Neuromuscular Relationships
| Motion Segment | Nerve Root | Myotome | Dermatome | Reflex |
|---|---|---|---|---|
| Occ–C1 | C1 | Ø | Skull vertex | Ø |
| C1–2 | C2 | Neck flexion: Rectus capitis & SCM | Temple, forehead, occiput | Ø |
| C2–3 | C3 | Neck SB: Trapezius & splenius capitis | Cheek, neck | Ø |
| C3–4 | C4 | Shoulder elevation: Levator scapula & trapezius | Clavicle & upper scapula | Ø |
| C4–5 | C5 | Shoulder abd: Deltoid, supra/infraspinatus, biceps | Anterior arm: Shoulder to base of 1st digit | Biceps |
| C5–6 | C6 | Elbow flex/Wrist ext: Biceps, ECRL, ECRB, supinator | Anterior arm to lateral forearm, 1st & 2nd digits | Brachioradialis |
| C6–7 | C7 | Elbow ext/wrist flex: Triceps, FCU, FCR | Lateral forearm, 2nd, 3rd, & 4th digits | Triceps |
| C7–T1 | C8 | Thumb ext/UD: EPL, EPB, FCU, ECU | Medial arm & forearm to 4th & 5th digits | Triceps |
| T1–2 | T1 | Ø | Medial forearm to base of 5th digit | Ø |
| T2–3 | T2 | Ø | Pectoralis & midscapula to medial upper arm & elbow | Ø |
| T3–5 | T3–5 | Ø | Upper thorax | Ø |
| T5–7 | T5–7 | Ø | Costal margins | Ø |
| T8–12 | T8–12 | Ø | Abdominal & lumbar regions | Ø |
| T12–L1 | L1 | Iliacus | Back to trochanter & inguinal region | Ø |
| L1–2 | L2 | Psoas, iliacus, & adductors | Back to mid-anterior thigh to knee | Cremasteric |
| L2–3 | L3 | Quads | Back & upper buttock to distal anterior thigh & knee | Adductor |
| T1–2 | T1 | Ø | Medial forearm to base of 5th digit | Ø |
| L3–4 | L4 | Anterior tibialis | Medial buttock to lateral thigh, medial tibia, & big toe | Patella |
| L4–5 | L5 | Extensor hallicus longus | Posterior lateral thigh, lateral leg, dorsum of foot, & toes 1, 2, 3 | Tib posterior, med. Hamstrings |
| L5–S2 | S1–2 | Gluteales, hamstrings, peroneales, gastroc-soleus | Posterior thigh & leg, lateral foot & heel | Achilles |
| S2–3 | S3 | Ø | Groin, medial thigh to knee | Ø |
| S3–4 | S4 | Bladder & rectum | Perineum & genitals | Ø |
Source: Gulick DT (2006).