Variations and Lesions of the Brachial Plexus at the Level of Nerve Trunks

Superior trunk injuries are usually the result of traction or radiation injuries, congenital lesions, or tumours. Upper root lesions are associated with combined damage of the axillary, musculocutaneous, and partially the radial nerve—affecting the muscles connected to C5 and C6 segments. Superior trunk damage can be accompanied by the suprascapular n. lesion. Bicipital and tricipital reflexes are absent. Damage of the middle trunk is presented with the combined damage of radial and partially the median nerves. Due to the damage to the median nerve, the pronation and opposition of the thumb are partially impaired, and the triceps brachii muscle reflex is missing. The inferior trunk lesions are associated with the partial median nerve, the entire ulnar nerve, and medial cutaneous brachial and antebrachial nerve injuries. This lesion occurs often as a result of traction lesions of the abducted arm during a difficult childbirth, tumours of the superior thoracic aperture, cervical rib, or radiation damage. The variations of the brachial plexus supraclavicular part—superior, middle, and inferior trunks—are shown in the table.