National Journal of Clinical Anatomy

: 2021  |  Volume : 10  |  Issue : 2  |  Page : 89--92

Correlational anatomy of biceps brachii muscle with its footprint and aponeurosis parameters

Suresh Narayanan 
 Associate Professor, Department of Anatomy, Sri Manakula Vinayagar Medical College and Hospital, Puducherry, India

Correspondence Address:
Suresh Narayanan
Department of Anatomy, Sri Manakula Vinayagar Medical College, Puducherry - 605 107


Background and Aims: The anatomy of the distal biceps tendon (DBT) and its insertional anatomy to radial tuberosity is important to understand the pathophysiology of tendon rupture and in surgical repair of the ruptured tendon. The present study aimed to evaluate the relationship between biceps brachii parameters with biceps footprint and lacertus fibrosus (LF) parameters. Materials and Methods: This was a cross-sectional observational study done on 23 cadavers. The biceps brachii perimeters, the length of the DBT, distance between the radial head and radial tuberosity, footprint length, footprint breadth, and LF width were noted (with measuring tape and digital vernier caliper. LF angle was measured using Image J software. Results: There was a weak positive correlation between biceps brachii perimeter and footprint length (r = 0.392), biceps brachii perimeter and footprint breadth (r = 0.341), biceps brachii perimeter and LF width (r = 0.300), and moderate positive correlation between footprint length and breadth (r = 0.686). Conclusion: The biceps brachii perimeter has a minimal role in influencing the footprint dimensions and LF morphology. The study has explored the biomechanical aspect of the biceps brachii insertional anatomy. The data on footprint dimension and aponeurosis could help the surgeons in the effective repair of the ruptured tendon and achieving a better postoperative outcome.

How to cite this article:
Narayanan S. Correlational anatomy of biceps brachii muscle with its footprint and aponeurosis parameters.Natl J Clin Anat 2021;10:89-92

How to cite this URL:
Narayanan S. Correlational anatomy of biceps brachii muscle with its footprint and aponeurosis parameters. Natl J Clin Anat [serial online] 2021 [cited 2022 Aug 10 ];10:89-92
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The biceps brachii muscle (BBm) consists of two heads, the long head arising from the supraglenoid tubercle and a short head arising from the coracoid process. The fibers from both the long and short head fuse to form a single muscle belly which continues distally as biceps tendon.[1],[2] The distal biceps tendon (DBT) rotates externally and gets inserted on the posterior aspect of the radial tuberosity.[1],[2] As the DBT passes anterior to the elbow joint, the lacertus fibrosus (LF) emerges from DBT at an angle, merges with the deep fascia of the forearm covering the origin of the flexor muscles of the forearm, and gets attached to the posterior subcutaneous border of the ulna.[3],[4] This structure helps in reinforcing the antebrachial fascia, protecting the underlying neurovascular structures, and increasing the force on the biceps tendon.[5],[6]

A sudden force to a flexed elbow can result in avulsion of DBT either partially or completely from the radial tuberosity.[7] This rupture is often associated with pain in the antecubital fossa, deformity, and cramping.[8] Hence, the knowledge of the DBT insertional anatomy is vital in understanding the pathophysiology of tendon rupture and in surgical repair of the ruptured tendon.[9],[10],[11],[12] In literature, the morphometry of the DBT and its footprint (oval and semilunar configuration) over the radial tuberosity are not consistent.[13],[14],[15],[16] However, studies have not investigated the role of BBm morphometry over the footprint dimensions.

From a clinical point of view, a thick LF has a higher risk of median nerve compression.[6] Previous studies have enumerated the origin, morphometry, and attachment of the LF.[3],[6] Studies have speculated that LF plays a role in altering the tension of BBm tendon,[17] but it lacks substantial evidence to support the biomechanics behind the mechanism. A recent study has reported no significant correlation between the LF morphology and the upper limb parameters.[3] Hence, it is imperative to find the correlational anatomy between the BBm morphometry and LF parameters.

The present study aimed to evaluate the relationship between the BBm perimeter with the distal tendon parameters. The objective of this study was to estimate the strength of association between the parameters of BBm, footprint, and LF.

 Materials and Methods

This was a cross-sectional observational study. Specimens that showed signs of prior trauma or surgery were excluded from the study. Twenty-three formalin-fixed cadavers (20 males and 3 females) with ages ranging from 62 to78 years from the Department of Anatomy, Sri Manakula Vinayagar Medical college, Puducherry were included in the study. After making the required incisions, the skin and fascia were delineated to expose the BBm belly, distal tendon, and LF. The shoulder was abducted, with the elbow extended and forearm supinated. All the parameters were measured using a standard digital Vernier caliper (twice by the first author to minimize the errors). To measure the biceps footprint parameters, the DBT was detached from its insertion.

The measured parameters include the perimeter of BBm (P) – the maximum perimeter of the BBm belly measured using measuring tape, length of distal biceps brachii tendon (L) – from the point of muscle fiber termination to the biceps tendon insertion in radial tuberosity, distance between the superior limit of the radial head and superior limit of radial tuberosity (RH-RT) [Figure 1], length of biceps footprint insertion (FL), breadth of biceps footprint insertion (FB) [Figure 2], and width of LF at the point of emergence from DBT (LFW). The LF angle (LFA) – Superior view photographs were taken from a fixed camera (height between the specimen and the camera is 15 cm) of 20 megapixels to minimize parallax error. In the image obtained, points were marked at the proximal, middle, and distal end of the biceps tendon and LF. The LFA was measured between the axis representing biceps brachii tendon and LF axis (measured using Image J software) [Figure 3].{Figure 1}{Figure 2}{Figure 3}

The mean and standard deviation of the parameters were calculated and analyzed for normality using the Shapiro–Wilk test. The strength of association between the parameters was evaluated by Pearson's correlation coefficient. Correlations were considered acceptable if r > 0.70. The statistical analysis was done using SPSS software, version 17.0 (IBM Inc, USA). P < 0.05 was registered and assumed as significant.


The short and long heads of the BBm were identified in all limbs (the extra head of the biceps was not observed). In the distal part, a single fused tendon was inserted in the radial tuberosity in a spiraling configuration. However, in two limbs (same cadaver), the biceps tendon had a distinct band-shaped arrangement. The LF was identifiable in all the specimens, and it was found to arise from the musculoaponeurotic junction and merge with the antebrachial fascia over the forearm group of muscles.

The mean and standard deviation were 8.70 ± 1.64 mm for perimeter of BBm, 66.35 ± 12.02 mm for L of BBm tendon, 20.54 ± 0.77 mm for distance between RH-RT, 16 ± 2.89 mm for FL, 7.43 ± 1.43 mm for FB, 19.35° ± 1.93° for LFA, and 16.01 ± 1.88 mm for LFW. There was a weak positive correlation between BBm perimeter and FL (r = 0.392), BBm perimeter and FB (r = 0.341), BBm perimeter and LFW (0.300), and moderate positive correlation between FL and FB (r = 0.686) [Table 1].{Table 1}


Snoeck et al. reported a mean BBm circumference of 8.7 ± 1.9 cm but did not correlate the data with the footprint parameters.[3] The weak correlation between the BBm perimeter and the footprint dimensions observed in the study indicates that the insertional dimensions of the footprint do not represent the biomechanical load passing through it and could be due to other mechanical factors. Hence, the author speculates that the footprint dimensions are just a morphological variation and do not have any biomechanical advantage.

Athwal et al. reported FL of 21 mm (range: 17–25) and FB of 7 mm (range: 6–10).[1] Cho et al. documented FL of 20.5 ± 2 mm and FB of 9.7 ± 1.3 mm.[11] Bhatia et al. reported FL of 23.8 ± 2.4 mm and FB of 13.4 ± 1.8 mm.[16] The mean FL (16 ± 2.89 mm) and FB (7.43 ± 1.43 mm) obtained from the current study were comparable with other studies. The lower values of FL observed in the current study could be due to the removal of the soft tissues at the insertional site or variation due to ethnicity. Studies have reported that the tendon reconstruction should cover the biceps footprint area adequately for better clinical outcomes.[10],[11] The morphometric data from the study can be useful for surgeons in restoring the normal anatomy of the tendon. The moderate correlation observed between FL and FB provides an insight into the occurrence of an oval-shaped footprint. However, the occurrence of the semilunar morphology could not be explained by the data obtained from the study and requires further biomechanical research.

Joshi et al. measured the LFA using a goniometer and obtained 21.16° ± 6.95°.[18] The LFA measured using the photographic method in the present study was 19.35° ± 1.93°. This could be due to the difference in the methodology used in measuring the values. Studies have suggested that the functional role of LF is to pull the biceps tendon medially, thereby reducing the tension load on the DBT.[2],[11] A previous study has established a weak positive correlation between biceps tendon length and LF length parameters.[3] In our study, there was a weak association between the BBm perimeter and the LFW and a lack of association between BBm parameters with the LFA. This indicates that the LF exhibits a variable morphology and is independent of its muscle and tendon anatomy. From a surgical perspective, a study has suggested that repairing both the BBm tendon and LF is needed to prevent the complication of a decreased range of elbow movements.[13] The LFA obtained from the current study can be utilized to restore the anatomical relationship between the LF and the tendon.

The average distance from the articular margin of the radial head to the upper margin of the radial tuberosity was 20.54 ± 0.76 mm. Previous cadaveric studies have reported similar values of 19–23 mm.[1],[11] Since there was no correlation between the BBm circumference or DBT length parameters with the RH-RT distance, it can be understood that the relative position of the radial tuberosity is a fixed landmark and was not subjected to biomechanical loading of the tendon inserted. This morphometric data can be useful as a surgical landmark in locating the distal tendon during reconstructive surgeries.[10],[19],[20]

The present study was unique in correlating the BBm parameters with the footprint and LF parameters which were not explored before. The limitations of the study include the lack of correlation of morphometric data with the footprint area and the orientation axis of the biceps tendon insertion. Future research can focus on the difference in the morphometric parameters between specimens with “oval” and “semilunar” shaped footprints in a larger sample size.


The study has demonstrated that the biceps brachii perimeter and its tendon have a minimal role in influencing the footprint dimensions and LF morphology. The morphometric data on footprint dimension and LF could help the surgeons in the effective repair of the ruptured tendon and achieving a better postoperative outcome.


The author would like to acknowledge the donor cadavers for the use of research.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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