Muscles
Musculus trapezius (xlas)
Preview:
simple/clean drawings; arm movements included; lots of additional info (+latin names)
Synonyms: Traps; Trapezius muscle; Trapezius; Neck muscle
Summary
The Musculus trapezius is the biggest neck muscle (surface area) we have and very relevant in several head and arm movements. Its name giving shape, the trapezoid, significantly shapes the upper back, especially around the neck and the shoulder blades (scapulae). There are 3 parts to the trapezius (top part, middle part, bottom part) and each one pulls in a slightly different direction.
Basics
left: general view (white parts = tendons); right: the 3 parts of the muscle + pull direction
two ways of interpreting the name: 1. muscle shape, viewed from the back; 2. front view: trapezius muscle and clavicles form a trapezoid
Origin
- Occipital bone (Os occipitale; lower back of the skull)
- Cervical vertebrae (spine, neck part)
- Down to the 12th thoracic vertebra (spine, chest part)
Originating from a vertebra means the tendons connect to the spinous process (little bumps you can feel on your spine) of each vertebra.
Insertion
- Spine of the shoulder blade (Spina scapula)
- Acromion (Pars transversa) = highest part of the shoulder blade
- Clavicle (clavicula)
origin and insertion; back and front view
Functions
- Top part:
- Lifting the shoulder
- Twisting the shoulder blade (scapula)
- Tilting and turning the head, also leaning the head backwards
- Lifting the shoulder
- Middle part:
- Pulling the shoulder back
- Twisting the shoulder blade (scapula)
- Bottom part:
- Pulling the shoulder/shoulder blade (scapula) down
How to draw the muscle
muscle is marked in red; notice how the muscle varies with arm movement
a more realistic view; only a few parts of the muscle are visible on average
Advanced
Everything beyond the basics
There is one vertebra, that sticks out at the center of the trapezius. This is the seventh cervical vertebrae, the last neck vertebra before the thoracic vertebrae start.
Drawing the trapezius for a woman you should always consider that the subcutaneous fat layer is thicker. This means that bumps and depressions caused by muscles, bones, etc. are less visible on women. Concentrate on the main depression, the corner where the trapezius meets the shoulder blade, and don't go for too many details to make it look convincing. Of course there are exceptions. The same goes for the average man (especially if the body fat is high), focus on the shoulder blade depression.
On many people the significant areas of the trapezius aren't visible at all.
The trapezius is also used when the shoulder blade needs to be pressed against the body, for example in a handstand. Chest muscles (+ serratus anterior) and back muscles, including the trapezius (mostly the middle part) contract at the same time to achieve that.
The rhomboids often contract simultaneously with the trapezius. They pull in a similar direction with the top and middle part of the trapezius and have similar origin and insertion. The bottom part of the trapezius on the other hand pulls down, so its kinda opposite to the rhomboids. The rhomboids are located below the trapezius, so you cannot see them on a person usually. However with very particular shoulder movement both muscles can be visible at the same time - at the very bottom of the trapezius.
The rhomboids are partly causing the middle part of the trapezius to look relatively big.
On first sight one could think that the trapezius has a large diameter, but thats not true. The trapezius is large in surface area but its cross-section shows that its relatively thin. In the following drawing I compare the cross section of the trapezius and the Musculus erector spinae (lower back muscle for straightening your upper body) to give you a comparison.
Reference Pictures (for study only)
From Wikimedia, Pixabay, Unsplash
credit to: Harmony412
credit to: Harmony412
credit to: KÜRŞAT GÜNEY
credit to: KÜRŞAT GÜNEY
credit to: Raman_Spirydonau
credit to: George M. Gould and Walter L. Pyle
credit to: אנדר-ויק
credit to: Max Rebo Band
credit to: Vox Efx; this image is modified (cropped)
credit to: Elements Of This World; this image is modified (cropped)
credit to: vishstudio
credit to: capsulanudes; image is modified (cropped)
credit to: Raman_Spirydonau
Back and Shoulder Muscles (Alizz Art)
Preview:
Learn more about the most important back and shoulder muscles.
Synonyms: deltoid muscle; trapezius muscle; latissimus dorsi muscle; infraspinatus muscle; teres major muscle
Summary
Deltoid muscle : What are deltoid muscles? Your deltoid muscles are in your shoulder, which is the ball-and-socket joint that connects your arm to the trunk of your body. Deltoid muscles help you move your arms in different directions. They also protect and stabilize your shoulder joint.
Trapezius muscle :Your trapezius muscles are two big muscles on either side of your upper back. They help you move your head, neck and upper back, and maintain and adjust your posture.
Latissimus dorsi muscle : The latissimus dorsi (or "lats") is a large back muscle crucial for arm movement like extending, adducting (bringing towards the body), and internally rotating the shoulder, essential for activities like climbing or pull-ups, and also helps with spine stability. and forced breathing (inspiration/expiration).
Infraspinatus muscle : The infraspinatus muscle's action on the shoulder is primarily through its function as a rotator cuff muscle providing glenohumeral stability. The rotator cuff applies compression upon the head of the humerus that allows for the stabilization of the humeral head during shoulder abduction.
Your shoulder joint (glenohumeral joint) is a ball-and-socket joint that connects your upper arm bone (humerus) and shoulder blade (scapula).
Teres major muscle : It's crucial for stabilizing the shoulder joint, helping to keep the humeral head in place, and assists in pulling the trunk upward during activities like climbing.
How to draw the muscles
the first drawing shows the skeleton structure where the muscles are positioned.
The second drawing shows all the muscles stretched so they can be more easily identified.
The third drawing shows a closer look and the shoulder joint and its muscle group that help with the movement.
Origin and Insertion
Back muscles originate from various points, primarily the vertebrae (spinous & transverse processes), ribs, skull, scapula (shoulder blade), and the iliac crest (hip bone)
All of these muscles are present in the back or dorsal part if the upper body.
Function
Strengthening of the dorsal upper body and helping with complex movements
Advanced
Everything beyond the basics
No advanced section for now.
Reference Pictures (for study only)
From Obscura 29, Grafit Studio, Reference.Pitcures
credit to: Grafit Studio
credit to: Grafit Studio
credit to: Reference.Pictures
credit to: Reference.Pictures
credit to: Reference.Pictures
credit to: Grafit Studio
credit to: Grafit Studio
credit to: Obscura 29
credit to: Obscura 29