Large Animal Pelvic Limb - Muscles

Question 1

When you unlock the patella (in the horse) the stifle and the hock can _______ and ______ in unison.

Answer 1

Flex ; Extend

Important: The Reciprocal Apparatus ensures that the hock and stifle DO FLEX AND EXTEND AT THE SAME TIME!!! A horse with a normal working Reciprocal Apparatus cannot flex the stifle while extending the hock (and Visa-Versa)… They must BOTH flex or Both extend at the same time.

(Note: If the patella stays there the stifle CANNOT flex)

Question 2

What determines left pelvic limb vs. right pelvic limb (in the horse) ? (2 determinants)

Answer 2

1. Extensor muscles are on the lateral side (or the convexity of the tibia)
2. There are two sides of the trochlea on the femur. The medial one is LARGER than the lateral one in the equine species.

Question 3

The boney patella and the _________ _________ blend together and form a loop (in equine).

Answer 3

Parapatellar fibrocartilage

Question 4

True or False

In equine, there are 3 patellar ligaments: middle, intermediate and lateral ?

Answer 4

False

medial, intermediate(or middle), and lateral

Question 5

The __________ ___________ on the (medial and lateral side of the femor) keep the femor and the patella from getting too far away from each other in equine species.

Answer 5

Femorolpatellar ligament

Question 6

Laterally the femorolpatellar ligament comes from the _______ _________ to the patella. (aka origin)

Answer 6

lateral epicondyle (of the femor in equine species)

Question 7

True or False

Collateral ligaments (medially and laterally) stabilize the stifle joint and keep it from luxating; dislocating in equine species.

Answer 7

True

The collateral ligament is in the cranio-caudal plane

Question 8

What is the origin and insertion of the lateral collateral ligament (in equine species)?

Answer 8

Origin: Lateral epicondyle of the femor
Insertion: Lateral condyle of the tibia

(Medial does the same thing on the opposite side)

Question 9

The Reciprocal Apparatus in equine species, ensures that the stifle and hock joints move in unison for energy conservation; if one of these joints flexes or extends, the action is reciprocated at the other joint.

What are the two muscles involved in this?

Answer 9

1. Fibularis (peroneus) tertius
   - Cranial
2. Superficial digital flexor
   - Caudal

(Fibrous components of the gastrocnemius also supports the Reciprocal Apparatus)