Chapter Six - Muscles in the forearm moving the hand Flashcards
How many bones articulate the elbow joint? Which ones? What type of movements can the elbow do? Which muscles are involved?
Elbow joint: 3 bones articulating (humerus, radius and ulna).
Movements at the elbow joint proper:
- Flexion
- Extension
Muscles:
• Bicepsbrachii
- Brachialis
- Brachioradialis
• Tricepsbrachii
What are the three joints that we can find in the forearm (radioulnar joints)? What movements do they do?
Forearm joints (radioulnar joints):
- Proximal radioulnar joint
- Middle radioulnar joint
- Distal radioulnar joint
Note: Middle radioulnar joint, i.e., the interosseous membrane, is a syndesmosis. Proximal and distal joints are synovial.
Movements at radioulnar joints:
- Supination
- Pronation
What does the annular ligament of radius do?
Anular ligament of radius:
holds the head of radius against the radial notch of ulna, and allows radius to rotate during pronation and supination.
Name the carpal (wrist) bones and their positions (with a drawing).
Carpals:
Proximal row (4):
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
Distal row (4):
- Trapezium
- Trapezoid
- Capitate
- Hamate
* Wrist (or radiocarpal) joint: radius, scaphoid, lunate and triquetrum
Which bones compose the radiocarpal joint? What are the movements of the hand?
Wrist (radiocarpal) joint: radius and 3 carpal bones (scaphoid, lunate and triquetrum)
What are the muscle compartments in the forearm? What does each group do and what is their innervation?
Muscle compartments in the forearm
- Anterior compartment
- Posterior compartment
Anterior compartment muscles = flexors of the hand and digits.
All are innervated by the Median nerve, except 1.5 muscles innervated by Ulnar nerve.
Posterior compartment muscles = extensors of the hand and digits. All innervated by the Radial nerve.
Name the muscles in the four layers of the anterior (flexor) muscle compartment of the forearm. What do the muscles in the 1st and 4th layer do? The ones in the 2nd and 3rd?
Anterior (flexor) muscle compartment of the forearm
Layer 1: Pronator teres, Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris
Layer 2: Flexor digitorum superficialis
Layer 3: Flexor digitorum profundus, Flexor pollicis longus
Layer 4: Pronator quadratus
Muscles in the 1st and 4th layer move the hand and forearm; muscles in the 2nd and 3rd layer move the digits.
Give the origin, insertion, action and innervation of the palmaris longus.
Origin: Medial epicondyle of humerus *
Action: Flexes hand (wrist)
Insertion: Palmar aponeurosis
Nerve: Median nerve
Give the origin, insertion, action and innervation of the pronator teres.
Origin: Medial epicondyle of humerus
Action: Pronates and flexes forearm (and hand is pronated with it)
Insertion: lateral surface of the radius, mid-shaft
Nerve: Median nerve
Give the origin, insertion, action and innervation of the flexor carpi radialis.
Origin: Medial epicondyle of humerus
Action: Flexes and abducts hand (wrist)
Insertion: Anterior aspect of the bases of the second and third metacarpals
Nerve: Median nerve
Give the origin, insertion, action and innervation of the flexor carpi ulnaris.
Origin: Medial epicondyle of humerus and olecranon process of ulna
Action: Flexes and adducts hand (wrist)
Insertion: Pisiform bone and base of the 5th metacarpal bone
Nerve: Ulnar nerve !
Give the origin, insertion, action and innervation of the pronator quadratus.
Origin: Anterior surface of distal ulna
Action: Pronates forearm (and hand)
Insertion: Anterior surface of distal radius
Nerve: Median nerve
Name the muscles of the posterior (extensor) muscle compartment of the forearm.
Supinator, extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris
Movements of the wrist / hand are achieved by combined actions of what?
Movements of the wrist / hand are achieved by combined actions of the flexors and extensors on the carpus (wrist).
In the movements of the wrist/hand, which muscles are responsible for flexion? Extension? Radial deviation (= abduction)? Ulnar deviation (= adduction)?
Flexion: Flexor carpi radialis, Flexor carpi ulnaris, Palmaris longus
Extension: Extensor carpi radialis longus, Extensor carpi radialis brevis, Extensor carpi ulnaris
Radial deviation (= Abduction): flexor + extensors on radial side: 1. Flexor carpi radialis 2. Extensor carpi radialis (longus and brevis)
Ulnar deviation (= Adduction): flexor + extensor on ulnar side:
- Flexor carpi ulnaris
- Extensor carpi ulnaris
Circumduction requires all of the above muscles used in series.
Give the origin, insertion, action and innervation of the supinator.
Origin: Lateral epicondyle of humerus and proximal ulna
Action: Supinates forearm (and hand)
Insertion: Dorsal and lateral surfaces of upper third of radius
Nerve: Radial nerve
Give the origin, insertion, action and innervation of the extensor carpi radialis longus.
Origin: Lateral supracondylar ridge of humerus
Action: Extends and abducts hand (wrist)
Insertion: Posterior surface of the second metacarpal bone
Nerve: Radial nerve
Give the origin, insertion, action and innervation of the extensor carpi radialis brevis.
Origin: Lateral epicondyle of humerus
Action: Extends and abducts hand
Insertion: Posterior surface of the third metacarpal bone
Nerve: Radial nerve
Give the origin, insertion, action and innervation of the extensor carpi ulnaris.
Origin: Lateral epicondyle of humerus
Action: Extends and adducts hand
Insertion: Posterior surface of the 5th metacarpal
Nerve: Radial nerve
