Anterior Forearm Compartments (2024/2025) PDF

MUST MSK(101-1) Academic year: 2024/2025 ANATOMY DEPARTMENT FOREARM Prof. Dr. Hayam Elsaady Farhoud Compartment of forearm Muscles of anterior compartment of the forearm  MUSCLES OF THE FRONT OF FOREARM The flexor group which ar...

MUST MSK(101-1) Academic year: 2024/2025 ANATOMY DEPARTMENT FOREARM Prof. Dr. Hayam Elsaady Farhoud Compartment of forearm Muscles of anterior compartment of the forearm  MUSCLES OF THE FRONT OF FOREARM The flexor group which are arranged into : superficial and deep layers. MUSCLES OF SUPERFICIAL LAYER (5 muscles) : - pronator teres -flexor carpi radialis - palmaris longus -flexor digitorum superficials -flexor carpi ulnaris. -The flexor digitorum superficials is situated deeper to the flexor carpi radialis and palmaris longus. Muscles of anterior compartment of the forearm Pronator teres Origin: 1- Humeral head: from the medial epicondyle and medial supra condylar ridge. 2- Ulnar head: from the medial side of the coronoid process of the ulna. Insertion: Rough area at the middle of the lateral surface of radius Nerve supply: Median nerve. Action: Pronation of the forearm Main relations: -Between its 2 heads the median nerve passes. -The ulnar head (deep head) separates the median nerve from the ulnar artery. Flexor carpi radialis It lies just medial to the pronator teres. Origin: from the front of the medial epicondyle of the humerus (common flexor origin). Insertion: Into the palmar surface of the bases of the 2nd and 3rd metacarpal bones. Nerve supply: median nerve (while in the cubital fossa). Action: Flexion and abduction of the hand at the wrist joint. Palmaris longus It lies medial to the flexor carpi radialis. It may be absent. Origin: from the front of the medial epicondyle of the humerus (common flexor origin). Insertion: Into the apex of palmar aponeurosis, The tendon crosses superficial to the flexor retinaculum. Nerve supply: median nerve (while in the cubital fossa). Action: Flexion of the hand at the wrist joint. Flexor carpi ulnaris It lies along the ulnar side of forearm Origin: 1- humeral head: from the front of the medial epicondyle of the humerus (common flexor origin). 2- ulnar head: from the medial margin of the olecranon and by aponeurosis from the posterior border of the ulna. N.B. -The aponeurosis gives origin to the extensor carpi ulnaris and flexor digitorum profundus). Insertion: -Into the pisiform bone -The base of the 5th metacarpal bone. -Hamat N.B. Insertion: into the pisiform bone from which the insertion extends to 2 bones through 2 ligaments : 1-To the base of 5th metacarpal bone: through the piso-metacarpal ligament. 2. To the hamate: through the piso-hamate ligament. Nerve supply: Ulnar nerve. Action: -Flexion and adduction of the hand at the wrist joint if act alone. -Flexion of the hand at the wrist joint if act with the flexor carpi radialis. (with neither adduction nor abduction). * Main relations: In the upper 2/3 of forearm: the ulnar nerve lies deep to the muscle. In the lower 1/3 of forearm: the ulnar nerve and artery lie on the lateral side of the tendon of the muscle, where they come superficial beneath the skin and Flexor digitorum superficialis It lies superficial to the flexor digitorum profundus and deep to both the flexor carpi radialis and palmaris longus. Origin: 1- humero-ulnar head: from the front of the medial epicondyle of the humerus and medial side of coronoid process. 2- radial head: from the oblique upper 1/3 of the anterior border of the radius (anterior oblique line). Insertion: -into the middle phalanges of the medial 4 fingers N.B. The tendons take the following course: -Above the wrist: the muscle gives off 4 tendons for the medial 4 digits. -In the carpal tunnel: the tendons are arranged so as the 2 tendons of the middle and ring fingers are superficial to the 2 tendons of the index and little fingers. In the palm: the tendons diverge from each other to reach Nerve supply: Median nerve, while in the cubital fossa Action: -Flexion of the middle and proximal phalanges of the medial 4 fingers. -Assists flexion of the hand at the wrist joint Main relations: -The radial artery and superficial terminal branch of radial nerve run superficial to the origin of the radial head of the muscle. -The median nerve in the forearm runs deep to the muscle. However, in the carpal tunnel the nerve lies on the lateral side of the tendons of the muscle. - In the hand , The superflcial palmar arch and palmar aponeurosis are superficial to the tendons of the muscle.  MUSCLES OF DEEP LAYER (3 muscles) Flexor pollicis longus: related to the radius. Flexor digitorum profundus: related to the ulna. Pronator quadratus: related to both radius and ulna. Flexor pollicis longus Origin: From the upper 2/3 of the anterior surface of the radius and adjoining part of the interosseous membrane. Insertion: -into the base of the distal phalanx of the thumb. The tendon of insertion passes deep to the flexor retinaculum and then curves laterally in the hand, just medial to the thenar muscles Nerve supply: Anterior interosseous branch of median nerve. Action: -Flexion of all joints of the thumb. Flexor digitorum profundus Origin: 1- upper 2/3 of the anterior and medial surface of the ulna. 2-from the posterior border of the ulna by aponeorosis. 3- from the interosseous membrane. Insertion: -into the bases of the distal,terminal, phalanges of the medial 4 fingers. The tendons pass through the carpal tunnel deep to the tendons of the flexor digitorum superficialis. In the palm, the tendons diverge to reach the fingers. Each tendon gives attachment to a lumbrical muscle. In the finger, each tendon pierces the corresponding tendon of the flexor digitorum superficialis and continues to get attached to the base of the terminal phalanx. Each tendon is connected to the phalanges by vascular fibrous bands called vincula which carry blood vessels to supply the tendon. Nerve supply: Anterior interosseous branch of Action: -Flexion of all joints of the medial 4 fingers ( Flexes the proximal, middle and distal phalanges of the medial 4 fingers) - Helps in flexion of the wrist joint. Main relations: - The median nerve: passes on its anterior surface between it and the flexor digitorum superficialis. -The ulnar nerve and artery: pass along its medial aspect between it and the flexor carpi ulnaris. - The anterior interosseous nerve and artery: pass on the interosseous membrane along the lateral side of the muscle between it and the flexor pollicis longus.  Pronator quadratus Origin:- lower ¼ of the anterior surface of the ulna. Insertion: -into the lower ¼ of the anterior surface of the radius. Nerve supply: Anterior interosseous branch of median nerve Action: -Pronation of the forearm. - Help to binds the radius to the ulna.