Muscles of the Forearm & Hand Flashcards
What are the compartments of the forearm, their parts, and the number of muscles in each?
Anterior compartment (Flexors) - 8
- Superficial (4)
- Intermediate (1)
- Deep (3)
Posterior compartment (Extensors) - 11
- Superficial (6)
- Deep (5)
Muscles of the anterior compartment of the forearm
Superficial:
1. Pronator Teres
2. Flexor carpi radialis
3. Palmaris
4. Flexor carpi ulnaris
Intermediate:
1. Flexor digitorum superficialis
Deep:
1. Flexor digitorum profundus
2. Pronator quadratus
3. Flexor pollicis longus
Muscles of the posterior compartment of the forearm
Superficial:
1. Brachioradialis
2. Extensor carpi radialis longus
3. Extensor carpi radialis brevis
4. Extensor digitorum
5. Extensor digiti minimi
6. Extensor carpi ulnaris
Deep:
1. Supinator
2. Abductor pollicis longus
3. Extensor pollicis brevis
4. Extensor pollicis longus
5. Extensor indicis
What is the CFO (common flexor origin)
-The medial epicondyle of the humerus
-This is the origin or the superficial muscles of the anterior compartment:
* Pronator teres
*Flexor carpi radialis
* Palmaris longus
* Flexor carpi ulnaris
Pronator teres: Compartment and OIAI
Compartment: Anterior compartment, superficial
Origin: Medial epicondyle of the humerus (CFO)
Insertion: Lateral Radius
Action: Pronation
Innervation: Median nerve
Flexor carpi radialis: Compartment and OIAI
Compartment: Anterior compartment, superficial
Origin: Medial epicondyle of the humerus (CFO)
Insertion: 2nd & 3rd metacarpals
Action: Wrist flection and wrist abduction
Innervation: Median nerve
Palmaris longus: Compartment & OIAI
Compartment: Anterior compartment, superficial
Origin: Medial epicondyle of the humerus (CFO)
Insertion: Palmar aponeurosis (fan)
Action: Wrist flexion
Innervation: Median nerve
What is the palmar aponeurosis
- A thickening of palmar fascia
- continuous withe the palmaris longus tendon
Flexor carpi ulnaris: Compartment & OIAI
Compartment: Anterior compartment. superficial
Origin: Medial epicondyle of the humerus (CFO) & the olecranon of the ulna
Insertion:
- Pisiform
- Hook of hamate
- 5th metacarpal
Action:
- Wrist flection and wrist adduction
Innervation: Ulnar nerve
The trick for the superficial anterior compartment
- CFO:
- They all have the same origin!
- PASS/FAIL/PASS/FAIL
- Thumb on CFO
Index - P: Pronator Teres
Middle - F: Flexor carpi radialis
Ring - P: Palmaris longus
Pinky - Flexor carpi ulnaris
Flexor digitorum superficialis: Compartment & OIAI
Compartment: Anterior compartment, intermediate
Origin:
- Medial epicondyle of the humerus (CFO)
- Anterior surface of the radius and ulna
Insertion:
- 4 Tendons split and insert on middle phalanges 2-5
Action:
- Flexion of the wrist
- Flexion of the metacarpophalangeal joints 2-5
- Flexion of the proximal interphalangeal joints 2-5
Innervation: Median nerve
Flexor digitorum profundus: Compartment & OIAI
Compartment: Anterior compartment, Deep
Origin:
- Ulna
- Interosseus membrane
Insertion: Distal phalanges 2-5
Action:
Same as FDS
- Flexion of the wrist
- Flexion of the metacarpophalangeal joints 2-5
- Flexion of the proximal interphalangeal joints 2-5
AND
- Flexion of DIP 2-5
Innervation:
- Medial half: Median nerve
- Lateral half: Ulnar nerve
Flexor digitorum memory trick
Flexor digitorum Superficialis - Splits in two to allow, Flexor digitorum Profundus to Pass through
Flexor pollicis longus: Compartment & OIAI
Compartment: Anterior compartment, Deep
Origin:
- Anterior radius
- interosseus membrane
Insertion: Distal phalanx of the thumb
Actions: Flexion of the thumb
Innervation: Median nerve
Pronator quadratus: Compartment & OIAI
Compartment: Anterior compartment, Deep
Origin: Distal anterior surface of the ulna
Insertion: Distal anterior surface of the radius
Action: Pronation
Innervation: Median nerve
What is the Flexor Retinaculum?
- Fibrous connective tissue band
- Located on the palmar surface of the hand (near wrist)
- Forms the roof of the carpal tunnel
- Holds the tendons of the flexor muscles in place
- Allows median nerve to pass into the hand
Brachioradialis: Compartment & OIAI
Compartment: Posterior compartment, superficial
Origin: Lateral supracondylar ridge of the humerus
Insertion: Styloid process of radius
Actions: Flexes forearm at the elbow
Innervation: Radial nerve
Extensor carpi radialis longus & brevis: Compartment & OIAI
Compartment: Posterior compartment, Superficial
Origin: Lateral epicondyle of the humerus (CEO)
Insertion: 2nd & 3rd metacarpals
Actions: Extension of the wrist and Abduction of the wrist
Innervation: Radial nerve
Extensor carpi ulnaris: Compartment & OIAI
Compartment: Posterior compartment, superficial
Origin: Lateral epicondyle of humerus (CEO)
Insertion: 5th metacarpal
Actions:
- Extension of wrist
- Adduction of wrist
Innervation: Radial nerve
Extensor digitorum: Compartment & OIAI
Compartment: Posterior compartment, superficial
Origin: Lateral epicondyle of the humerus (CEO)
Insertion: Phalanges 2-5, posterior surface
Actions:
- Extension of wrist
- Extension of fingers (MCPs, PIPs, DIPs)
Innervation: Radial nerve
Extensor digiti minimi: Compartment & OIAI
Compartment: Posterior Compartment, superficial
Origin: Lateral epicondyle of humerus (CEO)
Insertion: posterior surface of the 5th digit
Actions:
- Extension of wrist
- Extension of pinky finger
Innervation: Radial nerve
Supinator: Compartment & OIAI
Compartment: Posterior compartment, Deep
Origin:
- Lateral epicondyle of humerus (CEO)
- Proximal ulna
Insertion: Lateral proximal radius
Actions: Supination
Innervation: Radial nerve
Abductor pollicis longus: Compartment & OIAI
Compartment: Posterior compartment, Deep
Origin: Proximal ulna & posterior surface of radius
Insertion: 1st metacarpal
Actions: Abduction of thumb & wrist
Innervation: Radial nerve
Extensor pollicis longus: Compartment & OIAI
Compartment: Posterior compartment, deep
Origin:
- Posterior ulna
- Interosseus membrane
Insertion:
- Distal phalanx of thumb
Actions:
- Extension of thumb
Innervation: Radial nerve
Extensor indicis: Compartment OIAI
Compartment: Posterior compartment, deep
Origin:
- Posterior distal ulna
- interosseus membrane
Insertion: index finger (2nd distal phalanx)
Actions:
- Extension of index finger
- Extension of wrist
Innervation: Radial nerve
What is the anatomical snuffbox
A triangular depression on the dorsal aspect of the hand
Lateral border:
- Abductor pollicis longus tendon
- Extensor pollicis brevis tendon
Medial border:
- Extensor pollicis longus tendon
What nerve innervates all the posterior forearm muscles
Radial nerve
What nerve innervates most anterior forearm muscles
Median nerve
What muscles of the anterior forearm are not innervated by the median nerve and what are they innervated by?
Flexor carpi ulnaris and the medial half of flexor digitorum profundus
What is the extensor retinaculum?
Fibrous connective tissure band on the dorsal surface of the hand, near the wrist
It holds the tendons of the extensor muscles in place
About the extrinsic muscles of the hand
- They originate in the forearm and inset on the hand
- These control crude movements
About the intrinsic muscles of the hand
- They originate and insert within the hand
- These control fine movements
The intrinsic muscles of the hand
Hypothenar muscles: Pinky side
Thenar muscles: Thumb side
