Superficial brachial artery: a possible cause for idiopathic median nerve entrapment neuropathy

Nerve entrapment syndromes occur because of anatomic constraints at specific locations in both upper and lower limbs. Anatomical locations prone to nerve entrapment syndromes include sites where a nerve courses through fibro-osseous or fibromuscular tunnels or penetrates a muscle. The median nerve (MN) can be entrapped by the ligament of Struthers; thickened biceps aponeurosis; between the superficial and deep heads of the pronator teres muscle and by a thickened proximal edge of flexor digitorum superficialis muscle. A few cases of MN neuropathies encountered are reported to be idiopathic. The superficial branchial artery (SBA) is defined as the artery running superficial to MN or its roots. This divergence from normal anatomy may be the possible explanation for idiopathic MN entrapment neuropathy. This study presents three cases with unilateral presence of the SBA encountered during routine undergraduate dissection at the University of Johannesburg. Case 1 - SBA divided into radial and ulnar arteries. Brachial artery (BA) terminated as deep brachial artery. Case 2 - SBA continued as radial artery (RA). BA terminated as ulnar artery (UA), anterior and posterior interosseous arteries. Case 3 - SBA continued as UA. BA divided into radial and common interosseous arteries. Arteries that take an unusual course are more vulnerable to iatrogenic injury du-ring surgical procedures and may disturb the evaluation of angiographic images during diagnosis. In particular, the presence of SBA may be acourse of idiopathic neuropathies.

Origin of the subscapular artery in the South African Black population

There is great variability in the branching patterns of the axillary artery (AA). Racial differences have been reported to play a role in this variability. The subscapular artery (SA) is the largest and most variable branch of the AA. It usually arises from the third part of the AA at the inferior border of the subscapularis muscle. Approximately 4 cm from its origin, the SA divides into the circumflex scapular and thoracodorsal arteries. Two types of the SA have been described, depending on the site of its origin from the AA in relation to the point where the AA passes between the lateral and medial roots of the median nerve. It is referred to as the superficial SA (SSA), when proximal, and the deep SA (DSA), when distal to this point, respectively. This study aimed to determine the site and distance of origin of the SA from the outer border of the first rib in the South African Black population. The study comprised bilateral gross anatomical dissections of 50 adult Black South African cadavers (n = 100 AAs). The site and distance of origin of each vessel from the outer border of the first rib were recorded. Additional branches and variations were also noted. The SSA and DSA were found in 52.8% and 47.2% of cases, respectively. In 16.8% of cases, the SA gave rise to the posterior circumflex humeral artery and the lateral thoracic artery in 33.7% cases. The SA was absent in 11% of the cases. The prevalence of the SSA reported in this study differs from values ranging between 1.7% and 16% reported in the literature. The high incidence of the SSA in this study may have clinical significance as a superficial course of the arteries make them vulnerable to injury during surgical procedures.

Organization of the Middle Meningeal Artery in a Sample of Black South African Population: Clinical Correlates

BACKGROUND

The middle meningeal artery (MMA) is the leading supplier of the cranial dura and serves as a donor blood channel in craniotomy and cerebrovascular bypass procedures. However, the complex embryology of the MMA and population differences give rise to several anatomic variations that are of great importance in head injuries pertaining to the petrous and squamous parts of the temporal bone. Similarly, care must be taken to protect the artery during surgical operations that involve the maxillary artery and the vidian nerve.

AIM

To evaluate the morphometry and clinical correlates of the middle meningeal artery in the black population of South Africa.

METHODS

The current study investigated the organization of the MMA in 100 adult dry human skulls (n = 50 males: n = 50 females) by tracing its grooves and measuring the length of the MMA, its frontal branch (FB), parietal branch (PB), the angle between FB and PB, and the angle of MMA from the foramen ovale (FO) bilaterally.

RESULTS

In comparison to females, males had significantly longer left PB (P = 0.003) and a considerably larger right angle of the MMA from the FO (P = 0.018). Furthermore, the PB was significantly longer on the left side than the right side in the entire sample (P = 0.002). Other parameters had no significant differences in sex and side.

CONCLUSIONS

The longer PB and the larger angle of the MMA in males could be attributed to why there is a high incidence of chronic subdural hematomas and MMA aneurysms in males. The current study is the first to propose a possible explanation for the aforementioned findings with regard to the organization of the MMA.