Forelimb

Question 1

What is ground reaction force?

Answer 1

-ground reaction force = the force that acts on the body as a result of the body contacting the ground

Question 2

Why there is an uneven split of ground reaction force between the hindlimbs and forelimbs of a quadruped?

Answer 2

• the centre of mass of the animal is more cranial so there is greater GRF on the forelimbs

Question 3

Ground reaction force us a vector that can be resolved into two components, what are these components?

Answer 3

• horizontal ground reaction force, relevant during acceleration and deceleration
• mediolateral ground reaction force, relevant during manoeuvre, balance and changing direction

Question 4

From proximal - distal name the key bones in the thoracic limb

Answer 4

• scapula
• humerus
• radius
• ulna
• carpal bones
• metacarpal bones
• phalanges

Question 5

From proximal-distal name the joints in the thoracic limb

Answer 5

• scapulohumeral
• elbow (humeroradial, humeroulnar, radioulnar)
• carpus
• metacarpo-phalangeal
• proximal interphalangeal
• distal interphalangeal

Question 6

What is the thoracic girdle?

Answer 6

• unites limb to trunk
• greatly reduced in cursorial animals
• equivalent to clavicle in humans - some animals have have a loss or reduction in clavicle
• some animals will have a coracoid bone connecting the cranial edge of the sternum to the shoulder joint (lost in many mammals now)

Question 7

How is the scapula attached to the thoracic girdle?

Answer 7

• scapula attached to the thoracic girdle via extrinsic muscles (this enables sliding over the thorax to increase stride length)

Question 8

Where is the acromion found on the scapula?

Answer 8

• at the base of the scapula spine (not present in horses)

Question 9

what are the key features of the humerus bone?

Answer 9

• has a greater tubercle and a lesser tubercle
• has a humeral condyles at the base of the bone

Question 10

where is the olecranon found?

Answer 10

• found at the top of the ulna

Question 11

what is the different about the radius and the ulna in horses?

Answer 11

• radius and ulna fuse together in horses in order to reduce limb mass

Question 12

What is found at the base of the ulna?

Answer 12

• styloid processes found at the base of the ulna

Question 13

what is the difference between the carpal regions in a dog and in a horse?

Answer 13

• Horses have fever carpal bones than dogs
• 5 carpal bones in a dog but only 4 tend to be visible

Question 14

What is the brachial plexus

Answer 14

• the combination and reorganisation of spinal nerves in the thoracic limb

Question 15

What are extrinsic muscles?

Answer 15

• originate outside of the limb skeleton
• insert on the limb skeleton

Question 16

what are intrinsic muscles?

Answer 16

• originate and inset within the limb skeleton

Question 17

locomotory motions occur predominately in what plane?

Answer 17

• parasagittal plane

Question 18

What skin specialisations do digitigrade animals have?

Answer 18

• footpads
• claws

Question 19

what specialisations do unguligrade animals have?

Answer 19

• hoof capsule
• digital cushion within hoof
• laminae suspending distal phalanx