Musculus rectus abdominis (xlas)
Preview:
simple/clean drawings; men and women differences ; lots of additional info (+latin names) -> here is a counter: wordcounter.net
Synonyms: abs; rectus abdominis muscle; straight abdominis muscle; six pack; six-pack; sixpack; rectus
not final
Summary
The Musculus rectus abdominis, often referred to as "abs" (short for "abdominal muscles"), sits in front of your stomach and is visible on trained and low body fat people. In fact, there are two individual muscle cords right next to each other (that's why I'll refer to them in plural). Besides being used for breathing the muscles also bend the torso and lift the pelvis forward - thus the abs are the main antagonist of the back extensor muscles (M. erector spinae). There are tendons that separate the long muscle cords into packs for better muscle contraction precision.
Introduction
general placement of the M. rectus abdominis
some "good to know" things; the size relations are more important than you think
You can read more about "8 packs" in the details section below.
The 1st row of packs deviates on almost every human. In general this means, if you draw perfectly aligned abs, they will look less natural.
Origin
- Pubic bone (Os pubis), more specifically on the superior pubic ramus (Ramus superior; ramus = branch)
- Pubic symphysis (Symphysis pubica), thats the cartilage between the two pubic bones
Insertion
- Cartilage of the 5th, 6th and 7th rib (there is cartilage at the front tip of each rib)
- Some muscle fibers connect to the breastbone (Sternum)
*insert drawing for origin and insertion*
Ideally in one picture
Functions
- Bending and crunching the torso forward; the familiar "sit up" motion represents this function pretty well
- Lifting/twisting the pelvis forward
- Breathing control; the abs are used mainly for exhaling
What is this muscle used for?
Different Viewpoints
You can work with simplified shapes so that other artists can memorize more information. You can also go more detailed, if that's what you prefer.
*insert drawings where the muscle can be seen from different viewpoints*
You can also include drawings that visualize the functions mentioned before
Details
Everything beyond the basics
The tendinous intersections (Intersectiones tendineae) determine how many packs you can have. Most people (around 60%) have 3 intersections which equals 6 possible packs. In some media you see people with 8 packs to empathize their strength. In reality only 20% even have 4 intersections = 8 packs, which means its based on luck (genetics) if you are even able to develop an 8 pack.
What is also important if one wants to study this muscle beyond the basics?
Go over the muscle more in detail and share intermediate up to expert knowledge.
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*insert drawings if needed for explanation*
Reference Pictures (for study only)
Name the source (website) here
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*insert real life pictures*
Check out this page for resources and explanation
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