Notes
Upper Extremity, Anterior
Sections
Origins & Insertions: Upper Extremity, Anterior
- We'll look at the right side.
Origin
- The bone that remains stable upon muscle contraction.
Insertion
- The bone moves upon muscle contraction.
In the limbs, the origin is usually proximal to the insertion.
- Review key skeletal components:
Scapula & Clavicle
Humerus
Radius & Ulna
Hand
Insertion sites of muscles that act on the scapula:
Trapezius inserts along the superior lateral third of the clavicle, acromion, and spine of the scapula (here we just see its clavicular and acromial insertions).
Deltoid arises along the lateral third of the clavicle, acromion, and spine of the scapula (here we just see its clavicular and acromial origins).
Serratus anterior inserts along the medial border of the scapula.
Pectoralis minor inserts on the coracoid process.
Scapular origins of muscles that act on the upper arm:
Subscapularis lies within the subscapular fossa on the anterior surface of the scapula.
Long head of biceps brachii arises from the supraglenoid tubercle.
Coracobrachialis and the short head of biceps brachii arise from the coracoid process.
Long head of triceps brachii arises from the infraglenoid tubercle and scapular neck.
Omohyoid arises from the superior border of the scapula (omo = shoulder; hyoid = bone in the neck).
Insertions of muscles that act on the upper arm.
Supraspinatus inserts on the greater tubercle of the humerus.
Subscapularis inserts on the lesser tubercle of the humerus.
Pectoralis major, latissimus dorsi, and teres major insert just below the tubercles. Latissimus dorsi lies in the bicipital groove, while the other two muscles insert on either side of it.
Deltoid inserts on the shaft of the humerus laterally at the deltoid tuberosity.
Coracobrachialis inserts medially on the proximal shaft.
Origins of muscles that act on the forearm:
Brachialis lies directly on the anterior shaft of the humerus.
Brachioradialis, extensor carpi radialis longus, and the common extensor tendon arise on the lateral side of the humerus.
The humeral head of pronator teres arises from the medial epicondyle of the humerus.
The common flexor tendon arises from the medial condyle.
Insertions of muscles that act on the forearm.
Brachialis inserts on the proximal ulna.
Biceps brachii inserts on the radial tuberosity.
Supinator inserts lateral to biceps brachii.
Pronator teres inserts distal to supinator.
Pronator quadratus inserts on the distal end of the radius.
Brachioradialis inserts on the styloid process of the radius.
Origins of muscles that act on the wrist and hand.
Flexor digitorum superficialis arises on the shaft of the radius.
Flexor pollicis longus arises along the medial aspect of the radius and on part of the interosseous membrane.
Flexor digitorum superficialis and pronator teres arises on the medial aspect of the proximal ulna (each has two heads).
Supinator arises lateral to flexor digitorum superficialis and pronator teres (there is also a small portion that arises near the common extensor tendon on the humerus, not shown here).
Flexor digitorum profundus arises along the shaft of the ulna and on the interosseous membrane.
Pronator quadratus from the distal shaft of the ulna.
Insertions of muscles that flex the wrist and hand:
Flexor carpi ulnaris has three insertion sites:
- Two in the wrist (pisiform and hook of hamate).
- One at the base of metacarpal V.
Extensor carpi ulnaris inserts at the base of metacarpal V.
Flexor carpi radialis inserts at the bases of metacarpals 2 and 3.
Abductor pollicis longus inserts on the base of metacarpal 1.
Flexor pollicis longus inserts on the distal phalanx of digit 1.
Then, on the intermediate phalanges of digits 2-5, show the insertions of flexor digitiorum superficialis.
Flexor digitorum profundus inserts on the distal phalanges of digits 2-5, via tendons.