Lecture 18 - Muscles Of The Forearm Flashcards
What is the anterior compartment of the Forearm?
- made up of 4 layers; 8 muscles total
- First (superficial) layer
- Second layer
- third layer
- fourth layer (very deep)
How many muscles are in the first (superficial) layer? What are they?
- made up of 4 muscles
- Pronator teres, flexor carpi Radialis, Palmaris longus, flexor carpi Ulnaris
What is the origin/insertion/innervation/main action of the Pronator teres?
- O: Medial epicondyle of the humerus, Adjacent supracondylar ridge
- I: Mid-shaft of lateral radius
- Inn: Median Nerve
- MA: Radioulnar (forearm) pronation
What is the origin/insertion/innervation/main action of the flexor carpi Radialis?
- O: Medial epicondyle of humerus
- I: Base of metacarpals 2 & 3
- Inn: Median Nerve
- MA: Wrist flexion & abduction
What is the origin/insertion/innervation/main action of the Palmaris Longus?
- O: Medial epicondyle of humerus
- I: Palmar aponeurosis of hand
- Inn: Median nerve
- MA: Wrist flexion (tenses palmar aponeurosis (connects the skin to the underlying structures of the hand)
What is the origin/insertion/innervation/main action of the flexor carpi Ulnaris?
- O: Medial epicondyle of humerus
- I: Base of 5th metacarpal via pisiform
- Inn: Ulnar nerve
- MA Wrist flexion & adduction
How many muscles are in the second layer? What are they?
- 1
- flexor Digitorum superficialis; closer to the surface, or Profundus
What is the origin/insertion/innervation/main action of the flexor Digitorum superficialis?
- O: In an oblique line from medial epicondyle of the humerus to the mid-shaft of the radius, As it approaches the wrist, it splits into 4 tendons
- I: Palmar surfaces of middle phalanx on digits 2-5
- Inn: Median Nerve
- MA: Flexion at proximal interphalangeal & metacarpophalangeal joints
How many muscles are in the third layer of the anterior compartment? What are they?
- 2
- flexor Digitorum Profundus & flexor pollicis longus
What is the origin/insertion/innervation/main action of the flexor Digitorum Profundus?
- O: Anterior ulna & medial half of interosseous membrane
- I: Bases of the distal phalanges
- Inn: Lateral half Median nerve, medial half Ulnar nerve
- MA: Flexion of distal & proximal interphalangeal joints & metacarpophalangeal joints
What is the origin/insertion/innervation/main action of the flexor pollicis longus?
- O: Anterior radius & lateral half of the interosseous membrane
- I: Palmar surface of distal phalanx of the thumb
- Inn: Median nerve
- MA: Thumb flexion (at the interphalangeal joint as well as the metacarpalphalangeal joint)
How many muscles are in the fourth (very deep) layer? What are they?
- 1
- Pronator quadratus
What is the origin/insertion/innervation/main action of the Pronator quadratus?
- O: Lower/Distal 1/4 anterior ulna
- I: Lower/Distal 1⁄4 anterior radius
- Inn: Median nerve
- MA: Radio-ulnar (forearm) pronation
What is the posterior compartment of the forearm?
- made up of 2 layers; 11 muscles total, with one on its own & not part of the layers
- superficial layer
- deep layer
What is the muscle on its own and not part of the layers?
- Brachioradialis
What is the origin/insertion/innervation/main action of the Brachioradialis ?
- O: Lateral supracondylar ridge of the humerus
- I: Styloid process of the radius
- Inn: Radial nerve
- MA: Elbow flexion in semi-pronation
How many muscles are in the superficial layer of the posterior compartment? What are they?
- 5 total
- extensor carpi Radialis longus/brevis
- extensor Digitorum
- extensor Digiti Minimi
- extensor carpi Ulnaris
What is the origin/insertion/innervation/main action of the extensor carpi Radialis longus?
- O: Lateral epicondyle & lateral supracondylar ridge of the humerus
- I: Dorsal surface of base of metacarpal 2
- Inn: Radial nerve
- MA: Wrist extension & abduction
What is the origin/insertion/innervation/main action of the extensor carpi Radialis Brevis?
- O: Lateral epicondyle of humerus
- I: Dorsal surface of base of Metacarpal 2 & 3
- Inn: Radial nerve
- MA: Wrist extension & abduction
What is the origin/insertion/innervation/main action of the extensor Digitorum?
- O: Lateral epicondyle of humerus
- I: Dorsal aspect of base of distal phalanges of digits 2-5 – Via the extensor hoods
- Inn: Radial nerve
- MA: Extension of the distal & proximal IP joints & the MCP joints, Wrist extension
What is the origin/insertion/innervation/main action of the extensor Digiti Minimi?
- O: Lateral epicondyle of humerus
- I: Extensor hood of digit 5
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Extension of digit 5
What is the origin/insertion/innervation/main action of the extensor carpi Ulnaris?
- O: Lateral epicondyle of humerus & posterior border of ulna
- I: Medial side of base of 5th Metacarpal
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Wrist extension & adduction
How many muscles are in the deep layer of the posterior compartment? What are they?
- 5 muscles
- supinator
- extensor indices
- abductor pollicis longus
- Extensor Pollics longus/brevis
What is the origin/insertion/innervation/main action of the supinator?
- O: Lateral epicondyle of the humerus & the proximal end of the ulna
- I: Posterior proximal radius
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Radio-ulnar (forearm) supination
What is the origin/insertion/innervation/main action of the extensor indices?
- O: Posterior surface of distal ulna (distal to extensor pollicis longus) & adjacent interosseous membrane
- I: Extensor hood of digit 2
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Extension of digit 2
What is the origin/insertion/innervation/main action of the abductor pollicis longus?
- O: Posterior surfaces of proximal half ulna & middle third of radius (distal to attachments of supinator & anconeus) & intervening interosseous membrane
- I: Lateral side of base of first metacarpal
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Thumb abduction at CMC joint
What is the origin/insertion/innervation/main action of the extensor Pollicis longus?
- O: Posterior surface of middle third ulna (distal to abductor pollicis brevis) & adjacent interosseous membrane
- I: Dorsal surface of base of the distal phalanx of the thumb
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Thumb extension at CMC, MCP and IP joints
What is the origin/insertion/innervation/main action of the extensor Pollicis brevis?
- O: Posterior surface of radius (distal to abductor pollicis longus) & adjacent interosseous membrane
- I: Dorsal surface of base of the proximal phalanx of the thumb
- Inn: Posterior interosseous nerve (continuation of deep branch of Radial nerve)
- MA: Thumb extension at CMC & MCP joints
