National Physical Therapy Examination (NPTE) Practice Exam

Which cervical nerve roots are responsible for innervating the teres minor and deltoid?

1. Axillary nerve

2. C5 and C6

3. C4 and C5

4. C6 and C7

The correct answer is: C5 and C6

The correct answer is related to the specific innervation of the teres minor and deltoid muscles by the axillary nerve, which arises from the ventral rami of the cervical spinal nerves C5 and C6. The teres minor is a small muscle located in the shoulder that assists with the lateral rotation of the arm, while the deltoid is a larger muscle responsible for the abduction, flexion, and extension of the arm. Both of these muscles are crucial for shoulder mobility and stabilizing the shoulder joint. The axillary nerve, which innervates these muscles, has its roots in the brachial plexus, specifically originating from the C5 and C6 spinal nerves. This anatomical relationship emphasizes the importance of these nerve roots in facilitating movement and function of the shoulder girdle. Understanding the relationship between the cervical nerve roots and muscle innervation is essential for diagnosing and treating shoulder injuries, particularly those involving nerve damage or brachial plexus lesions, where symptoms can manifest as weakness or dysfunction in the shoulder muscles that the axillary nerve supplies.