Your shoulder joint, the body’s most mobile joint, is quite complex.
Most people think their shoulder is just the ball-and-socket shoulder joint (glenohumeral joint) on top of the arm bone (humerous). However, your shoulder actually connects three bones: the upper arm bone, the collarbone (clavicle) and the shoulder blade (scapula). In addition, another smaller joint (acromioclavicular joint) attaches the collarbone (clavicle) to the shoulder. This smaller joint acts as a stabilizing pivot point, which lets your arm lift above your head.
The main shoulder joint has two kinds of cartilage with two different roles. The white articular cartilage on the ends of the bones allows the bones to smoothly glide and move across each other. The labrum cartilage circles the shallow shoulder socket (glenoid) and deepens the socket. This cuff of fibrous, rigid cartilage increases the shoulder’s stability and allows for a wide range of movement.
The shoulder joint itself, is encapsulated within a tough, fibrous sleeve (synovium), which holds the joint together. The outer layer provides stabilizing protection while the inner layer produces a fluid to lubricate the joint and feed the cartilage. The four muscles grouped together in the shoulder, along with their accompanying tendons and ligaments, comprise the rotator cuff, which holds the joint together and controls movement. The tendons, tough cords of tissue holding the muscle to bone, enable the muscles to move the joint. The ligaments, fibrous tissue connecting bone to bone, hold the three shoulder bones to each other to help stabilize the shoulder joint.
Because of its unique construction, the shoulder joint is the only joint in your body that can complete so many actions. It can make your arm flex, bend, raise forward, extend, pull out, pull behind, pull away, pull into, rotate towards, rotate away from, or circle. Free movement of this joint is essential to complete all these activities.
Lifestyles like truck driving, which keep the shoulder immobile for extended periods of time, can impact the joint’s flexibility. People who spend long hours sitting in one position – whether behind the wheel or behind a computer screen – often sit relaxed, with their shoulders curved forward. Holding this position over a long period of time can eventually cause your shoulders to permanently retain an improper, hunched posture.
On occasion, continued immobility of the shoulder can lead to frozen shoulder (adhesive capsulitis). This immobility may be caused by chronic pain, rheumatic disease, tissue growth within the actual joint, or too little fluid to keep the joint lubricated. Common treatment for frozen shoulder includes medication (aspirin and ibuprofen) to reduce pain and swelling, heat to improve blood flow, gentle stretching exercises, electrical stimulation of muscles and nerves, cortisone injections, and as a last resort, surgery.
Rotator cuff disease can also affect the shoulder; this disease includes two conditions: tendinitis and bursitis. Tendonitis occurs when the tendons become inflamed after being pinched within the shoulder. Bursitis, inflammation of the small fluid-filled sac (bursa) that helps protect the shoulder joint can be caused by disease, such as rheumatoid arthritis, and/or by overuse of the shoulder in activities that include frequent overhead reaching.
Tendinitis and bursitis may occur independently or concurrently. Treatment for both can include rest, ice packs, medicine to reduce pain and swelling (aspirin and ibuprofen), ultrasound to warm deep tissues and improve blood flow, and gentle stretches and exercises to build strength, cortisone injections, and again as a last resort, surgery.
Often rotator cuff disease leads to a rotator cuff tear, which is treated like Rotator Cuff Disease with these additions: hot/cold packs, electrical stimulation of the muscles and nerves, and exercises to improve range-of-motion, strength, and function.
Recognizing all the arm movement your shoulders are involved in, it makes sense to keep them as strong and flexible as possible.
Some simple exercises can help maintain a good blood flow to your shoulder joint and also improve posture. While driving, complete 10 repetitions of this stretching sequence every few hours: tighten your shoulder muscles and pull your shoulders forward toward each other, hold 10 seconds, relax for 10 seconds, and then pull your shoulders backwards toward each other, hold for 10 seconds and relax for 10 seconds. Repeat every few hours.
At your destination, take a few minutes to complete these additional exercises: Holding your arms out horizontally to the side, slowly rotate them 10 times forward and backwards; Keeping your arms straight, slowly lift your hands above your head, hold for a few seconds and bring them back down; Standing against a wall with your hands behind your ears, touch your elbows to the wall, draw them forward towards each other as far as comfortably possible, then move them back against the wall. Repeat each 10 times.
You’ve got a lot of responsibilities on your shoulders; keep them flexible.