• 1. sacrum is tilted anteriorly • 2. L5/S1 iv disc is wedge shaped (taller anteriorly) • 3. L5 vertebra similarly wedge shaped • 4. superior vertebrae incline slightly backwards • 5. L1 aligned vertically over S1 Flexion of the lumbar spine = decrease of the lordosis
Iliolumbar ligament:
- Transverse processes of L5 to ilium
- Resists L5 slipping anteriorly off the sacrum
- Resists all directions of movement of L5 on the sacrum
Movements of the Lumbar vertebral column
FLEXION limited by:
FLEXION limited by: 1. impaction of articular processes 2. tension in: • Zygapophysial joint capsules • Supraspinous ligament • Interspinous ligament • Ligamentum flavum • Posterior annulus fibrosus 3. compression of: • Anterior annulus fibrosus
- flx - lifting inf. articular processes up = allows a bit of rotation b4 impact, therefore transfer load on ligaments, disc and AF
Movements of the Lumbar vertebral column
AXIAL ROTATION limited by:
AXIAL ROTATION limited by:
- Impaction of zygapophysial joints
- Tension in posterior ligaments
- Tension in annulus fibrosus
* more rotation range in flexion
Movements of the Lumbar vertebral column
EXTENSION limited by:
- impaction of spinous processes or inferior articular process with lamina below
- Tension in anterior AF
Scoliosis
“3D torsional deformity of the spine & trunk” lateral curvature + axial rotation + disturbance of sagittal curves structural (true) v’s functional (extrinsic cause) Structural: 80% idiopathic Classification: age of onset Cobb angle: 100; 300; 500 location of frontal plane deformity R thoracic scoliosis R rib hump Rotation of the vertebra moves the ribs
- flattening of lordosis or kyphosis
lft lat flexion = R lat rotation
Segmental muscles
Interspinales (Cx / Lx) / medial intertransversarii (Cx)
Small PCSA
Small moment arms
= small force production Proprioceptive function?
“all unisegmental muscles of the vertebral column have between 2 to 6 times the density of muscle spindles found in the longer polysegmental muscles”
Note
intertransversarii (lateral) are not intrinsic back muscles – they are innervated by ventral rami
transversospinales
attach to inferior transverse processes & superior spinous processes
Rotatores:
brevis & longus
most developed in Tx region but still very small PCSA = proprioceptive?
Multifidus:
more oblique alignment in Tx … better line of action for segmental rotation & lateral flexion than in lumbar region
most developed in lumbar spine
Semispinalis:
most developed in cervical & capitis regions
= main cervical extensors
(semispinalis thoracis spinous attachment C7 – T4)
Multifidus:
• View it as arising from the caudal edge of a lamina / spinous process
• 3 to 5 fascicles diverge inferiorly & attach to:
• superior articular process Cx
• base of transverse process Tx
• mammillary processes Lx, iliac crest & sacrum (depending on the region)
* fascicles diverge
* don’t consider as rotator
Action of multifidus: Acts over few segments
Lateral view:
• Vertical line of action & posterior position to axis = posterior sagittal rotation i.e. extension
(& maintains the lumbar lordosis)
= no translation results from contraction
Action of multifidus:
Posterior view:
• small horizontal component that could assist rotation (in Tx)
• The primary rotators of the lumbar spine are the oblique abdominals
The abdominals are anterolateral muscles… SO… they produce flexion + rotation
If the flexion component is not desired - recruit multifidus to produce extension moment F & E cancel to produce pure rotation of the trunk
- small horizontal component
Erector spinae
Use bony landmarks: 1. Spinalis
2. Longissimus over transverse processes
3. Iliocostalis over angle of ribs
2nd part of name usually indicates the superior attachment
Erector spinae aponeurosis
formed by the pars thoracis of:
• longissimus thoracis
• iliocostalis lumborum
Longissimus thoracis pars thoracis
Lx sp processes;sacrum&psis to Tx transverse processes/medial ribs
Iliocostalis lumborum pars thoracis
ilium&sacrum to lower 8 rib angles
- more lateral and can derotate thorax
Iliocostalis lumborum pars thoracis and Longissimus thoracis pars thoracis
Unilateral action = ipsil. LF
Bilateral action = E
The prime extensors of the thoracolumbar spine (trunk)
Most powerful extensors of the lumbar spine:
Vertical line of action
Large PCSA
Large posterior moment arm
* thoracic parts - large, long superficial
LIA = lumbar intermuscular aponeurosis
is formed by the caudal tendons of longissimus
Longissimus thoracis pars lumborum
5 fascicles: Medial end of each lumbar transverse process to psis area
Iliocostalis lumborum pars lumborum
4 fascicles: Tips of L1-4 transverse processes to medial iliac crest
Longissimus thoracis pars lumborum and Iliocostalis lumborum pars lumborum
Unilateral action: vertical line of action lateral to the axis = Lateral Flexor
Bilateral action: vertical line of action posterior to the axis
• posterior sagittal rotation i.e. extension
horizontal line of action
• + simultaneous posterior shear (or resist anterior shear)
* have more ant. > post. direction
Anterior & posterior shear forces on the lumbar spine
When lumbar spine flexes, the superior body weight exerts compressive and anterior shear force on the intervertebral joints.
Mechanisms to stabilise the motion segment:
1. Zygapophysial joints / articular processes
2. Intervertebral disc sagittal view 3. Ligaments
4. Muscles
* flx = straightening of lordosis
Anterior & posterior shear forces on the lumbar spine
multifidus and pars thoracis - vertical downwards pull
pars lumborum = horizontal downwards pull
Innervation of vertebral structures
Dorsal Rami:
medial branch
zygapophysial joint above & below
all muscles arising from spinous process / lamina
of that vertebra
= interspinales, rotatores, multifidus & semispinales + cutaneous branches in Cx & upper Tx
intermediate branch in lumbar spine longissimus
lateral branch erector spinae
+ cutaneous branches in lower Tx & Lx
* anterior innervates anterior
sinuvertebral nerves, sympathetic trunks & grey rami
branches from the sympathetic trunks & grey rami form an anterior plexus (anterior to vertebral bodies & iv discs)
branches from sinuvertebral nerve form a posterior plexus (posterior to vertebral bodies & iv discs)
Sympathetic trunk grey rami
communicantes
Nerve structure: Anterior plexus
Innervated structures: Anterior outer annulus fibrosus, ALL, anterior vertebral periosteum & vertebra, blood vessels
Ventral rami via sinuvertebral nerve
Nerve structure: Posterior plexus
Innervated structures: Posterior outer annulus fibrosus, PLL, anterior & ventral/lateral dura & nerve root sleeves, posterior vertebral periosteum & vertebra, blood vessels
Dorsal rami
Nerve structure: Medial branch
Innervated structures: - Zygapophysial joint above & below
- interspinales, rotatores, multifidus & semispinales
Nerve structure: Intermediate branch (in lumbar region only)
Innervated structures: longissimus
Nerve structure:Lateral branch
Innervated structures: erector spinae (except longissimus in Lx)
