HEHE THIS IS FUNNN
...l distribution. Dermatomes (pre to post axial): C5 - shoulder C6 - thenar eminence C7 - middle finger (rarely tested, difficult to deconvolute with neighboring dermatomes) C8 - hypothenar eminence T1 - medial aspect of forearm Myotomes (proximal to distal) Remember first that the plexus covers C5-T1. Page 120 in your class notes is good for looking at this. Note that proximal muscles of the shoulder and flexor compartment of arm are innervated by the most cranial segments of the plexus, C5-6 (axillary and musculocutaneous). As we get into superficial flexor compartment of the forearm (innervated by median nerve) we get into myotome C7. The flexor carpi ulnaris is also around level C7. BUT, if we look at the DEEP flexor compartment, we have levels at C8,T1 whether they come from median or ulnar. In the hand, we are distal, so we will be looking at contributions from the most caudal segements of the brachial plexus, C8-T1. As for the extensor compartment (radial nerve), the triceps will be C6-7, but in the forearm, it will be C7-8 levels. Myotome Breakdown: - Anterior Compartment of the Arm: C5-6 - Anterior Compartment of the Forearm: - Superficial Group: C7 - Deep Group: C8-T1 - Hand Muscles: C8-T1 - Posterior Compartment of Arm: C6-7 - Posterior Compartment of Forearm: C7-8 Compartmentalization Anterior compartments = Flexor Compartments Posterior compartments = Extensor Compartments Anterior compartment of the arm - three muscles - Brachialis - Coracobrachialis - Biceps Brachii Motor innervation by the musculocutaneous nerve (C5-7) Posterior Compartment of the Arm - Triceps brachii - Anconeus (closely related to the triceps) Innervated by the Radial Nerve C5-8 (The extensor compartment Nerve!!!) Anterior Compartment of the Forearm - divided into two groups Su...