1.11 Forelimb

Question 1

In which limb are the GRF higher?

Answer 1

Forelimb around 30% higher than the hindlimb

Question 2

Why does the hindlimb have higher horizontal forces during locomotion?

Answer 2

Hindlimb is involved in pushing the animal forwards and propulsion during locomotion

Question 3

Name the joints of the thoracic limb

Answer 3

Synsarcosis - scapulothoracic 
Scapulohumeral (shoulder)
Elbow (humeroradial, humeroulnar, radioulnar)
Carpus 
Metacarpo-phalangeal 
Interphalangeal (DIP, PIP)

Question 4

What is the thoracic girdle?

Answer 4

Unites limbs to trunk

• used for climbing, manipulation and grasping
• reduced in cursorial animals

Question 5

What has been the anatomical effect of the change in forelimb role from prehensile to supporting?

Answer 5

1. Loss/reduction of clavicle
2. Coracoid is reduced and part of scapula
3. Scapula attached by extrinsic muscles (synsarcosis) and slides across trunk increasing stride length

Question 6

What are extrinsic muscles?

Answer 6

Responsible for global movements of whole limb

• protraction
• retraction
• abduction
• adduction

Question 7

What are intrinsic muscles?

Answer 7

Responsible for local movements typically run from one limb to the other

Question 8

What are the medial forelimb extrinsics?

Answer 8

• serratus ventralis
• rhomboid
• deep pectoral
• superficial pectoral

Question 9

What are the lateral forelimb extrinsics?

Answer 9

• omotransverse
• trapezius
• latissimus dorsi
• brachiocephalicus

Question 10

What are the shoulder extensors?

Answer 10

Cranial aspect of the shoulder joint

• biceps brachii
• brachicephalicus
• supraspinatus

Question 11

What are the shoulder stabilisers?

Answer 11

• subscapularis
• supraspinatus
• teres minor
• infraspinatus

Question 12

What are the shoulder flexors?

Answer 12

• teres major
• deltoid
• triceps brachii (long head only)

Question 13

What are the elbow flexors?

Answer 13

Cranial aspect of the elbow joint

• biceps brachii
• brachialis

Question 14

What are the elbow extensors?

Answer 14

Caudal aspect of the elbow joint

• triceps, medial head
• triceps, long head
• triceps, accessory head
• triceps, lateral head

Question 15

What are the extensors for the carpus and digits?

Answer 15

Dorsal aspect of limb

• extensor carpi radialis
• abductor pollicis longus
• common digital extensor
• lateral digital extensor
• ulnaris lateralis

Question 16

What are the flexors of the carpus and digits?

Answer 16

Palmar aspect of the distal limb

• flexor carpi radialis
• superficial digital flexor
• deep digital flexor
• flexor carpi ulnaris

Question 17

What is the brachial plexus?

Answer 17

Nerves from the spinal cord enter forelimb via armpit or Zillah as a plexus

Question 18

What are cursorial specialisations of the antebrachium and manus?

Answer 18

1. Minimisation of distal limb mass i.e., loss of digits
2. Elastic energy storage and release i.e., tendons
3. Lesser requirement for manipulation and control i.e., as a result been able to enhance other anatomical features to allow for efficient locomotion

Question 19

What is the role of the interosseus muscle?

Answer 19

Responsible for individual movements of the digits with respect with one another

• ↓ in digits = ↓ in the need for the interosseus muscle
• ↓ in interosseus muscle = ↑ in ligamentous tissue