Surgical and clinical anatomy of the interclavicular ligament.

Dislocation of the sternoclavicular joint can be associated with life-threatening complications; therefore, a thorough knowledge of the ligaments contributing to sternoclavicular joint stability is essential for the clinician dealing with this anatomical area. The aim of our study was to examine the anatomy of the interclavicular ligament. We examined 50 human cadavers. The interclavicular ligament was identified in 90% of the specimens. The interclavicular ligament was located at the base of the sternal notch in 50% of the cases and connected the superior portions of the capsule of the sternoclavicular joints of each side. The interclavicular ligament connected with the posterior superior aspect of each medial end of the clavicle and with the fibers of the posterior and anterior interclavicular ligaments forming a continuous ligamentous layer. The mean length of this ligament was 2.1 cm, the mean width was 0.72 cm and the mean thickness was 0.36 cm. With the elevation of the shoulder joint and the abduction of the humerus, the interclavicular ligament remained lax. With the depression of the shoulder joint and the adduction of the humerus, this ligament became fully taut. As a result, the interclavicular ligament prevented the upward displacement of the clavicle during forceful depression of the humerus and the shoulder. The tensile force necessary for failure was >53.7 N/cm(2) in all the specimens. These data may be useful to surgeons for instituting techniques for surgical procedures that reconstruct the sternoclavicular joint. Moreover, a future study aimed at evaluating the long-term consequences of surgical transection of this ligament may be in order.

Anatomy and quantitation of the subscapular nerves.

Information regarding branches of the brachial plexus can be of utility to the surgeon for neurotization procedures following injury. Sixty-two adult cadaveric upper extremities were dissected and the subscapular nerves identified and measured. The upper subscapular nerve originated from the posterior cord in 97% of the cases and in 3% of the cases directly from the axillary nerve. The upper subscapular nerve originated as a single nerve in 90.3% of the cases, as two independent nerve trunks in 8% of the cases and as three independent nerve trunks in 1.6% of the cases. The thoracodorsal nerve originated from the posterior cord in 98.5% of the cases and in 1.5% of the cases directly from the proximal segment of the radial nerve. The thoracodorsal nerve always originated as a single nerve from the brachial plexus. The lower subscapular nerve originated from the posterior cord in 79% of the cases and in 21% of the cases directly from the proximal segment of the axillary nerve. The lower subscapular nerve originated as a single nerve in 93.6% of the cases and as two independent nerve trunks in 6.4% of the cases. The mean length of the lower subscapular nerve from its origin until it provided its branch into the subscapularis muscle was 3.5 cm and the mean distance from this branch until its termination into the teres major muscle was 6 cm. The mean diameter of this nerve was 1.9 mm. The mean length of the upper subscapular nerve from its origin to its termination into the subscapularis muscle was 5 cm and the mean diameter of the nerve was 2.3 mm. The mean length of the thoracodorsal nerve from its origin to its termination into the latissimus dorsi muscle was 13.7 cm. The mean diameter of this nerve was 2.6 mm. Our hopes are that these data will prove useful to the surgeon in surgical planning for potential neurotization procedures of the brachial plexus.