College of Massage Therapists of British Columbia (CMTBC) Practice Exam

What is the function of the thoracodorsal nerve?

1. To innervate the deltoid muscle

2. To supply the latissimus dorsi muscle

3. To innervate the forearm flexor muscles

4. To innervate the serratus anterior muscle

The correct answer is: To supply the latissimus dorsi muscle

The thoracodorsal nerve primarily functions to supply the latissimus dorsi muscle, which is crucial for various movements such as extension, adduction, and internal rotation of the shoulder joint. This nerve stems from the brachial plexus and is specifically derived from the posterior cord, with contributions from the sixth, seventh, and eighth cervical nerves. The latissimus dorsi is a large muscle of the back that plays a significant role in upper body movement, making the thoracodorsal nerve essential for its proper function. The other options pertain to different muscles or regions. The deltoid muscle is innervated by the axillary nerve, the forearm flexor muscles are primarily supplied by the median and ulnar nerves, and the serratus anterior muscle receives its innervation from the long thoracic nerve. Each of these nerves corresponds to specific muscles that engage in distinct movements and functions in the upper extremity, but they do not include the latissimus dorsi, which is directly related to the thoracodorsal nerve.