In ASIA Scoring system ten muscle groups innervation by the cervical and lumbosacral spinal cord are tested. The ASIA system does not include the abdominal muscles supplied by thoracic segments because they are not feasible to dleineate one from another and because these levels can be better marked by sensory levels.
It also excludes muscles like hamstrings because the segmental levels that innervate them are already represented by other muscles.
However it must be understood that every muscle received innervation from two or more segments. therefore the examination does not determine absolute level of injury but only a gross one.
Arm and Hand
- Elbow flexors (biceps) are innervated by C5
- C6 the wrist extensors
- C7 the elbow extensors (triceps),
- C8 the finger flexors
- T1 the little finger abductor (Movement of the little finger away from others).
Leg and foot
- L2 – hip flexors (psoas muscle)
- L3 - knee extensors (quadriceps)
- L4 the ankle dorsiflexors (anterior tibialis)
- L5 the long toe extensors (hallucis longus)
- S1 the ankle plantar flexors (gastrocnemius)
The anal sphincter is innervated by the S4-5 cord and represents the end of the spinal cord. If the person has any voluntary anal contraction, regardless of any other finding, that person is by definition a motor incomplete injury.