Lecture 8: Posterior Forearm muscles & Muscles of the hand Flashcards
What are the posterior forearm compartment (extensor-supinator) muscles?
Superficial layer:
-Brachioradialis
-Extensor carpi radialis longus & brevis
-Extensor digitorum
-Extensor digit minimi
-Extensor carpi ulnaris
-Anconeus
Deep layer:
-Supinator
-Abductor pollicis longus
-Extensor pollicis longus & brevis
-Extensor indicis
What are the primary actions of the Posterior (extensor-supinator) compartment of the forearm?
-Supination of the forearm
-If muscles cross the wrist=Extension of wrist
-If the muscles cross the digits= Extension of digits
Origin & Insertion of Brachioradialis (BR):
O: Proximal 2/3 of lateral supracondylar ridge of humerus
I: Lateral surface of distal end of radius proximal to styloid process
Innervation: Radial nerve
Origin & Insertion of Extensor Carpi Radialis Longus (ECRL):
O: Distal 1/3 of lateral supracondylar ridge of humerus
I: Base of 2nd metacarpal bone (index finger)
Innervation: Radial nerve
Origin & Insertion of Extensor Carpi Radialis Brevis (ECRB):
O: Lateral epicondyle of humerus (via common extensor tendon)
I: Base of 3rd metacarpal bone (middle finger)
Innervation: Radial Nerve
What three muscles make up the mobile wad of 3?
BR
ECRL
ECRB
Origin & Insertion of Extensor Digitorum (ED):
O: Lateral epicondyle of humerus (via common extensor tendon)
I: Distal & middle phalanges of fingers #2-5 (via its digital expansion)
Innervation: Radial Nerve
Origin & Insertion of Extensor digiti minimi (Edm):
O: Lateral epicondyle of humerus (via common extensor tendon)
I: Middle & distal phalanges of little finger (via its dorsal digital expansion)
Innervation: Radial Nerve
The extensor tendons flatten to form ________________ on the dorsal aspect of the digits.
dorsal digital expansions (extensor hoods)
Triangular tendinous aponeurosis that wrap around the metacarpophalangeal joints & extend along the proximal & middle phalanges across two interphalangeal joints to attach to distal phalanx.
Interossei & lumbrical muscles attach to their sides.
During flexion of the metacarpophalangeal joints by the lumbrical & interossei muscles, the proximal & distal interphalangeal joints are pulled by ______________into nearly complete __________.
-Extensor expansions
-Extension
Origin & Insertion of Extensor Carpi Ulnaris (ECU):
O: Lateral epicondyle of humerus (via common extensor tendon), Posterior border of ulna
I: Base of 5th metacarpal bone
Innervation: Radial Nerve
Origin & Insertion of Anconeus:
O: Lateral epicondyle of humerus
I: Olecranon process of ulna, Proximal of posterior surface of ulna
Innervation: Radial Nerve
Origin & Insertion of Supinator:
O:
1) supinator crest of ulna
2) Lateral epicondyle of humerus
I: Proximal 1/3 of lateral surface of radius
Innervation: Radial nerve
Which forearm muscle does the deep branch of the radial nerve pass through?
Between the two heads of the supinator
Origin & Insertion of Abductor Pollicis Longus (APL):
O: The middle of the radius, ulna, & interosseous membrane
I: Base of the 1st metacarpal
Innervation: Radial Nerve
Origin & Insertion of Extensor Pollicis Brevis (EPB):
O: Distal 1/3 of posterior surface of radius & interosseous membrane
I: Base of proximal phalanx of thumb
Innervation: Radial nerve
Origin & Insertion of Extensor Pollicis Longus (EPL):
O: Middle 1/3 of ulna & interosseous membrane
I: Base of distal phalanx of thumb
Innervation: Radial Nerve
Origin & Insertion of Extensor Indicis (EI):
O: Distal 1/3 of posterior surface of ulna & interosseous membrane
I: Dorsal digital expansion of the 2nd finger
Innervation: Radial Nerve
What tendons make up the anatomical snuff box?
Abductor pollicis longus (APL)
Extensor pollicis brevis (EPB)
Extensor pollicis Longus (gets drawn up with the other two)