From the Guidelines
The muscles of the upper limb are the biceps, triceps, deltoids, latissimus dorsi, and pectorals.
Upper Limb Muscles
- The biceps and triceps are located in the upper arm and are responsible for elbow flexion and extension, respectively.
- The deltoids are located in the shoulder and are responsible for shoulder flexion, extension, and rotation.
- The latissimus dorsi is a large muscle located in the back that extends, adducts, and rotates the shoulder joint.
- The pectorals are located in the chest and are responsible for shoulder flexion, extension, and rotation. These muscles are typically targeted in upper limb training, including aerobic regimens and resistance training, as described in the American Journal of Respiratory and Critical Care Medicine 1.
From the Research
Upper Limb Muscles
The muscles of the upper limb are complex and have been studied in various research papers. Some of the key findings include:
- The identification of nine basic units of muscle synergies derived from the upper limb muscles that are shared across all tasks 2
- The development of muscles in the human upper limb occurs in a progressive wave, from proximal to distal and from superficial to deep 3
- A mathematical model of the human upper limb has been developed, which includes 42 muscle bundles representing the actions of 26 muscle groups in the upper limb 4
- The relative sizes of muscles across upper limb joints in living subjects have been measured, with muscles crossing the shoulder, elbow, and wrist comprising 52.5,31.4, and 16.0% of the total muscle volume, respectively 5
- The moment arms and lengths of human upper limb muscles have been studied as functions of joint angles, with the relationship between moment arms and joint angles described by polynomials 6
Muscle Groups
The upper limb muscles can be grouped into several categories, including:
- Muscles crossing the shoulder, such as the deltoid
- Muscles crossing the elbow, such as the biceps and triceps
- Muscles crossing the wrist, such as the flexor and extensor muscles
- Muscles of the forearm, such as the flexor and extensor muscles of the wrist and fingers
Muscle Synergies
The concept of muscle synergies refers to the idea that the central nervous system utilizes motor primitives called muscle synergies to simplify the production of movements. Research has shown that there are basic units of muscle synergies that can explain a diverse range of manipulations 2. These muscle synergies are thought to be combined and modified by the central nervous system to produce a wide range of movements.