F1000Research F1000Research 2046-1402 F1000 Research Limited London, UK 10.12688/f1000research.132477.2 Research Article Articles Morphometry of pyramidalis muscle and its role in reconstructive surgeries: A cadaveric study in South Indian population

[version 2; peer review: 1 approved, 2 approved with reservations]

 Sumalatha Suhani Conceptualization Data Curation Formal Analysis Writing – Review & Editing 1 Rao Sharanya Data Curation Methodology Writing – Original Draft Preparation 1 Ankolekar Vrinda Hari Data Curation Investigation Methodology Supervision Writing – Review & Editing https://orcid.org/0000-0003-1200-5901 a 1 Department of Anatomy, Kasturba Medical College Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India vrinda.hari@manipal.edu

No competing interests were disclosed.

 28 9 2023 2023 12 484 26 9 2023 Copyright: © 2023 Sumalatha S et al. 2023 This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background: The pyramidalis muscle is a tiny triangular-shaped muscle that is located in the anterior abdominal wall, which originates from the body of the pubis and pubic symphysis and is inserted into linea alba. This study aimed to measure the different parameters of the pyramidalis muscle in adult cadavers.

Methods: This study was carried out on 31 adults (26 males and five females) 10% formalin embalmed cadavers of both sexes from the Department of Anatomy at Kasturba Medical College, Manipal.

Results: The mean length of the right pyramidalis muscle was 64.44 ± 12.52 mm and the left pyramidalis muscle was 64.73 ± 12.81 mm. The mean width of the muscle was 15 ± 4.18 mm and 15.03 ± 3.52 mm on the right and left sides, respectively. The mean thickness of the muscle was 1.32 ± 0.55 mm and 1.4 ± 0.80 mm on the right and left sides, respectively. The distance between the umbilicus to pubic symphysis ranged from 130–192 mm and their mean was calculated to be 159.77 ± 15.36. The distance between the umbilicus and the apex of the muscle ranged from 72–123 mm.

Conclusions: The measured parameters like length, width and thickness may help the surgeons to locate the muscle during infra umbilical surgeries.

 Abdominal muscles Anterior abdominal wall Pyramidalis Rectus sheath The author(s) declared that no grants were involved in supporting this work. Amendments from Version 1

As per reviewer’s suggestion

Title was modified

Four hand drawn diagrams depicting all the measurements of Pyramidalis is added in Materials and Methods section.

The embryology/phylogeny of Pyramidalis muscle is added as part of introduction

Additional clinical relevance for Pyramidalis muscle is added

Introduction

The pyramidalis muscle (PM) is a tiny triangular-shaped muscle that is located in the anterior abdominal wall in humans. 1 Muscle is present in the lower anterior part of the rectus abdominis muscle enclosed by the rectus sheath. The muscle originates from the anterior surface of the body of the pubis and pubic symphysis. Through the tendinous fibers, PM is fixed in the anterior part of the pubis and through the ligamentous fibers; it is attached to the pubic symphysis. Inferiorly PM has a broad base, as it ascends, the muscle becomes slender and gets inserted medially into linea alba. Insertion of muscle takes place halfway between the umbilicus and pubis.

It is believed that the action of the PM contracts the linea alba and strengthens the abdominal wall. 2 , 3 On the other hand, its absence does not tend to result in a functional loss. 4 As a result, authors believe it is a vestigial muscle left behind from the pouches of marsupials and monotremes. 5 Myotomes of the lower thoracic region migrate to the ventral part of the abdomen forming a pair of mesodermal primordium which further differentiate into fleshy bellies of the anterior abdominal wall in the prenatal period. 6 The literature regarding the embryogenesis of the pyramidalis muscle is scarce however, pyramidalis muscle is linked phylogenetically to the pouch inside monotremes like - hedgehog and the platypus and marsupials like - the koala or kangaroo. 7 With the evolution of the human, the pouch is responsible for the variation in the morphology and prevelance of the PM. 7 In primates and prosimians, the contraction of the pyramidalis muscle help in the expression of milk from the mammary gland. However due to the regression of supernumerary nipples in humans, pyramidalis muscle lost its importance and considered vestigial. 7

In humans, the PM has been linked to the assumption of upright posture. 8 The PM flap can be used to treat tiny intractable lesions in the foot and ankle, such as chemical wounds and prolonged osteomyelitis. 4 The PM, when cryopreserved, can be used as a source of stem cells that can then be employed to treat post-prostatectomy stress urinary incontinence. 9 When performing a longitudinal incision for a standard caesarean section, the PM was used to locate the linea alba and midline. 10

The morphometric study on PM in the south Indian adult human population is less studied. So this study aimed to explore the various parameters of PM in adult cadavers.

 Methods Ethical approval

The protocol was approved by the Institutional Ethics Committee (IEC-617/2021) Kasturba Medical College and Kasturba Hospitals, Manipal on September 15, 2021. Written informed consent was given by the body donors for teaching and research when they were alive.

 Study design and data collection

In this descriptive cross-sectional study, 31 adult cadavers of both sexes (26 males and five females) were utilized from the Department of Anatomy at Kasturba Medical College (KMC), Manipal for morphometric measurements. Data were collected between October 1, st 2021 to April 30 th, 2022, for a period of six months. Available cadavers in the department were used for the study purpose with the sample size 31. It was a convenient sampling approach. Specimens with damage to the anterior abdominal wall were not considered for the study. With the surgical instruments, cadavers were dissected and muscles were exposed. The following parameters were measured using a vernier caliper:

Length of muscle from the pubic symphysis to its attachment to linea alba (apex) along its medial border ( Figure 1A).

Width at the base/origin of the muscle ( Figure 1B).

The thickness of the muscle at the midpoint of the measured length.

A small gap was found in few cadavers between right and left PM ( Figure 2A). The length and breadth of this gap were measured ( Figure 2B, Figure 2C).

Distance between the umbilicus and pubic symphysis (DUP) and distance between the umbilicus and apex of the muscle (DUA) ( Figure 3).

Distance between the anterior superior iliac spine (ASIS) and lateral part of the base of the muscle (LBM) ( Figure 4).

Distance between ASIS to apex of the muscle ( Figure 4).

Distance between ASIS and the pubic symphysis (ASIS-PS) ( Figure 4).

Anterior abdominal wall with PM.

A) Measurement of length and B) width of PM near its origin. PM, pyramidalis muscle; RAM, rectus abdominis muscle; RPM, right pyramidalis muscle; LPM, left pyramidalis muscle; A, above; L, left.

 Anterior abdominal wall with PM.

A) Gap between the PM. B) Measurement of length and C) width of gap between the PM. PM, pyramidalis muscle; RAM, rectus abdominis muscle; RS, rectus sheath; RPM, right pyramidalis muscle; LPM, left pyramidalis muscle; A, above; L, left.

 Anterior abdominal wall showing PM.

PM, pyramidalis muscle; U, umbilicus; RAM, rectus abdominis muscle; DUP, distance between umbilicus to pubic symphysis; DUA, distance between umbilicus to apex of the muscle; RS, rectus sheath; A, above; L, left.

 Anterior abdominal wall showing PM.

ASIS-LBM: Distance between the anterior superior iliac spine to the lateral part of the base of the muscle. Distance between ASIS to tip of the muscle. Distance between ASIS and PS. PM, pyramidalis muscle; ASIS, anterior superior iliac spine; LBM, lateral part of the base of the muscle; PS, pubic symphysis; U, umbilicus; EOM, external oblique muscle; RS, rectus sheath; IEA, inferior epigastric artery; RAM, rectus abdominis muscle; A, above; L, left.

All the dimensions were completed by the same researcher to avoid inter observer variation.

 Data analysis

Descriptive statistics (mean, standard deviation, and range) were done for all measured parameters. To compare the right and left of each continuous variable, paired T-test was performed. P-value ≤ 0.05 was considered significant. The normally distributed data were correlated using Pearson's correlation coefficient analysis under the following combinations: i) Right and left PM length; ii) Right and left PM width; iii) Right PM length and right PM width; iv) Left PM length and left PM width; v) DUP and PM length (R and L); vi) DUP and PM width (R and L); vii) ASIS-PS (R) and PM width (R); viii) ASIS-PS (L) and PM width (L); ix) ASIS-PS (R) and PM length (R); and x) ASIS-PS (L) and PM length (L). SPSS (RRID:SCR_002865) version 16.0 (Chicago, SPSS Inc.) was utilized for data analysis.

 Results Morphometric measurements

Descriptive statistics

The length of the right PM ranged from 40–95 mm and the left PM ranged from 38–100 mm. The mean length of the right PM was 64.44 ± 12.52 mm and the left PM was 64.73 ± 12.81 mm. There was a 1–2 mm difference between the length of the right and left PM.

The width of the right PM and left PM ranged from 8–24 mm and 9–22 mm, respectively. The mean width of the right PM and left PM was 15 ± 4.18 mm and 15.03 ± 3.52 mm, respectively.

The PM thickness ranged from 0.5–2 mm on both sides. The mean thickness of muscle on the right side was 1.32 ± 0.55 mm and 1.4 ± 0.80 mm on the left side.

In 18 cadavers, a triangular gap was observed between right and left PM. Its length ranged from 8–26 mm and its width ranged from 5–17 mm.

Descriptive statistics of the remaining parameters are tabulated in Table 1. 16

Overview of descriptive statistics calculated in adult cadavers (mm).
Variables Mean ± Standard deviation Range
Length (R) 64.44 ± 12.52 40–95
Length (L) 64.73 ± 12.81 38–100
Width (R) 15 ± 4.18 8–24
Width (L) 15.03 ± 3.52 9–22
Thickness (R) 1.32 ± 0.55 0.5–2
Thickness (L) 1.4 ± 0.80 0.5–4
Length of the triangular gap * 17.33 ± 5.30 8–26
Breadth of the triangular gap * 10.05 ± 3.60 5–17
ASIS - LBM (R) 122.5 ± 10.41 104–149
ASIS - LBM (L) 120.75 ± 8.00 105–138
ASIS - Apex (R) 118.25 ± 10.75 100–148
ASIS - Apex (L) 114.55 ± 12.16 94–144
ASIS - PS (R) 139.81 ± 7.74 122–158
ASIS - PS (L) 140.81 ± 7.10 128–152
DUA 97.48 ± 14.33 72–123
DUP 159.77 ± 15.36 130–192

R, right; L, left; ASIS, anterior superior iliac spine; LBM, lateral part of base of muscle; PS, pubic symphysis; DUA, distance between umbilicus to apex of muscle; DUP, distance between umbilicus to pubic symphysis.

Length of the triangular gap as shown in Figure 2B; width of the triangular gap as shown in Figure 2C.

Paired T-test

A paired T-test was used to compare all the right and left dependent variables. ASIS-Apex (R) and ASIS-Apex (L) were significantly different from each other since the p-value was 0.0014. There was no significant difference between the two respective groups of other dependent variables.

Pearson's correlation coefficient analysis

Pearson's correlation coefficient analysis was done since the data were distributed normally. A significant positive correlation was observed between right and left PM length and right and left PM width. The above result suggests that the increase in length or width of the right PM was directly proportional to the length/width of left PM.

Correlation analysis between right PM length and width and left PM length and width showed a weak but positive correlation. From this, we can note that as the length of the muscle increases, the width of the muscle may or may not increase.

A weak correlation was observed when DUP and ASIS-PS was compared with the right and left PM length and width. From this, we can conclude that the DUP and ASIS-PS have negligible effects on the length and width of the PM. The correlation coefficient and its level, analyzed between the parameters are tabulated in Table 2.

Correlation coefficient and level of correlation between the measured parameters in adults.
Correlated variables Correlation coefficient Level of correlation
Muscle length R & L 0.8824 Very strong positive
Muscle width R & L 0.7149 Strong positive
Right side muscle length and width 0.3411 Weak positive
Left side muscle length and width 0.2525 Weak positive
DUP & Muscle length (R) 0.3036 Weak positive
DUP & Muscle length (L) 0.2602 Weak positive
DUP & Muscle width (R) 0.2719 Weak positive
DUP & Muscle width (L) 0.1586 Very weak positive
ASIS-PS (R) & width (R) 0.0908 Very weak positive
ASIS-PS (L) & Width (L) 0.1841 Very weak positive
ASIS-PS (R) & length (R) 0.2315 Weak positive
ASIS-PS (L) & length (L) 0.2609 Weak positive

R, right; L, left; ASIS, anterior superior iliac spine; DUP, distance between umbilicus to pubic symphysis; PS, pubic symphysis.

 Discussion

Length and width of PM varies in different populations and it is tabulated in Table 3. It was observed in the present study, the length of PM in the female population was almost equal to the length of the PM reported by Natsis et al., 11 Hojaij et al., 12 and Kipkorir et al. 13 The width of the PM noted in the present study is almost equal to the study by Natsis et al. 14 A study by Das et al., 7 reported the mean thickness of 32 ± 0.55 mm in the right PM and 1.4 ± 0.80 mm in the left PM. In our present study, the mean thickness of muscle on the right side was 1.32 ± 0.55 mm and 1.4 ± 0.80 mm on the left side, which was relatively less than the thickness reported in the study by Das et al. 7

Morphometric measurements of pyramidalis muscle done in other studies.
Authors (ref.) Year Population Pyramidalis measurements (mm)
Male Female
Mean length Mean width Mean length Mean width
R L R+L R L R+L R L R+L R L R+L
Anson (8) 1938 American - - 68.2 - - 19.8 - - - - - -
Ashley-Montagu (1) 1939 White Americans - - 83.5 - - 21.8 - - 72.3 - - 59.2
African Americans - - 76.3 - - 19.2 - - 59.2 - - 17.7
Kipkorir V (11) 2021 Kenyan - - 72 - - 71.5 - - 62.2 - - 64.7
Kaur H (6) 2016 North Indian 49.7 49.7 - 17.5 17.2 - 48.7 47.8 - 12.5 14.5 -
Natsis K (9) 2016 Greek 83.7 75.0 - 16.1 15.6 - 61.8 65.6 - 15.0 15.5 -
Das SS (12) 2017 Indian 52.2 53.9 - 18.3 17.0 - 50.1 51.2 - 17.8 16.2 -
Hojaij FC (10) 2020 Brazilian 70.6 68.0 - 18.5 18.3 - 64.2 63.8 - 19.1 19.4 -
Present study 2023 South Indian (Male & female) 64.4 64.7 - 15.0 15.0 - - - - - - -

R, right; L, left.

In the present study, strong positive correlations were found between the lengths and widths of the PM on both sides, which is in line with the results of the study by Natsis et al. 11

The present study also measured ASIS-PS, ASIS-LBM, ASIS-Apex, DUP and DUA. The mean, standard deviation and range values of the aforementioned parameters are tabulated in Table 1. These parameters were not recorded in the previous studies; therefore we were not able to compare it with the other studies.

The present study also showed correlations between the DUP and PM length (R and L), DUP and PM width (R and L), ASIS-PS (R) and PM width (R), ASIS-PS (L) and PM width (L), ASIS-PS (R) and PM length (R), ASIS-PS (L) and PM length (L). The correlation analysis showed a weak but positive correlation between them. This suggests that increases or decreases in ASIS-PS and DUP have negligible effects on the length and width of PM.

Plastic surgeons and general surgeons must be aware of potential regional differences, to reduce the chance of consequences and implement the most effective therapeutic strategy. 14 A prostate-cystopexy employing PM for prostate stabilization can treat individuals with functional dysuria caused by the prostate's retrograde inclination and those with bladder obstruction caused by motor neuron injuries. 15

Pyramidalis Pubo-Umbilical Index can be calculated by using length of PM and distance between umbilicus to pubic symphysis (DUP). Further the knowledge of PPUI could be useful for a variety of clinical and surgical procedure s as it encloses about 40.78% of lower abdominal wall. 3

There is no literature regarding the importance of each parameters or distances measured in this study.

However, it is essential for the surgeons to be aware of the morphometry of the pyramidalis muscle prior to making the different incisions needed for procedures involving the anterior abdominal wall.

Implications

PM act as a landmark for surgeons during infra-umbilical and suprapubic incisions while performing caesarean sections. The PM may be collected through a reasonably unnoticeable Pfannenstiel (pubic) opening with minimal donor site complications making it a desirable donor muscle for microsurgical transfer.

 Limitations

The limitation of the present study is the smaller female cadaver sample size, with respect to the male cadaver sample size. Therefore a sex-based comparison was not performed in this study.

 Recommendations for further research

This study can be done to explore the foetus morphometric data and its clinical implications.

 Conclusions

The parameters like length, width, and thickness and new parameters such as Anterior superior iliac spine Pubic symphysis, Anterior superior iliac spine - Lateral part of the base of the muscle, Anterior superior iliac spine - Apex, Distance between umbilicus to pubic symphysis and Distance between umbilicus to apex of the muscle may help the surgeons to locate the muscle in the suprapubic region while performing surgical procedures to remove the flap of donor pyramidalis muscle.

 Data availability Underlying data

Figshare: Morphometry of pyramidalis muscle and its role in reconstructive surgeries: A cadaveric study. https://doi.org/10.6084/m9.figshare.22200181. 16

This project contains the following underlying data:

EX sheet - Morphometric study of pyramidalis muscle.xlsx

STROBE-checklst.doc

Data are available under the terms of the Creative Commons Zero “No rights reserved” data waiver (CC0 1.0 Public domain dedication).

 Acknowledgements

Authors are thankful to all the teaching and non-teaching staffs at department of Anatomy, KMC Manipal for their support in completing this study.

 References Ashley-Montagu MF : Anthropological significance of the musculus pyramidalis and its variability in man. Am. J. Phys. Anthropol. 1939 Oct;25(3):435–490. 10.1002/ajpa.1330250332 Dickson MJ : The pyramidalis muscle. J. Obstet Gynaecol (Lahore). 1999 July 02;19(3):300. 10.1080/01443619965138 Suhani S Sharanya R Vrinda HA : Prevalence And Variations Of The Pyramidalis Muscle In Adults And Fetuses: Relevance And Clinical Implications. J. Pharm. Negat. Results. 2023;13(10):20. Van Landuyt K Hamdi M Blondeel P : The pyra-midalis muscle free flap. Br. J. Plast. Surg. 2003;56:585–592. 10.1016/S0007-1226(03)00211-X Skret-Magierło J Soja P Drozdzowska A : Two techniques of pyramidalis muscle dissection in Pfannenstiel incision for cesarean section. Ginekol. Pol. 2015;86(7):509–513. 26376528 10.17772/gp/57840 Rizk NN Adieb N : The development of the anterior abdominal wall in the rat in the Light of a new anatomical description. J. Anat. 1982;134(2):237–242. 6210649 PMC1167914 Das SS Saluja S Vasudeva N : Biometrics of pyramidalis muscle and its clinical importance. J. Clin. Diagn. Res. 2017;11(2):AC05–AC07. 28384845 10.7860/JCDR/2017/24179.9276 Kaur H Singla RK Brar RS : Study of the Morphometry of the Pyramidalis Muscle and Its Incidence in the Indian Population. Int. J. Anat. Res. 2016;4(2):2207–2211. 10.16965/ijar.2016.179 Sumino Y Hirata Y Hanada M : Long-term cryopreservation of pyramidalis muscle specimens as a source of striated muscle stem cells for treatment of post-prostatectomy stress urinary incontinence. Prostate. 2011;71(11):1225–1230. 21656833 10.1002/pros.21338 Anson BJ Beaton LE McVay CC : The pyramidalis muscle. Anat. Rec. 1938;72:405–411. 10.1002/ar.1090720403 Natsis K Piagkou M Repousi E : Morphometric variability of pyramidalis muscle and its clinical significance. Surg. Radiol. Anat. 2016;38(3):285–292. 26364033 10.1007/s00276-015-1550-4 Hojaij FC Kogima RO Moyses RA : Morphometry and frequency of the pyramidalis muscle in adult humans: A pyramidalis muscle’s anatomical analysis. Clinics. 2020;75(11):e1623–e1629. 10.6061/clinics/2020/e1623 Kipkorir V Olabu B Ongeti K : Prevalence and pubo-umbilical index of pyramidalis muscle in a select Kenyan population. Surg. Radiol. Anat. 2021;43(9):1461–1466. 33743034 10.1007/s00276-021-02733-6 Malcic-Gürbüz J Özdoǧmuş Ö Yüksel M : Unusual rectus abdominis and pyramidalis muscles: Clinical significance - A case report. Marmara Med. J. 2001;14(2):107–109. Dik P Van Gool JD De Jong TP : Urinary continence and erectile function after bladder neck sling suspension in male patients with spinal dysraphism. BJU Int. 1999 Jun;83(9):971–975. 10368238 10.1046/j.1464-410x.1999.00092.x Sumalatha S Rao S Ankolekar V : Morphometry of pyramidalis muscle and its role in reconstructive surgeries: A cadaveric study.[Dataset]. figshare. 2023. 10.6084/m9.figshare.22200181 10.5256/f1000research.156562.r210635 Reviewer response for version 2 Vallabhajosyula Ranganath 1 Referee Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore

Competing interests: No competing interests were disclosed.

 6 10 2023 Copyright: © 2023 Vallabhajosyula R 2023 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation approve-with-reservations

The authors have made a satisfactory attempt to revise and amend the manuscript. Indeed, the manuscript read well. 

Comments: 

In the methodology, under study design and data collection, the authors have included hand-drawn images of measurements taken.  However, figure 1 does not display 1A and 1B, though the measurements taken were indicated with dotted lines and abbreviations.  It is suggested to indicate the hand-drawn image just as in Figure 1 showing the measurements - length (L) of the pyramidalis muscle (PM) from pubic symphysis (PS) to Linea alba (LA); and width (W) at the origin.  

The legend of Figure 1 should be modified as some of the features that are not indicated in the figure were listed.  for example, RAM is not shown in the image but indicated in the legend, and RPM and LPM are indicated in the legend, but not indicated in the image.  It is suggestible to concise the legend according to the content of the image shown.

Likewise for hand-drawn figure 2, instead of 2A, 2B, and 2C, it is advised to represent as one single figure 2, with proper annotations and revised legend.  Indicate only the structures shown in the image.  for example, in the legend, a - above; and b - below were indicated but not shown in the image, likewise RPM, RS, LPM, and RAM.

As indicated in comments 2 and 3, the legends for the remaining figures are to be modified.

If the authors were able to change the figure numbers, there numbers at the corresponding tables to be modified.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Partly

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Partly

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Gross anatomy, histology, anatomical education, technologies in anatomy education,

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

 10.5256/f1000research.156562.r210633 Reviewer response for version 2 Markand Shanu 1 Referee A.T. Still University, Kirksville, Missouri, USA

Competing interests: No competing interests were disclosed.

 6 10 2023 Copyright: © 2023 Markand S 2023 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation approve

The authors have addressed all comments from reviewers.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Cell culture, anatomical variaitions, histology, and vision sciences.

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

 10.5256/f1000research.145401.r184844 Reviewer response for version 1 Yuksel Mehtap Tiryakioglu 1 Referee Near East University, Nicosia, TRNC Mersin, Turkey

Competing interests: No competing interests were disclosed.

 17 8 2023 Copyright: © 2023 Yuksel MT 2023 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation approve-with-reservations

The article is providing a good morphometrical and statistical data of the pyramidalis muscle which can be an additional information for the readers who are in the field of medical sciences. 

The cadaveric pictures are very clear to be read, yet a simply drawn diagram would also be a good addition to show the reference points for the measurements of the muscle-just a suggestion. 

The title would be specified as "Morphometry of pyramidalis muscle and its role in reconstructive surgeries: A cadaveric study in South Indian population" 

The embryology of pyramidalis muscle also could've been added as part of the Introduction as it may be absent in 20% of the people. Anatomical and morphometrical studies need a good emryological info, so the reason/s underlying the differences can be explained. Otherwise this is a good anatomical study to be indexed.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

I cannot comment. A qualified statistician is required.

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Anatomy

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Ankolekar Vrinda Anatomy, Manipal Academy of Higher Education, Manipal, Karnataka, India

Competing interests: No competing interests were disclosed.

 25 9 2023

Q1. The cadaveric pictures are very clear to be read, yet a simply drawn diagram would also be a good addition to show the reference points for the measurements of the muscle-just a suggestion. 

A. Four hand drawn diagrams to show the reference points for the measurements of pyramidalis muscle are added.

Q2. The title would be specified as "Morphometry of pyramidalis muscle and its role in reconstructive surgeries: A cadaveric study in South Indian population" 

A. The title is specified as above in the manuscript. 

Q3. The embryology of pyramidalis muscle also could've been added as part of the Introduction as it may be absent in 20% of the people. Anatomical and morphometrical studies need a good emryological info, so the reason/s underlying the differences can be explained. Otherwise this is a good anatomical study to be indexed.

The embryology/ phylogeny of pyramidalis muscle is added as part of introduction.

 10.5256/f1000research.145401.r184851 Reviewer response for version 1 Markand Shanu 1 Referee A.T. Still University, Kirksville, Missouri, USA

Competing interests: No competing interests were disclosed.

 17 8 2023 Copyright: © 2023 Markand S 2023 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation approve-with-reservations

The current focused on the morphometric analysis of pyramidal muscle (PM).

Strengths

The study design is good; the images are clear, and the results are interpreted thoroughly. Authors have been diligent in assessing all different aspects of PM morphometry. The paper is easy to follow. 

Areas to Improve

The tile describes the pyramidalis muscles with its role in reconstructive surgeries. The paper covers the former part well, but the latter needs more discussion rather than a sentence or two. The authors need to comment on how different measurements can potentially relate surgically. 

Was there any incidence of the unilateral presence of PM?

Abbreviations should be avoided in the conclusions. 

The triangular gap had a lot of variation, but this aspect was not discussed thoroughly. Additionally, what is the effect of embalming or quality of dissection and time passed after the dissection on these gap measurements (also other parameters)?

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Cell culture, anatomical variaitions, histology, and vision sciences.

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Ankolekar Vrinda Anatomy, Manipal Academy of Higher Education, Manipal, Karnataka, India

Competing interests: No competing interests were disclosed.

 25 9 2023

Q1.The tile describes the pyramidalis muscles with its role in reconstructive surgeries. The paper covers the former part well, but the latter needs more discussion rather than a sentence or two. The authors need to comment on how different measurements can potentially relate surgically. 

A. There is no literature regarding the importance of each and every parameters or how different measurements can potentially relate surgically. However these parameters can be useful for the plastic surgeons while giving abdominal incisions and removal of donor flap.

Q2.Was there any incidence of the unilateral presence of PM?

Yes, in one cadaver

Q3. Abbreviations should be avoided in the conclusions. 

It is removed

Q4. The triangular gap had a lot of variation, but this aspect was not discussed thoroughly. Additionally, what is the effect of embalming or quality of dissection and time passed after the dissection on these gap measurements (also other parameters)?

We used freshly embalmed cadavers and the dissections and measurements were done simultaneously. During suprapubic incisions, as well as while removing the donor flap,the knowledge of triangular gap between the pyramidalis muscle may be helpful for the plastic  surgeons.

 10.5256/f1000research.145401.r173177 Reviewer response for version 1 Vallabhajosyula Ranganath 1 Referee Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore

Competing interests: No competing interests were disclosed.

 14 7 2023 Copyright: © 2023 Vallabhajosyula R 2023 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation approve-with-reservations

There exists a good amount of literature on the morphometry of the pyramidalis muscle. The authors have made a decent attempt to add on the data to the existing information.

The introduction, material and methods, results are well presented. 

The results did not show whether the PM was observed in all the dissections and on both sides. In the results, the authors have reported a significant difference between the distance of ASIS to the TIP of PM on the right and left sides. It is suggestible to justify the reason for the significant difference. Did the authors observe any gender differences in the values, having less female sample though?

The authors would have explained in more detail the importance of the Pearson correlation that was applied in their study and how these observations are useful for clinical interventions.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Partly

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Partly

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

gross anatomy, histology, anatomical education, technologies in anatomy education,

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Ankolekar Vrinda Anatomy, Manipal Academy of Higher Education, Manipal, Karnataka, India

Competing interests: No competing interests were disclosed.

 18 7 2023

Q. The results did not show whether the PM was observed in all the dissections and on both sides.

A. PM was observed in 27 cadavers out of 31, in 26 cadavers it was bilateral and in one cadaver it was unilateral.

Q.  In the results, the authors have reported a significant difference between the distance of ASIS to the TIP of PM on the right and left sides. It is suggestible to justify the reason for the significant difference.

A. The distance of ASIS to tip of right & left PM were significantly different because of the difference in the length of right and left PM.

Q. Did the authors observe any gender differences in the values, having less female sample though?

A. We did not observe any gender differences

Q. The authors would have explained in more detail the importance of the Pearson correlation that was applied in their study and how these observations are useful for clinical interventions.

A. The Pearson's correlation was performed to see whether there is any relationship between the measured values. We found strong correlation with length of right and left side PM. This could help the surgeons to locate PM and acquire required amount of flap to treat minor lesions in ankle region.