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suprascapular notch variations and its clinical significance

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Aim: The suprascapular nerve that lies in the suprascapular notch of scapula requires special attention as it supplies muscles which initiate abduction of the shoulder. From its origin in the upper trunk of the brachial plexus, the suprascapular nerve passes through the suprascapular notch to supply the supraspinatus later it passes through the spinoglenoid notch to supply the infraspinatus. During its course there is a chance of entrapment of the nerve in the suprascapular notch due to its different shapes and dimensions which leads to suprascapular nerve entrapment syndrome. Materials & Methods: The present study was done on 43 dried human scapulae. The suprascapular notch was observed in each bone to find out variations in its shape. Results: This study showed three different types of suprascapular notches. The scapulae showed U, V, & J shaped notches, foramen formed by ossification of the transverse scapular ligament, and coexistence of notch and foramen due to ossification of the anterior coracoscapular ligament. Conclusion: These variations in the suprascapular notches are a great help to clinicians for early diagnosis of suprascapular nerve compression.
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Aradhyula Himabindu
et al
SUPRASCAPULAR NOTCH VARIATIONS AND ITS CLINICAL SIGNIFICANCE
Int J Cur Res Rev, Nov 2013/ Vol 05 (22)
Page 46
IJCRR
Vol 05 issue 22
Section: Healthcare
Category: Research
Received on: 11/10/13
Revised on: 09/11/13
Accepted on: 02/12/13
SUPRASCAPULAR NOTCH VARIATIONS AND ITS CLINICAL
SIGNIFICANCE
Aradhyula Himabindu1, B. NarasingaRao2, Nihar Sannala1
1Department of Anatomy, Maharajah’s Institute of Medical Sciences,
Nellimarla,Vizianagarum, AP, India
2University of Pittsburgh, Pittsburgh, U.S.A.
E-mail of Corresponding Author: abindu01@yahoo.com
ABSTRACT
Aim: The suprascapular nerve that lies in the suprascapular notch of scapula requires special attention
as it supplies muscles which initiate abduction of the shoulder. From its origin in the upper trunk of the
brachial plexus, the suprascapular nerve passes through the suprascapular notch to supply the
supraspinatus later it passes through the spinoglenoid notch to supply the infraspinatus. During its
course there is a chance of entrapment of the nerve in the suprascapular notch due to its different
shapes and dimensions which leads to suprascapular nerve entrapment syndrome.
Materials & Methods: The present study was done on 43 dried human scapulae. The suprascapular
notch was observed in each bone to find out variations in its shape.
Results: This study showed three different types of suprascapular notches. The scapulae showed U, V,
& J shaped notches, foramen formed by ossification of the transverse scapular ligament, and
coexistence of notch and foramen due to ossification of the anterior coracoscapular ligament.
Conclusion: These variations in the suprascapular notches are a great help to clinicians for early
diagnosis of suprascapular nerve compression.
Key words: scapula, suprascapular nerve, suprascapular notch, transverse scapular ligament
INTRODUCTION
The scapula is a flat bone of shoulder girdle that
lies on the posterolateral aspect of the thorax. In
the superior border of scapula, there is a
suprascapular notch which is bridged by transverse
scapular ligament converting into foramen. The
suprascapular nerve passes through this foramen
and supplies the supraspinatus and infraspinatus
which initiate abduction movement. The variations
in the shape and dimensions of the suprascapular
notch associated with partial or complete
ossification of the superior transverse scapular
ligament lead to compression of nerve in the notch
against the suprascapular ligment during abduction
leading to suprascapular nerve entrapment
syndrome. Koepell and Thomson were the first to
describe the suprascapular nerve entrapment
syndrome.(1) Many authors proposed different
classifications . Based on the shape Ticker and
collegues (2) defined two types of suprascapular
notches-U&V and Iqbal (3) defined three types-U,
V&J.
A new classification based on parameters such as
vertical and transverse diameters of suprascapular
notch was proposed by Natsis et al (4). The
present study is done on the basis of classification
proposed by Iqbal and Natsis et al. These
variations will help the clinicians to determine the
type of notch and the possibility of suprascapular
nerve entrapment.
Aradhyula Himabindu
et al
SUPRASCAPULAR NOTCH VARIATIONS AND ITS CLINICAL SIGNIFICANCE
Int J Cur Res Rev, Nov 2013/ Vol 05 (22)
Page 47
MATERIALS AND METHODS
The study is conducted on 43 dried scapula of both
sides from the department of anatomy, Maharaja’s
Institute of Medical Sciences, Nellimarla,
Vizianagarum. Variations in the shapes of
suprascapular notch were noted. The vertical and
transverse dimensions were measured to classify
the notch according to Natsis et al. Transverse
diameter is the distance between the two edges of
the notch and vertical diameter is the distance
between the deepest point of the notch to the
midpoint of the line joining the two edges of
suprascapular notch.
OBSERVATIONS
The present study followed the classifications of
Iqbal (3) and Natsis et al (4) to read the
suprascapular notch in detail. In this study three
different types of notches are observed along with
partial or complete ossification of transverse
scapular ligament.
The scapulae are grouped depending on the shape
of the notch following the Iqbal classification. Of
these scapulae, 29 showed U shaped, 5 J shaped
and 3 V shaped suprascapular notches (Fig.1)
But in this classification the author did not
mention ossification of the transverse scapular
ligament, where two bones with U shaped notches
showed partial ossification on the medial side of
the notch, five bones showed complete ossification
and one bone showed a rare feature of coexistence
of notch and foramen. In this last bone, an ossified
band is seen extending from root of coracoid
process to the middle of suprascapular notch
forming a foramen below the band and notch
above the band.
The present study also followed the Natsis et al
classification that was based on the dimensions of
the suprascapular notch. This study observed 3
scapulae without a discrete notch (Type I), 26
scapulae showed notches where transverse
diameter is more than vertical (Type II), in 8
scapulae vertical diameter is more than transverse
diameter (Type III), 5 scapulae had ossification of
transverse scapular ligament converting the notch
into foramen (Type IV) and only one scapula
presented with coexistence of notch and
foramen(Type V). (Fig.2)
DISCUSSION
Many authors classified SSN based on certain
parameters.
Based on gross examination of its shape, Ticker
and collegues (2) described only two types of
notches- U& V and Iqbal (3) defined three types-
U, V & J.
Depending on the inferior shape of suprascapular
notch and the degree of ossification, Rengachary
et al(5) classified SSN into six types.
Type I- Wide depression in the superior border of
the scapula
Type II- Wide blunted V shape, Type III-
Symmetric U shape
Type IV-Very small V shape, often with a shallow
groove for the suprascapular nerve
Type V- Partial ossified medial portion of the
suprascapular ligament
Type VI- Completely ossified suprascapular
ligament
The present study not followed this classification
as there is no description of coexistence of notch
and foramen.
Natsis et al (4) proposed a simple classification
based on the vertical and transverse dimensions of
the notch.
Type I- without a discrete notch,
Type II- a notch that was longest in its transverse
diameter,
Type III- a notch that was longest in its vertical
diameter,
Type IV- a bony foramen
Type V- a notch and a bony foramen
The size of the suprascapular notch plays a role in
the impingement of the nerve in the notch. A small
notch has higher chances of suprascapular nerve
entrapment than a large notch (5). In various cases
it was identified that partial or complete
ossification of the transverse scapular ligament is
Aradhyula Himabindu
et al
SUPRASCAPULAR NOTCH VARIATIONS AND ITS CLINICAL SIGNIFICANCE
Int J Cur Res Rev, Nov 2013/ Vol 05 (22)
Page 48
the predisposing factor for suprascapular nerve
entrapment (2, 6, 7). As the ossified ligament
decreases the size of the notch and reduces the
space available to the nerve, there is a higher
chance of suprascapular nerve entrapment (8). The
rare occurrence of the coexistence of
suprascapular notch and foramen was first
reported by Hrdicka (9) in 1942. Later Natsis et
al.(4) reported this feature in his study on 423
dried scapulae. Sinkeet et al.(8) described one case
suprascapular notch and foramen in his study on
Kenyan population.
The present study predominantly showed Natsis
type II suprascapular notches where the transverse
diameter is more than the vertical diameter and
Iqbal U- shaped notches. In this type of notch
there was less chance of suprascapular nerve
entrapment syndrome as more space is available
for the suprascapular nerve. Along with this the
present study also showed a scapula with an
ossified transverse suprascapular ligament and that
a bone with a rare feature of coexistence of notch
&foramen (anomalies). These cases are more
prone to suprascapular nerve entrapment due to
narrowing of the space for the suprascapular nerve
which irritates the nerve during different shoulder
movements. (5)
Avery et al (10) first described an additional
fibrous band anterior coracoscapular ligament in
American population. It is arranged either parallel
or obliquely to superior transverse scapular
ligament in the suprascapular notch. Later
Bayramogluet al(11) found this in Turkish
population and recently Piyawinijwong et al (12)in
Thai population.
Based on anatomical findings of Avery et al (10),
Michal Polgrej.et al.(13) explained the cause for
the coexistence of notch and foramen. If
ossification occurs only in anterior coracoscapular
ligament without affecting superior transverse
scapular ligament, it leads to coexistence of notch
and foramen reducing the space for the nerve. So
the nerve is irritated by the bony margins and
increases the risk of suprascapular neuropathy.
CONCLUSION
The suprascapular nerve is closely related to the
superior border of the scapula as it passes through
the suprascapular notch to innervate muscles. Due
to variations in the shape of the notch and
ossification of the suprascapular ligament the
space available to the nerve decreases leading to
suprascapular nerve entrapment syndrome. This
causes pain over the shoulder as the nerve supplies
the supraspinatus and infraspinatus which initiates
abduction of shoulder joint. The present study
described different types of suprascapular notches.
Of these, U shaped notches have lower chances
and ossified transverse scapular ligament have
higher chances of impingement of the
suprascapular nerve. These anatomical variations
can be defined by plain radiographs, so that, the
clinicians can easily correlate the nerve
entrapment with the type of notch.
REFERENCES
1. Kopell HP, Thompson WA. Pain and the
frozen shoulder. Surg Gynecol Obstet
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2. Ticker JB, Djurasovic M, Strauch RJ, April
EW, Pollock RG, Flatow EL et al. The
incidence of ganglion cysts and variations in
anatomy along the course of the suprascapular
nerve. J. Shoulder Elbow Surg. 1998;
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3. Iqbal K, Iqbal R, Khan SG. Anatomical
variations in shape of suprascapular notch of
scapula. J. Morphol. Sci. 2010; 27:1-2.
4. Natsis K, Totlis T, Tsikaras P, Appell HJ,
Skandalakis K. Proposal for classification of
the suprascapular notch: a study on 423 dried
scapulas. Clin. Anat. 2007; 20:135-139.
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Mohn MP, Matzke H. Suprascapular
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and comparative study, Part 2: anatomical
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Int J Cur Res Rev, Nov 2013/ Vol 05 (22)
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to an anomalous transverse scapular ligament.
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Fig.1 showing U,V &J shaped notches
Aradhyula Himabindu
et al
SUPRASCAPULAR NOTCH VARIATIONS AND ITS CLINICAL SIGNIFICANCE
Int J Cur Res Rev, Nov 2013/ Vol 05 (22)
Page 50
Fig.2 Showing notches following Natsis classification
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