understanding the shoulder article-2014

8/10/2019 Understanding the Shoulder Article-2014

1/11

The shoulder: understanding the sciencebehind both movement and dysfunction

By Chris Gellert, PT, MMusc & Sportsphysio, MPT,CSCS, MS

!ntroductionThe shoulder is a complex joint. That is involved in daily activities such as gettidressed orreaching into a cupboard. Because the shoulder is truly a ball and socket joint,providingit to move freely in six dierent motions, this makes it more susceptible to injurthis article,we will review the anatomy of the shoulder, common injuries to the shoulder,functional

assessments and training strategies to work with clients with previous shoulderinjuries.

"unctional natomyet!s look at two common functional tasks that everyone performs on a daily baThe "rst is getting dressed. The movement of putting a shirt on, biomechanicalre#uiresthe shoulder to undergo initial hori$ontal adduction, elbow %exion, then shouldabduction andexternal rotation. &natomically, the posterior deltoid contracts during hori$ontaabduction,

supraspinatus and medial deltoid abduct the shoulder, while teres minor andinfraspinatusexternally rotates the shoulder.a. 'etting dressed

"igure #$ Getting dressed "igure %$ Medial deltoid and supraspina

b. (eaching into cupboard

1


2/11

The process of reaching into the cupboard biomechanically re#uires shoulder %as seenin the "gure below. )ere during shoulder %exion, the humerus glidesinferiorly*down+ on theglenoid cavity. &natomically, the anterior deltoid and coracobrachialis %ex the

shoulder.

"igure $ "igure '$ nterior "igure ($ Coracobrachialis)eaching into a cupboard deltoid

Basic anatomyet!s look at the shoulder anatomically There are four major joints within theshoulder complex,which include the glenohumeral joint, acromioclavicular joint, sternoclavicular andscapulothoracic joint.

"igure *$ +oints ithin the shoulder comple-

MusclesThe four primary muscles that make up the rotator cu include supraspinatus,infraspinatus,teres minor and subscapularis. These four muscles provided stability and areinvolved in multipledaily activities, such as reaching, lifting, getting dressed and throwing a ball.

2


3/11

Supraspinatus muscle !nfraspinatus muscle Teres minor muscle

Subcapularis muscle-ide raises the arm xternally rotates the arm xternally rotates the armInternally rotates the arm

"igure .$ )otator cu/ muscles

Biomechanics/. 0uring shoulder %exion and abduction*side raising, there is #%0

degrees of movement that occurs at the glenohumeral joint and *0degreesat the scapulothoracic joint. This is called thescapulohumeral rhythm, *-)(+ as seen in "gure 1. -)( is de"ned asthe movement relationship between the humerus and the scapuladuring arm raising movements.2. &s seen in "gure 1, the humerus slides down in the glenoid cavityas the scapula rotates.3. & force couple is formed during abduction*side raising+ of theshoulder. The importance of this force couple*"gure 4+, is that whenthese low trape$ius and searattus anterior are working synergistically,they biomechanically together cause upward rotation of the scapula

on the thorax. This upward rotation of the scapula on the thorax isre#uired to raise them arm to the side. Individuals suering fromimpingement syndrome and rotator cu repair have an altered rthymas seen in the "gure below.

3


4/11

"igure 1$ 2ormal scapulohumeral rthym "igure 3$ forcecouple is formed by the

low trape$ius andserratus anterior causing

upward rotation and gliding

of the scapula on the thorax

"igure #0$ bnormal scapular rthym

Common in4uries and causesThere are dierent types of injuries the shoulder can sustain. The most commonthe shoulderare impingement syndrome, rotator cu repair and sprain,. In this next section,

will revieweach condition providing a deeper understanding of each.a$ !mpingement syndromeMechanism of in4ury5pathophysiology: -houlder impingement may be eitheprimary orsecondary, diagnosed by physicians. There are two types of shoulder impingemwhich isdescribed below.

#$ Primary6Mechanical7 impingement Is caused by a mechanical dysfunctionas bursa,

acromioclavicular joint, acromion, humerus or rotator cu5supraspinatus tendobeneath thecoracromial arch. This is a mechanicalproblem that may result from sub acromcrowding.%$ Secondary6Structural7impingement Is caused by a relative decrease insubacromial spacecaused by instability of the glenohumeral joint, tight posterior capsule and wea

4


5/11

ofscapulothoracic musculature.

0ecrease in subacromial space comprises the supraspinatus tendon,predisposing itto micro tears leading to degeneration and ultimately tearing.

Tightness of the posterior capsule causes the humerus to migrate into thacromioclavicular joint.

6eakness of scapulothoracicmuscles leads to abnormal positioning of thscapula.

b$ )otator cu/ repairMechanism of in4ury5pathophysiology: 7ommonly occurs as a result of atraumaticaccident or fall and is graded from one to three in severity. They are classi"ed aacute,chronic, degenerative, partial or full8thickness tears.

)ow dysfunctions develop

Impingement between the humeral head and coracromial arch occurs fromrepetitive loads.

6ith aging*degenerative+, the farthest portion of the supraspinatus tendon i

particularlyvulnerable to impingement or stress from overuse. 9steophytes*7alci"cationdeposits+develop resulting in decreased sub acromial space leading to continuous microtrauma andeventual gradual tears.

In &thletes, weakness of the rotator cu*supraspinatus, infraspinatus particuresults

in humeral head repositioning superiorly*up+ impinging the rotator cu*(T7+.This impingement leads to degenerative changes and gradual or sudden tears r

Medical treatment:Indications for surgery, include failure to make progress a

to ; months of conservative care, or an acute full8thickness tear in an activeindividualyounger than


6/11

Medical treatment: >hysical therapy*modalities are used such as electricstimulation to relaxmusculature and connective tissue as well as (9? and stretching exercises+.

"igure ##$ Shoulder bursitis

Common assessmentsThere are a few shoulder assessments that can prove to be eective.a$ 8all Push up test6ith men shirt o, women wearing a sports bra, have the client place arms showidth onwall with feet e#ual distance. Instruct them to lean forward*nose towards wall+ push backto starting position. *Look for shaking or juttering of shoulder(could indiceither weaknessor potential instability)

Winging of scapula indicates weakness of serratus anterior as seen in gure below.

"igure #%$ 8all push up test

b$ )each behind bac9 test

6


7/11

"igure #$ )eaching behind their bac9

Instruct the client to reach behind their back and raise their hand as far asup towards

their spine.

?ark this*the spinal segment+8serves as an objective improvement for

measuring andimproving internal rotation of shoulder.

Then repeat on the opposite arm.

Training strategies and programming for shoulder in4uriesa$ !mpingement syndrome)ecommendations for training5specic e-ercises ith rationale:

Continuationof posterior capsule stretching

-trengthening serratus anterior and low trape$ius together

Scapular retractionexercises such as mid row with cable machine and l

trape$iusstrengthening will decrease the load to front of the shoulder.

;-ternal rotation strengthening ideal is side lying which is more isolaforteres minor and infraspinatus recruitment*decreases the load to the antershoulder+.

"igure #'$ Seated mid ro e-er

7


8/11

"igure #($


9/11

;-ercises that are contraindicated include ith rationale

-eated 0B shoulder press*creates excessive load to the medial deltoid+.

at pull downs behind the head*at end or range places greatest stress on glenohumeral ligaments as well as on the labrum+.

Barbell s#uats*places compressive and loading forces on the surgical gra

pright row*at end of range8shoulder is maximally internally rotated whicplacesstress on all glenohumeral ligaments, labrum and connective tissue+.

-upine dumbbell pullovers*places greatest stress on the anterior capsule joint+.

c$ Shoulder Bursitis)ecommendations for training

Continuationof stretching pectoral and upper trape$ius muscles.

-trengthening the posterior upper extremity is key. Scapular retraction

e-ercisessuch as mid row with cable machine, bent over mid row, and lotrape$iusstrengthening alldecrease the load to front of the shoulder.

;-ternal rotation strengthening ideal is side lying which is more isolaforteres minor and infraspinatus recruitment*decreases the load to the antershoulder+.

voidance initially of shoulder press and side raises. It is important toreintegratethese exercises slowly.

SummaryThe shoulder is a complex unit that is comprised of a multitude ofligaments, tendons, connective tissue, muscles that synergisticallyinitiate and correct movement, and stabili$e when an unstableenvironment. nderstanding the anatomy, biomechanics and weaklinksof the shoulder, common injuries and evidenced based trainingstrategies, should provide you with the insight to better understandand work with clients with these kind of injuries more con"dently.

7hris is the 79 of >innacle Training C 7onsulting -ystems*>T7-+. &continuing education company, that provides educational material inthe forms of home study courses, live seminars, 0D0s, webinars,articles and min books teaching in8depth, the foundation science,functional assessments and practical application behind )uman?ovement, that is evidenced based. 7hris is both a dynamic physicaltherapist with /: years experience, and a personal trainer with /Eyears experience, with advanced training, has created over /=

9


10/11

courses, is an experienced international "tness presenter, writes forvarious websites and international publications, consults and teachesseminars on human movement. For more information, please visitwww.pinnacle8tcs.com

);";);2C;S

10


11/11

7o"eld, (, et al. 2==/, G-urgical (epair of 7hronic (otator 7u Tears& >rospective ong8 Term -tudy,! Hournal of Bone & Joint Surgery,vol.138a, no. /, pp. 23821.

?all, ., et al, 2=/=, G-ymptomatic >rogression of &symptomatic

(otator 7u Tears& >rospective -tudy of 7linical and -onographic Dariables,!Journal of Bone andSurgery,no. /E, vol. 42, issue /;, pp. 2;2382;33.

?oosmayer, -., et al., 2==4, >revalence and characteristics ofasymptomatic tears of therotator cu an ultrasonographic and clinical study,!Journal of Boneand Joint Surgery,vol. 4/8B no. 2, pp. /4;82==.

ho et al., 2==1, G(otator cu degeneration, etiology and pathogenesis,!AmericJournal ofSports Medicine,vol. 3;, number

understanding the shoulder article-2014

Documents