ESS 303 -- Biomechanics
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Transcript ESS 303 -- Biomechanics
ESS 303 – Biomechanics
Shoulder Joint
The Scapula (Right)
Humerus (Right)
Anterior View
Posterior View
The Shoulder Joint
Shallow ball-and-socket
Socket: Glenoid fossa of the shoulder blade
Ball: ½ the spherical head of the humerus
No more than ½ of the head is in the socket
at any given time
Bony stability is weak
In fact – the head may move up to 2-3 cm
away from the glenoid fossa
Stability
Keeping the humoral head in contact
with the glenoid fossa
Passive: Glenoid Labrum
Circles around the outside of the glenoid
cavity
Increases depth of concavity
Active: Rotator cuff
Rotator Cuff
Muscles tense to stabilize the humoral
head against the glenoid fossa
Helps prevent the head from rotating out of
the fossa
Allows the deltoid to contribute to abduction
4 muscles: supraspinatus, subscapularis,
infraspinatus, and teres minor
Rotator Cuff Injuries: Common
Types: Tendonitis, bursitis, strain or tear
Who: Baseball pitchers & anyone who
puts heavy demands on their shoulders
Most treated with simple care and
exercise
Causes: age (>40), poor posture,
breaking a fall with your arm, heavy
lifting (especially overhead), repetitive
stress, others
Rotator Cuff Injuries: Common
Rotator Cuff Injuries: Common
Self treatment:
Stop the activity – for a few days or until pain stops
Ice and heat
Medications
Exercises
Medical treatment
Severe or long-lasting (> 1 week) pain, immobile,
etc
Medications, surgery, etc
Dislocation & Subluxation
Movements & Major Muscles
Flexion: pectoralis major (clavicular),
anterior deltoid & coracobrcahialis
Extension: pectoralis major (sternal),
latissimus dorsi & teres major
Abduction: middle deltoid &
supraspinatus
Adduction: pectoralis major (sternal),
latissimus dorsi & teres major
Movements & Major Muscles
Horizontal (Transverse) Abduction: middle and
posterior deltoids, infraspinatus & teres minor
Horizontal (Transverse) Adduction: pectoralis
major, anterior deltoid, coracobrachialis
Medial Rotation: pectoralis major, latissimus dorsi,
teres major & subscapularis
Lateral Rotation: teres minor, infraspinatus &
posterior deltoid
Other movements are exaggerations or
combinations of above: Hyperextension,
Hyperabduction, Hyperadduction &
Circumduction