Shoulder Complex Overview/Pathology/Stabilizers Flashcards

1
Q

What are the joints that make up the shoulder complex?

A

sternoclavicular
acromioclavicular
glenohumeral
scapulothoracic

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2
Q

What is the one joint in the shoulder girdle that is not a true synovial joint?

A

scapulothoracic

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3
Q

SC joint

A

articulation between : Sternal end of clavicle, clavicular notch of sternum, superior surface of first costal cartilage; intra-articular fibrocartilaginous disc

type: saddle joint

motion: gliding and rotation motion

the articular disc divides the joint in two; increases the surface area of the joint, and increases shock absorption

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4
Q

SC joint convex and concave joint surfaces:

A

clavicle:
superior-inferior: convex
anterior posterior- concave

manubrium
superior-inferior: concave
anterior-posterior- convex

protraction:
-anterior roll and glide of the concave clavicle on the manubrium

retraction: posterior roll and glide of the clavicle

elevation: superior roll and inferior glide of the convex clavicle on concave manubrium

depression: inferior roll and superior glide of convex clavicle on concave manubirum

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5
Q

ligaments of the SC joint:

A

SC ligament - anterior and posterior; dense thickening of the capsule

costoclavicular ligament - taught with elevation and retraction

interclavicular ligament integrates into the fascia of the neck

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6
Q

What muscle stabilizes the SC joint?

A

subclavius muscle

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7
Q

SC joint dislocation:

A

-can happen ant or posterior

-very rare
-direct trauma or blow to the clavicle or with fall on an outstretched arm
-MUCH more common to fracture the clavicle
-anterior dislocation usually does well non-surgically
-posterior dislocation–> more risk to structures behind sternum

-surgery (autograft or allograft) may be indicated- semitendinosus tendon

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8
Q

AC joint characteristics

A

type: plane/gliding joint

articulation: Acromion of scapula, acromial end of clavicle

motions: gliding in all directions

ligaments:
-AC lig
-coracoclavicular ligament:
—trapezoid (more lateral)
—conoid (more medial, deeper)

with abduction-adduction of shoulder girdle- rotation of acromion on clavicle

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9
Q

AC joint sprain (separated shoulder)

A

-progressive disruption of ligaments
—AC lig
—coracoclavicular ligaments

-graded by degree of displacement

-grades 1-3 can be managed non-surgically

GRADE 1 - not torn AC lig just sprain, no medial lig damage
GRADE 2- AC torn, stretched medial ligs
GRADE 3- complete luxation of the joint due to tearing of all the ligaments
GRADE 4- clavicle is severely displaced posteriorly
GRADE 5 - clavicle is severely displaced superiorly
GRADE 6- clavicle is displaced under the coracoid process

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10
Q

Scapulothoracic joint characteristics

A

“pseudo” joint

-muscular joint between the scapula and the thoracic cage

-required for full ROM at the GH joint

-no direct ligament attachment

MOVEMENTS:
-abduction (protraction)
-adduction (retraction)
-upward rotations, downward rotation , IR, ER, anterior and posterior tilt
-depression and elevation

rotations are fully reliant on muscular control

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11
Q

Scapular positioning/scapulohumeral rhythm:

A

The glenoid moves like a seal’s nose to remain in the right spot to control the ball (head)– > congruency is very important

SCAPULOHUMERAL RHYTHM (movement coordination) function:
-allows for greater overall shoulder ROM
-maintains optimal contact between the humeral head and the glenoid fossa
-Assists with maintaining an optimal length-tension relationship of the glenohumeral muscles.

Characteristics SH Rhythm
-integrated movements of GH, ST, AC, AND SC JOINTS
-sequential fashion –> full motion of shoulder complex

ARM ELEVATION EVIDENCE:
-more elevation on non-dom side (more upward rotation)
-between 1:3 AND 1:5 scapula to humerus motion –> depends on plane of humeral motion, side of dominance, and age of patient
-movement patterns depend on if you’re moving unilaterally or bilaterally

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12
Q

How is the thoracic spine involved in scapulohumeral rhythm?

A

Bilateral shoulder motion: 10-30 degrees of thoracic extension
(primarily lower) with full shoulder elevation

  • Unilateral shoulder motion:10-30 degrees of thoracic rotation
    and/or side-bending
  • Clinical relevance: Assess thoracic motion in patients with shoulder symptoms!
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13
Q

Glenohumeral joint characteristics

A

shoulder joint
synovial
multiaxial
ball and socket

largest ROM and movement in the body
-shallow joint
-extensive joint capsule
-limited ligamentous support

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14
Q

Static stabilizers of the GH joint:

A

LABRUM
-the fossa is 1/4 the size of the humeral head
-fossa is pear-shaped–> reducing congruency
-the labrum helps increase concavity of the glenoid fossa as well as the articular cartilage (but to a lesser extent)
-fossa is smaller on the superior aspect than inferior
-the labrum deepens the socket 50-75%
-Glenoid faces lateral, anterior, and superior
–> angle of inclination changes with the position of the scapula (scapulohumeral rhythm)

JOINT CAPSULE
-tissue: anterior and
posterior continues laterally on
the humerus into the neck of the humerus
-anterior and inferior capsule much thicker than posterior

LIGAMENT COMPLEX
-SGHL
-MGHL
-IGHL

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15
Q

Dynamic stabilizers of the GH joint:

A

muscles surrounding the joint

ROTATOR CUFF - pulls head of humerus into glenoid fossa
-supraspinatus
-infraspinatus
-subscapularis
-teres minor
** Long head of the biceps (not technically)
-tendons intimate with capsule
-tendinitis is rarely isolated to one tendon –> muscles and tendons DO NOT function in isolation

DELTOID
-large stabilizing component, regardless of humeral position
-** primary function to swing humerus

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16
Q

Static stabilizers of the GH joint:

A

LABRUM
-the fossa is 1/4 the size of the humeral head
-fossa is pear-shaped–> reducing congruency
-the labrum helps increase concavity of the labrum as well as the articular cartilage (but to a lesser extent)
-fossa is smaller on the superior aspect than inferior
-the labrum deepens the socket 50-75%

JOINT CAPSULE
-tissue: anterior and
posterior continues laterally on
the humerus into the neck of the humerus
-anterior and inferior capsule much thicker than posterior

LIGAMENTS
-anterior GH ligaments
-inferior- pliable redundant ligamentous complex

17
Q

RESTRAINTS TO SHOULDER ER

A

0 ABDUCTION
-subscapularis
-SGHL

45 ABDUCTION
-SGHL
-MGHL

90 ABDUCTION
-anterior band of IGHLC

18
Q

RESTRAINTS TO SHOULDER IR

A

0 ABDUCITON
-posterior band of IGHLC

45 ABDUCITON
-anterior and posterior band IGHLC
-teres minor
-infraspinatus

90 ABDUCTION
-anterior and posterior band IGHLC

19
Q

RESTRAINTS TO INFERIOR TRANSLATION

A

0 ABDUCTION
-SGHL
-coracohumeral lig

90 ABDUCTION
-IGHLC (superior elements are lax)

20
Q

LOOSE AND CLOSED PACK POSITION GH JOINT

A

OPEN/LOOSE PACK
-55 deg abduction, 30 deg horizontal adduction

CLOSE PACK
-end range abduction and ER

21
Q

Research study about capsule tightness and how that affects motion of the GH joint:

A

The humeral head will glide away from the tightest portion of the capsule

  • generally, the humeral head will stay in the center of the glenoid fossa–> although the head will glide away from the tightest portion–> it’s important to work on capsular mobility
22
Q

Force coupling at GH joint

A

Need forces of the rotator cuff muscles to center the glenoid and oppose the shearing forces of the deltoid as the deltoid moves to swing the bone

-without rotator cuff the deltoid would pull the humeral head superiorly at 0 degrees of abduction

23
Q

Possible causes of subacrominal impingement

A

RTC tendon and/or LHB may get repeatedly compressed, along with the bursa

CAUSES:
-RTC dysfunction
-scapular positioning
-shape of acromion
-GH joint mobility deficit or hypermobility