Canine Forelimb Intrinsic Muscles

Question 1

Deltoidius

Answer 1

Origin: Spine and Acromional process of the scapula
Insertion: deltoid tuberosity of humerus
Action: flex shoulder

Question 2

Infraspinatus

Answer 2

• origin: infraspinous fossa of scapula
• insertion: lateral side of the greater tubercule of humerus
• action: laterally stabilizes the shoulder by preventing medial rotation while weight-bearing; abduct and laterally rotate shoulder and assists extension/flexion of shoulder

Question 3

teres minor

Answer 3

• origin: infraglenoid tubercle of scapula, the distal-caudal border of scapula
• insertion: teres minor tuberosity of humerus
• action: laterally stabilizes the shoulder, preventing medial rotation when weight bearing; laterally rotates shoulder

Question 4

four muscles of rotator cuff that have tendons (?) supporting the shoulder joint are

Answer 4

infraspinatus, supraspinatus, subscapularis, and teres minor

Question 5

supraspinatus

Answer 5

• origin: entirety of supraspinous fossa of scapula
• insertion: greater tubercle of humerous; has a thick tendon
• action: laterally stabilizes shoulder/prevents medial rotation when weight bearing AND extends shoulder

Question 6

subscapularis

Answer 6

• origin: subscapular fossa (medial face) of scapula
• insertion: lesser tubercle of humerus
• action: medially stabilizes the shoulder; adducts shoulder; extends shoulder

Question 7

teres major

Answer 7

• origin: caudal angle and caudal border of scaupla; subscapularis muscle
• insertion: teres major tuberosity of humeus
• action: flex shoulder; rotate arm medially

Question 8

coracobrachialis

Answer 8

• long tendon of origin surrounded by synovial sheath
• origin: coracoid process of scapula
• insertion: crest of lesser tubercle of humerus near teres major tuberosity
• action: mainly shoulder stabilizdr; can assist in adduction/extension of shoulder

Question 9

tensor fasciae antebrachii

Answer 9

• thin muscle on medial aspect of brachium
• origin: fascia cover lateral surface of lat. dorsi muscle
• insertion: olecranon of ulna, common tendon of insertion of triceps brachii
• action: extend elbow

Question 10

triceps brachii

Answer 10

• 4 heads: long, lateral, medial, and accessory; all cross the elbow joint
• origin: caudal border of scapula (long), tricipital line/proximal humerus (neck, lesser tubercle, and crest of LT
• insertion: olecranon of ulna
• action: flex shoulder (long head); extend elbow (all heads)

Question 11

anconeus

Answer 11

• covers olecranon fossa
• origin: lateral cupracondylar crest of humerus; lateral and medial epicondyles of humerus
• insertion: proximal and lateral aspect of ulna
• action: extend elbow

Question 12

biceps brachii

Answer 12

• tendon of origin passes btw greater and lesser tubercles within intertubercular groove of humerus;
• origin: supraglenoid tubercle of scapula
• insertion: radial + ulnar tuberosities
• action: extend shoulder/flex elbow

Question 13

transverse humeral retinaculum

Answer 13

extends from greater to less tubercle over the intertubercular groove, holding the tendon of the biceps brachii in place

Question 14

brachialis

Answer 14

• located in brachials groove of humerus; common insertion w/ b. brachii muscle, both are major elbow joint flexors
• origin: proximal + lateral aspect of humerus
• insertion: radial+ulnar tuberosities
• action: flex elbow