Shoulder AnatomyThe bones of the shoulderShoulder anatomy is made up primarily of bones, muscles, ligaments, nerves and blood vessels. The arm bone (humerus), the shoulder blade (scapular), the collar bone (clavicle), and the rib cage (bony thorax). Note particularly the ACROMION (part of the shoulder blade) and the
ACROMIOCLAVICULAR joint (AC joint).
ROTATOR CUFF MUSCLES
Infraspinatus
This large muscle is found "infra" or below the spine of the shoulder blade, and also inserts into the shoulder. It rotates the arm outwards. Next time you carve the Sunday roast lamb shoulder, look out for the spine of the shoulder blade, with the Supraspinatus above it, and the large flat muscle, the Infraspinatus below it. Sorry, anatomy is rather macabre. Chiropractors spend the best part of a year in the anatomy lab, so we become accustomed to such things ...
Biceps muscle
Scapula = Shoulder bladeThe shoulder blade, seen below side-on, or what we call the lateral view. It is an important bone for the both the attachment of the arm - the head of the humerus fits in the 'glenoid fossa' - and for many shoulder muscles.Here you can see the origin of the two heads of Biceps muscle - the short head starts from a bump of bone just in front of the shoulder called the Corocoid process (not important!), and the long head originates from deep inside the shoulder, from the Supraglenoid tubercle (just showing off! It's also not important!) It's the long head that gives grief due to the long journey of its tendon through a groove in the humerus to its attachment just above the glenoid fossa (where the humerus sits). It ruptures sometimes, particularly in older men suddenly taking on a frenzy of heavy work such as shovelling snow. Also after cortisone injections. See the two heads of the BI-ceps muscle? See if you can follow that long tendon of the biceps up to its origin at the Supraglenoid tubercle. If flexes the forearm, and rotates it into what we call supination. Outwards. If you prod with your thumb into your armpit, you'll feel the edge of the scapula, and between the scapula and the ribs is where you can feel the Subscapularis muscle - the very devil when it comes to a frozen shoulder.
Subscapularis muscle
This large flat muscle lies on the underside of the shoulder blade, between the scapula and the ribs. Opposite side to the Infraspinatus. It attaches to the arm at the Lesser Tuberosity (LT in the scan below). Have a good look for it too when carving the Sunday roast! The Subscapularis rotates the arm inwards.
For interesting cases of shoulder pain (and other) at the Chiropractic Coalface,
click here. Chiropractic Coalface.
After serious soft tissue injury, a Doppler ultrasound scan often yields information that cannot be obtained from the clinical examination alone. It does however require specialised interpretation, and is best left to the specialist. This scan of the subscapular tendon (SSC) shows scar tissue (arrows) in the deltoid muscle (D). However that scar tissue can produce a confusing shadow (arrowheads) that mimics a tear. See www.radiographics.rsna.org Regular stretching in the healing phase is what prevents the ugly scar tissue in muscles that can turn a relatively minor shoulder injury into a frozen shoulder.
Read more about FROZEN SHOULDER … Teres Minor muscle
Strains and tears can occur in all muscles in the body. Usually these occur from: * Injury eg a fall * Disturbed nerve innervation of the muscle eg a irritated nerve in the neck * Overuse eg. repetitive action * Improper warmup in sport eg Tennis players who do inadequate prematch preparation. Shoulder Anatomy: The ANATOMY LABYes, indeed, grotesque, but an important place where your chiropractor spent many long hours studying shoulder anatomy, preparing him or herself for a lifetime of helping you recover from your injury.
ROTATOR CUFF SYNDROME Shoulder conditions are often associated with NECK PAIN … Return from Shoulder Anatomy back to ARM PAIN … Go from Shoulder Anatomy to CHIROPRACTIC HELP home page … MONTHLY NEWSLETTER. Signed up yet?
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