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Questions and Answers
Which muscles are primarily responsible for scapular adduction?
Which muscles are primarily responsible for scapular adduction?
What is the nerve supply to the middle fibers of the trapezius?
What is the nerve supply to the middle fibers of the trapezius?
What is the range of motion of scapular adduction from the abduction position?
What is the range of motion of scapular adduction from the abduction position?
Which muscles assist in scapular downward rotation?
Which muscles assist in scapular downward rotation?
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What effect does weakness of scapular adductor muscles have?
What effect does weakness of scapular adductor muscles have?
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Where do the rhomboids major and minor insert?
Where do the rhomboids major and minor insert?
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What is the main action of the trapezius middle fibers?
What is the main action of the trapezius middle fibers?
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Which part of the trapezius plays a stabilization role during scapula downward rotation?
Which part of the trapezius plays a stabilization role during scapula downward rotation?
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Study Notes
Scapular Adduction and Downward Rotation
- Scapular adduction and scapular downward rotation are movements of the scapula.
- The primary muscles involved in scapular adduction and downward rotation include the middle fibers of the trapezius, the rhomboids major and minor, and the lower and upper fibers of the trapezius.
- The range of motion for scapular adduction is equivalent to the space of 3-4 fingers, measured from the abduction position to the adduction position.
- The middle fibers of the trapezius are primarily responsible for scapular adduction.
- The trapezius also plays a role in stabilizing scapular downward rotation.
- The rhomboid major and minor muscles adduct and elevate the scapula, positioning the glenoid cavity caudally.
- Weakness of these muscles results in scapular abduction and outward rotation of the inferior angle.
- This weakness also diminishes the strength of humerus adduction and extension.
- Contracture of these muscles, causing the scapula to be drawn into an adduction and elevation position.
Anatomy of Trapezius Middle Fibers
- Origin: Spinous processes of the first to fifth thoracic vertebrae
- Insertion: Superior lip of the scapular spine.
- Nerve Supply: Accessory nerve
- Action: Primarily responsible for scapular adduction. Also stabilizes during scapular downward rotation.
Anatomy of Rhomboids Major and Minor
- Rhomboids major origin: Spinous processes of the second to fifth thoracic vertebrae.
- Rhomboids minor origin: Ligamentum nuchae and spinous processes of the first thoracic vertebrae
- Rhomboids major insertion: Medial border of the scapula, between the spine and the inferior angle.
- Rhomboids minor insertion: Medial border at the root of the scapular spine.
- Nerve Supply: Dorsal scapular nerve
- Action: Adduct and elevate the scapula, and rotate it to position the glenoid cavity caudally.
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