The forearm is invested by the antebracial fascia which is attached to the olecranon and subcutaneous posterior border of ulna.
The floor of the anterior compartment is formed by the anterior surface of the radius,anterior and medial surfaces of the ulna and the interosseous membrane between them.
🔸Muscles – These are arranged in superficial and deep groups. The superficial muscle are five in number and the deep muscles are three in number
🔸Arteries-Radial and ulnar arteries
🔸Nerves-median and ulnar nerve
🔵Superficial flexor muscles—These are five in number:
√ Pronator teres
√ Flexor Carpi Radialis
√ Palmaris longus
√ Flexor carpi ulnaris
√ Flexor digitorum superficialis.
💠Origin,Insertion and action of the superficial muscles :
⚪PRONATOR TERES :
🔸Origin-Humeral head from the medial epicondyl of the humerus.Ulnar head from the medial margin of the Coronoid process of the ulna.
🔸Insertion-Middle one third of the lateral surface of the shaft of the radius.
🔸Action—Helps in pronation of the forearm and acts as weak flexor of elbow joint.
⚪FLEXOR CARPI RADIALIS :
🔹Origin-From the medial epicondyle as a common origin of the muscles.
🔹Insertion-Bases of 2nd and 3rd metacarpal bones.
🔹Action-It flexes and abducts hand of wrist joint.
⚪PALMARIS LONGUS :
🔹Origin-Medial epicondyl of the humerus
🔹Insertion-passes in front of the flexor retinaculum and continuous with the palmar aponeurosis
🔹Action-It is a weak flexor of the wrist
⚪FLEXOR CARPI ULNARIS :
🔹Origin -Humoral head from the medial epicondyl of the humerus. Ulnar head from the medial aspect of olecranon process and posterior border of ulna.
🔹Insertion- The tendon is inserted into the pisiform bone through the pisohamette and piso meta carpal ligaments.
🔹Action-Flexes and adducts the hand at the wrist joint
⚪FLEXOR DIGITORUM SUPERFICIALIS :
🔹Origin- Humero-ulnar head arises from the medial epicondyl of humerus and medial border of coronoid process of ulna.
The radial head from the anterior oblique line of the radius.
🔹Insertion-Muscle divides into 4 tendons.Each tendon divides into 2 slips which are inserted on sides of middle phalanx of 2nd to 5th digits.
🔹Action- Flexes middle phalanx of fingers.
🔴Deep muscles-These are three in number-
☑️Flexor Pollicis longus
☑️Flexor Digitorum profundus
🟣Origin,Insertion and Action of the deep flexor muscles :
⬜FLEXOR POLLICIS LONGUS :
★Upper three fourths of the anterior surface of the shaft of the radius.
★Adjoining part of the anterior surface of the interosseous membrane
🔸Insertion-It is inserted into the palmar surface of distal phalanx of the thumb.
🔸Action- Flexes the distal phalanx of the thumb and may also flex the proximal joints crossed by the tendon.
🟣FLEXOR DIGITORUM PROFUNDUS :
★Anterior and medial surfaces of the upper three-fourths of the shaft of the ulna.
★From the adjacent interosseous membrane.
🔸Insertion- The muscle forms 4 tendons for middle 4 digits.Each tendon is inserted into the palmar surface of the base of terminal phalanx of the medial four fingers.
🔸Actions – It flexes the terminal phalanges.
🟢PRONATOR QUADRATUS :
🔸Origin – Antero-medial surface of the lower one-fourth of the ulna
★superficial fibres into the lower one fourth of th anterior border of the radius
★Deep fibres into the triangular area above the ulnar arch.
★Superficial fibres are the principal pronator of the forearm
★Deep fibres prevents seperation of the lower parts of radius and ulna.
🟢Reference – A.K DATTA
Essentials of HUMAN ANATOMY, 5TH ED.
Platform Academic Division/ Sadia Afrin Ivy
CARe MEDICAL COLLEGE, DHAKA
Session : 2019-20