Muscles of the thoracic limb (Intrinsic muscles)

Question 1

What are intrinsic muscles? (2)

Answer 1

• attachments entirely on the limb
• related to the movement across the limb/joints

Question 1

Muscle acting on the entire limb (4 category, 2 muscles each)

Answer 1

all extrinsic muscles except serratus ventralis & rhoimboideus)

Abductors
* Trapezius m.
* Deltoideus m.

Adductors
* Superficial pectoralis m.
* Subscapularis m.

Protractors
* Brachiocephalicus m.
* Omotransversarius m.

Retractors
* Latissimus dorsi m.
* Deep pectoral m.

Question 1

Flexor muscles acting on shoulder joint are (6)

Answer 1

• Latissimus dorsi (extrinsic)
• Deltoideus
• Infraspinatus
• Teres major
• Teres minor
• Long head of triceps brachii

Question 2

Extensor muscles acting on the shoulder joint are (4)

Answer 2

• Brachiocephalicus (extrinsic)
• Supraspinatus
• Subscapularis
• Bicep brachii

Question 3

Deltoideus is divided into 2 parts which are

Answer 3

• Scapular part
• Acromion part

Question 4

Origin & insertion of deltoideus

Answer 4

• OR – Spine of scapular, and acromion
• IN – both has insertion at the deltoid tuberosity
  #shoulder flexor & limb abductor

Question 5

location & function of infraspinatus muscle (3)

Answer 5

• occupy infraspinous fossa
• lateral collateral ligament of the shoulder joint
• abductor of humerus

Question 6

Origin & insertion of infraspinatus

Answer 6

• OR – Infraspinous fossa, spine of scapula
  and caudal border of scapula
• IN – distal to great tubercle of humerus
  #shoulder flexor

Question 7

Origin & insertion of teres major (long, flat muscle)

Answer 7

*OR - caudal angle/scapula
*IN - teres major tuberosity
#shoulder flexor

Question 8

Origin and insertion of teres minor (round, triangular shape)

Answer 8

*OR - caudolateral angle of scapula
*IN - near greater tubercle & deltoid tuberosity
#shoulder flexor

Question 9

Long head of tripes is divided into 4 heads in dogs & 3 heads in ruminants & horses

Answer 9

• Long
• Lateral
• Medial
• Accessory

Question 10

Origin & insertion of long head of triceps

Answer 10

• OR – 2/3 caudal edge of the scapula, infraglenoid
  tubercle
• IN – olecranon of ulna
  #shoulder flexor

Question 11

Origin & insertion of supraspinatus (occupy supraspinous fossa)

Answer 11

*OR - supraspinous fossa, including spine of scapula
*IN - greater tubercle of humerus
#shoulder extensor

Question 12

Origin & insertion of subscapularis (occupy subscapularis fossa, medial collateral ligament, adductor)

Answer 12

*OR - subscapularis fossa
*IN - lesser tubercle of humerus
#shoulder extensor

Question 13

Origin & insertion of bicep brachii (proximal par of arm, cross shoulder & elbow joint) (single head in dogs)

Answer 13

*OR - supraglenoid tubercle
*IN - medial surface of olecranon of ulna
#shoulder extensor
#elbow flexor

Question 14

Flexor muscles acting on the elbow joint (2)

Answer 14

• Biceps brachii
• Brachialis

Question 15

Extensor muscles acting on elbow joint (2)

Answer 15

• triceps brachii
• anconeus

Question 16

Origin & insertion of brachialis (proximal part of arm) ( 2 insertion tendons in dogs, 1 in horse @ radius)

Answer 16

*OR - caudal surface of proximal humerus
*IN - medial side, radius & ulna tuberosity
#elbow flexor

Question 17

Origin (for all heads) & insertion of triceps brachii (all 4 heads involved in extension of elbow) (dissect deltoideus & lateral head to see long & accessory head)

Answer 17

*OR
LaH: lateral of humerus, deltoid tuberosity
LoH; edge of caudal 2/3 o scapula
AH: proximal caudal part of the humerus neck
MH: medial of humerus; teres
major tuberosity
*IN - all heads inserted @ olecranon of ulna
#elbow extensor

Question 18

Origin & insertion of anconeus (tenses antebrachial fascia)

Answer 18

• OR – lateral epicondyle & olecranon fossa of humerus
• IN – lateral surface, proximal part of ulna
  #elbow extensor

Question 19

Flexor muscles acting on carpus (2)

Answer 19

*flexor carpi radialis
*flexor carpi ulnaris

Question 20

Extensor muscles acting on carpus (2)

Answer 20

*Extensor carpi radialis
*ulnaris lateralis

Question 21

Origin & insertion of flexor carpi ulnaris (2 bellies)

Answer 21

OR – medially, proximal end of ulnar and humerus
IN – accessory carpal bone (2 tendons)
#carpus flexor
#forepaw abductor

Question 22

Origin & insertion of flexor carpi radialis

Answer 22

OR – medial epicondyle
IN – palmar side, metacarpal II and III
#carpus flexor

Question 23

Origin & insertion of extensor carpi radialis (also flex elbow joint)

Answer 23

OR – lateral epicondyle of humerus
IN – metacarpal II & III
#carpus flexor

Question 24

Origin & insertion ulnaris lateralis

Answer 24

OR – lateral epicondyle of humerus
IN – proximal end of fifth metacarpal

Question 25

Flexor muscles acting on digit (2)

Answer 25

• Superficial digital flexor m.
• Deep digital flexor m.

Question 26

Extensor muscles acting on digits (2)

Answer 26

• Common digital extensor m.
• Lateral digital extensor m.

Question 27

Origin & insertion & action of superficial digital flexor

Answer 27

OR – medial epicondyle of humerus
IN – metacarpophalangeal joint
Action – flex proximal and middle digital joints
(four principal digits)
#digit flexor

Question 28

Origin & insertion of deep digital flexor

Answer 28

OR – medial epicondyle of humerus
IN – distal phalanx
#digit flexor

Question 29

Origin & insertion & action of common digital extensor

Answer 29

OR – lateral epicondyle of humerus
IN – distal phalanges of digits II-IV
Action – also extend carpal/elbow
#digit extensor

Question 30

Origin & insertion & action of lateral digital extensor

Answer 30

OR – lateral epicondyle of humerus
IN – Proximal phalanges of digits III-IV
Action – also extend carpal/elbow
#digit extensor

Question 31

Muscles involved in the rotation of arm (3)

Answer 31

• Pronator quadratus m.
• Supinator m.
• Pronator teres m.

Question 32

Origin, insertion & action of pronator teres

Answer 32

OR – medial epicondyle of humerus
IN – radial tuberosity
Action - Outward rotation of forepaw
#arm rotation

Question 33

Origin, insertion & action of pronator quadratus

Answer 33

OR – interosseous space radius and ulna
IN – radius
Action- Inward rotation (forepaw
*arm rotation

Question 34

Origin & insertion of supinator

Answer 34

OR – lateral epicondyle of humerus
IN – radial tuberosity