Anatomy of the forearm Musculoskeletal Block - Lecture 9 Objective: ✓ List the names of the Flexors and Extensor Group of Forearm (superficial & deep muscles). ✓ Identify the common flexor origin of flexor muscles and their innervation & movements. ✓ Identify supination & pronation and list the muscles produced these 2 movements. ✓ Describe the effect of injury of the muscle or its origin ✓ Identify the common extensor origin of extensor muscles and their innervation & movements. Color index: Important In male’s slides only In female’s slides only Extra information, explanation Editing file Contact us: [email protected] Forearm 1- The forearm extends from the elbow to wrist. 2- It posses two bones radius laterally and ulna medially. 3- The two bones are connected to each other by interosseous membrane. 4- This membrane allows movement of pronation and supination while the two bones are connected together. 5- also it gives origin to the deep muscles. Fascial compartment of the forearm 1- The forearm is enclosed in a sheath of deep fascia, which is attached to the posterior border of ulna (it encircle the forearm completely (Without touching the radius) and return again to the posterior border of the ulna) 2- This fascial sheath together with the interosseous membrane and fibrous intermuscular septa divides the forearm into (anterior and posterior) compartments each having its own muscles, nerves and blood supply. (The radius and ulna are connected by 3 structures: the interosseous membrane, superior radioulnar joint and inferior radioulnar joint). Anterior compartment - FLEXOR GROUP 1- 8 muscles.. 2- They act on the elbow and wrist joints and the fingers. 3- They form fleshy masses in the proximal part and become tendinous in the distal part of the forearm. 4- They are arranged in Three groups which are : Superficial - Intermediate - Deep Flexor group Superficial : 4 muscles. Intermediate : 1 muscle. Deep 3 muscles. - Pronator teres. - Flexor digitorum - Flexor digitorum - Flexor carpi radialis. superficialis. profundus. - Palmaris longus - Flexor pollicis - Flexor carpi ulnaris. longus. - Pronator quadratus. Superficial Flexors : 1-They arise - more or less - from the common flexor origin (front of medial epicondyle). 2-All are supplied by median nerve EXCEPT one, flexor carpi ulnaris (FCU) which is supplied by the ulnar nerve. 3-All cross the wrist joint EXCEPT one, pronator teres (PT). Superficial flexors 1) Pronator teres 2)Flexor carpi 3)Palmaris 4)Flexor carpi 5)Flexor digitorum muscle radialis longus ulnaris superficialis (May be (Intermediate absent) group) -Common flexor Origin Common flexor origin (front of medial epicondyle) origin. -Coronoid process more or less of ulna. -Anterior surface of radius. Insertion middle of Base of into the - Pisiform Base of middle lateral 2nd flexor -Hook of phalanges of surface of metacarpal retinaculum hamate medial 4 radius. bone. & palmar -5th fingers. (does not aponeurosis metacarpal cross wrist) . bone Nerve Ulnar nerve Median supply Median nerve nerve pronation & flexion & Flexes hand Flexion and Flexion of: the Action flexion of abduction (wrist) and adduction of middle and forearm of the tightens the proximal wrist palmar hand.(wrist) phalanges of (Elbow) aponeurosis medial 4 fingers + the hand. Picture Deep flexor group of forearm Deep flexors of Flexor Digitorum Flexor Pollicis Longus Pronator Quadratus forearm Profundus (above,front of radius) (above both ulna and (above,front of ulna) radius,front of lower Double supply 4th of ulna) origin lower part of anterior surface of ulna. front surface of ulna. above the radius. Front of the lower 4th of ulna. insertion distal bases of Base of One fourth of distal phalanges of distal phalanx of anterior medial 4 digits. thumb. surface of radius action -pronates the -Flexes distal flexes all joints of the forearm (prime phalanges of medial 4 thumb mover). digits. (interphalangeal, -helps to hold the 2 -flexes the hand metacarpophalangeal, bones together (wrist). carpometacarpal). (ulna and radius) nerve -Medial ½ : by ulnar anterior anterior supply-all by Nerve. interosseous nerve interosseous nerve anterior -Lateral ½ : by (branch of median N.) (branch of median N.) interosseous anterior interosseous nerve EXCEPT nerve medial half of (branch of median N.) flexor digitorum profundus. supination and pronation (position of forearm) It occurs in the superior (proximal) and inferior (distal) radioulnar joints (pivot uniaxial synovial joint) Muscles produce supination: Muscles produce pronation: midprone (midprone supine) position (initiates pronation and supination) -Pronator teres. -Biceps brachii (strong supinator). -Pronator quadratus. -Supinator. (Prime mover ) Brachioradialis. !"#$% in case of a fully extended arm the supinator muscle is the main muscle in supination, otherwise its the biceps. Posterior compartment of forearm posterior compartment of forearm (12 muscles- 3 groups) superficial lateral superficial group (5) deep group (5) group (2) -Supinator. -Brachioradialis. -Extensor carpi radialis brevis. - (3) to thumb: -Extensor carpi radialis longus. -Extensor digitorum. - Abductor pollicis longus. -Extensor digiti minimi. - Extensor pollicis brevis. -Extensor carpi ulnaris. - Extensor pollicis longus. -Anconeus. - (1) to index: - Extensor indicis. ● Common Extensor Origin is front of lateral epicondyle of the humerus. ● Except the superficial lateral group which originated from the lateral supracondylar ridge ● superficial extensors (7): muscle origin insertion action pictures lateral Brachioradialis Base of -Flexes superficial (BR) styloid forearm(elbow). group process of the -Rotates forearm to radius. midprone position Lateral supracondylar ridge of Extensor carpi humerus. Posterior -Extends and radialis longus surface of Abducts hand (ECRL) base of 2nd (radial rotation) at metacarpal wrist joint. bone. Dorsal surface superficialis Extensor carpi Base of 3rd group radialis brevis (middle finger) (ECRB) metacarpal bone. Extensor Extensor digitorum expansion of (ED) the medial 4 fingers. Common extensor origin (the front of Extensor digiti lateral Extensor minimi epicondyle). expansion of (EDM) the little from lateral to medial from lateral finger. Extensor carpi Base of the ulnaris 5th (ECU) metacarpal bone. Anconeus From the back of Superior (upper) (AN) lateral part of the epicondyle of the posterior humerus. (back) of ulna shaft (lateral side of the olecranon). ● All cross the wrist EXCEPT two, brachioradialis, anconeus. ● Nerve supply: All supplied by deep branch of radial nerve (posterior interosseous nerve), EXCEPT ABE are supplied by the radial nerve itself. - A-> anconeus. - B-> Brachioradialis. - E-> Extensor carpi radialis longus. Posterior compartment: Deep group: 5 muscles : (3 to the thumb+1 to index & suinator) 1- Abductor pollicis longus, (APL). 2- Extensor pollicis brevis, (EPB). 3- Extensor pollicis longus, (EPL). 4- Extensor indicis (EI). 5- Supinator. Female dr: just know their names ● All back muscles of forearm are supplied by: posterior interosseous nerve except, ABE by Radial nerve. Dorsal Extensor Expansion: It is formed on the dorsum of medial 4 fingers by the union of the long extensor tendons: Extensor digitorum, Extensor digiti 1 minimi, Extensor indicis with palmar & dorsal interossei & lumbricals muscles. *وﺣدة ﻣن اﻟـ extensors راح ﺗﺟﻲ و ﺗﺳوي اﻟـ long tendon (ﺣﺳب اﻹﺻﺑﻊ) All these tendons unite to form one tendon ﺑﻌدﯾن راح ﯾﻧﺿم ﻟﮭﺎ اﻟـ palmar & dorsal interossei و اﻟـ dorsal Extensor tendon) which divides into 3 2 lumbricals) muscles ھذوﻻ ﻛﻠﮭم راح ﯾﺳوون ﻟﻲ اﻟـ slips, a median one attached to middle dorsal extensor tendon phalanges and 2 lateral attached to the terminal phalanges. MCQs Q1:Which one of the following Q2:Which muscle is supplied by Q3:Which muscle is related to muscles contributes as powerful median nerve? common flexor origin? supinator of forearm in case of a fully flexed arm? A.Anconeus. A.Flexor digitorum profundus. B.Brachioradialis. B.Flexor pollicis longus. A. Palmaris longus. C.Extensor carpi radialis longus. C.Pronator quadratus. B. Pronator teres. D.Flexor digitorum superficialis. D.Pronator teres. C. Biceps brachii. D. Supinator. Q4:The Insertion of Brachioradialis? Q5:Ulna and radius are Q6:Which one is a flexor connected together by which of superficial muscle ? nd A.Posterior surface of base of 2 the following ? metacarpal bone A.pronator teres rd B.base of 3 metacarpal bone. A. interosseous membrane B.flexor digitorum superficialis C.Base of styloid process of radius th B. biceps brachii C.flexor digitorum D.Base of the 5 metacarpal bone. C. iliac crest D.pronator quadratus D. pronator teres Q7:which of the following Q8:flexor carpi ulnaris is Q9:All back muscles of forearm muscles might be absent in the supplied by which nerve ? are supplied by: posterior upper limb? interosseous nerve except? A.radial nerve A.pronator teres B.ulnar nerve A.EPB B.palmaris longus C.median nerve B.ABE C.flexor carpi ulnaris D.axillary nerve C.APL D.median nerve D.EPL Q10:The origin of Extensor Carpi Q11:which muscle is unrelated to Q12: the muscle that puts radialis longus? common extensor origin: forearm in midprone position: A.•Anterior surface of radius. A.anconeus. A.anconeus. B.Coronoid process of ulna. B.extensor digitorum. B.brachioradialis. C.Lateral supracondylar ridge of C.extensor carpi ulnaris. C.biceps brachii. humerus. D.extensor digiti minimi. D.pronator teres. D.A&B SAQs Q1:Name 5 extensor muscles from the deep group of the posterior compartment? Q2:write the origin of all superficial flexors ? Q3: List pronators. 2-pronator quadratus. 2-pronator Q3: 1-pronator teres. 1-pronator Q3: epicondyle) more or less or more epicondyle) Common flexor origin (front of medial medial of (front origin flexor Common Q2: 5- Supinator. 5- 4- Extensor indicis. Extensor 4- 3- Extensor pollicis longus. pollicis Extensor 3- 2- Extensor pollicis brevis.. pollicis Extensor 2- 1- Abductor pollicis longus. pollicis Abductor 1- Q1: This lecture is done by: Yasmine Alqarni Mohammed AL-Turki Sumo Abdulrahman Special thanks to Ghada Alothman Team leaders: Mayasem Alhazmi Fahad Alajmi SPECIAL THANKS TO THE AMAZING #MED438 ANATOMY TEAM.