Journal List > J Korean Ophthalmol Soc > v.49(5) > 1008271

Kang and Shin: A Study of the Anatomical Characteristics of External Ocular Muscles in Adults Cadavers

Abstract

Purpose

This research was performed to investigate if the insertion site of the rectus muscle and the type of the insertion anatomically correspond for both eyes in Korean cadavers.

Methods

Thirty-four eyes from seventeen cadavers were anatomized for this research. We measured minimum distances from the insertion of each muscle to the tangential lines passing through the corneal limbus using a vernier caliper. Center, temporal, and nasal portions are used as an insertion for the vertical muscle, while center, upper, and lower portions are used as an insertion for the horizontal muscle. The average values of those minimum distances were compared for both eyes. Moreover, the type of the insertion of the rectus muscle is observed to determine whether it is identical for both eyes.

Results

Anatomical data does not show a significant difference between the right and left eyes except for the distance from an insertion of the inferior and lateral rectus muscle to the corneal limbus. With regard to the morphologic type of the insertion, the most common types are oblique and nonspecific shapes in the vertical muscles, and straight and concave shapes in the horizontal muscles.

Conclusions

Although there was not a significant difference between the eyes, precautions should still be taken during eye operations due to possible anatomical differences between the eyes.

References

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Figure 1.
The imaginary tangential line passing the corneal limbus was drew parallel to vertical or horizontal axis. Distances from an insertion of each muscle to the tangential line were measured using a vernier caliper at center, temporal, and nasal portions for the vertical rectus muscle, and center, upper, and lower portions for the horizontal rectus muscle.
jkos-49-811f1.tif
Figure 2.
The morphological types of insertion in rectus muscles. (A) Straight, (B) Oblique, (C) Convex, (D) Concave, (E) Nonspecific type.
jkos-49-811f2.tif
Figure 3.
The double insertions of medial rectus muscle were observed in both eyes.
jkos-49-811f3.tif
Table 1.
Age distribution in cases
Age (Year) Cases (n=17)
< 40 1
40-60 6
60-80 8
> 80 2
Table 2.
The width and distance from limbus to insertion in the superior rectus muscle
Case Right
Left
Nasal (mm) Central (mm) Temporal (mm) Width (mm) Nasal (mm) Central (mm) Temporal (mm) Width (mm)
1 7.26 6.49 9.27 7.50 8.60 5.56 10.50 6.93
2 8.08 7.90 9.22 10.31 8.10 6.27 9.54 11.10
3 6.50 8.26 10.49 10.32 7.10 7.92 9.80 9.86
4 7.01 8.33 7.33 12.58 6.70 8.48 7.27 12.58
5 6.54 6.66 7.64 9.34 5.73 7.92 8.38 9.43
6 5.67 6.35 7.60 10.79 6.65 5.45 7.75 9.33
7 9.23 5.64 9.72 10.21 7.49 9.30 10.02 9.25
8 8.14 6.67 9.50 13.42 7.47 7.91 10.67 12.09
9 8.00 7.29 8.40 9.60 7.11 7.63 7.69 9.55
10 6.20 7.44 9.60 8.68 7.80 7.78 10.10 9.15
11 8.00 6.94 9.10 11.74 8.00 6.51 7.50 9.33
12 7.50 8.00 8.50 10.74 6.11 6.30 8.37 9.41
13 6.10 5.13 7.20 10.59 7.50 6.21 9.10 8.98
14 6.99 7.43 7.56 8.74 7.15 7.42 8.89 9.12
15 6.48 6.93 7.39 11.08 6.82 6.28 8.08 11.15
16 6.37 6.63 8.39 9.07 5.93 6.41 9.01 8.83
17 4.95 7.00 7.05 6.69 5.49 7.31 8.11 7.43
Table 3.
The width and distance from limbus to insertion in the inferior rectus muscle
Case Right
Left
Nasal (mm) Central (mm) Temporal (mm) Width (mm) Nasal (mm) Central (mm) Temporal (mm) Width (mm)
1 6.00 5.51 6.90 7.70 7.00 5.77 8.50 8.92
2 7.08 6.75 10.96 8.48 7.05 7.12 8.54 8.67
3 8.00 6.64 9.30 9.44 7.70 8.23 9.60 8.99
4 7.70 5.04 9.07 7.23 6.94 6.78 9.90 8.90
5 7.10 5.55 7.10 8.59 8.71 5.80 8.87 8.90
6 6.37 5.71 9.40 9.54 6.65 7.37 8.58 8.09
7 6.28 6.31 9.08 10.00 7.21 6.52 8.66 10.64
8 8.72 6.60 8.99 8.41 7.86 7.43 9.70 8.66
9 8.00 7.20 9.50 8.37 6.88 7.33 8.44 8.65
10 7.00 6.04 7.20 8.37 8.50 6.38 60 9.04
11 6.90 6.27 8.50 10.21 7.00 5.93 9.00 8.90
12 6.20 6.04 8.10 10.65 5.34 6.28 6.04 9.68
13 6.20 6.32 8.00 9.77 6.20 6.59 9.10 9.51
14 6.77 7.00 9.73 8.49 6.22 6.53 8.60 8.28
15 7.53 5.39 9.39 8.68 7.07 5.46 9.27 7.93
16 5.46 5.65 6.22 8.66 6.55 5.66 6.89 8.54
17 5.42 5.93 8.34 7.72 5.68 6.33 8.62 8.78
Table 4.
The width and distance from limbus to insertion in the lateral rectus muscle
Case Right
Left
Superior (mm) Central (mm) Inferior (mm) Width (mm) Superior (mm) Central (mm) Inferior (mm) Width (mm)
1 7.70 5.61 7.10 11.42 7.50 5.62 8.10 13.56
2 7.45 6.26 8.32 10.54 7.27 6.72 7.90 9.98
3 8.80 6.81 7.00 9.91 6.90 6.10 8.20 9.17
4 7.58 6.05 8.14 9.36 6.45 6.35 7.39 9.58
5 8.09 6.26 7.74 10.27 7.29 5.76 8.08 9.87
6 7.00 6.25 6.57 7.14 6.92 5.51 7.07 7.57
7 7.52 6.42 7.48 8.62 7.04 6.20 7.44 7.65
8 8.47 7.80 9.09 9.88 8.46 8.06 8.50 9.20
9 9.50 6.12 8.75 7.96 7.07 5.64 7.65 7.43
10 8.50 6.60 9.50 9.14 6.00 6.43 7.20 9.14
11 7.80 7.02 8.00 9.38 7.50 6.79 9.00 9.09
12 8.00 6.08 7.50 12.44 7.12 6.73 6.86 9.35
13 8.60 6.32 8.20 10.05 8.20 6.40 9.90 10.23
14 8.06 5.96 8.26 8.84 7.92 6.24 6.69 12.46
15 8.51 6.07 8.12 11.57 7.50 6.77 7.00 10.62
16 7.90 6.65 7.58 10.15 7.41 6.36 7.24 9.61
17 7.12 6.65 6.88 6.20 7.17 6.24 6.84 7.26
Table 5.
The width and distance from limbus to insertion in the medial rectus muscle
Case Right
Left
Superior (mm) Central (mm) Inferior (mm) Width (mm) Superior (mm) Central (mm) Inferior (mm) Width (mm)
1 5.70 4.90 7.70 10.72 5.10 4.79 5.30 13.96
2 7.90 5.95 7.51 11.52 6.87 5.42 6.52 9.51
3 6.10 6.53 7.20 9.49 7.74 6.90 8.54 8.93
4 6.78 5.08 7.71 8.44 7.71 5.87 6.70 8.93
5 6.96 4.87 5.92 7.00 7.14 4.92 7.68 8.07
6 5.50 5.09 7.65 10.06 5.05 4.94 7.00 10.2
7 7.65 6.19 7.74 10.25 7.39 6.23 7.68 8.81
8 7.31 6.39 8.12 10.12 6.62 5.99 7.93 11.61
9 8.50 6.27 9.00 9.53 8.00 5.53 6.91 9.99
10 8.00 4.88 7.20 10.10 7.50 5.66 8.50 10.10
11 6.90 5.69 8.10 10.81 9.00 6.64 7.00 8.90
12 7.20 4.23 6.10 11.05 6.96 5.38 7.13 9.36
13 7.80 6.35 7.10 8.84 6.50 5.17 6.10 7.91
14 6.33 7.54 7.50 8.60 5.87 6.14 7.15 7.83
15 8.21 5.61 8.30 10.94 5.92 5.10 7.42 11.64
16 5.84 4.22 5.93 10.74 6.90 4.43 6.82 9.93
17 4.99 5.10 6.01 9.59 5.05 4.92 5.15 10.18
Table 6.
The morphological types of insertion in rectus muscles
Type Right
Left
Vertical Rectus Horizontal Rectus Vertical Rectus Horizontal Rectus
SR IR LR MR SR IR LR MR
S 2 2 6 5 1 1 7 8
O 10 5 3 5 8 9 2 4
CC 0 3 8 5 2 2 7 4
CV§ 0 3 0 0 0 0 1 0
NS 5 4 0 2 6 5 0 1

S = Straight;

O = Oblique;

CC = Concave;

§ CV = Convex;

NS = Nonspecific.

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