Maximus Gage
The forearm is the section of the upper limb that extends from the elbow to the wrist, and it contains twenty muscles that act on the elbow and wrist joints, as well as the joints of the hand. These muscles are divided into two compartments: the anterior (flexor) and the posterior (extensor). The muscles in the posterior compartment are responsible for extending the forearm, with the triceps brachii being one of the primary muscles involved in this action. The anconeus, located in the superficial region of the posterior compartment, also helps to extend the forearm at the elbow. The supinator muscle, located in the deep region of the posterior compartment, allows for supination of the forearm, or turning the palm upward. The extensor pollicis brevis, also located in the posterior compartment, allows for the extension of the thumb, while the extensor indicis helps extend the index finger.
Explore related products
What You'll Learn
Extensor Carpi Radialis Longus
The extensor carpi radialis longus is a long muscle that starts on the lateral side of the humerus and attaches to the base of the second metacarpal bone (metacarpal of the index finger). It is one of the five main muscles that control movements at the wrist.
The extensor carpi radialis longus is classified as a superficial layer muscle, together with the brachioradialis, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris. It is partly overlapped by the brachioradialis, and these muscles often blend together. The radial nerve courses laterally to the muscle, becoming more superficial approximately 10 cm proximal to the radial styloid process.
The extensor carpi radialis longus can be palpated in the upper lateral portion of the posterior forearm. The tendon of the extensor carpi radialis longus can be felt in the floor of the anatomical snuffbox when wrist extension and abduction are performed.
Cockroaches: Muscular Insects or Not?
You may want to see also
Explore related products
Extensor Carpi Ulnaris
ECU originates from the lateral epicondyle of the distal humerus and the posterior aspect of the ulna. It then inserts onto the dorsal base of the fifth metacarpal after passing through the sixth compartment of the extensor retinaculum. The muscle fibres curve towards the ulnar side of the hand, and just proximal to the wrist, the muscle gives off a tendon that passes beneath the extensor retinaculum. This tendon passes through a groove on the posterior surface of the head and styloid process of the ulna.
ECU is innervated by the posterior interosseous nerve (C7, C8), a branch of the deep division of the radial nerve. The blood supply to the muscle is provided by branches of the radial recurrent and posterior interosseous arteries, which are themselves branches of the radial and ulnar arteries, respectively.
ECU is susceptible to injuries due to its involvement in forceful and repetitive wrist movements. Tennis elbow is a common injury to the ECU, caused by activities that require repetitive arm, elbow, and wrist movements, especially when tightly gripping an object. Symptoms include pain when shaking hands or squeezing/gripping an object, with the pain intensifying during forceful wrist movements. Treatment options for ECU injuries include occupational therapy, physical therapy, anti-inflammatory medication, and rest from the aggravating activity.
Hydration's Healing Power: Muscle Recovery with Water
You may want to see also
Explore related products
Extensor Digitorum
The extensor digitorum muscle, also known as the extensor digitorum communis, is a long muscle located in the posterior compartment of the forearm. It is a superficial muscle, meaning it can be easily palpated in the lateral aspect of the posterior forearm, especially during the extension of the hand when it is contracted. The extensor digitorum is one of twenty muscles that act on the elbow and wrist joints, as well as the carpometacarpal, metacarpophalangeal, and interphalangeal joints of the hand.
The extensor digitorum extends the medial four digits of the hand, i.e., the four fingers. In the fingers, the extensor digitorum acts principally on the proximal phalanges, extending the metacarpophalangeal joint. It also extends the proximal and distal interphalangeal joints, although this is mediated predominantly by the dorsal and palmar interossei and lumbricals of the hand. The extensor digitorum also participates in the extension of the wrist and the elbow.
The extensor digitorum arises from the lateral epicondyle of the humerus, by the common tendon; from the intermuscular septa between it and the adjacent muscles, and from the antebrachial fascia. It divides below into four tendons, which pass through a separate compartment of the dorsal carpal ligament, within a mucous sheath. The tendons then diverge on the back of the hand and are inserted into the middle and distal phalanges of the fingers. Opposite the metacarpophalangeal articulation, each tendon is bound by fasciculi to the collateral ligaments and serves as the dorsal ligament of this joint.
The extensor digitorum is innervated by the posterior interosseous nerve, which is a branch of the radial nerve. It is vascularized by the branches of three different arteries: the anterior and posterior interosseous arteries, which are branches of the common interosseus artery that arises from the ulnar artery, and the radial recurrent artery, which is a branch of the radial artery.
The Mystery of Extra Muscles: Unveiling the Unknown
You may want to see also
Explore related products
Extensor Carpi Radialis Brevis
The extensor carpi radialis brevis is a muscle in the lateral part of the posterior forearm. It is a fusiform muscle, and it belongs to the superficial forearm extensor group. The extensor carpi radialis brevis is located in the radial (or lateral) part of the forearm, sitting deep to the extensor carpi radialis longus. It is the shorter of the two muscles.
The extensor carpi radialis brevis originates from the lateral epicondyle of the humerus via the common extensor tendon. It shares this origin with the extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris muscles. Some fibres of the extensor carpi radialis brevis also originate from the lateral intermuscular septum, a thick aponeurosis that covers the muscle itself, and from the radial collateral ligament. The muscle courses inferiorly, giving off a long tendon in the middle of the forearm, which descends towards the dorsal hand.
The tendon of the extensor carpi radialis brevis passes through a groove on the posterior surface of the radius, deep to the extensor retinaculum. After traversing the extensor retinaculum space, the tendon inserts into the posterior aspect of the base of the third metacarpal bone, with a few fibres inserting into the medial dorsal surface of the second metacarpal bone. The tendon lies on the back of the radius in a shallow groove, to the ulnar side of that which lodges the tendon of the extensor carpi radialis longus, and is separated from it by a faint ridge.
The extensor carpi radialis brevis is an extensor and an abductor of the hand at the wrist joint. It works together with the extensor carpi ulnaris and extensor carpi radialis longus to extend the hand at the wrist joint. Like all the muscles in the posterior forearm, the extensor carpi radialis brevis is supplied by a branch of the radial nerve.
Understanding Muscle Tone: What Produces This?
You may want to see also
Explore related products
Triceps Brachii
The triceps brachii is a three-headed muscle in the arm, with long, medial, and lateral heads. It is the only constituent of the posterior muscle group of the arm, spanning almost the entire length of the humerus. The triceps brachii is the muscle primarily responsible for the extension of the forearm at the elbow joint. It also plays a role in extending and adducting the arm at the shoulder joint.
The triceps brachii can be trained in a variety of ways, including isolation and compound elbow extension movements. Isolation exercises include lying triceps extensions, cable push-downs, and arm extensions behind the back. Compound exercises include pressing movements like push-ups, bench presses, and dips. The triceps can also be contracted statically to keep the arm straight against resistance.
The triceps brachii is innervated by the radial nerve, which provides a distinct branch for each head. The C6 root value of the radial nerve innervates the lateral head, the C7 root value innervates the long head, and the C8 root value supplies the medial head. However, recent studies have found that in some individuals, the long head of the triceps brachii is innervated by the axillary nerve, or by both the radial and axillary nerves.
The triceps brachii is supplied with oxygen and nutrients by the branches of the deep brachial artery and the superior ulnar collateral artery, which originates from the brachial artery. The medial head of the triceps brachii is predominantly composed of small type I muscle fibres and motor units, allowing for precise, low-force movements. In contrast, the lateral head is composed of larger type IIb fibres and motor units, enabling high-intensity force movements.
Vintage Muscle: Is It FDA-Approved Yet?
You may want to see also
Frequently asked questions
The triceps brachii, anconeus, and supinator muscles extend the forearm.
The triceps brachii is a muscle in the posterior compartment of the upper arm that extends the forearm.
The anconeus is located in the superficial region of the forearm posterior compartment and extends the forearm at the elbow.
The supinator muscle is located in the deep region of the forearm posterior compartment and supinates the forearm, allowing the palm to face up.
The extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, and extensor carpi ulnaris extend the wrist and move the hand away from the direction of the thumb. The extensor digiti minimi extends the little finger. The abductor pollicis longus, extensor pollicis longus, and extensor indicis extend the thumb and index finger.
