Principles of Functional Exercise

SERRATuS ANTERIOR

Joint Action of the Scapula

1. Protraction


2. Abduction


3. Scapular stabilizer (fastens medial border to rib cage)

Origin – Rib surface located at upper 8th or 9th vertebrae

Insertion – Scapula at the anterior surface and medial border.

Common distortions caused by weakness are winging of medial border of scapula and shortness
of the rhomboid muscles.

BACK

Latissimus Dorsi

Joint Action performed by the Shoulder (glenohumeral)

1. Adduction


2. Extension


3. Internal Rotation


4. Horizontal Abduction

Joint Action performed by the Scapula (assists)

1. Depression


2. Downward rotation


3. Adduction

Joint Action performed by Trunk

1. Unilaterally: Laterally flexes trunk


2. Bilaterally: anteriorly tilts pelvis

For example the pulling down of your arm from above your head brings the shoulder
blades (scapular) together. The ability to pull the body upand forward when hanging from
the arms is also an example.