The Shoulder

The shoulder is a versatile and very necessary joint for normal human

activity, but if injured proper recovery must be applied to restore movement and

strength. The shoulder is a very interesting and useful joint. The structure of the

bones and positioning of muscles allows for a wide range of movement and makes

it powerful. The shoulder comparative to other joints is fairly durable but injuries

do occur. The diagnosis of the injury must be accurate and there are many test to

assess the type of injury and insure that the type of injury is known. These test are

very specific and use exterior examination. In some cases surgery is needed and in

others simple rest and exercises are needed. There is a wide range of injuries that

an occur to the shoulder joint. The injuries are classified into two groups acute

injuries and chronic injuries. In both cases the injuries can be equally severe and

should be checked by a doctor. For each of the injuries there is a special treatment

that will be prescribed. The treatment can range from simple rest to surgery.

Sports are a major cause of shoulder injuries but different sports are known to

cause different injuries. There are specific injuries that a majority of the time are

caused by a certain sport. Preventative medicine should be applied in these

situations so that the risk of injury is lessened.

The shoulder is a major joint in the human body and performs many tasks.

These task that it performs can be either small very precise movement like

reaching into a small space or very large or heavy tasks like pick up a weight. It

performs these task through interaction with other joints and muscles but this will

discuss the shoulder primarily.

Below is an anterior and posterior view of the bones in the shoulder ("Relevant

Anatomy and Mechanics, Online)

.

There are two main bones in the shoulder the humerus and the scapula. The

humerus is the long slim bone that extends from your shoulder to your elbow. The

scapula or shoulder blade is the scapula which extends from the top of your

shoulder down the posterior side of the shoulder and forms a triangular shape. At

the top of the humerus there is ball-shaped projection that fits into the socket or

glenoid of the scapula, this is why it is a ball and socket joint. The round end of

the humerus fits into the socket of the scapula and allows a wide range of

movement. The glenoid cavity is rather shallow so the head of the humerus merely

perches on the cup like a golf ball on a tee ("Relative Anotomy and Mechanics",

Online). The reason that the ball does not fit directly in the socket is to allow the

arm to rotate in a complete circle. Below is an anterior and posterior view of the

muscles in the shoulder (Relevant Anatomy and Mechanics", Online).

The rotator cuff is the complex of four muscles that arises from the scapula and

their tendons attach to the humerus. The four muscles are the supraspinatus, the

infraspinatus, the subscapularis, and the teres minor. The connection of tendons

around the humeral head permits the cuff muscles to perform many different

movements. The cuff muscles have three basic functions: they rotate the humerus

to perform different movements, they provide muscular balance, and they stabilize

the shoulder by holding the humerus into the glenoid. The glenoid has a ring of

fibrous cartilage to support the joint called the labrum. The movement of the

bones at the joint are lubricated by sinovial membranes or articular cartilage that

cover the head of the humerus and the face of the scapula. The scapula extends up

and around the shoulder joint at the rear to form a roof called the acromion and

around the front of the shoulder to form the coracoid process. The acromion is a

scapular process arising from three ossification centers or places of bone growth.

The three centers are the preacromiom, the mesoacromion and the meta-acromion.

These three centers of ossification are usually fused by age 22. If the three centers

do not fuse the ununited portion is called the osacromiale. The coracoid process

arises from two or three ossification centers that provide a medial attachment for

ligaments. Above the scapula there is a lateral bone called the calvicle that runs

from the top of the shoulder joint to the brestbone or sternum. The clavicle meets

the aromion to form the acromioclavicular join or AC joint. The ligaments in the

shoulder are unlike those in other joints. The ligaments that usually support the

shoulder are weak and this is the reason for many dislocations. A lot of the

stability is provided by the muscles that control movement as well. The most

important muscles in the shoulder are a series of fan shaped ones that run from the

scapula to the top of the humerus and to the end of the clavicle. Among these

muscles is the deltoid, the pectoralis major and the trapezuis. Those are three

major muscles that support the shoulder. The following is a list that describes the

movements that the muscle is responsible for whether it be by itself or through

interaction with other muscles.

Trapezius- elevation, depression, and retraction of the scapula.

Pectoralis major- adduction and flexion.

Pectoralis minor- depression of the scapula.

Latissimus dorsi- adduction and extension.

Teres major- extension and rotation of the scapula.

Deltoid- anterior fibers- flexion.

posterior fibers- extension.

middle fibers- abduction.

Serratus anterior- depression and protraction.

Rhomboid- elevation, depression, and retraction of the scapula.

Levator scapulae- elevation and downward.

Biceps- flexion of arm.

Triceps- extension of arm.

Four short muscles begin on the scapula and pass around the shoulder where their

tendons fuse together to form the rotator cuff. Many tendons are in the shoulder

because they connect the muscles to the bones of the shoulder and allow the

muscles move the bones. The bicep is connected to the shoulder by the bicep

tendon and helps to stabilize the joint

Shoulder injuries need proper assessment and evaluation so that proper

rehabilitation methods can be applied. The shoulder is a difficult joint to assess

because of its intricate makeup. To properly assess a shoulder injury the examiner

must obtain specific details pertain to what happened when it was hurt. The

questions that are asked should be specific so the information needed can be

obtained. Some questions that might be asked are:

-What happened at the time of the injury?

-What position was your arm in at the time of injury?

-Did you hear anything?

-Was there immediate pain and did you stop activity because of it?

-Have you injured this shoulder before?

-Do you have any pain when you are at rest?

Once the proper information has been gathered then the visual inspection of

the area can begin. The examiner should look at the patients neck, shoulders,

scapulae, and upper thorax. Then look at the neck and follow the contours of the

tissue to look for deformity, scars or marks. The AC joint should be looked at for

symmetry. Asymmetry is indicative of a AC separation. Discoloration may be

apparent from a rotator cuff injury, fracture or bicep rupture. Significant

disformity of the deltoid muscle could indicate glenohumeral dislocation. A

indentation of the upper bicep region and/or a bunching of bicep tendons usually

signifies a rupture of the biceps tendon. If the scapulae appears uneven then it

could be a sign of poor muscle balance. If the scapulae is sticking out or winging it

usually means there is weakness of the serratus anterior muscle. If the patient has

a forward head and rounded posture than he/she could have impingement

syndrome at the AC joint. The next step in the visual examination is to palpate the

shoulder. The examiner while standing behind the athlete looks for places of

tenderness, deformities and temperature changes. First you palpate the area where

the clavicle connects to the sternum or the sternoclavicular joint for signs of

dislocation. Then move to the clavicle to search for possible fractures. The AC

joint is palpated for signs of partial or total separation. The bicep tendon is

palpated with the patients thumb touching their shoulder and their arm rotated

outwards to look for tendinitis. Next the supraspinatus muscle is palpated beside

the acromion while the patient puts his/her hands on their hips to look for

tendinitis or a tear. After these areas have been palpated the examiner then moves

onto strength testing. These are resisted isometric movements that are performed

with the patient laying on their spine. The examiner will note which movements

cause pain and will begin to determine which muscles are being used. A careful

record should be kept of which muscles are painful when moved. The record can

be compared to a general guideline of patterns of pain and weakness. The

guidelines are as follows:

strong and painful- tendinitis

weak and painful- serious

weak and painless- muscle tear

all strong and painful- hysteria

all strong and painless- normal

pain with repetition- vascular

After the examiner had completed the initial evaluation which is described above

he/she should have a good idea of the injury that the patient has. But if the

examiner has mixed findings or needs to confirm his/her findings then the special

test listed below should be applied.

Supraspinatus Test- the patients arms are stretched outward at a 90 degree angle

to their side and then the arm is internally rotated so the thumbs are pointing

downward. The examiner applies downward pressure and the patient resists. If

there is pain or weakness it indicates supraspinatus involvement.

Drop Arm Test- the patients arms are stretched outward at a 90 degree angle to

their side and then the patient lower the arm to their side. If the patient is unable to

actively lower the arm or is able to lower the arm but with considerable pain.

Another result is if the patient cannot lower the arm but can hold it straight out

then the examiner should give a light tap on the wrist and the arm will fall. This

tests for rotator cuff tears, especially in the supraspinatus.

Bicep Test- the examiner resists forward movement of the arm while the arm is

straight out and the elbow is completely extended. Pain or weakness indicates

bicep strain or bicepital tendinitis.

Test for a Subluxing Bicep Tendon and Bicipital Tendinitis- the patient lies flat

on their back and extends the arm off the side of the table with the palm up then

bring the arm in and flip the palm over to lay the arm flat on the table with the

palm facing down. If pain occurs then tendinitis is possible. If the bicep tendon

pops out at the top of the bicep then there is a tear of the bicep tendon.

Impingement Sign- the arm is extend straight out from the body with the thumb

pointing up and then turn the arm over internally so the thumb is almost pointing

down. If there is reproducible pain then there is a problem in the subacromial

space.

Cross Adduction Test- the arm is extend out infront of the body and is then

brought across the front of the body. If there is pain on the back of the shoulder

then it is possible that there is a cubcoracoid bursitis or capsule tear.

Apprehension Test- the patient lies on their back and examiner brings the arm

straight up from the body and then has the elbow bent at a 90 degree angle. The

examiner then externally rotates the arm by holding the elbow and pushing on the

hand. If the patient looks apprehensive or alarmed and feel that if the arm is

rotated anymore the shoulder will dislocate.

Relocation Test- immediately following the apprehension test and any positive

results this test should be done. Apply pressure to the humeral head by gently

pressing the humerus into the shoulder.

Load and Shift Test- the patient lies flat on their back and the examiner applies

pressure to the glenohumeral joint from different sides. If the humeral head moves

excessive amounts, especially if it feels as if it has moved over the labrum, then uni

or multi-directional instability could be the problem. If the joint clicks as the

pressure is applied then it could be a torn labrum.

The shoulder can be injured quite easily and the complexity of the shoulder

allows for a wide variety of injuries. The injuries are classed under two different

categories- acute and chronic. Acute injuries are those injuries that are cause by

sudden impact or shifting of the shoulder. Chronic injuries are those that are

caused over long periods of time and the muscles are usually overworked. Below

some of the injuries that can occur are discussed.

Acromioclavicular Joint Separation

A shoulder separation is actually a dislocation of the AC joint and is

classified as an acute injury because of the sudden onset. It usually occurs when

the shoulder is forced beyond its limits or when the elbow strikes the ground. The

AC joint is the place where the clavicle meets the scapula (acromion). There are

three grades of an AC joint separation. The first grade is a simple sprain of the

ligaments around the joint. The second grade is when the ligaments around the

joint are actually torn. The third grade is when the ligaments around the joint are

torn and the ligaments that attach to the clavicle to the coracoid process are torn.

This results in a bump on the shoulder. In all cases the joint will be tender and

there might be bluish discoloration. In grade two and three there will be a

considerable amount of swelling. In grade three there could be the feeling of

popping due to the looseness of the ligaments and the joint shifting. X-rays are

usually used to show the extent of the injury. They have the patient hold a weight

in both hand and let there arms hang. They then take an X-ray of the shoulders.

The weight separates the AC joint that has been injured and the extent can be seen

by how big a space there is. Treatment for grade one and two is just a sling, pain

medicine and rest until the ligaments have healed. Most cases the shoulder

becomes relatively pain free in 3 weeks. The treatment for grade three separations

is somewhat controversial. Many studies have been conducted but there seems to

be no difference between surgery and doing nothing. Many people who have

surgery will need another surgery later in life because the injury cause the joint to

degenerate and become painful. But some people believe in the surgery because

they feel it will benefit the person. The surgery that the person undergoes involves

relocating the joint and repairing the ligaments.

Bicep Tendonitis

This is classified as a chronic injury because it develop over a considerable

amount of time. There is a tendon that holds the bicep tendon on the attachment of

the shoulder joint, if the shoulder has been injured previously then the ligaments

have been stretched previously, this may cause the bicep tendon to fray and rub

against the bone causing the tendonitis. Treatment for this injury is simple rest,

ice, and refraining from activity will decrease the pain. There is a surgery but only

to used in extreme cases.

Frozen Shoulder

Frozen shoulder is a term used to identify a painful condition of the

shoulder. The shoulder may be "frozen" and there by making it difficult to lift and

hard to reach for a wallet in the back pocket. Other difficulties may be taking

shirts or jackets off. Frozen shoulder develops from a strain or sprain but are

classified as chronic because they become painful but are the result of an acute

injury. The shoulder becomes painful and the person refrains from using it there

by becoming "frozen". Frozen shoulder can be the result of scar tissue developing

on the shoulder but it can also involve the subscapularis which is one of the rotator

cuff muscles. Sometimes the injury will go away but a physical therapist should be

consulted to receive exercises and hands on techniques.

Bursitis or Impingement

A shoulder busitis is very painful and is classified as a chronic injury but

can be the result of an acute injury. A bursa is a fluid filled sack that lubricates the

joint. If the bursa becomes inflamed it is painful because the tissue is pinched

between the humeral head and the acromion. Painful bursitis may lead to a

decrease in shoulder motion and result in Frozen shoulder. They can be caused by

overuse or degenerative changes in the shoulder. The treatment of the injury

consists of physical therapy to strengthen the rotator cuff muscles, steroid

injections to keep swelling down and surgical decompression in some cases.

Rotator Cuff Tendonitis

The four muscles that make up the rotator cuff are important for elevation of

the arm and lifting the arm away from the side of the body. If the muscles are

damaged then use is limited. Tendonitis is classified as a chronic injury but can be

the result of an acute injury. A partial tears may cause significant pain and limited

use. Total ruptures of the cuff can lead to total disability of the shoulder and

extremity. If a rupture occurs then surgical reattachment is needed. Tendonitis of

the cuff may be caused by muscle imbalance. People that work with weight a lot

build the chest and back muscles and forget the rotator cuff. Also weight lifters

usually perform many over head lifts which further aggravates the rotator cuff.

Tendonitis in the cuff can be caused by degenerative changes in the clavicle. The

tendons of the muscles rub against the extra bone that has been formed and cause a

lot of pain and immobility. In this case a surgery called acromioplasty is

performed. Tendonitis can be caused by a weak rotator cuff also. Simple

exercises are applied to regenerate the strength of the muscles.

Sports are the major cause of shoulder injuries. Almost any sport, contact

or non contact, can result in a chronic or acute injury. For example baseball is not

a contact sport but an acute injury can occur when a player is diving and a chronic

injury can be caused by throwing the ball to hard. Certain sports are known to

cause certain injuries and using this information can be avoided. Two sports that

are looked over when considering shoulder injuries but are very popular are alpine

skiing and weight lifting. In a survey conducted in the United States 11.4 percent

of all injuries obtained while alpine skiing were shoulder injuries (Feagin,

Oniline). Even though women are thought to be injured more easily the ratio of

men that hurt their shoulders to women is 3:1 (Feagin, Online). The most common

cause of a shoulder injury was falls, followed by collisions with other skiers and

collisions with trees (Feagin, Online). The most common injuries were rotator cuff

strains, AC joint separations, and clavicle fractures (Feagin, Online). Another

sport that caution should be taken is in weight lifting. Weight lifters will develop

an imbalance in their muscles. Usually they have oversized deltoids or pectorals

and weak rotator cuff muscles. This results in less flexibility in the joint and leads

to problems. Also many use improper technique when they lift. They will hyper

flex and hyper extend their joints. This leads to problems. In both cases, alpine

skiing and weight lifting, proper stretching before the joint is used is crucial to

keeping the shoulder in good shape and injury free.

The shoulder is a very intricate and versatile joint but it can be injured

easily if proper techniques are not applied in preparation for an activity. The

structure of the shoulder is a dense collection of bones, tendons, muscles, and

ligaments that work together to provide support, a wide range of movement, and

power so the shoulder can perform task necessary to normal human life. The

shoulder can be injured in many ways and there are many types of shoulder

injuries. If the shoulder is injured then proper rehabilitation must take place to fit

the type of injury. This rehabilitation should obtained from a doctor to ensure

quick and proper rehabilitation. Some injuries require different methods of

rehabilitation, the rehabilitation ranges from simple rest to surgery. Preventative

medicine should be applied before doing any activity. Certain sports cause certain

injuries so the proper preparation should be applied. The shoulder is an important

joint in the human body.....if not the most important.

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