Muscles of shoulder region (Lateral aspect)
•Supraspinatus muscle-
Origin – Supraspinous fossa and scapular spine
Insertion – Lateral and medial tuberosity of humerus
Action – to extend the shoulder joint
•Infraspinatus muscle-
Origin – Infraspinous fossa and scapular spine
Insertion – The lateral part insert to the round rough area below the lateral tuberosity of humerus and the medial part inserts to the medial aspect of lateral tuberosity of humerus.
Action – to abduct the arm.
•Teres minor – It is situated below infraspinatus muscle.
Origin – Distal part of infraspinous fossa and posterior border of scapula.
Insertion – Deltoid tuberosity of humerus.
Action – To abduct the forelimb.
•Deltoideus–
Origin – Acromion process and posterior border of scapula
Insertion – Deltoid tuberosity
Action – To abduct the forelimb.
Medial aspect
•Subscapularis muscle
Origin – Subscapular fossa
Insertion – Medial tuberosity of humerus.
Action – To adduct the forelimb
•Teres major
Origin – Caudo – dorsal angle of scapula
Insertion – Medial tuberosity of humerus
Action – To adduct the forelimb
•Coracobrachialis
Origin – Coracoid process of scapula
Insertion – Area above the teres tubercle of humerus Action – To adduct the forelimb.
Muscle of arm region
•Triceps brachii – The angle formed by scapula and humerus is filled up by triceps muscle. It consist of 3 parts
Lateral head of triceps
Long head of triceps
Medial head of triceps
Origin – Caudal border of scapula and the medial surface of the shaft of the humerus.
Insertion – Olecranon process of ulna.
Action – to extend the elbow joint
•Tensor fascia antibrachii-
Origin – the proximal part of the posterior border of the scapula.
Insertion – Olecranon process of ulna.
Action – to extend the elbow joint.
•Biceps brachii –
Origin – tuber scapulae
Insertion – radial tuberosity
Action – to flex the elbow joint
•Brachialis –
Origin – area behind the head of humerus
Insertion – medial aspect of proximal end of radius and ulna.
Action – to flex the elbow joint.
•Anconeus –
Origin – caudal surface of the distal part of humerus
Insertion – olecranon process of ulna
Action – to extend the elbow
Muscles of forearm and manus Lateral side
•Extensor carpi radialis
Origin – Crest of lateral condyle and coronoid fossa of humerus.
Insertion – Metacarpal tuberosity.
Action – To extend the carpal joint.
•Extensor carpi obliqus
Origin – Anterolateral surface of radius and lateral border of ulna at their distal fourth of radius.
Insertion – Proximal extremity of metacarpal bone.
Action – To extend the carpal bone
• Medial digital extensor
Origin – The rough depression outside the coronoid fossa in common with extensor carpii radialis.
Insertion – Second and third phalanges of the medial digit.
Action – To extend the joints of the medial digit.
•Common digital extensor
Origin – Lateral epicondyle of humerus and lateral border of ulna above proximal interosseous space.
Insertion – Extensor process of corresponding third phalanx.
Action – To extend the forelimb.
• Lateral digital extensor
Origin – Lateral aspect of proximal end of radius and ulna.
Insertion – Second and third phalanges of the lateral digit.
Action – To extend the joints of lateral digit.
Medial side
•Flexor carpi radialis–
Origin – Medial condyle of humerus.
Insertion – Posterior aspect of proximal extremity of large metacarpal bone.
Action – To flex the carpal joint.
• Flexor carpi ulnaris
Origin – Medial condyle of humerus and medial aspect of olecranon process.
Insertion – Accessory carpal bone.
Action – To flex the carpal joint.
• Superficial digital flexor-
Origin – Medial condyle of humerus.
Insertion – 2nd Phalanx.
Action – To Flex the forelimb.
•Deep digital flexor-
Origin – Medial condyle of humerus and olecranon process of ulna.
Insertion – 3rd Phalanx.
Action – To flex the forelimb.
• Ulnaris lateralis
Origin – Lateral condyle of humerus.
Insertion – Accessory carpal bone and lateral aspect of proximal end of metacarpal bone.
Action – To flex the carpus and extend the digit.
• Pronator teres
Origin – Medial condyle of humerus.
Insertion – At the upper third of medial surface of humerus.
Action – To flex the elbow joint.
