Which of the following is the lateral attachment of the trapezius muscle?

• A. Medial border of the scapula
• B. Lateral third of the clavicle
• C. Spinous processes of thoracic vertebrae
• D. Acromion process of the scapula

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the anatomy of the trapezius muscle. The trapezius is a large, triangular muscle located in the upper back and neck region. It has multiple attachment points and functions to move the scapula and support the arm.
2. Step 2: Identify the lateral attachment of the trapezius muscle. The term 'lateral attachment' refers to the point where the muscle connects to a structure on the outer side of the body.
3. Step 3: Review the specific attachment points of the trapezius muscle. The trapezius has three main regions: upper, middle, and lower fibers. The lateral attachment of the upper fibers includes the lateral third of the clavicle and the acromion process of the scapula.
4. Step 4: Compare the options provided in the question. The medial border of the scapula is not a lateral attachment; it is associated with other muscles like the rhomboids. The spinous processes of thoracic vertebrae are medial attachments of the trapezius, not lateral.
5. Step 5: Conclude that the correct lateral attachment of the trapezius muscle includes the lateral third of the clavicle and the acromion process of the scapula, as these are the points where the muscle connects laterally to the skeleton.