Brachial Plexus

Branches from Trunk:

1. Suprascapular Nerve ( C5, 6 )
2. N. to subclavius    ( C 5, 6 )

Branches from Roots:

1. Long thoracic nerve ( C 5, 6, 7)
2. Dorsal scapular nerve ( C 5)

Arcade of frohse

The most superior part of the superficial layer of the supinator muscle is named as the arcade of Frohse (AF). The deep branch of the radial nerve runs under this arch. The AF is reported to be the most common structure causing entrapment neuropathy of the deep branch of the radial nerve(PIN syndrome).

Osborne's ligament ( Band of Osborne )

roof of cubital tunnel is formed by aponeurosic attachment of 2 heads of FCU, which spans in arcade like manner from medial 
                epicondyle of humerus to the olecranon process of the ulna (also known as Osborne's ligament);
                - cubital tunnel begins where the ulnar nerve passes beneath Osborne's ligament;

Arcade of Struthers

    - in middle of the arm, ulnar nerve pierces medial intermuscular septum and descends in front of the medial head of the triceps;

    - in 70-80% of individuals, nerve passes under arcade of Struthers;
    - the arcade is a thin aponeurotic band extending from medial head of triceps to the medial intermuscular septum;
           - it lies approximately 8 cm proximal to the medial epicondyle;
    - the arcade may appear as medial triceps muscle fibers crossing superficial to the ulnar nerve;
    - arcade is not site for entrapment under ordinary circumstances, but it may become point of kinking if anterior transposition of ulnar nerve is performed;
           - following transposition procedures, the surgeon should release the arcade if it appears that the nerve is under tension;

Ulnar Nerve

Ulnar nerve is the branch of the medial cord of brachial plexus with root value C8 and T1. 


it supplies flexor carpi ulnaris and the medial half of flexor digitorium profundus in forearm.


 In the hand through its superficial branch it supplies palmaris brevis and digital branches to the volar side of the little finger and medial half of ring finger. 


The deep branch supplies the hypothenar, the dorsal and palmar interossei, two medial lumbricals and the adductor pollicis muscles of the hand.