The muscles of the forearm are in total 20; of these 20 muscle elements, 8 make up the so-called anterior compartment of the forearm (muscles of the forearm), while the remaining 12 constitute the so-called posterior compartment of the forearm (muscles of the forearm rear).
To understand…
The muscles of the human body always have two ends: an "end called proximal, which corresponds to their origin, and a" end called distal, which corresponds to their terminal section.
At the aforesaid extremities, all the muscles have one or more tendons, which are the bands of fibrous connective tissue responsible for their connection to the skeletal system.
In anatomy, the tendons present at the extremities of the muscles represent the origin and terminal insertion of these.
and radio.The fact that the aforesaid muscles reside in the anatomo-skeletal section composed of ulna and radius does not necessarily imply their connection to the aforementioned bones; in other words, there are muscles in the forearm that do not interact in any way with the ulna or the radius.
Forearm definition for short
The forearm is the anatomical region of the upper limb including the arm, on the proximal front, and the hand, on the distal front (assuming, of course, that the upper limb is stretched along the body and the palm of the hand is facing the "observer).
Bordering the arm, there is the elbow joint, which joins the ulna and radius to the humerus (ie the arm bone); on the border with the hand, on the other hand, there is the wrist joint, which connects the ulna and radius with the carpal bones.
Brief review of the proximal-distal terms
"Proximal" means "closer to the center of the body" or "closer to the point of origin"; "distal", on the other hand, means "farther from the center of the body" or "farther from the point of origin".
Examples:
- The femur is proximal to the tibia, which is distal to the femur.
- In the femur, the end bordering the trunk is the proximal end, while the end bordering the knee is the distal end.
Distal end: attaches to the pisiform bone of the carpus.
Innervation: belongs to the ulnar nerve.
Spraying: it belongs to the ulnar artery.
Contributes to wrist flexion.
Proximal end: originates from the medial epicondyle of the humerus.
Distal end: Hooks onto the transverse carpal ligament, also known as the flexor retinaculum.
Innervation: belongs to the median nerve
Spraying: it belongs to the ulnar artery.
Proximal end: originates from the medial epicondyle of the humerus.
Distal end: attaches to the base of the 2nd and 3rd metacarpals of the hand.
Innervation: it belongs to the median nerve.
Spraying: it belongs to the radial artery.
- Round pronator. Equipped also with two original heads (one on the humerus and one on the ulna), the pronator round provides for the pronation movement of the forearm.
Proximal end: with a head it originates from the medial epicondyle of the humerus; with the other head, however, it originates from the coronoid process of the ulna.
Distal end: hooks onto the body of the radius, exactly in the middle of the lateral surface.
Innervation: belongs to the median nerve.
Spraying: it belongs to the ulnar artery and to the radial artery.
MUSCLES OF THE MIDDLE PLANE
To compose the intermediate plane of the forearm is only one muscle: the superficial flexor of the fingers.
- Superficial flexion of the fingers. The superficial flexor of the fingers contributes to the flexion of the fingers of the hand (thumb excluded); in fact, it controls the flexion movement of the proximal metacarpophalangeal and interphalangeal joints.
Proximal end: it has two heads of origin, one based on the radius and one based on the medial epicondyle of the humerus.
Distal end: it is divided into 4 terminal heads, in which they hook to the base (front side) of the intermediate phalanges of the 4 fingers of the hand following the thumb (c "is a terminal head for each intermediate phalanx).
Innervation: belongs to the median nerve.
Spraying: it belongs to the ulnar artery.
DEEP PLANE MUSCLES
The muscles of the forearm belonging to the deep plane are (obviously) three and are called: deep flexor of the fingers, long flexor of the thumb and square pronator.
- Deep flexion of the fingers. The deep flexor of the fingers contributes to the flexion of the hand and fingers (excluding the thumb); in fact, it controls the flexion movement of the wrist, the interphalangeal joints and the metacarpophalangeal joints.
Proximal end: it originates in several points: from the medial surface of the body of the ulna, from the interosseous membrane interposed between the ulna and the radius, and from the deep fascia of the forearm.
Distal end: it is divided into 4 terminal heads, which are hooked to the distal phalanges of the second, third, fourth and fifth fingers of the hand.
Innervation: it belongs, in part, to the ulnar nerve and, in part, to the anterior interosseous branch of the median nerve.
Spraying: belongs to the anterior interosseous artery (sub-branch of a branch of the ulnar artery).
What is the radioulnar interosseous membrane?
The interosseous radio-ulnar membrane is a thin sheet of fibrous tissue which, interposed between the ulna and the radius, indirectly joins the aforementioned bones.
- Long thumb flexor. Located lateral to the deep flexor of the fingers, the long flexor of the thumb provides for flexion of the thumb; in fact, it controls the movements of the interphalangeal and metacarpophalangeal joint of the first finger of the hand.
Proximal end: originates in the middle of the anterior surface of the radius and on the adjacent interosseous membrane.
Distal end: attaches to the base of the distal phalanx of the thumb.
Innervation: belongs to the anterior interosseous branch of the median nerve.
Spraying: belongs to the anterior interosseous artery. - Square pronator. Square in shape, it contributes to the pronation movement of the forearm.
Proximal end: originates on the anterior medial surface of the ulna.
Distal end: snaps onto the front lateral surface of the radius.
Innervation: belongs to the anterior interosseous branch of the median nerve.
Spraying: belongs to the anterior interosseous artery.
Did you know that ...
The deep flexor of the fingers is the muscle of the forearm which has the exclusive task of controlling the flexion of the distal interphalangeal joints.
Muscles of the rear forearm
The muscles of the posterior forearm are the muscles located in the part of the forearm that is in continuity with the back of the hand.
The muscles of the rear forearm are 12 in all and are arranged on only two different depth planes, whose names are superficial and deep planes.
MUSCLES OF THE SURFACE
The muscles of the posterior forearm belonging to the superficial plane are 7 and are called: brachioradialis, long radial extensor of the carpus, short radial extensor of the carpus, extensor of the fingers, extensor of the little finger, ulnar extensor of the carpus and anconeus.
- Brachioradialis. It plays a pivotal role in elbow flexion.
Proximal end: originates from the lateral supracondylar crest of the humerus
Distal end: attaches to the styloid process of the radius (on the distal epiphysis of the radius).
Innervation: belongs to the radial nerve.
Spraying: belongs to the recurrent radial artery. - Long radial carpus extensor. Located in a lateral position, it deals with the extension and abduction of the wrist.
Proximal end: originates from the lateral supracondylar crest of the humerus.
Distal end: finds hook on the second metacarpus.
Innervation: belongs to the radial nerve.
Spraying: it belongs to the radial artery. - Short radial extensor of the carpus. Located in a lateral position, close to the long radial extension of the carpus, it supports the latter in the extension and abduction movements of the wrist.
Proximal end: originates from the lateral epicondyle of the humerus.
Distal end: attaches to the base of the III metacarpus.
Innervation: belongs to the radial nerve.
Spraying: it belongs to the radial artery.
- Finger extensor. It provides for the extension of the fingers at the level of the metacarpophalangeal and interphalangeal joints.
Proximal end: finds insertion on the lateral epicondyle of the humerus.
Distal end: it is divided into 4 terminal heads, which are hooked to the intermediate and distal phalanges of the second, third, fourth and fifth fingers of the hand.
Innervation: belongs to the deep branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery (branch of the ulnar artery). - Little finger extensor. Parallel to the extension of the fingers (and in some individuals fused to the latter), it controls the extension of the little finger and contributes to the extension of the wrist.
Proximal end: originates from the anterior portion of the lateral epicondyle of the humerus.
Distal end: attaches to the base of the proximal phalanx of the little finger.
Innervation: belongs to the deep branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery. - Extensor carpus ulnar. Located medially, it provides adduction and extension of the wrist.
Proximal end: originates from the lateral epicondyle of the humerus.
Distal end: finds connection to the base of the fifth metacarpus.
Innervation: belongs to the deep branch of the radial nerve.
Spraying: it belongs to the ulnar artery. - Anconeus. Small in size and placed close to the elbow, it provides for the extension and stabilization of the elbow, and for the abduction of the ulna, during pronation of the forearm.
Proximal end: origin of the lateral epicondyle of the humerus.
Distal end: it engages in two distinct points of the ulna, on the olecranon and on the posterior surface of the proximal extremity.
Innervation: belongs to the radial nerve.
Spraying: belongs to the deep brachial artery and the recurrent interosseous artery.
Did you know that ...
The short radial extensor of the carpus, the extensor of the fingers, the ulnar extensor of the carpus and the extensor of the little finger share the same tendon at the proximal end.
DEEP PLANE MUSCLES
The muscles of the posterior forearm located in the deep plane are (obviously) 5 and are known as: supinator, long abductor of the thumb, short extensor of the thumb, long extensor of the thumb and proper extensor of the index finger.
- Supinator. Located in the lateral position, it controls the supination movement of the forearm.
Proximal end: it has two heads of origin, one attached to the lateral epicondyle of the humerus and one attached to the supinatory crest of the ulna (on the proximal epiphysis of the ulna).
Distal end: it engages in a point of the proximal section of the body of the radius.
Innervation: belongs to the deep branch of the radial nerve.
Spraying: belongs to the recurrent radial artery. - Long abductor of the thumb. Located just below the supinator, it provides thumb abduction.
Proximal end: originates in a point of the interosseous membrane and the nearby surface of the radius and ulna.
Distal end: finds insertion on the lateral surface of the base of the 5th metacarpus.
Innervation: belongs to the posterior interosseous branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery. - Short extensor of the thumb. Slightly medial to the abductor of the thumb and located just below, it controls the extension of the metacarpophalangeal and carpometarcarpal joints of the thumb.
Proximal end: originates from a point on the posterior surface of the radius and in the adjacent interosseous membrane portion.
Distal end: hooks onto the proximal phalanx of the thumb.
Innervation: belongs to the posterior interosseous branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery.
- Long thumb extensor. It provides for the extension of all the joints of the thumb (therefore the carpometacarpal, metacarpo-phalangeal and interphalangeal joints).
Proximal end: originates in a point of the posterior surface of the ulna located about halfway through the bone and in the portion of the adjacent interosseous membrane.
Distal end: finds insertion on the distal phalanx of the thumb.
Innervation: belongs to the posterior interosseous branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery. - Extensor of the index finger. It deals with the extension of the index finger.
Proximal end: originates in a point of the posterior surface of the distal portion of the ulna and in the adjacent interosseous membrane portion.
Distal end: it attaches to the dorsal aponeurosis of the index finger.
Innervation: belongs to the posterior interosseous branch of the radial nerve.
Spraying: belongs to the posterior interosseous artery.
