Medial Angle. The mean value was found to be with a higher value for the right side as compared with the left side in the present study Table 1 , although the observed mean difference was not statistically significant Table 2. When compared with the two available studies by Solanki [ 7 ] and Sharma et al. The mean value of the medial angle obtained by Solanki [ 7 ] was comparable with that in the present study, whereas that of Sharma et al. This wide difference may have been as a result of methodological difference as Sharma et al.
The angular description of the scapula has remained triangular even with the recent findings of Sharma et al. The findings of this study have led us to believe that the scapula is quadrangular rather than triangular morphometrically and the inclusion of the medial border now regarded as the spinovertebral angle increases the external angle of the scapular to four 4 in contrast with the current documentation by Moore and Dalley [ 2 ], Marieb and Mallatt [ 3 ], Moore et al.
The medial border of the scapula has always been regarded as a straight continuous border, but careful observation of all measured scapula indicates that the medial border of the scapula possesses two distinct areas borders for muscular attachment. Medial border from the pointed edge close to origin of the spine extending to the superior angle of the scapula can be regarded as the superomedial border which gives attachment to the levator scapulae.
Another border from the origin of the scapula spine to the inferior angle of the scapula can be regarded as the inferomedial border which gives attachment to the rhomboid group of muscles rhomboid minor, superiorly, and rhomboid major, inferiorly. The borders are illustrated in Figure 1 b. The levator scapula originating from the first four cervical vertebrae C1—C4 attaches to the superomedial border extending to the superior angle of the scapula in a downward diagonal manner; this is due to the position of the superomedial border of the scapula: 1 Alteration or widening of this border may increase the steepness of the muscle, altering the attachment of the fibres of the levator muscle.
This may also create slacks within the lower fibres at the origin resulting in the inability of the levator muscle to pull the scapulae superomedially and possible loss of the burden bearing ability of the muscle when a heavy load is carried on the shoulder Figure 3 a.
This structurally discriminates the function of the rhomboid muscle and the levator muscles. Attachment of fibres of the rhomboid muscle across the spinovertebra angle may give it an elevating function as well as its retracting action when trapezius is contracted Figure 3 b. In summary, this research has provided baseline data for the medial angle of the scapulae for the Nigerian population.
This research has postulated that medial angle may be referred to as the spinovertebra angle. It has also defined the role in providing base, direction, and leverage to various muscles. With the observation of superomedial and inferomedial borders which form the spinovertebrae angle, the scapular may now be structurally described as being quadrangular rather than a triangular bone. The authors declare that there is no conflict of interests regarding the publication of this paper.
Oladipo et al. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Special Issues. Oladipo, 1 E. Aigbogun , 1 and G. Academic Editor: Robert J. Received 25 Jun Accepted 03 Aug Published 07 Oct Abstract Background.
Introduction The scapulae are a pair of flat bones, approximately triangular in shape [ 1 , 2 ]; situated dorsally on the rib cage, they lie between the second rib superiorly and the seventh to ninth rib inferiorly. Methods The material for this study was scapulae comprising 75 Figure 1. Figure 2. Table 1. Descriptive characteristics of the medial angle of the scapula. Parameters compared Test for equality of variances -test for equality of means Inference Sig.
Table 2. Analysis of variance and mean difference in the sides of the medial angle. Table 3. Comparison of the observed values of this study with earlier studies. Cookies allow us to analyze and store information such as the characteristics of your device as well as certain personal data e. For more information, see our privacy policy. You can freely give, refuse or withdraw your consent at any time by accessing our cookie settings tool.
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Verify now. Toggle navigation. Institutional subscriptions support Language. The costal or ventral surface [Fig. The medial two-thirds of this fossa are marked by several oblique ridges, which run lateralward and upward.
The ridges give attachment to the tendinous insertions, and the surfaces between them to the fleshy fibers, of the Subscapularis. The lateral third of the fossa is smooth and covered by the fibers of this muscle. The subscapular fossa is separated from the vertebral border by smooth triangular areas at the medial and inferior angles, and in the interval between these by a narrow ridge which is often deficient.
These triangular areas and the intervening ridge afford attachment to the Serratus anterior. At the upper part of the fossa is a transverse depression, where the bone appears to be bent on itself along a line at right angles to and passing through the center of the glenoid cavity , forming a considerable angle, called the subscapular angle; this gives greater strength to the body of the bone by its arched form, while the summit of the arch serves to support the spine and acromion.
The dorsal surface [Fig. The dorsal surface is marked near the axillary border by an elevated ridge, which runs from the lower part of the glenoid cavity, downward and backward to the vertebral border, about 2.
The ridge serves for the attachment of a fibrous septum, which separates the Infraspinatus from the Teres major and Teres minor. The surface between the ridge and the axillary border is narrow in the upper two-thirds of its extent, and is crossed near its center by a groove for the passage of the scapular circumflex vessels; it affords attachment to the Teres minor. Its lower third presents a broader, somewhat triangular surface, which gives origin to the Teres major , and over which the Latissimus dorsi glides; frequently the latter muscle takes origin by a few fibers from this part.
The broad and narrow portions above alluded to are separated by an oblique line, which runs from the axillary border, downward and backward, to meet the elevated ridge: to it is attached a fibrous septum which separates the Teres muscles from each other. The acromion forms the summit of the shoulder, and is a large, somewhat triangular or oblong process, flattened from behind forward, projecting at first lateralward, and then curving forward and upward, so as to overhang the glenoid cavity.
The head, processes, and the thickened parts of the bone, contain cancellous tissue; the rest consists of a thin layer of compact tissue.
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