Intrinsic Muscles of the Shoulder and Brachium

Question 1

Characteristics of intrinsic muscles

Answer 1

-located within limb
-crosse at least one joint
-have action on joint
-action depends on location of muscle attachment

Question 2

Deltoideus m.

Answer 2

Origin:
1. Scapular part: spine of scapula by an aponeurosis
2. Acromion of scapula
Insertion: deltoid tuberosity
Innervation: Axillary n.
Action: Flex shoulder joint

Question 3

Infraspinatus m.

Answer 3

Origin: infraspinous fossa
Insertion: greater tubercle
Innervation: suprascapular n.
Action: extend of flex, laterally stabilize, abduct shoulder joint

Question 4

Teres minor m.

Answer 4

Origin: infraglenoid tubercle and distal third of caudal border of scapula
Insertion: teres minor tuberosity of humerus
Innervation: Axillary n.
Action: flex shoulder joint, rotate shoulder laterally, prevent medial rotation when weight bearing

Question 5

Supraspinatus m.

Answer 5

Origin: supraspinous fossa
Insertion: greater tubercle
Innervation: suprascapular n.
Action:extend and laterally stabilize shoulder joint

Question 6

Subscapularis m.

Answer 6

Origin: subscauplar fossa
Insertion: lesser tubercle
Innervation: subscapular n and axillary n.
Action: adduct, extend, and medially stabilize shoulder joint, rotate the shoulder medially and prevent lateral rotation when weight bearing. flex shoulder joint

Question 7

Teres major m.

Answer 7

Origin: caudal angle and caudal border scapula, caudal surface of subscapularis
Insertion: teres major tuberosity of humerus
Innervation: Axillary n.
Action: flex shoulder joint, rotate shoulder medially

Question 8

Coracobrachialis m.

Answer 8

Origin: coracoid process of scapula
Insertion: crest of lesser tubercle of humerus, proximal to teres major tuberosity
Innervation: musculocutaneous n.
Action: adduct, extend, and stabilize shoulder joint

Question 9

Tensor fasciae antebrachii m.

Answer 9

Origin: Fascia covering lateral side of latissimus dorsi m.
Insertion: olecranon
Innervation: radial n.
Action: extend elbow

Question 10

Triceps brachii m. (long, medial, accessory, and lateral head)

Answer 10

Origin:
-long head: caudal border of scapula
medial head: crest of lesser tubercle near teres major tuberosity
-accessory head: neck of humerus
-medial head: tricipital line
Insertion: olecranon
Innervation: radial n.
Action: flex shoulder joint and extend the elbow

Question 11

Anconeus m.

Answer 11

Origin: lateral supracondylar crest, medial and lateral humeral epicondyles
Insertion: lateral surface of the proximal end of ulna (olecranon)
Innervation: radial n.
Action: extend elbow

Question 12

Epitrochleoanconeus m.

Answer 12

-present ONLY in cat
-part of anconeus m.
-associated with the supracondylar foramen medically

Question 13

Biceps brachii m.

Answer 13

Origin: supraglenoid tubercle
Insertion:
dog - radial and ulnar tuberosities
cat - radial tuberosity
Innervation: musculocutanous n.
Action: extend shoulder joint and flex elbow

Question 14

Brachialis m.

Answer 14

Origin: proximal third of lateral surface of humerus
Insertion:
dog - radial and ulnar tuberosities
cat - ulnar tubercle
Innervation: musculocutanous n.
Action: flex elbow