Spine (Lesson Notes)

Spine – classical anatomy Deep spinal muscles (left) 1. rotatores cervicis 2. rotators thoracis 3. Levatores costarum 4. Multifidi 5. Multifidi 6. Semispinalis thoracis 7. Semispinalis capitis Intermediate spinal muscles (right) 1. rectus capitis posterior minor 2. Obliquus capitis superior 3. Rectus capitis posterior major 4. Obliquus capitis inferior 5. Spinalis cervicalis 10 6. Longissimus cervicis 7. Iliocostalis thoracis 8. Longissimus thoracis 9. Iliocostalis lumbrorum 10. Erector spinae Spine - Functional anatomy Axis & atlas The odontoid peg (axis) is held in place by the transverse ligament of the atlas Synovitis here may damage the peg and ligament, leading to Cl/C2 instability and cord damage. Common in severe OA. Worsened by steroids Ruptured transverse ligament of atlas à dens is free to move resulting in atlano-axial subluxation. If complete subluxation occurs the dens can be driven into the spinal cord à quadriplegia or into medulla à death Rupture of alar ligaments These are weaker than the transverse ligament of atlas. Can be torn by combined flexion & rotation of head. à 30o increase in movement to opposite side Dens # If the Dens #s from the body of the axis it is usually very unstable à Hangman’s # because usually kills instantly For this reason “ALL UNCONSCIOUS HEAD INJURIES HAVE CSPINE INJURY UNTIL PROVEN OTHERWISE” Imaging the Dens Requires a mouth open view due to the position of the jaw Imaging C6-T1 Difficult to see because the shoulder sits in the way So pull arms down or do swimmers (trans-axillary) view Foramen transversarium (transverse foramen) In C-spine transmit vertebral arteries to foramen magnum Vessels unite at C1 à basilar artery Injury to the C-Spine can à verterbral artery dissection Intervertebral discs Intervertebral discs (IVDs) are complex symphyses comprising about 25% of the total height of the spine. Annulus fibrosus fibrocartilaginous with concentrically arranged fibres (kept under tension by the nucleus), firm attachment to the vertebral bodies, and innervation to its outer layer The interwoven concentric fibre arrangement affords great tensile strength while facilitating torsional movements Nucleus pulposus Central mucoid, containing a high proportion of water, permitting shape (but not volume) change in response to compressive force Loss of spinal height with age largely results from decrease in water content of the nucleus (from about 90% in youth to 65% in old age: associated decrease in turgor slackens tension in the annulus, predisposing to tears). IVD height (and movement between vertebrae) is greatest in the cervical and lumbar regions, and their anteroposterior asymmetry largely determines the normal spinal curves Herniations Usually occur postolaterally (where annulus is thin & ligaments are few). Localised pain is due to pressure on the longitudinal ligaments & from chemical irritation from contact with substances from nucleus. Chronic pain is localised to the dermatome 95% of herniations are L4-5 or L5-S1 Can also herniated cervically Reflexes Biceps – C5,6 Neurology Triceps – C8, T1 The narrow, Supinator – C5-6rigid confines of the Knee Jerk spinal – L3-4canal and emerging foramina may cause problems relating to or, less commonly, cord compression. Ankle Jerkroot – S1-2 The cervical cord is widest and most susceptible to compression; it is also vulnerable to damage by atlanto-axial subluxation. The lumbar cord ends opposite the L1/2 disc space, so lower lesions cause root syndromes only. (L5-S1 in neonate) NB: LP at L3-4 or below = level between iliac crests Nerve roots are most vulnerable as they emerge from their dural sheaths, just after leaving the exit foramina: they lie in the immediate path of a prolapsing lateral disc. In the lumbar spine such prolapse compresses the lower emerging root Understanding of the nerve root values of movements dermatomes allows assessment of the level of injury Pain and Pain Syndromes Spinal pain is localised to the dermatome, but poorly defined within that 'Mechanical' spinal pain The pain is predominantly axial (unilateral, bilateral, or central) It may be made worse by movement (usually in one plane) or prolonged standing or lifting, and is usually relieved by rest. O/E - may be painful restriction of movement in one direction, a localised site of maximal tenderness (reproducing the pain); 'referred' tenderness and spasm of paraspinal muscles; and absence of neurological signs. A = quadratus lumborum syndrome B = iliolumbar syndromes Nerve root entrapment Symptoms may be three-fold: Axial or unilateral proximal girdle pain from unilateral compression and tension of the dura mater. Root pain along part or all of the dermatome (variable between individuals) from pressure on dural sheath. Weakness, paraesthesiae and numbness due to nerve root (parenchymal) compression Root pain may occur on its own or be superimposed or follow mechanical back pain. It is characteristically sharp and shooting, and made worse by movement and increased intrathecal pressure (coughing, sneezing, straining at stool). O/E - may reveal neurological signs (altered sensation, reduced power, reduced reflex) consistent with single root involvement. Lumbar canal stenosis Symptoms typical of low 'mechanical' back pain, except that: Paraesthesiae (non-dermatomal) occurs in one or both legs. Although symptoms worsen on activity, they may be absent or improve when the lumbar spine flexes forward, increasing the diameter of the canal (walking up steep inclines is better than down, cycling may cause no problems). The patient may adopt a 'simian' posture for this reason (hips, knees, lumbar spine slightly flexed). Neurological signs (decreased sensation, reflexes) may be present, though these may occur only after exercise. 'Inflammatory' neck or back pain This is characterised by diffuse axial pain and stiffness, worsened by rest, but improved by continuing exercise (initial movement may worsen it). Early morning and inactivity stiffness may be marked. O/E - diffuse, symmetrical tenderness and muscle spasm, and restriction of movement in several or all directions. It may accompany sacroiliac symptoms or signs. Sacroiliac pain Characterised by diffuse, ill-defined pain in the ipsilateral buttock, radiating down the back of the leg sacroiliac pain is worsened by stressing the joint, e.g. by running, or by standing on one leg. 'Bony pain' Neck or back pain that is constant, severe, progressive, and present at night is very suggestive of malignancy or infection. Referred pain This may be from proximal locomotor structures (especially glenohumeral, hip joints), the major viscera, retroperitoneal structures, the urogenital system, or aorta. Associated features in the history and general examination should suggest the correct diagnosis; the pain shows no clear relationship to spinal movement; and examination of the spine is predominantly normal (referred tenderness can occur, but the patient's pain will not be reproduced by pressure on spinal structures). Kyphosis = hunchback = abnormal increase in thoracic curvature Can result from erosion of anterior parts of vertebrae à loss of height + kyphosis Dowager hump = wedge #s causing kyphosis in elderly women Lordosis = hollow back Anterior rotation of pelvis à excess curve Assoc with weak abdominal muscles, esp anterior abdominal wall Occurs normally in women during late pregnancy in response to extra weight Scoliosis = crooked back Abnormal lateral curve + rotation of vertebrae Spinious processes turn towards the cavity of the curvature F>M, apparent by 10-15 yrs Back strain Stretching / microscopic tearing of muscle fibres / ligaments of the back Due to extreme movements of vertebral column Usually in the lumbar IV joints Usually due to incorrect lifting of heavy weights Following this injury the muscles commonly go into spasm Spine - Examination Inspect From in front, from the side and from behind & during walking Check for: Loss of normal curves (cervical and lumbar lordosis, thoracic kyphosis) Scoliosis (apex determines level, convex side determines direction) Reduced chest movement (from intrathoracic disease or arthropathy) Paraspinal muscle spasm (muscles look as though they are bulging out) Skin changes (Moles, vascular malformations, and hairy tufts may indicate the site of underlying congenital abnormalities of vertebral bodies. Note any scars or nodules (most common over the bony prominences). Asymmetry, restriction, or pain on movement Spinal movements Bend forward to check for movement of lumbar vertebra (feel spinous processes) Stabilise pelvis & bend spine forward, backward & side-to-side Rotation (arms folded across chest) Chin on chest, look up in air Turn head side to side Put ear on each shoulder Palpation Lay the patient face down on the couch, relaxed with arms folded underneath. For palpation of the neck, place a pillow under the upper chest; for the thoracic and lumbar spine, move the pillow under the abdomen - this helps to relax the muscles, supports the spine in flexion, and aids separation of the spinous processes Skin and subcutaneous tissues. Palpate in a line down each side of the trunk. Use a 'skin rolling' technique to look for areas of hyperaesthesiae. The paraspinal muscles. Feel for increased tone and tenderness on one or both sides. The interspinous ligaments. Apply firm pressure over each in turn. Tenderness with reproduction of the patient's pain suggests local ligamentous or disc disease. Other abnormalities to note during palpation include defects in the spinous processes (spina bifida occulta), or a 'step' deformity of spondylolisthesis (usually L4/5) or retrolisthesis (more common in the cervical spine). The facet joints. Applying firm, jarring pressure with each thumb just lateral to the spinous process may cause pain relating to local facet joint, disc, or ligament lesions. Mid-trapezius. This is palpated for hyperalgesia of fibromyalgia syndrome. The medial iliac crest. This is a common site of tenderness, with reproduction of the patient's pain ('iliolumbar' or 'iliac crest syndrome'). Examination of the SIJ Is difficult to assess clinically Tests designed to stress the SIJs and reproduce pain in the buttock are nonspecific and include: Distraction tests. Firm downward pressure over both sides of the pelvis with the patient lying supine, or over the pelvis with the patient lying on one side 'Knee- to-shoulder' test. With the patient lying flat, flex and adduct one hip and push the flexed knee towards the opposite shoulder, stressing the ipsilateral SIJ. This test is helpful only if the hip and lumbar spine are normal.