The 9 Muscles Of The Arm (classified And Explained)
What we commonly call the arm is actually the entire upper extremity, composed of the arm and the forearm being anatomically precise.
The muscles of the arms and forearms allow us to do everyday actions such as writing, picking up an object, pointing, holding a weight and many more. Our upper limbs are capable of performing many movements without which human life would be very different.
Here we will see what they are like the muscles of the arm and forearm all of them involved in the manual tasks of our daily lives, and below we are going to discover them.
The muscles of the arm and forearm can be classified according to different criteria. In this article we are going to explain the muscles of the upper extremity according to their position, but it is also common to find them differentiated depending on whether they are short or long, which allows the muscles to have one movement or another.
But before going into detail about what the muscles of the arm are, we must first understand that what we commonly call the arm is not anatomically correct. The arm in its popular sense corresponds to the human upper limb in the anatomical sense, because terminologically speaking correctly, the arm is just part of our upper extremities. So we can say that the human upper extremities can be divided into two:
Within these two anatomical regions we can differentiate two other parts:
Anterior surface of the arm and forearm
The anterior surface of the arm and forearm is that which is located on the palm side of the hand To see the front part of your upper extremities you only need to place your arms close to the trunk, with your palms facing up. By doing this simple exercise you will be seeing the front of your arms and forearms.
The back of the arm and forearm is the part that is on the back of the hand To see the back of your limbs, simply place your arms as before, only with your palms facing down.
Types of arm muscles
In the arm itself we can find two groups of muscles: the muscles of the anterior face and the muscles of the posterior face The muscles of the anterior face are responsible for flexion movements, while those of the posterior face are responsible for contraction (contractor muscles). These groups of muscles are called antagonistic or antagonistic to each other because, when an anterior muscle flexes, the posterior muscle contracts.
1. Anterior muscles of the arm
The main anterior muscles of the arm are as follows.
1. 1. Biceps brachii
The biceps brachii is a muscle that extends from the clavicle to the elbow, in the intertubercular groove of the humerus Its main functions are rotation of the forearm and flexion of the forearm at the elbow. The biceps brachii is a very voluminous muscle that, when contracted, can be easily observed. It consists of two parts or “heads” (that’s why it is called biceps): the short head of the biceps and the long head of the biceps.
1.2. Brachial
This muscle It is located at a deeper level than the biceps brachii and is smaller in size Its shape is wide and flattened. The brachialis is the main forearm flexor muscle on the arm.
1.3. Coracobrachialis
The coracobrachialis is a thick, prismatic muscle that occupies the space that runs from the scapula to the biceps through the short head of the biceps brachii. This muscle specializes more in fast movements than in generating force, something that the much larger biceps is responsible for. The main function of the coracobrachialis is to elevate the arm while keeping the shoulder low, balancing the movement of the arm and restoring the anatomical position.
As for the posterior muscles of the arm, the two main ones are the following:
2.1. Triceps brachii
This muscle occupies most of the posterior region of the arm As its name suggests, the triceps is made up of three portions or “heads”: long portion and internal and external vastus. The main function of this movement is antagonistic to that of the biceps, in this case being responsible for the extension of the forearm over the elbow.
2.2. anconeus muscle
The anconeus muscle is small and triangular in shape, and contacts the triceps and elbow at its proximal end It cooperates with the triceps brachii during extension of the forearm above the elbow.
You may be interested: “Daniels Scale: what it is, characteristics, and functions”
3. Muscles of the forearm
The muscles found in the forearm They can be classified into the following three groups
Finger flexors: on the anterior surface of the forearm.
Finger extensors: on the back of the forearm.
Supinators or external rotators of the forearm: on the radial edge, towards the thumb.
3.1. Muscles of the anterior part of the forearm
The list of muscles of the anterior part of the forearm is the one that follows.
pronator teres muscle
pronator quadratus muscle
flexor carpi radialis muscle
Palmaris longus muscle
flexor carpi ulnaris muscle
Flexor digitorum superficialis muscle
deep flexor digitorum muscle
Flexor pollicis longus muscle
Among them we can highlight the following.
3.1.1. deep flexor digitorum muscle
The deep flexor digitorum muscle together with the superficial common flexor of the fingers of the hand, it allows the fingers to be flexed, except the thumb. This muscle is associated with a long tendon that runs along the forearm and crosses the carpal tunnel until it inserts into the palmar side of the phalanges of the fingers.
The flexor digitorum superficialis muscle, together with the anterior one, allows the fingers to be flexed, specifically flexion of the middle phalanx on the proximal phalanx and the hand on the forearm
3.2. Muscles of the back of the forearm
The list of the muscles of the back of the forearm is as follows:
Extensor finger muscle
Extensor carpi ulnaris muscle or posterior ulnaris muscle
abductor pollicis longus muscle
Extensor pollicis brevis muscle
Extensor pollicis longus muscle
Extensor index finger muscle
Palmar brevis muscle or palmar cutaneous muscle
Of all these muscles, the most notable is the extensor digitorum muscle
The finger extensor muscle runs through the entire forearm, going from the elbow to the dorsal part of the wrist where it is associated with four tendons, passing through them to fingers two (index), three (middle or middle), four (ring finger) and five (pinky) of the hand, all except the thumb. This muscle is responsible for the extension of the wrist and the proximal phalanx of the fingers, although it is also slightly involved in the extension of the arm.
3.3. Lateral muscles of the forearm
Finally it’s time to talk about the lateral muscles of the forearm. Among them we find:
Short supinator muscle
First radial or long radial
Second radial or short radial
Long supinator muscle
The most notable muscle in this region is the supinator longus muscle
This is located on the upper outer part of the forearm, near the elbow. This muscle helps rotate the forearm both externally and internally. Depending on the disposition of the elbow, different movements can be made, which gives the forearm a great variety of movements.
