Equine Skeletal System

Question 1

What is the vertebral column formula?

Answer 1

Cervical - 7
Thoracic - 18
Lumbar - 6
Sacral - 5
Caudal - 15 to 20

Question 2

What are the 10 forelimb bones and joints?

Answer 2

• scapula
• shoulder
• humerus
• elbow
• radius and ulna
• knee (carpus)
• cannon and 2 splint bones (metacarpals)
• fetlock
• long pastern, short pastern and pedal bone (3 phalanges)
• sesamoid bones (2 sesamoid)

Question 3

What are the 10 hindlimb bones and joints?

Answer 3

• pelvis
• hip
• femur
• stifle joint and patella
• tibia and fibula
• hock (tarsus)
• cannon and 2 splint bones (metatarsals)
• fetlock
• long pastern, short pastern and pedal bone (3 phalanges)
• sesamoid bones (2 sesamoid)

Question 4

What are the 4 synovial joints?

Answer 4

Spheroidal (ball and socket)

Hinge

Plane

Pivot

Question 5

What is the spheroidal joint?
(ball and socket)

Answer 5

• the most moveable joint
• shoulder and hip joints

Question 6

What is the hinge joint?

Answer 6

• allows movement in 1 plane only
• pedal bone, short pastern and long pastern bones

Question 7

What is the plane joint?

Answer 7

• the least moveable, slide over each other
• carpal (knee) and tarsal (hock)

Question 8

What is the pivot joint?

Answer 8

• allows movement round 1 axis and rotational movement
• joint between axis and atlas, allows head to rotate to a limited extent

Question 9

What are tendons?

Answer 9

• tendons are fibrous cords of connective tissue that attach skeletal muscles to bones, they are relatively inelsatic but are made up of crimped fibres giving slight ability to lengthen

Question 10

Where do tendons originate?

Answer 10

• they originate from bone and attach to bone

Question 11

What are ligaments?

Answer 11

• the suspensory ligament of the horse differs from other ligaments in that it is a modified muscle
• meaning its more elastic than other ligaments

Question 12

What are the 4 ligaments?

Answer 12

Supporting or suspending

Annular

Inter-osseous

Funicular (or cord like)

Question 13

What is an example of a supporting/suspending ligament?

Answer 13

• suspensory ligament

Question 14

What is an example of an annular ligament?

Answer 14

• broad bands composed of deep fascia, which fold around tendons to maintain alignment and in effect, direct the pull on a tendon

Question 15

What is an example of an inter-osseous ligament?

Answer 15

• it ties bones together
• for example the pedal and navicular bones

Question 16

What is an example of a funicular ligament?

Answer 16

• holds bones together
• collateral ligaments, which are of the funicular type, are situated at the side of a joint

Question 17

What are the 4 types of tendons?

Answer 17

Common digital extensor tendon

Lateral digital extensor tendon

Deep digital flexor tendon

Superficial digital flexor tendon

Question 18

What is the origin and insertion of the common digital extensor tendon?

Answer 18

Origin - distal humerus

Insertion - phalange all bones 1, 11 and 111

Question 19

What is the action for the common digital extensor tendon?

Answer 19

• extends the lower limb and foot
• flexes the elbow

Question 20

What is the origin and insertion of the lateral digital extensor tendon?

Answer 20

Origin - lateral elbow

Insertion - phalangeal bone 1

Question 21

What is the action of the lateral digital extensor tendon?

Answer 21

• helps to straighten and extend the lower leg

Question 22

What is the origin and insertion of the deep digital flexor tendon?

Answer 22

Origin - medial humerus and ulna

Insertion - palmar aspect of phalangeal bone 111 (pedal bone)

Question 23

What is the action for the deep digital flexor tendon?

Answer 23

• flexes the joints of the lower leg
• extends the elbow

Question 24

What is the origin and insertion of the superficial digital flexor tendon?

Answer 24

Origin - medial humerus and caudal radius

Insertion - back of long and short pastern bones (phalangeal bones 1 and 11)

Question 25

What is the action of the superficial digital flexor tendon?

Answer 25

- extends the elbow - flexes the carpus and phalangeal bones

Question 26

What is the stay apparatus?

Answer 26

- this is a group of ligaments, tendons and muscles which lock joints in the limbs of the horse

Question 27

What does the stay apparatus allow?

Answer 27

- allows the horse to enter a light sleep while standing - allows for each limb to rest

Question 28

What is the suspensory apparatus?

Answer 28

- this is part of the stay apparatus which supports fetlock and prevents it form falling to the ground - also supports the pastern joint

Question 29

What does the suspensory apparatus consist of?

Answer 29

- it consist of intraosseous muscle which has been replaced by fibrous material to form the suspensory ligament

Question 30

Where is the suspensory ligament located?

Answer 30

- it lies between the deep digital flexor tendon and the cannon bone - it splits at the level of the sesamoid bone

Question 31

What does the suspensory ligament do?

Answer 31

- it joins the common digital extensor tendon at the front of the pastern - it prevents over extension of the fetlock joint

Question 32

What is the stifle locking stifle?

Answer 32

- found in the hind leg - allows the horse to immobilise the stifle joint

Question 33

What happens in the stifle locking system?

Answer 33

- to lock the stifle the joints extend past certain points and then cartilage hooks onto trochlea tubercle, and medial and patella ligaments are stabilised over the medial ridge - this locks the join tin plate without any effort

Question 34

Where does the stifle locking system occur?

Answer 34

- trochlear groove of femur and patella -> 3 patella ligaments and medial patella cartilage -> medial ligaments attaches to this cartilage

Question 35

What is the reciprocal?

Answer 35

- the final component of the stay apparatus - when the stifle is in extension the hock is also in extension due to muscle attachments - when the femur moves caudal the distal limb moves causally and vice versa

Question 36

What are the 5 functions of muscles?

Answer 36

- carry out intricate manoeuvres - contract and initiate movement - stabilise joints - maintain posture - aid temperature control (shivering)

Question 37

What are intramuscular injection sites?

Answer 37

- superficial gluteal - biceps femoris - abdominal oblique - medial gluteal - quadriceps femoris - gastrocnemius