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Neck and Shoulder Pain Stan Andrzejewski, PT Anatomy of the Spine and Shoulder Girdle A basic vertebra is comprised of a bony block, called a vertebral body, and a bony ring. The disk is sandwiched between two blocks. The ring houses the precious spinal cord. The ring consists of 2 pedicles, 2 lamina, 1 spinous process, and 2 transverse processes. Processes are levers that attach to muscles. Each vertebra has 4 facets [joints], 2 superior, 2 inferior attached on the lateral posterior side of the vertebral body. A thoracic vertebra has 4 more facets attaching to the ribs. Facets are the synovial joints of the spine. This means they have a synovial membrane, that secrete synovial fluid, and a capsular ligament that holds the synovial fluid. The angle of orientation of the facets change with each vertebra. The angle influences the direction of movement. The spine is segmental, consisting of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral [fused], and 4 coccygeal [fused] vertebras. We must consider that each vertebrae has any direction of movement. The image of vertebra floating in all directions is useful. We categorize each vertebra movement as flexion, extension, rotation, and side bending. Some vertebras move less, some more. This is called the relative flexibilities or inflexibilities of the spine. Lumbar vertebras are massive for weight bearing. The facets have a sagittal orientation allowing little rotation, but a lot of flexion, extension. Thoracic vertebras are medium size with ribs attached. Ribs are the armor of our vital organs. We have 4 more facets per vertebrae. Since there are more facets to become hypomobile, thoracic movement is more likely to be restricted. The spinous processes are sharply angled down to prevent excessive backbending. Cervical vertebras are the smallest, designed for mobility of our head. They are the easiest to wear away because of their size and mobility. Facets are angled at 45 ° from the horizontal. The cervical vertebras have 2 additional atypical joints called the lateral interbody joints or the uncovertebral joints of Luschka. These joints are on the posterior lateral vertebral bodies of the cervical spine. They have no articular cartilage or synovial components. Cervical disks are shaped with the anterior part of the disk, 2 times higher than posterior part. The shoulder girdle consists of the scapula, humerus, and clavicle. The scapula [shoulder blade] is a broad flat bone that consists of a spine, acromium process, coricoid process, and an inferior angle. The glenoid fossa is shallow pear shaped socket about the size of a quarter. The humerus [upper arm bone] has a head, 45 ° neck angle, a greater and a lesser tubercle, as well as a deltoid tuberosity. The clavicle [collar bone] is "S" shaped. Spinal ligaments allow efficient passive joint stabilization. They limit and direct vertebral movement. These ligaments have many pain receptors. The anterior longitudinal ligament [ALL] is thin, stretching from the occiput to the sacrum. The ALL stretches with backbends. The posterior longitudinal ligament [PLL] is thick, but tapers from the lumbar to the sacrum. The PLL stretches in forward bends. There many more spinal ligaments connecting vertebras to each other in every imaginable direction. Disks are fluid-filled cylinders. Their water content decreases with age. Most disk surgery is performed on people in their 30s to 50s, when the water content is enough to make them bulge. Normal spinal curves allow even disk compression. There is 3x more interdiscal pressure in sitting than in standing. Muscles are divided into 2 types. Deeper, postural muscles, such as the multifudus and scaleni, sustain posture with lower energy. Surface, phasic, 2 joint muscles, such as the erector spinae and the sternocleidomastoid are quick and explosive. The muscle contractions can be concentric [shortening], isometric [same muscle length], or eccentric [lengthening] contractions. Normal weight bearing through the spine is a tripod design. The 2 facets in the back and the disk to the front. The disk / facet weight bearing is [80 / 20] through the lumbar spine and [50 / 50] in the cervical spine. Joint of the Shoulder Girdle The shoulder is considered to have 4 joints : gleno humeral, acromio- clavicular, sterno clavicular, and the scapulothoric. The gleno humeral joint is a shallow ball and socket synovial joint. The congruent area where the humerus and fossa meet is the size of quarter. The acromio- clavicular joint [AC] is more prone to fracture and dislocations than the SC. The coracoclavicular ligament is considered both the conoid and trapezoid ligaments. These ligaments allow the clavicle to move in first 30 degrees of elevation, then become taut, The AC joint is stable through the rest of elevation. The sterno clavicular [SC] joint is highly mobile and allows 30 ° of elevation and protraction, 50 ° of backward rotation. The articular disk of the SC provides mobility and shock absorption. The scapulothoracic joint is not a synovial joint, but essentially muscles attached from the rib cage and spine to the scapula. The scapula literally slides upon the rib cage. Normal Biomechanics The plumb line in stance runs vertically down through the ear lobe through cervical spine through shoulder through greater trochanter through knee through front ankle. Vertical alignment allows for efficient posture because of the reliance on the bony structures. There is a tripod support of disk / lateral interbodies and both facets in the cervical spine. More bony support means less muscular work. Normal cervical and thoracic posture shows capital flexion with cervical and thoracic extension. Facets take 50%, disks / lateral interbodies take 50% of the weight. Lumbar facets take only 20% and lumbar disks take 80%. Ideal scapular posture on the back ribs is down, in and in. But the scapula should not retract in towards each. ö down
- depression
Ideal vertebral movement is segmental, each vertebrae moves slightly, but total range is considerable. Vertebral movement is rotational [3D] movement in all directions. Cervical vertebral movement is much more than thoracic. Cervical facet orientation of horizontal plane allows rotation and sidebending as well as flexion and extension.
Occipital - C1 ö nodding
"yes" C1 - C2 ö shaking
head "no" C2-C7 ö gliding
in all directions
Thoracic vertebral movement is restricted by rib cage and downward facing spinous processes. There is more less thoracic than cervical movement in all directions. The thoracic spine has more rotation but less flexion and extension than the lumbar spine. The entire spine allows ö 75°
of cervical flexion This movement pinches the anterior disk, as well as bulges the posterior disk. The inferior facets of cepheid body slide up and forward, gap, pull on capsule and tendons. The entire spine has ö 75°
of cervical extension This movement pinches the posterior disk and bulges anterior disk. The inferior facets of cepheid body slide down and back compressing facet. Spinal rotation compresses the disk with torque. The facet, rotating toward, flexes [back and down], other facet extends [forward and up.] Movements of the scapula sliding upon the rib cage are considered scapular thoracic movement. ö protraction
- retraction Both posterior tipping and inner edges moving into ribs are synergistic with thoracic extension. The clavicle moves relate to the sternum at the SC joint. The clavicle moves relative to the scapula at the acromium at the AC joint. Clavicular movements are called : ö elevation
- depression Glenohumeral movement is that of the humerus moving in the glenoid fossa of the scapula. The movement is in all possible directions. We categorize this movement in the cardinal planes of flexion, extension, horizontal adduction, horizontal abduction, external rotation, internal rotation. But the movement of the arm must be considered as the combination of scapular thoracic, sterno clavicular, acromial clavicular, and glenohumeral movement. Elevation in plane of scapula [POS] is about 45° between the sagittal and frontal planes, 45° in-between flexion and abduction. In the plane of the scapula the humerus and glenoid fossa joint surfaces have the most contact [most congruent] in surface area with each other. The initial 30° of elevation of the arm is initiated by the supraspinatus muscle. The scapula is still stabilized on the ribs. The scapula first moves relative to the clavicle at the AC joint with protraction, elevation, and external rotation. Then the AC joint close packs. Then the scapular- clavicular unit moves relative to the sternum at the SC joint with backwards rotation and elevation. After first 30 ° of elevation, humerus [90 - 110°] moves on the scapula [60°] in a 2:1 ratio. This is called scapular humeral rhythm. The distal end of the clavicle lifts and backward rotates once the AC joint closes and the movement is at the SC joint. The rotator cuff and long head of biceps stabilizes and glides head of humerus inferiorly [cinches] in glenoid fossa as humerus elevates. The humerus externally rotates to avoid greater tubercle into AC shelf especially in abduction, less in flexion. But in the last 30° of elevation, the humerus internally rotates to 180°. The last 20 ° to elevation needs thoracic extension and side bend. Faulty Biomechanics The common thread of all neck and shoulder faulty mechanics is the forward head posture. ö capital
extension - tension at occipital ridge ö unstable
scapulae winging and premature elevation ö pelvis
out of neutral ö ungrounding
lower extremities
The joints of the mid cervical spine [C 4,5,6] are typically compressed due to a lack of skill of lightness or lengthening. The relative inflexibilities commonly show little movement in the lower cervical and upper thoracic spine [ C 6 - T 3], combined with relative excessive movement at C 4,5,6. Shoulder impingement is a common injury of the rotator cuff due to poor upper quarter biomechanics. The rotator cuff cannot do its job on gliding head of humerus downwards because of the thoracic spine, scapula, and clavicles don’t do theirs. ö the
rotator cuff does not cinch head of humerus downwards for elevation The supraspinatus stress c |