The level of the cervical spinal cord affected by injury can be inferred from the pattern of muscle function shown by the patient.
Spinal Segments |
Muscle |
Function |
C3, C4, C5 |
diaphragm |
inspiration |
C5, C6 |
biceps brachii, brachialis |
elbow flexors |
C6, C7 |
extensor carpi radialis longus and brevis |
wrist extensors |
C7, C8 |
triceps brachii |
elbow extensors |
C8, T1 |
interossei, thenar group |
hand instrinsics |
The muscles (except for the diaphragm) are innervated by 2 segments or roots.
If both segments are functional, then the muscle strength is normal.
If one segment is functional, then muscle strength is weak.
If neither segment is functional, then the muscle is paralyzed.
Injury Level |
Normal Muscles |
Weak Muscles |
Nonfunctioning Muscles |
C1 or C2 |
|
|
diaphragm |
C3 or C4 |
|
diaphragm |
elbow extensors |
C5 |
diaphragm |
elbow extensors |
wrist extensors |
C6 |
elbow extensors |
wrist extensors |
elbow extensors |
C7 |
wrist extensors |
elbow extensors |
hand intrinsics |
C8 |
elbow extensors |
hand intrinsics |
|
T1 or below |
hand intrinsics |
|
|
Specialty: Neurology
ICD-10: ,