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Anatomy and Sites of Compression of Cubital Tunnel

Anatomy & Sites of Compression of Cubital Tunnel

- Discussion:
- cubital tunnel extends from medial epicondyle to olecranon;
- it serves as the major contraint for the ulnar nerve as it passes behind the elbow;
- w/ flexion the cubital tunnel becomes taunt, and with extension the cubital tunnel becomes lax;
- aponeurotic roof of the cubital tunnel becomes maximally taut during flexion because the 2 points of
attachment (the medial epicondyle and the olecranon) are farthest apart during this position;
- it has been suggested that individuals w/ ulnar subluxation may have a deficient cubital tunnel;
- the floor the cubital tunnel includes the MCL, the joint capsule, and olecranon;

- Sites of Compression:
- Arcade of Struthers
- located 8 cm above elbow;
- in most cases of transposition, division of the ligament of Struthers is not necessary, but should be considered;
- Medial head of Triceps
- Medial Intermuscular Septum:
- becomes thick distally and flares as it inserts onto the medial epicondyle;
- distal segment of medial intermuscular septum is excised, just above the medial epicondyle;
- some authors recommend excision of the distal 5-6 cm of the intermuscular septum inorder to avoid iatrogenic
compresssion with transposition;
- references:
The relationship of the ulnar nerve to the medial intermuscular septum in the arm and its clinical significance.
- Medial Epicondyle: nerve may be irritated by medial epicondyle osteophytes;
- Cubital tunnel (FCU Aponeurosis)
- 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;
- aponeurosis of origin of the flexor carpi ulnaris;
- aponeurosis is drawn taut over nerve w/ elbow flexion;
- point of constriction is 1.5-3.5 cm distal to epicondyle;
- floor is formed by MCL of elbow, which extends in fanlike fashion from medial border of olecrnaon process
to base of  epicondyle;
- in majority of cases sharp proximal margin of musculoaponeurotic arcade is constricting agent in pts w/
cubital tunnel syndrome;
- at level of medial epicondyle before nerve enters cubital tunnel, it gives off the articular branches to the elbow joint;
- ulnar nerve reaches groove behind medial epicondyle accompanied by ulnar collateral artery;
- anterior band of medial collateral ligament is anterior to ulnar nerve, which does not cross it;
- branches to FCU & medial half of FDP are given off distal to entry of nerve into cubital tunnel, yet these 2 muscles are usually
spared in cubital tunnel syndrome;
- Anconeus epitrochlearis
- anomalous muscle which arises from medial border of olecranon & adjacent triceps & inserts into the medial epicondyle;
- may be found in about of 10% patients undergoing cubital tunnel release;
- it crosses ulnar nerve posterior to the cubital tunnel, and may cause ulnar neuritis;
- Arcuate Ligament: (Aponeurosis of FCU)
- connects the ulnar and humeral heads of the FCU;
- often requires division into the proximal 1/3 of forearm;
- Deep Flexor-Pronator Aponeurosis:
- distal to cubital tunnel (> 4 cm beyond the epicondyle);
- palpation of the distal course of the nerve can ensure that there is no fascial constriction;
- ref:
- Entrapment of the ulnar nerve by the deep flexor pronator aponeurosis.