The C8 myotome is tested by finger flexion, the ISNCSCI key movement for C8, measured at the tip of the middle finger. It supplies the long finger flexors in the forearm and many small hand muscles together with T1. Grip strength depends heavily on C8.
| Nerve root | C8 |
|---|---|
| Area | Finger flexion (ISNCSCI key muscles: finger flexors, tested at the distal phalanx of the middle finger) |
| How to test | The patient bends the tip of the middle finger while the examiner holds the middle phalanx and resists flexion of the distal phalanx. Strength is graded 0-5 on the Medical Research Council scale and compared side to side. |
| Muscles | |
| Nerve Supply | Median nerve (anterior interosseous nerve); Ulnar nerve |
Bends the fingers and thumb and provides most grip strength.
C8 radiculopathy, usually at C7-T1, weakens grip with little finger numbness. Ulnar neuropathy and lower brachial plexus lesions are the main mimics; weakness of median supplied thumb muscles points away from a pure ulnar nerve lesion. Myotome charts vary slightly between sources, and most muscles receive more than one root, so a single root lesion usually weakens rather than paralyses.
Compression at C7-T1 causing weak grip and finger flexion with little finger numbness.
Damage to C8-T1 fibres, as in Klumpke palsy or thoracic outlet syndrome, causing hand weakness and a claw-like posture.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
