shoulder anatomy as well as the
structures that are often injured can help in both prevention and
treatment of sports injuries.
shoulder joint is commonly injured
during sporting activities that involve the arms and upper body.
Overhead athletes such as baseball players, swimmers, tennis players,
and other athletes that use the upper extremities are often susceptible
to numerous shoulder injuries.
starts with the bones that make
up the shoulder joint. The shoulder joint is a ball and socket type of
joint, with articulation of two primary bones, the humerus
(upper arm), and the scapula
The head of the humerus touches against the glenoid fossa of the
scapula. Although this is referred to as a ball and socket joint, a
better description of the shoulder joint would be to picture a
basketball placed on a tea saucer.
The shoulder joint in itself is a very mobile joint, allowing for
motion in multiple planes in a very wide range. However, with this
mobility comes decreased stability, and shoulder instability problems
are common athletic injuries.Take the Shoulder Anatomy Video Tour
Ligaments of the Shoulder
The ligaments are an important part of shoulder anatomy. The primary
static stabilizers of the shoulder joint are the ligaments of the
The joint capsule
surrounds the entire humeral
head, and attaches it to the shoulder blade. Within the shoulder joint
capsule, there are areas of thickening, which are referred to as
The primary ligaments of the shoulder can be divided into anterior
(back), and inferior
These areas of the shoulder capsule become tight at different ranges of
motion, providing stability to the shoulder joint during activities.Learn more about the ligaments and joint
Next in shoulder anatomy is the muscles.
Shoulder stability is highly dependent upon the muscles of the
shoulder, specifically the rotator cuff muscles.
The rotator cuff is comprised of four seperate muscles, all originating
from the scapula and inserting on the humeral head. The rotator cuff
muscles can be classified by their positions on the body. The posterior
includes two muscles on the back of the
shoulder. The infraspinatus
and the teres
. These muscles are responsible for external rotation of
superior rotator cuff
found on top of the shoulder, and includes the supraspinatus
This muscle is commonly injured with a rotator cuff tear.
third and final group of rotator cuff
muscles is the anterior rotator cuff, which includes the subscapularis
This muscles sits on the front of the shoulder, and causes internal
rotation of the humerus.
Together, the rotator cuff muscles help to keep the humerus centered in
the glenoid fossa, and to provide stability to the shoulder joint
Other muscles that play an important role in shoulder stability include
the scapular stabilizers. This group of muscles originate from the
spine, and run to the scapula.
The primary scapular stabilizers are the rhomboids and trapezius. In
addition to the rotator cuff and scapular stabilizers, the deltoid is
another important shoulder muscles, found on the outside of the upper
Tendons of the Shoulder
the muscles of the
shoulder are attached with tendons. The rotator cuff tendons, and the
biceps long head tendon are the most commonly injured shoulder tendons.
Tendons are susceptible to tendonitis
and other overuse
injuries. Learn more about the shoulder tendons
Cartilage of the Shoulder
The glenoid labrum
is a type of fibrocartilage
tissue that surrounds the rim of the glenoid fossa, and provides shock
absorbtion at the shoulder joint.
The labrum also helps to increase the depth of the "socket", making the
shoulder joint a bit more congruent. Labral tears are often associated
with shoulder injuries such as dislocations.
Togther, all of the ligaments, bones, and
muscles of the shoulder work together to provide stability and keep the
shoulder working. Understanding shoulder anatomy is the key to
prevention and treatment of shoulder injuries. Take
the Shoulder Video Tour