Does the eighth cervical nerve (C8) enter the brachial plexus?

From the Guidelines

Yes, the eighth cervical nerve (C8) enters the brachial plexus.

Brachial Plexus Formation

The brachial plexus is formed from the C5-T1 ventral rami, which includes the C8 nerve [(1, 2)].

• The C5 to T1 nerve roots, including C8, pass between the anterior and middle scalene muscles with the subclavian artery to form the trunks.
• These trunks then split into anterior and posterior divisions, form cords, and travel with the subclavian artery and vein within the infraclavicular region.
• The cords form terminal branches at the lateral margin of the pectoralis minor muscle and continue through the axilla, eventually innervating the upper extremity. The formation of the brachial plexus from the C5-T1 ventral rami, including the C8 nerve, is consistently described in both the 2021 1 and 2017 2 studies, confirming the role of C8 in the brachial plexus.

From the Research

Brachial Plexus Composition

• The brachial plexus is formed by the union of the ventral primary rami of the spinal nerves, C5-C8 & T1 3
• The brachial plexus is a series of nerves formed by roots of cervical segments 5 to 8 (C5-C8) as well as the first thoracic nerve (T1) 4
• The brachial plexus begins with the anterior rami of C5, C6, C7, C8, and the first thoracic nerve 5

Role of C8 in the Brachial Plexus

• C8 participates in the innervation of thumb and finger extensors 6
• C8 radiculopathy may be due to C8-root compression at C7/T1, but can also be caused by other factors such as C7-root compression or cervical cord compression 7
• The eighth cervical nerve (C8) is one of the roots that contribute to the formation of the brachial plexus 3, 4, 5

Conclusion on C8's Role

• Based on the studies, it can be confirmed that the eighth cervical nerve (C8) does enter the brachial plexus, as it is one of the roots that form the plexus 3, 4, 5