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Question 7
Anatomy → Region
Classification
Question
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A patient develops separation of a vertical abdominal incision. Which anatomical characteristic of the lateral abdominal-wall muscles contributes to the greater tension and dehiscence risk of a vertical rather than transverse incision?
Question Stem
A) Predominantly longitudinal orientation of the flank muscle fibres
B) Predominantly transverse orientation of the flank muscle fibres
C) Complete absence of tendinous fibres in the lateral abdominal wall
D) Fusion of external oblique with rectus abdominis
E) Vertical orientation of transversus abdominis fibres
B) Predominantly transverse orientation of the flank muscle fibres
C) Complete absence of tendinous fibres in the lateral abdominal wall
D) Fusion of external oblique with rectus abdominis
E) Vertical orientation of transversus abdominis fibres
Options
A
Predominantly longitudinal orientation of the flank muscle fibres
B
Predominantly transverse orientation of the flank muscle fibres
C
Complete absence of tendinous fibres in the lateral abdominal wall
D
Fusion of external oblique with rectus abdominis
E
Vertical orientation of transversus abdominis fibres
Explanation
The fibres of the flank muscles are predominantly transversely orientated. A vertical abdominal incision therefore cuts across this general orientation and is exposed to greater transverse tension, making it more prone to wound separation and dehiscence than a transverse incision. The predominantly transverse orientation of the flank muscle fibres means that vertical abdominal incisions are exposed to greater transverse tension and consequently a greater risk of wound dehiscence. This is a deeper musculoaponeurotic principle and is educationally distinct from the transverse orientation of fibres in the dermal layer of the skin. External oblique, internal oblique and transversus abdominis have differing individual directions, but collectively the lower abdominal-wall architecture favours transverse surgical approaches.
Option Validity
A) the general orientation of the flank muscle fibres as transverse rather than longitudinal.
C) The increased dehiscence risk is related to fibre orientation, not absence of tendinous tissue.
D) External oblique does not fuse with rectus abdominis to explain this incision behaviour.
E) Transversus abdominis is not characterised by a vertical fibre direction.
Further Reading
Part 1 MRCOG Revision Notes and Sample SBAs. Cambridge University Press, 2020. Section 1: Anatomy, Chapter 1. https://doi.org/10.1017/9781108644396