THE MUSCLES OF THE ANTERIOR COMPARTMENT OF FOREARM AND FLEXOR RETINACULUM LEARNING OBJECTIVES

Transcription

1 Semester 2 Anatomy lecture THE MUSCLES OF THE ANTERIOR COMPARTMENT OF FOREARM AND FLEXOR RETINACULUM LEARNING OBJECTIVES At the end of the lecture, the student should be able to: Describe the muscles of forearm. Tell the nerve supply of these muscles. Explain actions of the muscles of anterior compartment of forearm. Describe attachment and functions of flexor retinaculum MUSCLES OF THE ANTERIOR COMPARTMENT OF FOREARM Arranged in two Groups. Superficial Group of Muscles. Deep Group of Muscles.

2 SUPERFICIAL MUSCLES Pronator teres. Flexor carpi radialis. Flexor digitorium superficials. Palmaris longus. Flexor carpi ulnaris. DEEP MUSCLES Flexor digitorium profundus. Pronator quaradatus. Flexor pollicis longus.

3 SUPERFICIAL MUSCLES Have a common origin. Arise from anterior surface of medial epicondyles. Three have additional origin also i.e. Pronator teres, flexor carpi radials, flexor digitorium superficials. Origin : A. LARGE SUPERFICIAL HEAD: 1. Common origin. 2. Supra condylar ridge. PRONATOR TERES B. SMALL DEEP HEAD: From medial border of the coronoid process of ulna just distal to the tubercle on it. Insertion : By flat tendon into the middle of lateral surface of shaft of radius at its most prominent part of its outward convexity.

4 PRONATOR TERES NERVE SUPPLY: Muscular branches of median nerve. Anterior view of the left elbow showing the median nerve going under the superficial head of pronator teres. PRONATOR TERES ACTION: Pronates the forearm. Weak flexor of elbow

5 FLEXOR CARPI RADIALIS Common origin. Fleshy turn in to long tendon. Grooves trapezium. INSERTION : On the bases of 2 nd and 3 rd metacarpals. NERVE SUPPLY: median nerve. FLEXOR CARPI RADIALIS Actions: Flexor and radial abductor of the wrist. It is stabilizer of the wrist

6 FLEXOR DIGITORIUM SUPERFICIALIS Common origin Medial ligament of the elbow. Tubercle of the coronoid process of ulna (sublime tubercle). Fibrous arch continues the origin across the radius from whole length of anterior oblique line. Insertion: Enters the fibrous flexor sheath. divides in two halves attached to the margins of the front of the middle phalanges. FLEXOR DIGITORIUM SUPERFICIALIS Nerve supply: Median nerve(7,8). Action: flexor of proximal interphalangeal joints, metacarpophalangeal joints, wrist joint and assists in flexion of elbow.

7 PALMARIS LONGUS Common origin. Broadens as it passes flexor retinaculum to which it is partially adherent. It slits to form longitudinally directed fibers. Action: weak flexor of wrist. Anchors the skin and fascia of hand. FLEXOR CARPI RADIALIS common origin. Wide apponeurosis from the medial border of olecronon process and subcutaneous border of ulna. Ulnar nerve lies between humeral and ulnar head. INSERTION: on the pisiform and end by the pisohamate and pisometacarpal ligament into the hamate and 5 th metacarpal.

8 FLEXOR CARPI RADIALIS NERVE SUPPLY: Ulnar nerve (C7,8). ACTION: It is flexor and ulnar adductor of wrist.

9 Deep muscles FLEXOR DIGITORIUM PROFUNDUS Medial surface of the olecronon. Upper three quarters of anterior and medial surface of ulna (including its subcutaneous border and interosseus membrane). Tendon of the index finger separates in the forearm. INSERTION: At the base of terminal phalanges of fingers. NERVE SUPPLY: Anterior interosseus branch of median nerve and ulnar nerve (C 8,T1 little finger side). ACTION:

10 Flexes terminal interphalangeal joint. Great gripping muscle. FLEXOR POLICIS LONGUS Anterior surface of the of the radius below the oblique line and above the insertion of Pronator quaradatus and from interosseus membrane. Tendon forms on ulnar side. Passes underneath the flexor retinaculum. INSERTION: at the base of first distal phalanx. NERVE SUPPLY: Anterior interosseus branch of median nerve (C6,7). ACTION: Flexor of interphalangeal joint of thumb. Also flexes metacarpophalangeal joint and carpometacarpophalangeal joints of thumb and wrist joint. FLEXION OF THE METACARPOPHALANGE AL JOINT

11 PRONATOR QUARADATUS From a ridge on anterioromedial aspect of ulna. INSERTION: Anterior surface of lower fourth of radius and triangular area above ulnar notch. PRONATOR QUARADATUS NERVE SUPPLY: Anterior interosseus branch of median nerve. ACTION: Pronates the forearm and help to hold lower end of radius and ulna together.

12 FLEXOR RETINACULUM Strong fibrous band. Lies across the carpus bones at proximal part of hand. ATTACHED TO THE, Hook of hamate and pisiform medially. Tubercle of the scaphoid and ridge of trapezium laterally. As carpal bones are concave so flexor retinaculum forms carpal tunnel. Median nerve and long flexor tendons pass through the capal tunnel. Superficialis tendon pass through in two separate rows, middle and ring fingers in frontof the index and Little fingers tendons.

13 CARPAL TUNNEL SYNDROME. Median nerve pass deep between flexor digitorium superficialis flexor carpi radialis when it is liable to compression causing carpal tunnel syndrome xxxxxxxxxxxxxxxx