The abductor pollicis longus muscle, combined with the extensor pollicis brevis, creates a narrow, triangular muscle form which wraps around the lower end of the radius. The abductor pollicis longus originates on the back side of the ulna and radius and inserts at the base of the metacarpal bone of the thumb near the palm. The abductor pollicis longus is innervated by the radial nerve and is supplied by branches of the radial artery. This muscle extends the thumb away from the hand. It also rotates and flexes the hand at the wrist. The combination of the abductor pollicis longus and the extensor pollicis brevis forms the oblique carpal muscle group. Research Abductor Pollicis Longus
The anconeus is a small triangular muscle that originates just below the elbow joint at the lateral condyle of the humerus and extends a fourth of the way down the forearm to insert in the olecranon process and back of the ulna. It is located on the outer back corner of the elbow. The anconeus is innervated by the radial nerve and supplied by the radial artery. It extends and stabilizes the elbow joint. Research Anconeus
The arm is the upper limb in man, connected with the thorax or chest by means of the scapula or shoulder-blade, and the clavicle or collar-bone. It consists of three bones, the arm-bone (Humerus), and the two bones of the forearm (radius and ulna), and it is connected with the bones of the hand by the carpus or wrist. The head or upper end of the arm-bone fits into the hollow called the glenoid cavity of the scapula, so as to form a joint of the ball-and-socket kind, allowing great freedom of movement to the limb. The lower end of the humerus is broadened out by a projection on both the outer and inner sides (the outer and inner condyles), and has a pulley-like surface for articulating with the fore-arm to form the elbow-joint. This joint somewhat resembles a hinge, allowing of movement only in one direction. The ulna is the inner of the two bones of the fore-arm. It is largest at the upper end, where it has two processes, the coronoid and the olecranon, with a deep groove between to receive the humerus. The radius - the outer of the two bones - is small at the upper and expanded at the lower end, where it forms part of the wrist-joint. The muscles of the upper arm are either flexors or extensors, the former serving to bend the arm, the latter to straighten it by means of the elbow-joint. The main flexor is the biceps, the large muscle which may be seen standing out in front of the arm when a weight is raised. The chief opposing muscle of the biceps is the triceps. The muscles of the fore-arm are, besides flexors and extensors, pronators and supinators, the former turning the hand palm downwards, the latter turning it upwards. The same fundamental plan of structure exists in the limbs of all vertebrate animals. Research Arm
The brachialis is a slender, flat muscle that lies under the biceps along the front of the lower half of the humerus and in front of the elbow joint. It originates from the front of the humerus and inserts in the coronoid process of the ulna. The brachialis is innervated by the musculocutaneous nerve and the radial nerve. It is supplied by the brachial artery and radial artery. This muscle protects the elbow, and helps flex and rotate the forearm. Research Brachialis
The carpus or carpals, consist of eight individual bones which compose each wrist. The small bones fit together in an exacting way to allow a wide range of flexibility in the wrist, while maintaining structural integrity. The eight bones of each wrist include the hamate, navicular, trapezium, pisiform, trapezoid, lunate, triquetrum, and capitate bones, which articulate with the metacarpals, the radius, and the ulna. Research Carpus
The coronoid fossa is a depression located on the lower end of the front of the humerus. It accepts the coronoid process of the ulna when the elbow joint is in flexion. Research Coronoid Fossa
The humerus, radius, and ulna join to form the elbow joint. This joint features a number of complex prominences which serve as attachment sites of ligaments and muscles, serving to control the flexibility and adduction of the bones about the elbow. The articulation of the elbow is called a hinge joint, because, like a hinge on a door, the joint only permits flexion in a single plane. Research Elbow Joint
The extensor carpi ulnaris originates by two heads: one from the lateral epicondyle of the humerus and the other from the border of the ulna (forearm bone). It narrows into a tendon three-fourths of the way down the arm and inserts on the ulnar side of the base of the metacarpal bone of the little finger. It is innervated by the radial nerve and supplied by the posterior interosseous artery. This muscle is the most superficial muscle on the ulnar side of the forearm. The
extensor carpi ulnaris works with the flexor carpi ulnaris to bend the hand at the wrist. Research Extensor Carpi Ulnaris
The extensor indicis (extensor indicis proprius) is located deep in the forearm, where it originates from the back of the ulna. At the wrist it develops into a tendon that extends along the back of the hand with the extensor digitorum and inserts in the index finger. It is innervated by the radial nerve and supplied by the posterior interosseous artery. This muscle extends and adducts the index finger. Research Extensor Indicis
The extensor pollicis longus originates deep in the forearm from the shaft of the ulna (the forearm bone on the index finger side), crosses over the tendons of the extensor carpi radiales brevis and longus and descends along the back of the thumb and inserts in the last phalanx of the thumb. It is innervated by the radial nerve and supplied by the posterior interosseous artery. This muscle extends the thumb and helps to extend the hand at the wrist. Research Extensor Pollicis Longus
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Abductor Pollicis Longus
