Multiple Choice
Which term is used to describe a muscle that contracts or compresses an organ?
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9. Muscle Tissue
Introduction to Muscles and Muscle Tissue
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All fibers of the trapezius muscle are innervated by which nerve?
A
Long thoracic nerve (C5–C7)
B
Spinal accessory nerve (cranial nerve XI)
C
Phrenic nerve (C3–C5)
D
Dorsal scapular nerve (C5)
Verified step by step guidance1
Step 1: Understand the anatomy of the trapezius muscle, which is a large superficial muscle extending from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula.
Step 2: Recall that innervation refers to the nerve supply that controls muscle function, including motor control and sensory feedback.
Step 3: Identify the nerves listed in the problem and their typical areas of innervation: the Long thoracic nerve (C5–C7) innervates the serratus anterior muscle; the Phrenic nerve (C3–C5) innervates the diaphragm; the Dorsal scapular nerve (C5) innervates the rhomboid muscles and levator scapulae.
Step 4: Recognize that the Spinal accessory nerve (cranial nerve XI) is responsible for motor innervation of the trapezius muscle, enabling movements such as scapular elevation, retraction, and rotation.
Step 5: Conclude that all fibers of the trapezius muscle are innervated by the Spinal accessory nerve (cranial nerve XI), distinguishing it from the other nerves listed.
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