6 - The Stay Apparatus In Horses

Question 1

What enables the horse both fore- and hindlimbs to be on its feet for long periods with a minimum of muscular effort.

Answer 1

PASSIVE STAY-APPARATUS

Question 2

The effort of the intrinsic limb muscles of horses is greatly reduced by the non-tiring tendons and ligaments of the ?, which stabilizes the joints in a position suitable for the support of the body.

Answer 2

stay-apparatus

Question 3

In most joints _____________ means preventing them from flexing

Answer 3

stabilization

Question 4

Joints in the standing horse, however, are extended and overextended, respectively; their stabilization requires them not to overextend further so as to prevent the fetlock from sinking to the ground

Answer 4

Pastern and fetlock joints

Question 5

The fleshy attachment (synsarcosis) of the forelimb to the trunk is not part of the stay-apparatus, though what muscle serves as the principal weight-bearing connection is heavily interlaced with non-tiring tendinous tissue?

Answer 5

serratus ventralis

Question 6

Though no collateral ligaments are present, the movements in what joint are restricted largely to flexion and extension in the sagittal plane by the subscapularis medially and the infraspinatus and (to a lesser degree) the supraspinatus laterally?

Answer 6

shoulder joint

Question 7

The principal stabilizer of the shoulder joint in the standing horse is ? that pressing against the cranial (extensor) surface of the joint. The way the tendon caps the intermediate tubercle of the intertubercular groove suggests a partial locking of the joint.

Answer 7

biceps tendon

Question 8

collapsing (flexing) of the shoulder joint is further prevented by the y what tendon ? that anchors the muscle to the most proximal part of the radius and, via the lacertus fibrosus and extensor carpi radialis, to a similar point on the large metacarpal bone.

Answer 8

internal tendon of the biceps

Question 9

Principally stabilized (i. e., prevented from flexing) by tension in a group of ? that arise on the medial and lateral epicondyles of the humerus and contain much fibrous tissue. (Stabilization of the Elbow Joint)

Answer 9

carpal and digital flexors

Question 10

Eccentrically placed what ligaments in elbow joint inhibit flexion to a lesser degree?

Answer 10

collateral ligaments

Question 11

The principal extensor of the elbow joint, the ?, seems inactive by its flabbiness in the quietly standing horse, although some believe that its tonus alone would prevent collapse of this key joint.

Answer 11

triceps

Question 12

What joint is stabilized (prevented from flexing) by the (dorsal) “pressure” of the extensor carpi radialis tendon?

Answer 12

carpal joint

Question 13

The carpal joint is stabilized (prevented from flexing) by the (dorsal) “pressure” of what tendon?

Answer 13

extensor carpi radialis tendon.

Question 14

What muscles ending on the accessory carpal and being tensed by the weight of the trunk via scapula, fixed shoulder joint, and humerus, “pulls” on the flexor surface of the carpal joint in an attempt to keep the joint extended.

Answer 14

flexor carpi ulnaris and ulnaris lateralis

Question 15

What ligaments attaching on the palmar surface of radius and large metacarpal bone above and below the carpus tend to supply a similar “pull”, again by the weight of the animal, but in the opposite direction—distally. Some ascribe a similar potential to the interosseus

Answer 15

accessory ligaments of the supficial and deep digital flexors

Question 16

What joint needs to be stabilized by being prevented from further overextending, i. e., sinking toward the ground. This is accomplished by three elements: the suspensory apparatus associated with the interosseus, and the supf. and deep digital flexor tendons. These attach to the palmar surface of the limb skeleton proximal and distal to the joint and are tensed when the weight of the horse overextends the joint.

Answer 16

fetlock joint

Question 17

suspensory apparatus consists of three parts:

Answer 17

1. interosseus, 2. proximal sesamoid bones, and 3. sesamoidean ligaments.

Question 18

What arises from the carpus and a The intense sarise rond the es. one droni ese of the laser branchepal bone around the proximal phalanx to the common extensor tendon.)

Answer 18

interosseus

Question 19

What bones articulate with the distal end of the large metacarpal bone to reduce friction between the suspensory apparatus and the palmar surface of the fetlock joint.

Answer 19

proximal sesamoid bones

Question 20

What ligaments tie the proximal sesamoid bones to the cannon bone and proximal phalanx?

Answer 20

Collateral ligaments

Question 21

What ligaments unites the proximal sesamoid bones and forms a smooth bearing surface for the digital flexor tendons?

Answer 21

palmar ligament

Question 22

What joint is prevented from overextension by four pastern ligament that connect the two bones that form the joint on the palmar surface?

Answer 22

pastern joint

Question 23

The pastern joint is prevented from overextension by what ligament? that connect the two bones that form the joint on the palmar surface.

Answer 23

four pastern ligament

Question 24

What joint actually flexes when the fetlock sinks under weight and can be disregarded in the consideration of the stay apparatus?

Answer 24

coffin joint

Question 25

When horses stand quietly for extended periods they support the hindquarters with only?

Answer 25

one hindlimb

Question 26

An important part of the passive stay-apparatus is the so-called ? that links the actions of stifle and hock joints.

Answer 26

reciprocal mechanism

Question 27

An important part of the passive stay-apparatus is the so-called reciprocal mechanismthat links the actions of stifle and hock joints. This is accomplished by the ?, both crossing the joint spaces of the two joints.

Answer 27

tendinous peroneus tertius muscle and the nearly tendinous supf. digital flexor muscle

Question 28

What muscle arises (by a common tendon with the long digital extensor) from the lateral condyle of the femur and, passing cranial to the tibia, ends by complex attachments on certain tarsal bones and the proximal end of the large metatarsal bone.

Answer 28

peroneus tertius

Question 29

What muscle lies caudal to the tibia and connects the caudal surface of the femur with the calcanean tuber?

Answer 29

supf. digital flexor

Question 30

By being able to lock the stifle, the horse converts the jointed column of its hindlimb into?

Answer 30

weight-bearing pillar

Question 31

Patellar Locking Mechanism • By being able to lock the stifle, the horse converts the jointed column of its hindlimb into a weight-bearing pillar. • This is accomplished by the?

Answer 31

very asymmetrical femoral trochlea, the patella, and two of the three patellar ligaments

Question 32

The medial ridge of the trochlea is larger than the lateral and is prolonged proximally to form a rounded?

Answer 32

tubercle

Question 33

What ligament connects to the medial border of the patella via the patellar fibrocartilage?

Answer 33

medial patellar ligament

Question 34

The medial patellar ligament connects to the medial border of the patella via the patellar fibrocartilage, while what ligament attaches directly on the patellar apex?

Answer 34

intermediate patellar ligament

Question 35

When the horse is standing squarely on both hindlimbs the patella rests at the proximal end of the ?, without the loop fully embracing the tubercle.

Answer 35

trochlea

Question 36

When the horse rests one hindlimb on the toe of the hoof, the patella in the supporting limb rotates medially about what degrees?

Answer 36

15 degrees

Question 37

When the horse rests one hindlimb on the toe of the hoof, the patella in the supporting limb rotates medially (about 15 degrees) and the ? slide farther caudally on the tubercle, fully locking the stifle.

Answer 37

fibrocartilage and medial patellar ligament

Question 38

What joints are supported as in the forelimb by the interosseus and the supf. and deep flexor tendons?

Answer 38

fetlock and phalangeal joints

Question 39

What arises proximal to the fetlock, attaches on the proximal sesamoid bones in the hind limb?

Answer 39

tendinous interosseous

Question 40

The tendinous interosseous arises proximal to the fetlock, attaches on the proximal sesamoid bones, and is functionally continued by the ? that attach on the plantar surface of the proximal two phalanges.

Answer 40

distal sesamoidean ligaments

Question 41

What tendons also attach proximal and distal phalanx to the fetlock in the hind limb and lend further support?

Answer 41

The supf. and deep flexor tendons

Question 42

What ligament of the hind limb is much thinner and may be absent compared on the fore limbs?

Answer 42

accessory (check) ligament of the deep flexor

Question 43

What tendon has no accessory ligament, but this is compensated for in the hindlimb by its firm attachment on the calcanean tuber: its attachment proximal and distal to the fetlock joint still helps to prevent overextension in this joint when the limb is supporting weight

Answer 43

supf. digital flexor tendon