Accessory heads of the biceps brachii muscle: A systematic review and meta‐analysis

Abstract

The anatomy of the biceps brachii muscle has been a subject of interest to many researchers. In particular, the presence of one or more accessory heads has been reported to be the most common variation of the biceps brachii muscle. In fact, contemporary knowledge is quite inconsistent and lacks a definitive summary. Taking this into account, the present study aims to investigate the overall prevalence of the accessory heads and related questions, such as their broad morphological features, population variance, sexual dimorphism, side distribution or the changes in prevalence rates over time. A literature search of major scientific databases was conducted and produced 78 eligible articles, including 10,603 upper limbs, for our study. Relevant data were extracted and consequently analysed with the use of random-effects metaanalysis. As a result, the accessory heads occur with an overall prevalence of 9.6% (95% CI 8-11%) and by far the most common is the presence of a single accessory head (8.4%; 95% CI 7-10%). Additional sub-analyses revealed that accessory heads appear more frequently unilaterally and in males. Differences between the occurrence on the right or left side were not significant. Moreover, a decreasing trend in prevalence rates over time was observed, pointing towards an evolutionary adaptation. The innervation and blood supply of the accessory heads are nearly identical to that of the normal biceps brachii muscle. Although the accessory heads are usually asymptomatic, their potential presence must be kept in mind while interpreting various conditions. In addition, their direct clinical importance is speculated and is thought that they might be conductive to several pathological processes around the shoulder girdle and brachial region. While many of the morphological and morphometric aspects of the accessory heads are well documented, their functional value is still a matter for future investigations.

The superior thyroid artery origin pattern: A systematic review with meta-analysis

“…Notably, signi cant heterogeneity was observed during subgroup analysis, a common challenge in anatomical metaanalyses [12,30]. Furthermore, the AQUA Tool identi ed a high risk of bias in most of the included studies, which is also a typical issue in anatomical meta-analyses [12,30].…”

“…Notably, signi cant heterogeneity was observed during subgroup analysis, a common challenge in anatomical metaanalyses [12,30]. Furthermore, the AQUA Tool identi ed a high risk of bias in most of the included studies, which is also a typical issue in anatomical meta-analyses [12,30]. Regrettably, the available literature lacked additional parameters for study, such as the number and distribution of branches originating from the STA.…”

Study protocol: Accommodative effects on the musculoskeletal system

“…Two abdominal muscles (rectus abdominis muscle and abdominal external oblique muscle) were chosen because of their important function in lumbar spine movements [35,36]. The biceps brachii muscle has been selected as an important muscle for proper upper limb function [37,38].…”

The Rest-Pause Biceps Curl Exercise Effect on Biceps Brachii Muscle of Women: A Study of Mechanical Responsiveness

“…It has two heads, the short head and the long head, that originate from different parts of the scapula (shoulder blade) and insert on the radius bone of the forearm [1]. It is responsible for flexion of the elbow joint, supination of the forearm, and assisting in shoulder movement [2]. The contraction of the BB muscle, like in all skeletal muscles, sets in motion a highly regulated series of biological events, culminating in the deliberate generation of force [3].…”