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Table of Contents
ORIGINAL ARTICLE
Year : 2021  |  Volume : 70  |  Issue : 2  |  Page : 101-105

Anatomical variations in scapula: A study with correlation to gender and sides


Department of Anatomy, Pt. B.D. Sharma Postgraduate Institute of Medical Sciences, Rohtak, Haryana, India

Date of Submission01-Feb-2020
Date of Acceptance27-Apr-2021
Date of Web Publication30-Jun-2021

Correspondence Address:
Dr. Ritu Singroha
House No - 15/9J, PGIMS Medical Campus, Rohtak, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JASI.JASI_21_20

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  Abstract 


Introduction: Anatomical variation is defined as the normal flexibility in the topography and morphology of body structures. The present study was planned to study anatomical variations in dry scapula of North Indian population and their comparison between males and females on both sides. Material and Methods: The study was performed at the Department of Anatomy, PGIMS, Rohtak, on fifty pairs of human scapulae, out of which thirty were males and twenty were females. Various anatomical variations were noted such as sulcus for circumflex scapular artery, costal facets, horizontal inferior border, scapular foramina, and facet on inferior surface of acromion process. Morphological types of tip of acromion process, inferior surface of acromion process, and superior border of scapula were studied. These parameters were compared in both sexes on both the sides. Results: Majority of the anatomical variations were common in females in comparison to males. Discussion and Conclusion: Knowledge of the anatomical variations of scapula is the key to a successful outcome in the clinical setting.

Keywords: Anatomical, costal, morphology, topography


How to cite this article:
Singroha R, Verma U, Rathee SK. Anatomical variations in scapula: A study with correlation to gender and sides. J Anat Soc India 2021;70:101-5

How to cite this URL:
Singroha R, Verma U, Rathee SK. Anatomical variations in scapula: A study with correlation to gender and sides. J Anat Soc India [serial online] 2021 [cited 2021 Jul 31];70:101-5. Available from: https://www.jasi.org.in/text.asp?2021/70/2/101/320275




  Introduction Top


The scapula is a large, flat, and triangular bone which lies on the posterolateral aspect of the chest wall, covering parts of the second to seventh ribs. It has costal and dorsal surfaces; superior, lateral, and medial borders; inferior, superior, and lateral angles; and three processes, the spine, the acromion, and the coracoid process.[1]

Anatomical variation is defined as the normal flexibility in the topography and morphology of body structures.[2] Not many anatomical variations have been reported in scapula, yet some of these variations have got clinical significance.

Typically, the anterior surface of the scapula is smooth and articulates indirectly with the posterior thoracic wall through the scapulothoracic joint. The anterior surface of the scapula has sometimes been reported to have distinct synovial articulations with the ribs that restrict its motion. This has been reported occurring near the inferior angle, superior angle, and superior border of the scapula. Fontan described a pair of scapulae, which possessed two costal facts each. They articulated with the posterior surfaces of the third and seventh ribs, respectively, and had associated with them both a capsule and synovial membrane.[3]

The supraspinous and infraspinous fossae are located on the posterior aspect of scapula, and the bone in this region can become quite thin. Hence, the incidence of scapular foramina is more in these fossae.[3]

Increased degenerative changes are associated with increased length of the acromion, and length is in turn related to the shape of the acromion. The longest specimens are “cobra” shaped with a mean length of 6.2 cm. The shortest specimens are “square tipped” with a mean length of 5.2 cm.[4]

The superior border of scapula is the most variable of the scapula's borders. It can appear horizontal, moderately oblique, markedly oblique, deeply saddle shaped, concave or semilunar, and wavy.[3]

Although nearly all possible human anatomical variations have been reported and cataloged, their combinations continue to arouse interest. Second, there appear to be ethnic differences in the frequency of these variations. Consequently, there is a need for continuous appraisal for emphasis and to encourage anatomists and clinicians to beware of their existence. Unfortunately, continuous appreciation of variations is being undermined by current trends in the undergraduate medical training characterized by reduced exposure to dissection and dissected specimens, increased use of plastic bones, computer-generated images, loss of experienced teachers, especially those who are medically trained, and loss of morphological approach.[5]

Since there is dearth of literature regarding the anatomical variations of scapula in North Indian population, so, the present study was planned to study these anatomical variations in dry scapula of North Indian population and their comparison between males and females on both sides.


  Material and Methods Top


The present study was conducted on fifty pairs of dry human scapulae in the Department of Anatomy at our institution in the year 2017–2018. Out of fifty pairs, thirty belonged to males and twenty were of females. Gender determination of scapulae was done on the basis of bone register maintained in our department. In our department, complete skeleton is procured by maceration and is then numbered. Hence, gender of all the scapulae was known to us. Bones with clear and intact features were included in this study. The various anatomical variations taken into consideration are as follows:

Sulcus for circumflex scapular artery

Its presence or absence was noted on dorsal surface of lateral border of scapula [Figure 1]a.
Figure 1: (a) Sulcus for circumflex scapular artery (arrow); (b) Costal facet along horizontal superior border (red arrow) and scapular foramen at root of spine (black arrow)

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Costal facets

The presence or absence of costal facets for ribs was noted on superior border and inferior angle of scapula[3] [Figure 1]b.

Presence of inferior border of scapula

Its presence or absence was noted down [Figure 2]a.
Figure 2: (a) Presence of inferior border of scapula (marked with red line). (b) Rough inferior surface of acromion process with an accessory facet in addition to clavicular facet (arrow)

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Scapular foramina

The presence or absence of scapular foramina other than suprascapular foramen was noted [Figure 1]b.

Inferior surface of acromion process

The inferior surface of anterior third of acromion process was classified into rough and smooth types as suggested by Paraskevas et al.[6] and their incidence was noted down [Figure 2]b.

Facet on the inferior surface of acromion process

The presence or absence of accessory facet on the inferior surface of acromion process other than the clavicular facet on medial border of acromion process was noted down [Figure 2]b.

Tip of acromion process

The tip of acromion process as viewed from superior surface was classified into cobra, square, and intermediate types as suggested by Edelson and Taitz[4] and their incidence was noted down [Figure 3]a, [Figure 3]b, [Figure 3]c.
Figure 3: Tip of acromion process; (a) Cobra type; (b) Intermediate type; (c) Square type tip

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Superior border of scapula

The superior border of scapula was classified into horizontal, moderately oblique, markedly oblique, saddle-shaped, and wavy types as suggested by Hrdlička[7] and their incidence was noted down [Figure 1]b and [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d.
Figure 4: Superior border of scapula; (a) Moderately oblique; (b) Markedly oblique; (c) Saddle shaped; (d) Wavy

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Data obtained were compared in males and females on both sides.


  Results Top


Sulcus for circumflex scapular artery

The sulcus for circumflex scapular artery was observed in 60/100 scapulae, out of which 32/60 were in males, 28/40 in females, 27/50 on right side, and 33/50 on left side [Table 1].
Table 1: Number (percentage) of anatomical variations in scapula in males and females on both sides

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Costal facets

The costal facets were observed in 2/100 scapulae, out of which 2/40 were in females and 2/50 on right side, whereas no costal facet was observed in males and on left side. Both costal facets were observed in females on right side on superior angle of scapula [Table 1].

Presence of inferior border of scapula

The inferior border was observed in 12/100 scapulae, out of which 7/60 were in males, 5/40 in females, 6/50 on right side, and 6/50 on left side [Table 1].

Scapular foramina

The scapular foramina were observed in 5/100 scapulae, out of which 2/60 were in males, 3/40 in females, 4/50 on right side, and 1/50 on left side. Out of five scapular foramina observed, three were present in infraspinous fossa, one in supraspinous fossa, and one at root of spine [Table 1].

Inferior surface of acromion process

The inferior surface of anterior third of acromion process was found smooth in majority of the scapulae (51/100), followed by rough surface (49/100). The rough surface was more prevalent in males and on right side, whereas the smooth surface was more prevalent in females and on left side [Table 1].

Facet on the inferior surface of acromion process

The accessory facet on the inferior surface of acromion process other than the clavicular facet on medial border of acromion process was observed in 14/100 scapulae, out of which 5/60 were in males, 9/40 in females, 7/50 on right side, and 7/50 on left side [Table 1].

Tip of acromion process

The most common type of tip of acromion process found was square type (42/100), followed by intermediate and cobra types, i.e., 40/100 and 18/100, respectively. The same pattern was observed in females and on right and left sides except in males, in which intermediate type was predominant, followed by square and cobra types [Table 1].

Superior border of scapula

The most common type of superior border of scapula found was horizontal type (40/100), followed by moderately oblique (27/100), markedly oblique (15/100), saddle-shaped (12/100), and wavy (6/100) types. The same pattern was observed in males and on right and left sides except in females, in which the pattern observed was horizontal > moderately oblique > wavy > markedly oblique > saddle shaped [Table 1].


  Discussion Top


Anatomical variations in scapula are not so frequent, but if present, may prove to be clinically significant.

Sulcus for circumflex scapular artery

In a study on French scapulae, Vallois found the sulcus in 64% of scapulae on the right side and 61.7% of scapulae on the left side.[8] In the present study, we found the sulcus in 54% on the right side and 66% on the left side. Our findings are near to the findings of Vallois.

Costal facets

Vallois found 13 costal facets in 180 (7.2%) scapulae.[8] Gray found costal facets in 64 of 1152 (5.55%) scapulae.[9] In the present study, we found the costal facets in 2% of scapulae.

Presence of inferior border of scapula

To the best of our knowledge, no previous study was found on inferior border.

Scapular foramina

The defects due to scapular foramina can be seen radiographically and remain unchanged over time. They are problematic if the resulting radiolucency is mistaken for a lesion of the lung.[3] Gray studied 1152 scapulae with 28 possessing foramina, i.e., 2.4%.[9] In the present study, we found the scapular foramina in 5% of scapulae.

Inferior surface of acromion process

Paraskevas et al.,[6] Singh et al.,[10] and Gupta et al.[11] found that the inferior surface of the anterior third of the acromion process was smooth 42%, 55.8%, and 10% of scapulae, respectively, and rough in 57.9%, 44.2%, and 90% of scapulae, respectively, whereas in our study, the inferior surface anterior two-third was smooth in 51% and rough in 49% of scapulae.

Facet on the inferior surface of acromion process

Gray reported 240 (20.8%) facets on the inferior surface of acromion process in 1152 scapulae.[9] In the present study, the accessory facet on the inferior surface of acromion process other than the clavicular facet on medial border of acromion process was observed in 14% of scapulae.

Tip of acromion process

Comparison with previous studies is done in [Table 2].
Table 2: Comparison of types of acromion in different regional and international population

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Superior border of scapula

To the best of our knowledge, no previous study was found on types of superior border of scapula.


  Conclusion Top


Clinical awareness of known and newly discovered anatomical variations, which can be achieved through a frequent review of the pertinent literature in specialized journals, is the key to a successful outcome in the clinical setting.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.





 
  References Top

1.
Singroha R, Verma U, Malik P, Rathee SK. Morphometric study of acromion process in scapula of North Indian population. Int J Res Med Sci 2017;5:4965-9.  Back to cited text no. 1
    
2.
Sikka A, Jain A. Bilateral variation in the origin and course of the vertebral artery. Anat Res Int 2012;2012:1-3.  Back to cited text no. 2
    
3.
Ward PJ. Scapula. In: Tubbs RS, Shoja MM, Loukas M, editors. Bergman's Comprehensive Encyclopaedia of Human Anatomic Variation. Hoboken, New Jersey: John Wiley & Sons; 2016. p. 40-50.  Back to cited text no. 3
    
4.
Edelson JG, Taitz C. Anatomy of the coraco-acromial arch. Relation to degeneration of the acromion. J Bone Joint Surg Br 1992;74:589-94.  Back to cited text no. 4
    
5.
Ogeng'o J. Clinical significance of anatomical variations. Anat J Afr 2013;2:57-60.  Back to cited text no. 5
    
6.
Paraskevas G, Tzaveas A, Papaziogas B, Kitsoulis P, Natsis K, Spanidou S. Morphological parameters of the acromion. Folia Morphol (Warsz) 2008;67:255-60.  Back to cited text no. 6
    
7.
Hrdlička A. The scapula: Visual observations. Am J Phys Anthropol 1942a; 29:73-94.  Back to cited text no. 7
    
8.
Vallois HV. The human scapula. Bull Soc Anthrop 1932;3:3-153.  Back to cited text no. 8
    
9.
Gray DJ. Variations in the human scapulae. Am J Phys Anthropol 1942;29:57-72.  Back to cited text no. 9
    
10.
Singh J, Pahuja K, Agarwal R. Morphometric parameters of the acromion process in adult human scapulae. Indian J Basic Appl Med Res 2013;2:1165-70.  Back to cited text no. 10
    
11.
Gupta C, Priya A, Kalthur SG, D'Souza AS. A morphometric study of acromion process of scapula and its clinical significance. Chrismed J Health Res 2014;1:164-9.  Back to cited text no. 11
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12.
Coskun N, Karaali K, Cevikol C, Demirel BM, Sindel M. Anatomical basis and variations of the scapula in Turkish adults. Saudi Med J 2006;27:1320-5.  Back to cited text no. 12
    
13.
El-Din WA, Ali MH. The patterns of the Acromion process and Glenoid cavity in Egyptian scapulae. J Clin Diag Res 2015;9:AC08-11.  Back to cited text no. 13
    
14.
Wasavade SS, Yadav AK. A study of anatomical basis of coraco-acromial arch impingement. Med Pulse Int Med J 2017;4:573-6.  Back to cited text no. 14
    
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Boyan N, Ozsahin E, Kizilkanat E, Soames RW, Oguz O. Assessment of scapular morphometry. Int J Morphol 2018;36:1305-9.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2]



 

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