Análisis de libros de texto

The shoulder girdle helps us reach, hold, and push away. It is a series of bones wrapped around but separate from our rib cage. The clavicle, at its joint with the manubrium, begins the wrapping. The clavicle is an S-curved bone which extends laterally and meets the acromion process of the scapula at about the place a strap crosses your shoulder, the acromioclavicular joint. The acromion process curves around to the back surface of the body, like an epaulet on a uniform. There the acromion becomes the spine of the scapula and travels towards the vertebrae, horizontal to the earth. The vertical edge parallel to your spine is called the medial border, the bottom-most tip is the inferior angle, and diagonal up to your armpit is called the lateral border. Collectively they form the familiar wing-like triangle of the scapula on your back; the whole scapula slides freely over the ribs. The lateral border continues to the side of the body and helps form the glenoid fossa or shoulder socket, underneath the curving acromion, like a cave under a cliff. The arm attaches to the shoulder girdle at the glenoid fossa and includes the humerus (upper arm), the radius and ulna (forearm), the eight carpal bones of the wrist, and the five metacarpals and fourteen phalanges of the hand. These

Process

Years ago, I was overlooked for a role in a dance because I did not have classically curved arms. This decision motivated my visit to a bodyworker to begin addressing the tension in my shoulder girdle. After a one-hour session of gentle manipulation and repatterning, I left relaxed and seemingly unaffected. The next day my arm was very sore. As that subsided, my neck went into a spasm which lasted a week. When that passed, my left arm began to ache. I began to realize that the work was travelling through my body. For several months, my left leg would go numb whenever I was tense. Sometimes when I was per-forming, I wouldn't be able to feel my foot touch the floor. Eventually, this too

left and the process was complete; it had moved through the skeleton and reached the ground.

Sculpture: Gordon Thorne

"Air"

65

Shoulder girdle: posterior view of left arm

peripheral bones provide a levering system into the center of the body for force and for shock absorption. Two portions of the scapula extend from the back to the front surface of the body:

the acromion, and the bony coracoid process which protrudes forward, under the acromion, for muscle attachments. If all of the bones involved in the shoulder girdle were extended laterally, we wouldn't be able to walk through a door! The main problem with the front to back wrapping is that we often forget to involve the scapula in the action, connecting the humerus instead directly to the clavicle and slightly dislocating the shoulder, causing various discomforts. The humerus should articulate evenly with the entire surface of the cup of the glenoid fossa. The only joint connecting the shoulder girdle to the axial skeleton is between the clavicle and the manubrium (see page 40). This is a fluid-filled, synovial joint, and allows free movement of the shoulder girdle separate from the ribs. The shoulder girdle along with the

Scapula: anterior view of right shoulder joint and ligaments, ribs removed

66

pelvis and legs developed as weight bearing structures after our evolution to land and constitute the appendicular skeleton.

If we trace the levering from the fingers through the shoulder girdle and the skeleton when catching a ball, we see that the impact goes into the wrists, around and through the radius and ulna to the elbow, up the humerus, into the glenoid fossa (not the clavicle) which takes the force to the back of the body into the scapula, down to the inferior angle and around the medial border, the spine and the acromion, then into the clavicle on the front surface (through the acromioclavicular joint), and into the axial skeleton at the manubrium. It then travels down the sternum, out and around each of the attaching ribs, and into the transverse processes, bodies and discs of the vertebrae. There it travels down the front of the

spine and spreads into the pelvis, which generally provides equal and opposite rotational force if the ball is caught in a spiral. The force tra-vels down through the legs to the feet and into the earth.

Holding in any of the joints causes stress.

The ideal is even and equal distribution of weight or force at each joint. For

ex-ample, shoulder injuries for racquetball or tennis players can be caused by locking the elbow before impact, thus sending all the force to the next available joint, the shoulder. Stability of muscles at a joint is necessary, but skipping a joint can cause stress. Efficient use of the arm involves clear levering from the periphery to the back of the body (scapula) to the front of the body (clavicle, manubrium, sternum) to the center of the body (through the ribs to the bodies of the vertebrae) to the earth.

The nerves for the arms and hands pass between the cervical vertebrae in their journey from the spinal cord to the periphery. Tension in the neck can cause pain or numbness in the arm and hand; balance of the neck on the spine can reduce arm stress. When working with the shoulder girdle, check postural alignment of the three body weights over the base of support. Integrated alignment of the axial skeleton: the skull, spine, ribs and hyoid bone, is the foundation for efficiency of movement in the appendicular skeleton: the shoulder and pelvic girdles.

Movement can draw us towards center, towards our axial skeleton; or into space, through our appendicular skeleton. Proximal initiation is movement initiated by bones or joints closest to the center of the body. It will bring your movement towards your center. Distal initiation is movement initiated by the bones furthest from center and will take you into space. For example, if you initiate a movement from your shoulder, your movement stays close to the body; if you initiate from your hand, the movement takes you into space. Try crawling on your hands and knees:

reach with your shoulder as you crawl; reach with your hand. Both are useful, but they have different results. •

Scapula: posterior view

68