Posterior aspect of the forearm Flashcards
What are the 2 muscles on the right side
Up: Extensor carpi radialis longus
Down: Extensor carpi radialis brevis
Brachioradialis muscle
What’s the origin of the Brachioradialis muscle?
Lateral supracondylar crest
What’s the insertion of Brachioradialis muscle?
Radial styloid
What’s the function of Brachioradialis muscle?
Elbow flexion
What nerve intervenes the Brachioradialis muscle?
Radial nerve
What’s the origin of the Extensor carpi radialis longus?
Lateral supracondylar crest
What’s the insertion of the Extensor carpi radialis longus?
2nd metacarpal
What’s the function of Extensor carpi radialis longus muscle?
Wrist extension
Lateral abduction / Radial deviation
What’s the origin of the Extensor carpi radialis brevis muscle?
Lateral epicondyle
What’s the insertion of the Extensor carpi radialis brevis muscle?
3rd metacarpal
What’s the nerve intervening in the Extensor carpi radialis brevis muscle?
Radial nerve
What’s the nerve intervening the Extensor carpi radialis longus muscle?
Radial nerve
What’s the function of the Extensor carpi radialis brevis muscle?
Wrist extension
Lateral abduction / Radial deviation
Small muscle on left
Anconeus
What’s the origin of the Anconeus?
Lateral epicondyle
What’s the insertion of the Anconeus?
Olecranon
What’s the function of the Anconeus?
Elbow extension
What’s the nerve intervening the Anconeus?
Radial nerve
What are the lateral portion muscles?
Anconeus, Extensor carpi radialis longus, Extensor cardi radialis brevis
What are the lateral portion muscles?
Anconeus, Extensor carpi radialis longus, Extensor cardi radialis brevis?
What are all the extensor muscles supplied by?
Radial nerve or one of its branches
What happens if there is an injury to the radial nerve at a high location?
Extensor carpi radialis longus, brevis and Anconeus will be affected
Under anconeus on left side
Extensor carpi ulnaris
What’s the origin of Extensor carpi ulnaris?
Lateral epicondyle
What’s the insertion of the Extensor carpi ulnaris?
5th metacarpal
What’s the function of the Extensor carpi ulnaris?
Wrist extension
Medial abduction / Ulnar deviation
What’s the nerve intervening the Extensor carpi ulnaris?
Posterior interosseous nerve
Under the extensor carpi ulnaris?
Extensor digitorum
Extensor digitorum
Extensor digiti minimi
What’s the origin of the Extensor digitorum?
Lateral epicondyle
What’s the insertion of the Extensor digitorum?
2-5 fingers
What’s the function of the Extensor digitorum?
Finger extension
Wrist extension
What’s the nerve intervening the Extensor digitorum?
Posterior interosseous nerve
What’s the origin of the Extensor digiti minimi?
Lateral epicondyle
What’s the insertion of the Extensor digiti minimi?
5th finger (little finger)
What’s the function of the Extensor digiti minimi?
Finger extension
Wrist extension
What’s the nerve intervening the Extensor digiti minimi?
Posterior interosseous nerve
Yellow label
Abductor policis longus
Purple label
Extensor policis brevis
Blue label
Extensor policis longus
What’s the insertion of the Abductor policis longus?
Lateral side of thumb
What’s the insertion of the Extensor policis brevis?
Proximal metacarpalphalangeal joint
What’s the insertion of the Extensor policis longus?
Base of distal phalanx, flexion of interphalangeal joint of thumb
What’s the nerve intervening the Abductor pollicis longus, Extensor polliciis brevis and Extensor pollicis longus?
Posterior interosseous nerve
Blue
Abductor pollicis longus
Green
Extensor pollicis brevis
Yellow
Extensor pollicis longus
Yellow
Extensor pollicis longus
Triangle
Anatomical snuffbox (sniffing place)(dimple between)
Scaphoid bone (under anatomical snuffbox)
Deep branch of radial nerve
What is the clinical importance of the scaphoid bone?
Most frequently fractured bone
What if the patient complains about wrist pain from falling on hand?
If you press on the anatomical snuffbox and pain increases this means the scaphoid bone is fractured.
Extensor indicis
What’s the function of the Extensor indicis?
Single extension to the index finger (same structure as extensor digiti minimi)
What’s the nerve intervening the Extensor indicis?
Posterior interosseous nerve
Green: Supinator (superficial layer)
Purple: Supinator (deep layer)
What’s the origin of the supinator?
Lateral epicondyle
What’s the insertion of the supinator?
Supinator crest
What other muscle is also a supinator?
Bicep brachii muscle
Where does the supinator begin?
Spirals around the radius pulls the radius and turns it outward creating supination
What is the nerve intervening the supinator?
Deep branch of radial nerve?
Where is the extensor retinaculum located?
Distal aspect of the ulna and radius, it is a fibrous structure attached to the ulna and radius at differentr regions
What does the extensor retinaculum do when it attaches to the radius and ulna?
Extensor compartments
What does the 1st compartment of the extensor retinaculum contain?
Extensor pollicius brevis and Abductor pollicis longus
What’s the clinical importance of 1st compartment of the extensor retinaculum?
Most frequently injured
How does the Radial nerve begin?
Radial nerve completely spirals around the humerus, starts from medial side turns posterior then lateral then passes anterior. The rotational movement is done beneath the lateral head of the tricep brachii muscle within the radial groove.
Radial nerve
Radial nerve (in radial groove)
What 2 branches does the radial nerve divide to?
Deep branch of radial nerve
Superficial branch of radial nerve
Red, green and purple
Red: radial nerve
Purple: Deep branch of radial nerve
Green: superficial branch of radial nerve
Where is the deep branch of radial nerve?
Passes between the head of supinator muscle (because it tries going to posterior aspect of forearm)
Where is the superior branch of radial nerve?
Courses the undersurface of the brachioradialis muscle, follows all the way down to the wrist, goes to subcutaneous tissue and branches to skin at dorsum of hand.
What type of branches are the lateral muscles and from where do they receive fibers?
Motor branches, Radial nerve
What type of branch does a nerve passing a joint give?
Sensory branch
What is the deepest branch of the radial nerve called?
Posterior interosseous nerve
What are the muscles in the superficial division of the Posterior interosseous nerve?
Superficial extensor muscles:
Extensor digitorum, Extensor digiti minimi, Extensor carpi ulnaris
What are the muscles in the deep division of the Posterior interosseous nerve?
Deep muscles:
Abductor pollicis longus, Extensor pollicis brevis, Extensor pollicis longus, Extensor indicis and Supinator
Where does the Posterior interosseous nerve end?
Dorsal aspect of the wrist joint and provides sensory innovation to joint
What are the lateral epicondyle group
Brachioradialis
Extensor carpi radialis Lg/Br
Supinator
What is the lateral epicondyle group?
Brachioradialis
Extensor carpi radialis Lg/Br
Supinator
What is the superficial Posterior interosseous nerve(PIN) group?
Extensor carpi ulnaris
Extensor digitorum
Extensor digiti minimi
What is the Deep PIN group?
Abductor pollicis Lg
Extensor pollicis Br / Lg
Extensor indicis
What nerve is the lateral epicondyle group intervened by?
Radial nerve
Checking brachioradialis by resisting the function
The more distal the muscle what happens to the muscle mass and what type of resistance should you apply?
Less muscle mass and less resistance appleid
What is fractured, what nerve is affected, syndrome and muscles that are affected and result?
Humeral fracture which means the damage of the radial nerve proximal to the elbow joint. Leads to drop hand syndrom where the carpels can’t be lifted indivisually. Only muscles that aren’t affected is the Tricep brachii muscle (recieves branches in Axilla).
Result: Disfunction of the entire muscle of upper extremity.
What is happening to PIN, what muscles are affected and the syndrome?
Constricted axon in the nerve. Nerve is made up of nerve fibers and axons(flows toward distal side and is constricted). Extensor carpi ulnaris is affected (small weakness). Extensor digitorum, Extensor digiti minimi and Extensor indicis are completely affected. Posterior Interosseous Nerve Syndrome
What happens to the tendon each time you supinate and syndrome?
Tendon will compress on PIN creating entrapment causing the Supinator syndrome
What happens to the tendon each time you supinate and syndrome?
Tendon will compress on PIN creating entrapment causing the Supinator syndrome
Red
Superior lateral cutaneous nerve of arm(from axillary nerve)- comes from posterior fasciculus
Purple
Posterior cutaneous nerve of arm (from radial nerve)- close to armpit
Yellow
Inferior lateral cutaneous nerve of arm (from radial nerve)- comes from posterior fasciculus
Green
Posterior cutaneous nerve of forearm(from radial nerve)
What does the posterior fasciculus give off and what is it responsible for?
It gives off the radial nerve (main branch) and is responsible for the entire inervation of the posterior shoulder, forearm, arm and dorsum of hand.
What does each spinal nerve have?
Representation in upper extremity
What is the spinal representation of the lateral arm?
C5
What is the spinal representation of the lateral aspect of the forearm and tip of the thumb?
C6
What is the spinal representation of the middle finger?
C7
What is the spinal representation of the little finger and anterior aspect of forearm?
T1
What is the spinal representation of the Medial aspect of the arm and armpit?
C2
What happens if you damage the radial nerve at the midshaft?
Entire posterior side of forearm and hand will be numb
Where does the radial nerve start in forearm?
Arrives at the anterior aspect of the elbow joint and goes to the deep branch.
Superficial branch of radial nerve
Where is the Superficial branch of radial nerve located?
Under brachioradialis–> provides branches to posterior aspect of the hand (dorsal aspect of thumb, index and middle finger, lateral portion of ring finger)–> Near wrist pierces to deep fascia (superficial)
