Forearm & Hand Anatomy - Part 2 & Axilla & Arm Part 1 PDF

Forearm & Hand – Part 2 Axilla & Arm – Part 1 BiBi N. Singh, DPM September 20, 2024 Objectives Describe the bones of the forearm and hand. Describe the muscles of the forearm and hand. Identify the joints and ligaments associated with the forearm. Describe the Anatomical s...

Forearm & Hand – Part 2 Axilla & Arm – Part 1 BiBi N. Singh, DPM September 20, 2024 Objectives Describe the bones of the forearm and hand. Describe the muscles of the forearm and hand. Identify the joints and ligaments associated with the forearm. Describe the Anatomical snuff box. Describe Carpal Tunnel Syndrome. Muscles of the Forearm - Posterior These muscles are the Extensors of the wrist and digits Superficial Group 7 muscles Deep Group has 5 muscles Superficial Group – 7 Muscles Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Anconeus  Superficial Group Muscle Origin Insertion Innervation Blood Supply Action Brachioradialis Proximal 2/3 of the lateral supracondylar ridge Lateral surface of the radius Radial nerve Radial recurrent artery Flexes the forearm of the humerus and the lateral intermuscular above the styloid process septum Extensor carpi Lower 1/3 of the lateral supracondylar ridge Posterior base of 2nd metacarpal Radial nerve Muscular branches of Extends an ABducts the hand radialis longus the Radial artery Extensor carpi Lateral epicondyle by the common extensor Posterior aspect of the 2nd & 3rd Posterior interosseous nerve Muscular branches of Extends an ABducts the hand radialis brevis tendon. Radial collateral ligament of the elbow metacarpal (branch of the radial nerve) the Radial artery joint Extensor Lateral epicondyle by the common extensor In the lateral and dorsal surface Posterior interosseous nerve Posterior interosseous Extends the proximal phalanges on digitorum tendon. of the phalanges of the 4 medial (branch of the radial nerve) artery the metacarpals digits Extensor digiti Lateral epicondyle by the common extensor Proximal phalanx of the 5th digit Posterior interosseous nerve Posterior interosseous Extends the 5th digit minimi tendon. (branch of the radial nerve) artery Extensor carpi Lateral epicondyle by the common extensor Medial side of the 5th metacarpal Posterior interosseous nerve Posterior interosseous Extends hand ulnaris tendon. (branch of the radial nerve) artery Adducts with the Flexor carpi ulnaris Anconeus Posterior aspect of the Lateral epicondyle Lateral surface of the olecranon Radial nerve Profunda brachii Joint stabilizer and assists triceps in Posterior surface of the ulna extending the forearm Deep Group – 5 Muscles Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis  Deep Group – 5 Muscles Muscle Origin Insertion Innervation Blood Supply Action Supinator Lateral epicondyle of the humerus Lateral and anterior surface Deep branch of the Radial recurrent Supinator of the forearm Annular ligament of the radius of the upper 1/3 of the radial nerve (Passes artery Supinator crest Radial shaft. through the muscle) Fossa of ulna Abductor pollicis Posterior surface of the ulna Base of the 1st metacarpal Posterior Posterior Abducts the thumb and longus Interosseous membrane interosseous nerve interosseous artery wrist Middle 1/3 of the posterior surface of ulna (Radial nerve) Extensor pollicis Posterior surface of the radius Proximal phalanx of the Posterior Posterior Extends the thumb brevis thumb interosseous nerve interosseous artery Extensor pollicis Middle of the posterior surface of the ulna Base of the distal phalanx of Posterior Posterior Extends distal phalanx of longus the thumb interosseous nerve interosseous artery the thumb Abducts the thumb Extensor indicis Posterior surface of the ulna Dorsum of the proximal Posterior Posterior Extends the proximal Interosseous membrane phalanx of the index finger interosseous nerve interosseous artery phalanx of the index finger Clinical Pearls Tennis elbow Pain and tenderness at the origin of the common tendon Lateral epicondylitis Clinical Pearls De Quervain’s tenosynovitis Pain and tenderness when the fibrous sheath of the Abductor pollicis longus and Extensor pollicis brevis become thickened Anatomical Snuff Box When the thumb is extended, a hollow is seen between the extensor pollicis longus (medially), the tendon of the Abductor pollicis longus and extensor pollicis brevis (laterally). Contents Radial Artery Superficial branch of the Radial Nerve Radial Nerve Superficial branch is cutaneous and ends in the dorsum of the hand Deep branch ends in the dorsum of the hand No muscle supply in the hand Ulnar Nerve No branches in the arm Accompanied by Ulnar Collateral Artery in the Arm Major supply is in the hand Branches in the forearm Flexor carpi ulnaris Flexor digitorum profundus 4 & 5 Median Nerve No branches in the arm 7 branches in the forearm 5 branches in the hand Passes through the Carpal tunnel Numbering of Digits Digit Name 1st (Thenar) Pollex 2nd Index 3rd Middle 4th Ring 5th Little (Hypothenar) Flexor retinaculum Strong fibrous band that binds the flexor tendons with synovial sheaths and Median nerve in the arch of the carpus Palmar aponeurosis Strong triangular membrane overlying the tendons of the palm Anchors to the flexor retinaculum and tendon of the palmaris longus, if present Intrinsic Muscles of the Hand Thenar Muscles (Thumb) Hypothenar (5th Digit) Palmar and Dorsal Interossei Lumbricals Nerve supply Motor T1 via median and ulnar nerves Muscles of the Thumb Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis Adductor pollicis 1st Palmar & 1st Dorsal interossei  Thenar Eminence - Muscles Muscle Origin Insertion Innervation Blood Supply Action Abductor pollicis brevis Scaphoid Lateral sesamoid bone Recurrent branch of Superficial branch Abducts the thumb Forms lateral border of Trapezium Base of the proximal the Median nerve from the Radial thenar eminence Flexor retinaculum phalanx of the thumb artery Flexor pollicis brevis Trapezium Lateral sesamoid bone Recurrent branch of Superficial branch Flexes the proximal phalanx of the Forms medial border of Flexor retinaculum of the proximal phalanx the Median nerve from the Radial thumb thenar eminence of the thumb Deep branch of the artery Assists in medial rotation of the Ulnar nerve metacarpal bone Opponens pollicis Trapezium Lateral border and front Recurrent branch of Superficial branch Draws the 1st metacarpal forward Covered by the Flexor retinaculum shaft of 1st metacarpal the Median nerve from the Radial & medially ABductor pollicis brevis artery Opposes thumb to each of the other digits Adductor pollicis Oblique head – trapezium,trapezoid, capitate, Medial sesamoid bone Deep branch of the Adducts the thumb base of 2nd and 3rd metacarpal bones Proximal phalanx of the Ulnar nerve Opposes the thumb Transvers head-anterior surface of 3rd thumb metacarpal bone Muscles of the 5th Digit Abductor digiti minimi Opponens digiti minimi Flexor digiti minimi brevis Interossei Lumbricals  Muscles of the Hypothenar Eminence Muscle Origin Insertion Innervation Blood Action Supply Abductor digiti Pisiform Medial side of the posterior Deep branch Deep branch ABducts the 5th digit from the 4th minimi Tendon of aspect of the proximal of ulnar of ulnar Flexor carpi phalanx of the 5th digit nerve artery ulnaris Flexor digiti Hook of the Proximal phalanx of the 5th Deep branch Deep branch Flexes the proximal phalanx of the minimi brevis Hamate of ulnar of ulnar 5th Flexor nerve artery retinaculum Opponens Hook of the 5th metacarpal bone Deep branch Deep branch Draws the 5th metacarpal bone digit minimi Hamate of ulnar of ulnar forward to face the thumb Flexor nerve artery Deepens the hollow of the hand retinaculum Lumbricals Digit Lumbrical Innervation 1st N/A N/A 2nd Lumbrical 1 Digital branch of Median nerve 3rd Lumbrical 2 Digital Branch of Median nerve 4th Lumbrical 3 Deep branch of the Ulnar nerve 5th Lumbrical 4 Deep branch of the Ulnar nerve Lumbricals Originate: from the Flexor digitorum profundus Insert: with the tendons of the extensor digitroum and interossei into the base of the terminal phalanges of the medial 4 digits Action: Flex the at the metacarpophalangeal joints, extend at the interphalangeal joints Interossei Palmar Group 4 ADductors Dorsal Group 4 ABductors Interrosei Muscle Origin Insertion Innervation Action Palmar Each arises by Proximal Deep branch of ADduct the a single head phalanx of each Ulnar nerve digit from the digit metacarpal shaft of the digit Dorsal Each arises by Each side of the Deep branch of ABduct the digit 2 heads from proximal Ulnar nerve adjacent sides phalanx of metacarpal bones Carpal Tunnel Syndrome Increased pressure in the Flexor retinaculum causes pressure on the carpal tunnel Structures passing through Median Nerve Flexor digitorum superficialis Flexor digitorum profundus Flexor pollicis longus Carpal Tunnel – Clinical Signs & Symptoms Paresthesia to 3 ½ digits Impaired Abduction of thumb Impaired Flexion of thumb, Index finger and middle finger Impaired opposition Impairment of lumbricals 1 & 2 and Abductor pollicis Dupuytren’s Contracture