Variations of the pubic vascular anastomoses in black South Africans.

Variations of the arterial and venous pubic anastomoses (APA, VPA) were studied. Forty-four percent of the APA were replaced by an obturator artery arising from the inferior epigastric and 25% by an obturator artery arising from the external iliac. Seven percent of the VPA were replaced by a single obturator vein, 37% by the superior companion of a double obturator vein, and 2% by a double obturator vein. Black South African subjects exhibit a higher incidence of variations of the pubic anastomoses than North American, European and Japanese populations.

Incidence of the coracoclavicular joint in South African populations.

The presence of a diarthrotic coracoclavicular joint, as represented by an articular facet on the conoid tubercle of the clavicle and the superior surface of the coracoid process of the scapula, was investigated. The sample consisted of 60 white and 180 black South African (60 Sotho, 60 Xhosa and 60 Zulu) skeletons. Each group consisted of 30 male and 30 female skeletons. The presence of the articular facet was recorded as either bilateral, unilateral left or unilateral right. The effect of clavicular length, scapular size and first rib angle on the presence of the coracoclavicular joint was also investigated. The presence of the articular facet was noted in 23 (9.6%) of the 240 individuals studied. Of these 23 individuals, 6 (26.1%) were white and 17 (73.9%) were black. Males (56.5%) presented a higher incidence of this anomaly than females (43.5%). The articular facet occurred bilaterally in 47.9% (11/23), unilaterally on the left in 30.4% (7/23) and unilaterally on the right in 21.7% (5/23). Sexual, racial and tribal differences were not statistically significant. Individuals possessing the joint showed statistically significantly (P < 0.01) larger scapulae (increased border lengths and superior angles), longer clavicles and longer first ribs. No statistically significant differences in the first rib angles were observed between individuals who possessed the joint and those who did not, thus implying similar thoracic inlet size. It is proposed that the aforementioned morphometry of the scapulae, clavicles and first ribs may restrict associated movements of the scapulae, resulting in the development of the coracoclavicular joint.

High incidence of the third head of biceps brachii in South African populations.

Three different origins were found for the third head of the biceps brachii: (1) an origin from the humeral shaft inferior to and in common with the insertion area for the coracobrachialis; (2) a brachial origin in which the muscle originated distally from the medial humeral shaft, adjacent to and in common with the brachialis muscle; (3) a dual origin in which the medial fibres originated from the short head of biceps and the lateral fibres from the deltoid fascia and the insertion area of this muscle. In all cases, the third head inserted together with the other 2 heads of biceps brachii into the bicipital aponeurosis and the radial tuberosity. The third head receives its innervation from the musculocutaneous nerve, as do the other 2 heads of biceps. When there is a dual origin, partial innervation from the axillary nerve is possible since the fibres of the third head intermingle with those of the deltoid. There was a 20.5% incidence of the third head in South African blacks and only an 8.3% incidence in South African whites. Statistical analysis showed the difference between South African whites and blacks to be significant (P < 0.05). Not all of the blacks, however, had a higher incidence, since the Zulus showed a significant absence (P < 0.05) of the third head when compared with the other black populations.