In human anatomy, the supinator is a broad muscle in the posterior compartment of the forearm, curved around the upper third of the radius. Its function is to supinate the forearm. Supinator consists of two planes between which the deep branch of the radial nerve ls; the two planes arise in common — the superficial one by tendinous and the deeper by muscular fibers — from the supinator crest of ulna, the lateral epicondyle of humerus, the radial collateral ligament, the annular radial ligament. The superficial fibers surround the upper part of the radius, are inserted into the lateral edge of the radial tuberosity and the oblique line of the radius, as low down as the insertion of the pronator teres; the upper fibers of the deeper plane form a sling-like fasciculus, which encircles the neck of the radius above the tuberosity and is attached to the back part of its medial surface. The proximal aspect of the superficial head is known as the arcade of the supinator arch, it is innervated by the deep branch of the radial nerve.
The deep branch becomes the posterior interosseous nerve upon exiting the supinator muscle The radial nerve divides into deep and sensory superficial branches just proximal to the supinator muscle — an arrangement that can lead to entrapment and compression of the deep part resulting in selective paralysis of the muscles served by this nerve Many possible causes are known for this nerve syndrome, known as supinator entrapment syndrome, including compression by various soft-tissued masses surrounding the nerve, stress caused by repetitive supination and pronation. The deep radial nerve passes through the belly of supinator in 70% of cases and via the arcade of Frohse in remaining cases. Encircling the radius, supinator brings the hand into the supinated position. In contrast to the biceps brachii, it is able to do this in all positions of elbow flexion and extension. Supinator always acts together except when the elbow joint is extended, it is the most active muscle in forearm supination during unresisted supination, while biceps becomes active with heavy loading.
Supination strength decreases by 64 %. The term "supinator" can refer more to a muscle that causes supination of a part of the body. In older texts, the term "supinator longus" was used to refer to the brachioradialis, "supinator brevis" was used to describe the muscle now known as the supinator; this article incorporates text in the public domain from page 454 of the 20th edition of Gray's Anatomy Boles, CA. "The Forearm: Anatomy of Muscle Compartments and Nerves". Am. J. Roentgenol. 174: 151–159. Chien, A. "Sonography and MR Imaging of Posterior Interosseous Nerve Syndrome with Surgical Correlation". Am. J. Roentgenol. 181: 219–221. Duqion, TR. "Innervation of the Supinator Muscle and Its Relationship to Two-Incision Distal Biceps Tendon Repair: An Anatomic Study". Clinical Anatomy. 23: 413–419. Doi:10.1002/ca.20982. Platzer, W. Color Atlas of Human Anatomy, Vol. 1: Locomotor System. Thieme. ISBN 1-58890-159-9. Ross, Lawrence M.. Thieme Atlas of Anatomy: General Anatomy and Musculoskeletal System. Thieme. ISBN 1-58890-419-9.
CS1 maint: Extra text: authors list
Flexor carpi radialis muscle
In anatomy, flexor carpi radialis is a muscle of the human forearm that acts to flex and abduct the hand. The Latin carpus means wrist; this muscle originates on the medial epicondyle of the humerus. It runs just laterally of flexor digitorum superficialis and inserts on the anterior aspect of the base of the second metacarpal, has small slips to both the third metacarpal and trapezial tuberosity. On the anterior aspect of a person's forearm, proximal to the wrist, flexor carpi radialis is the most lateral tendon visible when the wrist is brought into flexion. Like most of the flexors of the hand, FCR is innervated by the median nerve, it gets its blood from the radial artery. The muscle, like all flexors of the forearm, can be strengthened by exercises that resist its flexion. A wrist roller can be used, wrist curls with dumbbells can be performed. Flexor retinaculum of the hand Flexor carpi ulnaris
Extensor digitorum muscle
The extensor digitorum muscle is a muscle of the posterior forearm present in humans and other animals. It extends the medial four digits of the hand. Extensor digitorum is innervated by the posterior interosseous nerve, a branch of the radial nerve, it arises by the common tendon. It divides below into four tendons, which pass, together with that of the extensor indicis proprius, through a separate compartment of the dorsal carpal ligament, within a mucous sheath; the tendons diverge on the back of the hand, are inserted into the middle and distal phalanges of the fingers in the following manner. Opposite the metacarpophalangeal articulation each tendon is bound by fasciculi to the collateral ligaments and serves as the dorsal ligament of this joint. Opposite the first interphalangeal joint this aponeurosis divides into three slips; as the tendons cross the interphalangeal joints, they furnish them with dorsal ligaments. The tendon to the index finger is accompanied by the tendon of extensor indicis, which lies on its ulnar side.
On the back of the hand, the tendons to the middle and little fingers are connected by two obliquely placed bands, one from the third tendon passing inferior and laterally to the second tendon, the other passing from the same tendon inferior and medially to the fourth. The extensor tendons are connected to the second by a thin transverse band, known as the juncturae tendinum. Injuries may allow the tendon to dislocate into the intermetacarpal space; this may be corrected surgically by using a slip of the extensor tendon to replace the damaged ligamentous band. The extensor digitorum communis extends the phalanges the wrist, the elbow, it tends to separate the fingers. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint. Extension of the proximal and distal interphalangeal joints, however, is mediated predominantly by the dorsal and palmar interossei and lumbricals of the hand. Extensor digitorum brevis muscle Extensor digitorum longus muscle Extensor digitorum reflex This article incorporates text in the public domain from page 451 of the 20th edition of Gray's Anatomy
Extensor carpi ulnaris muscle
In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. It acts to adduct at the carpus/wrist from anatomical position. Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm, it originates from the lateral epicondyle of the humerus and the posterior border of the ulna, crosses the forearm to the ulnar side to insert at the base of the 5th metacarpal. The extensor carpi ulnaris extends the wrist, but when acting alone inclines the hand toward the ulnar side; the muscle has become a flexor in ungulates. In this case it is described as ulnaris lateralis. Despite its name, the extensor carpi ulnaris is innervated by the posterior interosseous nerve, the continuation of the deep branch of the radial nerve, it would therefore be paralyzed in an injury to the posterior cord of the brachial plexus. A common injury to the extensor carpi ulnaris is tennis elbow; this injury occurs in people that participate in activities requiring repetitive arm and wrist when they are gripping an object.
Some symptoms include pain when squeezing/gripping an object. The pain worsens; the pain intensifies because the extensor carpi ulnaris has an injury near the elbow area and as a person moves their arm, the muscle contracts, thus causing it to move over the medial epicondyle of the humerus. This causes irritation to the existing injury; some treatments for tennis elbow include occupational therapy, physical therapy, anti-inflammatory medication, rest from the activity that caused the injury. A similar injury involving the medial elbow is known as golfers elbow. An ECU injury most requires imaging for diagnosis. After the ECU injury is diagnosed, a physician will choose a course of treatment, which depends upon the severity of the injury. Conservative treatments include immobilization and stabilization of the affected wrist by placing it in a cast. A long arm cast may be required in order to ensure; the duration of the immobilization is at the treating physician's discretion. After the immobilization period has ended, the cast will be removed and further analysis of the injury will be required.
If the injury did not improve with the conservative courses of treatment, or if the injury was too severe for conservative treatment, invasive procedures may become necessary. Steroid injections and surgical procedures are the most prominent invasive procedures. Surgical repair or reconstruction of the ECU is not required, yet a severe ECU injury may cause these approaches to be necessary
Extensor digiti minimi muscle
The extensor digiti minimi is a slender muscle of the forearm, placed on the ulnar side of the extensor digitorum communis, with which it is connected. It arises from the common extensor tendon by a thin tendinous slip and from the intermuscular septa between it and the adjacent muscles, its tendon passes through a compartment of the extensor retinaculum, posterior to distal radio-ulnar joint divides into two as it crosses the dorsum of the hand, joins the extensor digitorum tendon. All three tendons attach to the dorsal digital expansion of the fifth digit. There may be a slip of tendon to the fourth digit. An additional fibrous slip from the lateral epicondyle. Absence of muscle rare. Variations to the fifth extensor compartment, which the extensor digiti minimi runs through, may cause tenosynovitis and can limit the use of the extensor digiti minimi. Extensor digiti minimi can be bifurcated, which means split, at many different points in the muscle; the extensor digiti minimi is a two joint muscle.
It acts as an extensor in both joints. It extends the wrist, it extends the little finger, which means it straightens the little finger from a fist. This article incorporates text in the public domain from page 451 of the 20th edition of Gray's Anatomy Saladin, Kenneth S. Anatomy & Physiology: the Unity of Form and Function; the McGraw-Hill. ISBN 978-0-07-337825-1. Tanaka, T. "Anatomic variation of the 5th extensor tendon compartment and extensor digiti minimi tendon". Clin. Anat. 20: 677–82. Doi:10.1002/ca.20480. PMID 17352412. Yoo, Moon-Jib. "Tendon impingement of the extensor digiti minimi: clinical cases series and cadaveric study". Clinical Anatomy. Wiley Periodicals. 25: 755–61. Doi:10.1002/ca.22017. PMID 22162183. Hand kinesiology at the University of Kansas Medical Center
Anatomical terms of motion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints and specific sections of the body; the terminology used describes this motion according to its direction relative to the anatomical position of the joints. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands and eyes. In general, motion is classified according to the anatomical plane. Flexion and extension are examples of angular motions, in which two axes of a joint are brought closer together or moved further apart. Rotational motion may occur at other joints, for example the shoulder, are described as internal or external. Other terms, such as elevation and depression, describe movement above or below the horizontal plane. Many anatomical terms derive from Latin terms with the same meaning. Motions are classified after the anatomical planes they occur in, although movement is more than not a combination of different motions occurring in several planes.
Motions can be split into categories relating to the nature of the joints involved: Gliding motions occur between flat surfaces, such as in the intervertebral discs or between the carpal and metacarpal bones of the hand. Angular motions occur over synovial joints and causes them to either increase or decrease angles between bones. Rotational motions move a structure in a rotational motion along a longitudinal axis, such as turning the head to look to either side. Apart from this motions can be divided into: Linear motions, which move in a line between two points. Rectilinear motion is motion in a straight line between two points, whereas curvilinear motion is motion following a curved path. Angular motions occur when an object is around another object decreasing the angle; the different parts of the object do not move the same distance. Examples include a movement of the knee, where the lower leg changes angle compared to the femur, or movements of the ankle; the study of movement is known as kinesiology.
A categoric list of movements of the human body and the muscles involved can be found at list of movements of the human body. The prefix hyper- is sometimes added to describe movement beyond the normal limits, such as in hypermobility, hyperflexion or hyperextension; the range of motion describes the total range of motion. For example, if a part of the body such as a joint is overstretched or "bent backwards" because of exaggerated extension motion it can be described as hyperextended. Hyperextension increases the stress on the ligaments of a joint, is not always because of a voluntary movement, it may be other causes of trauma. It may be used in surgery, such as in temporarily dislocating joints for surgical procedures; these are general terms. Most terms have a clear opposite, so are treated in pairs. Flexion and extension describe movements; these terms come from the Latin words with the same meaning. Flexion describes a bending movement that decreases the angle between a segment and its proximal segment.
For example, bending the elbow, or clenching a hand into a fist, are examples of flexion. When sitting down, the knees are flexed; when a joint can move forward and backward, such as the neck and trunk, flexion refers to movement in the anterior direction. When the chin is against the chest, the head is flexed, the trunk is flexed when a person leans forward. Flexion of the shoulder or hip refers to movement of the leg forward. Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts. For example, when standing up, the knees are extended; when a joint can move forward and backward, such as the neck and trunk, extension refers to movement in the posterior direction. Extension of the hip or shoulder moves the leg backward. Abduction is the motion of a structure away from the midline while adduction refer to motion towards the center of the body; the centre of the body is defined as the midsagittal plane. These terms come from Latin words with similar meanings, ab- being the Latin prefix indicating "away," ad- indicating "toward," and ducere meaning "to draw or pull".
Abduction refers to a motion that pulls a part away from the midline of the body. In the case of fingers and toes, it refers to spreading the digits apart, away from the centerline of the hand or foot. Abduction of the wrist is called radial deviation. For example, raising the arms up, such as when tightrope-walking, is an example of abduction at the shoulder; when the legs are splayed at the hip, such as when doing a star jump or doing a split, the legs are abducted at the hip. Adduction refers to a motion that pulls a structure or part toward the midline of the body, or towards the midline of a limb. In the case of fingers and toes, it refers to bringing the digits together, towards the centerline of the hand or foot. Adduction of the wrist is called ulnar deviation. Dropping the arms to the sides, bringing the knees together, are examples of adduction. Ulnar deviation is the hand moving towards the ulnar styloid. Radial deviation is the hand moving towards the radial styloid; the terms elevation and depression refer to movement below the horizontal.
They derive from the Latin terms with similar meaningsElevation refers to movement in a superior direction. For example
Distal radioulnar articulation
The distal radioulnar articulation is a joint between the two bones in the forearm. It is one of two joints between the radius and ulna, the other being the proximal radioulnar articulation; the distal radioulnar articulation is the one of the two closest to the hand. The distal radioulnar articulation pivot-joint formed between the head of ulna and the ulnar notch on the lower extremity of radius; the articular surfaces are connected together by the following ligaments: Palmar radioulnar ligament Dorsal radioulnar ligament Articular disk The function of the radioulnar joint is to lift and maneuver weight load from the distal radioulnar joint to be distributed across the forearm’s radius and ulna as a load-bearing joint. Supination of the radioulnar joint can move from 0 degrees neutral to 80-90 degrees where Pronation of the Radioulnar Joint can move from 0 degrees neutral to 70-90 degrees. Supination vs. pronation. Muscles that contribute to function are all pronator muscles. Injuries to the distal radioulnar articulation result from falls onto an outstretched hand.
Injury can be isolated. A classification system has been proposed by colleagues. Estaminet classified injuries of the distal radioulnar articulation into four categories with two subclasses: purely ligamentous and those with associated boney injury. Estaminet I - Attenuation on MRI only Estaminet II - Volar distal radioulnar ligament is involved. Unstable in supination. Fixation should be in pronation. Estaminet III - Dorsal distal radioulnar ligament is involved. Unstable in pronation. Fixation should be in supination. Estaminet IV - Both ligaments are involved. Unstable in both supination and pronation. Fixation is in neutral. Proximal radioulnar articulation This article incorporates text in the public domain from page 325 of the 20th edition of Gray's Anatomy elbow/elbowbones/bones5 at the Dartmouth Medical School's Department of Anatomy