Muscles of the Posterior Compartment of the Arm Flashcards
Insertion of Brachioradialis
Lateral Surface of distal end of radius proximal to styloid process
Origin of Brachioradialis
Proximal 2/3 of the lateral supracondylar ridge of the humerus
Innervation of Brachioradialis
Radial Nerve (C5,C6,C7)
Action of Brachioradialis
Relatively Weak Flexion of the Elbow, maximal when the forearm is in midpronated position
Origin of Extensor Carpi Radialis Longus (ECRL)
Lateral Supra-Epicondylar Ridge of the humerus
Insertion of the Extensor Carpi Radialis Longus (ECRL)
Dorsal Aspect of Base of 2nd Metacarpal
Innervation of Extensor Carpi Radialis Longus (ECRL)
Radial Nerve (C6, C7)
Action of Extensor Carpi Radialis Longus (ECRL
Extend and ABduct wrist joint
Origin of Extensor Carpi Radialis Brevis (ECRB)
Lateral Epicondyle of the Humerus
Insertion of Extensor Carpi Radialis Brevis (ECRB)
Dorsal Aspect of Base of 3rd Metacarpal
Innervation of Extensor Carpi Radialis Brevis (ECRB)
Deep Branch of Radial Nerve (C7, C8)
Action of Extensor Carpi Radialis Brevis (ECRB)
Extend and ABduct the Wrist Joint; Extensor Carpi Radialis Brevis active during clenching of fist
Origin of Extensor Digitorum
Lateral Epicondyle of the Humerus
Insertion of Extensor Digitorum
Extensor Expansion of Medial Four Fingers
Innervation of Extensor Digitorum
Posterior Interosseous Nerve (C7,C8), Continuation of Deep Branch of Radial Nerve
Action of Extensor Digitorum
1) Extend Wrist Joint
2) Extend Medial Four Fingers primarily at metapophalangeal joints, secondarily at interphalangeal joints
Origin of Extensor Digiti Minimi
Lateral Epicondyle of Humerus
Insertion of Extensor Digiti Minimi
Extensor Expansion of 5th Finger
Innervation of Extensor Digiti Minimi
Posterior Interosseous Nerve (C7,C8) , continuous of deep branch of radial nerve
Action of Extensor Digiti Minimi
1) Extends wrist joint
2) Extends 5th finger primarily at the metacarpophalangeal joint, secondarily at the interphalangeal joint
Origin of Extensor Carpi Ulnaris (ECU)
1) Lateral Epicondyle of the Humerus
2) Posterior Border of Ulna via a shared aponeurosis
Insertion of Extensor Carpi Ulnaris
Dorsal Aspect of Base of 5th Metacarpal
Innervation of Extensor Carpi Ulnaris (ECU)
Posterior Interosseous Nerve (C7,C8), continuation of deep branch of radial nerve
Action of Extensor Carpi Ulnaris (ECU)
1) Extend and ADDuct the wrist joint
2) Extensor Carpi Ulnaris also active during fist clenching
Superficial Layer of Muscles of Posterior Compartment of Forearm
Brachioradialis Extensor Carpi Radialis Longus Extensor Carpi Raidalis Brevis Extensor Digitorum Extensor Digiti Minimi Extensor Carpi Ulnaris
Which Muscle is in the Deep Layer of the Posterior Compartment of the Forearm
Supinator
Origin of the Supinator
1) Lateral Epicondyle of the Humerus 2) Radial Collateral and Anular Ligament 3) Supinator Fossa 4) Crest of Ulna
Insertion of Supinator
Lateral, Posterior, and Anterior Proximal 1/3 of the Radius
Innervation of Supinator
Deep Branch of Radial Nerve (C7,C8)
Action of Supinator
1) Supinates the Forearm 2) Rotate the Radius to turn palm anteriorly or posteriorly (if Elbow is flexed)
Origin of Abductor Pollicis Longus
Posterior Surface of Proximal Halves of Ulna, Radius, and Interosseous Membrane
Insertion of the Abductor Pollicis Longus
Base of the 1st Metacarpal
Innervation of Abductor Pollicis Longus
Posterior Interosseus Nerve (C7, C8), Continuation of Deep Branch of Radial Nerve
Action of Abductor Pollicis Longus
1) Extends Wrist Joint 2) Abducts the thumb and extends it at carpometacarpal joint
What muscles make the “outcropping” of deep layer of posterior compartment of arm?
1) Abductor Pollicis Longus
2) Extensor Pollicis Longus
3) Extensor Pollicis Brevis
4) Extensor Indicis
Origin of the Extensor Pollicis Longus
Posterior Surface of Middle Third of Ulna and Interosseous Membrane
Insertion of the Extensor Pollicis Longus
Dorsal Aspect of the Base of the Distal Phalanx of the Thumb
Innervation of Extensor Pollicis Longus
Posterior Interosseous Nerve (C7,C8), Continuation of deep branch of radial nerve
Action of Extensor Pollicis Longus
1) Extend wrist joint
2) Extend the distal phalanx at the interphalangeal joint, extend metacarpophalangeal and carpometacarpal joints
Origin of Extensor Pollicis Brevis
Posterior Surface of Distal Third of Radius and Interosseous Membrae
Insertion of Extensor Pollicis Brevis
Dorsal Aspect of Base of Proximal Phalanx of Thumb
Innervation of Extensor Pollicis Brevis
Posterior Interosseous Nerve (C7,C8), Continuation of Deep Branch of Radial Nerve
Action of Extensor Pollicis Brevis
1) Extends Wrist Joint
2) Extends Proximal Phalanx at metacarpophalangeal joint; extends carpometacarpal joint
Origin of Extensor Indicis
Posterior Surface of Distal Third of Ulna and Interosseous Membrane
Insertion of Extensor Indicis
Extensor Expansion of 2nd Finger (Index Finger)
Innervation of Extensor Indicis
Posterior Interosseous Nerve (C7, C8), Continuation of Deep Branch of Radial Nerve
Action of Extensor Indicis
1) Extend wrist joint
2) Extend 2nd Finger (enabling its independent extension); helps extend hand at wrist