Week 1: Clinical Biomechanics of the Shoulder Flashcards
Primary function of the GHJ/shoulder
Mobility, at the expense of stability
What factors create the mobility of the GHJ?
- Shallow glenoid
- Lax capsule
- Limited stability from ligaments
Shoulder girdle joints
- Glenohumeral
- Sternocavicular
- Acromioclavicular
- Scapulothoracic
What kind of joint is the SC joint?
Saddle synovial
What covers the SC joint?
Fibrocartilage
What movements occur at the SC joint?
- Pump handle (w/ abduction/adduction)
- A/P (w/ scapular protraction/retraction)
- Rotation (w/ flexion/extension or throwing motion)
Ligaments of the SC joint
- Costoclavicular
- Sternoclavicular
- Interclavicular
AC joint type
Planar synovial
Ligaments of the AC joint
- AC joint
- Coracoclavicular (trapezoid and conoid)
- Coracoacromial
Scapulothoracic joint type
“Pseudo” joint, only connection to the body is at the SC joint
Function of the ST joint
- Stable platform for shoulder movement
- Optimize length/tension relationship of GH muscles
- Attachment site for many muscles
Average Scapulothoracic rhythm
2:1
Scapulothoracic rhythm broken down by section
- 0-30: GH joint only
- 30-90: 2:1/GH:ST
- 90-180: 1:1
GH Open Pack Position
- 55 degree abduction
- 30 degree horizontal adduction
- 30 degree ER
GH Close Pack Position
- 90 degree abduction w/ full ER
- Full abduction
GH Capsular Pattern
-
SC Capsular Pattern
-
AC Capsular Pattern
-
Passive restraints to motion in the GH joint
- Bony architecture
- Labrum/capsule
- Capsuloligamentous structures
Ligaments of the GH joint
- Superior GHL
- Middle GHL
- Inferior GHL
- Coracohumeral
Why are the GH ligaments considered capsuloligamentous?
The ligaments blend with the capsule
Superior GHL
Limits inferior translation with the arm at the side
Middle GHL
Limit ER and anterior translation with the arm at 40-90 degrees abduction
Inferior GHL
Limit ER @ 90 degrees
Coracohumeral
-
Rotator cuff muscles
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
OIAN Supraspinatus
- Origin
- Insertion
- Action
- Nerve
OIAN Infraspinatus
- Origin
- Insertion
- Action
- Nerve
OIAN Teres minor
- Origin
- Insertion
- Action
- Nerve
OIAN Subscapularis
- Origin
- Insertion
- Action
- Nerve
Muscles controlling dynamic stability
- Rotator cuff
- Deltoid
- Teres major
- Bicep
- Tricep
- Serratus anterior
- Trapezius
- Rhomboids
- Pec major/minor
