Upper Extremity - SPORTS MEDICINE

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Upper

Extremity

Shoulder Complex

Elbow

Wrist

(Hand)

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Shoulder

Ligamentous Support

• no ligament to prevent backward displacement

– fossa angle slightly anterior

– prevents backward displacement

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Shoulder

Complex

sternoclavicular

acromioclavicular

coracoclavicular

scapulothoracic

glenohumeral

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Shoulder

Girdle

• an “open” mechanical system

– R and L sides not directly

attached so can move

independently

• sternoclavicular jt

• acromioclavicular jt

• scapulothoracic jt

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Sternoclavicular Articulation

• articulation between the

sternum and clavicle

• a modified ball-and-socket joint

– mobile in frontal and transverse

plane

– limited sagittal movement

Clavicle

Articular

disk

Costal

cartilage

Clavicle

Sternoclavicular

Ligament

Costoclavicular

Ligament

Sternum

Interclavicular

Ligament

• site of most movement of shoulder girdle

– elevation/depression (up and down, 30-40o)

– rotation (40-50o)

– protraction/retraction (A/P, rowing, 30o)

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Acromioclavicular

Articulation

•articulation between

acromion process and

distal end of clavicle

Bony Support -- WEAK!

very dense capsule +

AC ligaments

provide support

coracoclavicular ligament

serves as axis of rotation for

associated scapular mvmts

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protraction/retraction: acromion process

moves on meniscus, scapula rotates

about medial coracoclavicular ligament

(conoid) 30-50º

upward/downward rotation: clavicle

moves on meniscus, scapula rotates

about lateral coracoclavicular

ligament (trapezoid) 60º

elevation/depression: relative motion of

acromion & clavicle with no rotation

30º

Note: mvmts @ AC joint will be

opposite those at SC joint

(e.g., AC elevation -- SC depression)

AC Mvmts

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Shoulder Joint(aka glenohumeral)

- articulation of humerus and

glenoid fossa

- designed for mobility

(greatest ROM of any jt

in body)

- lacks bony and ligamentous

support

- shallow glenoid fossa

(1/4 size of humeral head)

-half-spherical humeral head

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Supporting Structures for Shoulder

• labrum

– a lip of cartilage

surrounding the joint

– increases depth of fossa

– increases contact area

by 75%

– assists in holding the

humerus in place

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Shoulder depends on ligamentous and muscular

contributions for support

articular capsule

2X volume of humeral

head - laxity

anterior support

capsule, labrum, glenohumeral

ligaments 3 “reinforcements” in

the capsule coracohumeral

ligament, and fibers of the

subscapularis and pec. major

that blend into the jt capsule

posterior support

capsule, labrum, fibers from

the teres minor &

infraspinatus that blend into

the capsule

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Scapulohumeral Rhythm

• scapular rotation to facilitate

shoulder movements (abduction &

flexion)

– 1st 30 º of abduction or 45º of

flexion -- scapula moves to a

position of stability on thorax

– beyond this initial range -- a

2:1 ratio of glenohumeral to

scapular movements up to 90

Degrees

– for total ROM have a 2:1 ratio

(e.g. 180 º of abduction have

120 º of glenohumeral mvmt

and 60 º of scapular mvmt.

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Often associated with overarm motions

such as throwing

Preparatory phase -- shoulder

abducted to 90, shoulder ext

rotation, scapular retraction,

and elbow flexion

Soft tissue injuries

Anterior capsule and

subscapularis muscle are

susceptible to strain or tendinitis

at the insertion on the lesser

tubercle

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Extreme External

Rotation in Overarm

Pitching

• external rotation

terminated by forces from

– anterior joint capsule &

ligaments

– subscapularis

– pectoralis major

– triceps brachii

– teres major

– latissimus dorsi

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Acceleration Phase

• explosive phase characterized by – initiation of elbow extension

– shoulder internal rotation

– maintenance of shoulder abduction at 90

– shoulder transverse adduction

– scapular protraction

• posterior capsule and labrum susceptible to injury as anterior shoulder is tightened driving the humeral head backwards

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Follow-Through

Phase• Rotator cuff works to

decelerate shoulder’s internal

rotation

• infraspinatus and teres minor

very susceptible to muscle

strain or tendinitis

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Muscular StrengthShoulder Complex

adduction

extension

flexion

abduction

internal rotation

external rotation

STRONGEST

WEAKEST

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Rotator Cuff Muscles

3 originate

on posterior

scapula

(S I T)4th originates

on anterior

scapulaTeres Minor

Infraspinatus Supraspinatus Subscapularis

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Stabilizing Influence of

Rotator Cuff

• muscles have a large

stabilizing component when

active

– all have a ‘large’ horizontal

component

– so play a significant role in

stabilizing the humerus

against the glenoid fossa

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Bursae in Shoulder

• sacs secreting synovial fluid

• distributed throughout shoulder complex to

reduce friction between tissues

• e.g. subacromial bursae

– cushions rotator cuff muscles (supraspinatus) from

laying directly on acromion process

– overuse can lead to irritation of bursae

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coracoacromial

ligament

provides a “buffer”

for the rotator cuff

muscle tendons

Subacromial Arch

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coracohumeral

ligament

glenohumeral

ligaments

superior

middle

inferior

these ligaments

merge with the

articular capsule

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Abduction/Flexion

1) primary movers

2) humeral head stabilization

3) orienting the glenoid fossa

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1) Primary movers

deltoid ~50%, rotator cuff ~50%

Abduction/Flexion

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Abduction/Flexion

2) humeral head stabilization

early: teres minor depresses head

late: subscapularis & infraspinatus

stabilize head

>90º: supraspinatus remains active

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Abduction/Flexion

3) orienting the glenoid fossa

requires protraction, elevation, upward

rotation with posterior clavicular rotation

upper trapezius and serratus anterior

responsible muscles

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Adduction & Extension

Primary Movers: If no resistance then use

eccentric actions of abduction/ flexion

muscles BUT if resistance (e.g. weight

machine or swimming) main contributors

are

latissumus dorsi teres major sternal portion of

pectoralis major

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Adduction & Extension

Accompanying movements: retraction, depression,

downward rotation with anterior clavicular rotation

Rhomboid

downwardly rotates

& retracts

Pectoralis minor

depresses &

downwardly rotates

Mid & lower trapezius

retracts

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Internal & External Rotation

Important to many sport skills plus a necessary

movement to accommodate mvmt when arm is at

90º or greater abduction or flexion

External rotation: infraspinatus & teres minor

primary muscles on posterior side

insert posteriorly on humerus

Internal rotation: subscapularis & teres major

primary muscles on anterior side

insert posteriorly on humerus

(also lat. Dorsi and pect. major)

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Horizontal Ab-/Adduction

Similar musculature as for flexion and abduction

BUT more sig. contribution from

pec. major & ant. deltoid for hor. adduction

infraspinatus, teres minor, & pos. deltoid for hor. abduction