What muscle initiates shoulder abduction, and which muscle causes the shoulder to abduct 90 degrees and beyond?
Understand the Problem
The question is asking us to identify the muscles responsible for shoulder abduction. Specifically, it wants to know which muscle initiates the abduction movement and which muscle(s) are responsible for continuing the abduction beyond 90 degrees.
Answer
The Supraspinatus initiates abduction; the deltoid abducts from 15-90 degrees; the trapezius and serratus anterior muscles abduct beyond 90 degrees.
The Supraspinatus muscle initiates shoulder abduction (0-15 degrees). The deltoid muscle abducts the arm from 15-90 degrees. The trapezius and serratus anterior muscles abduct the arm from 90 degrees and beyond.
Answer for screen readers
The Supraspinatus muscle initiates shoulder abduction (0-15 degrees). The deltoid muscle abducts the arm from 15-90 degrees. The trapezius and serratus anterior muscles abduct the arm from 90 degrees and beyond.
More Information
Shoulder abduction is a complex movement involving several muscles working together to achieve a full range of motion.
Tips
A common mistake is thinking only one muscle is responsible for the entire abduction movement. Remember that different muscles contribute to different phases of the motion.
Sources
- Anatomy, Rotator Cuff - StatPearls - NCBI Bookshelf - ncbi.nlm.nih.gov
- Shoulder Muscles: Anatomy, Function, and More - Healthline - healthline.com
- Biomechanics of the Shoulder - Physiopedia - physio-pedia.com
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