Pectoral Girdle, Scapular Movements and Muscles Flashcards
The entire upper limb and pectoral girdle articulate at one small joint only - which is this
Acromioclavicular joint
Which is inferior and which is superior?
What can help to orientate and side a clavicle?
The lateral aspect of a clavicle is flatter than the medial aspect
The superior surface is smoother than the inferior surface
The conoid tubercle – attachment for the conoid ligament – is on the inferior aspect of the lateral portion of the clavicle
Which part of the clavicle is weakest and commonly breaks (fractures) during a fall?
Lateral and middle thirds
What type of synovial joint are the acromioclavicular (AC) and sternoclavicular (SC) joints?
- AC joint Plane type*
- SC joint Saddle*
What are the 2 stages abduction of the arm occurs in?
The first 30 degrees of abduction is caused by muscles acting at the shoulder joint (gleno-humeral joint).
Beyond 30 degrees, abduction relies on the scapula being pulled upwards (elevated) and laterally rotating on the chest wall (“scapula-thoracic” movement).
Explain scapulo-humeral rhythm
For every 3 degrees of abduction past the initial 30 degrees – 2 degrees occurs at the gleno-humeral joint, and 1 degree occurs due to “scapula-thoracic” movement (2:1 ratio).
What causes elevation of the scapula?
Upper trapezius
Levator scapulae
What causes depression of the scapula?
Lower trapezius
What causes protraction of the scapula?
Serratus anterior
What causes retraction of the scapula?
Trapezius and rhomboids
