| A | B |
|---|
| C3, C4 Dermatome | Region at base of neck, extending laterally over shoulder |
| Dermatome C5 | Lateral aspect of arm (i.e., superior aspect of abducted arm) |
| Dermatome C6 | Lateral forearm and thumb |
| Dermatome C7 | Middle and ring fingers (or middle three fingers) and center of posterior aspect of forearm |
| Dermatome C8 | Little finger, medial side of hand and forearm (i.e., inferior aspect of abducted arm) |
| Dermatome T1 | Medial aspect of forearm and inferior arm |
| Dermatome T2 | Medial aspect of superior arm and skin of axillaa |
| Supraclavicular nerves | C3, C4 |
| Superior lateral cutaneous nerve of arm | C5, C6 |
| Inferior lateral cutaneous nerve of arm | C5, C6 |
| Posterior cutaneous nerve of arm | C5-C8 |
| Posterior cutaneous nerve of forearm | C5-C8 |
| Lateral cutaneous nerve of forearm | C6-C7 |
| Medial cutaneous nerve of forearm | C8, T1 |
| Medial cutaneous nerve of arm | C8-T2 |
| Intercostobrachial nerve | T2 |
| Supraclavicular nerves | Cervical plexus |
| Superior lateral cutaneous nerve of arm | Terminal branch of axillary nerve |
| Inferior lateral cutaneous nerve of arm | Radial nerve (or posterior cutaneous nerve of arm) |
| Posterior cutaneous nerve of arm | Radial nerve (in axilla) |
| Posterior cutaneous nerve of forearm | Radial nerve (with inferior lateral cutaneous nerve of arm) |
| Lateral cutaneous nerve of forearm | Musculocutaneous nerve (terminal branch) |
| Medial cutaneous nerve of forearm | Medial cord of brachial plexus (in axilla) |
| Medial cutaneous nerve of arm | Medial cord of brachial plexus (in axilla) |
| Intercostobrachial nerve | Second intercostal nerve (as its lateral cutaneous branch) |
| Supraclavicular nerves | Pass anterior to clavicle, immediately deep to platysma, and supply skin over clavicle and superolateral aspect of pectoralis major |
| Superior lateral cutaneous nerve of arm | Emerges from beneath posterior margin of deltoid and supplies skin over lower part of this muscle and on lateral side of midarm |
| Inferior lateral cutaneous nerve of arm | Perforates lateral head of triceps, passing close to cephalic vein to supply skin over inferolateral aspect of arm |
| Posterior cutaneous nerve of arm | Crosses posterior to and communicates with intercostobrachial nerve and supplies skin on posterior arm as far as olecranon |
| Posterior cutaneous nerve of forearm | Perforates lateral head of triceps, descends laterally in arm, then runs along and supplies posterior forearm to wrist. |
| Lateral cutaneous nerve of forearm | Emerges lateral to biceps tendon deep to cephalic vein, supplying skin of anterolateral forearm to wrist |
| Medial cutaneous nerve of forearm | Descends medial to brachial artery, pierces deep fascia with basilic vein in midarm, dividing into anterior and posterior branches that enter forearm and supply skin of anteromedial aspect to wrist |
| Medial cutaneous nerve of arm | Communicates with intercostobrachial nerve, continuing to supply skin of medial aspect of distal arm |
| Intercostobrachial nerve | Extends laterally, communicating with posterior and medial cutaneous nerves of arm, supplying skin of axilla and medial aspect of proximal arm |
