Comparative Limb Anatomy Demonstration

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Comparative Limb Anatomy Demonstration
2014-12-28 10:14:13
Anatomy Limb

Vet Med - Module 7
Show Answers:

  1. How does the vertebral column influence forward movement in ruminants and horses when compared to dogs and cats?
    Horses and ruminants have a fairly rigid vertebral column so most of the stride length comes from the limbs.  This also means we can ride horses.  Cats and dogs have a relatively flexible vertebral column so flexion of the vertebral column also contributes to stride length.
  2. How does the orientation of the wing of the ilium of ruminants and horses differ from that of the dog and cat?
    • Horses and ruminants - horizontal
    • Dogs and cats - vertical
  3. What is the function of the muscles that insert onto the greater trochanter of the horse?  Why is this the case?
    Gluteal muscles - hindlimb retraction and hip extension.  There is not much abduction possible in the horse due to the presence of accessory ligaments stabilising the hip joint and a large surrounding muscle mass.
  4. Why is there a large tubercle at the proximal end of the medial trochlear ridge in the horse?
    It is part of the patellar locking mechanism: it becomes located between the middle and medial patellar ligaments locking the patella onto the resting surface of the trochlear groove, and locking the stifle in extension.
  5. What is the purpose of the angled trochlear ridges on the talus of the horse?
    These direct the limb laterally when the tarsus/hock is flexed therefore reducing the chance of 'over reach' injuries occurring
  6. Which palpable features would you use to assess pelvic symmetry and check for hip dislocation in the horse and ruminant compared to the dog?
    Tuber ischium, greater trochanter, tuber coxae
  7. Which palpable feature can be used to located the sacroiliac joint in the ruminant and horse?
    Tuber sacrale
  8. What is the function of the patellar locking mechanism in the hindlimb of the horse?
    The patellar locking mechanism allows the horse to fix its limb in extension so it can sleep standing up.  It is a mechanism for passive weight bearing.
  9. How many sesamoid bones are associated with the stile joint of he horse and ruminant and what is/are their name/s?
    1 - patella
  10. How does the position of the tendons of insertion of the cranial tibial and peroneus tertius muscles influence your ability to palpate the tarsus/hock?
    They run over the dorsal aspect of the joint and joint capsule cannot be palpated through them. This therefore limits palpation of the joint capsule to 5 areas - distolateral, distomedial, dorsomedial, plantolateral and plantomedial
  11. What is the function of the reciprocal apparatus in the horse and how does it work?
    The reciprocal apparatus is made up of the SDFT and peroneus tertius.  These attach to both the stifle and tarsus meaning the stifle and tarsus must move together.  SDFT is responsible for hock extension when the stifle extends and peroneus tertius is responsible for hock flexion when the stifle is flexed.
  12. When a horse extends it tarsus where is the force directed and which anatomical feature is responsible for this?
    Straight backwards - the trochlear ridge of the talus directs the distal limb towards the axial plane of the limb as the tarsus extends during kicking
  13. What is the functional significance of the gluteal muscles being well developed in the horse and the biceps femurs, semitendinosus and semimebranosus having extra heads?
    This means the horse has very powerful hind limbs that allow them to run fast and jump
  14. Which muscles insert onto the patella and what is their common function and nerve supply?
    Quadriceps and Sartorius - stifle extension, femoral nerve
  15. Which joint in the tarsus would have the worst prognosis for return to work if it was affected by degenerative joint disease and why?
    Tibio-tarsal joint as most movement occurs here
  16. What is the function of the tendon that inserts onto the calcanean tuberosity and what are its components?
    • Tarsal extension
    • Biceps femoris, gracilis, semitendinosus/SDFT/Gastrocnemius
  17. Which important structures attach to the medial and lateral malleoli?  Give a brief description of these structures
    Medial and lateral collateral ligaments of the tarsus.  Long collateral ligaments run from the tibia to the medial and lateral aspect of the 3rd metatarsal bone.  Short collateral ligaments bridge between bones in different rows.
  18. Why do ruminants and pigs not need a frog?
    As they are cloven hoover and can splay their digits
  19. Where is the horn that forms the hoof wall produced?  Is this the only part of the germinative layer that produces keratin?
    The coronary band.  Normally this is the only location with active germinative epithelium.  However, if the hoof wall becomes damaged the germinative layer on the surface of the dermis that covers the distal phalanx becomes temporarily active and produces an amorphous patch of keratin that provides temporary protection until the normal horn grows down from the coronary band.
  20. Which area of the bovine sole is most prone to damage or ulceration?
    The parapedal groove (the transition between hard to soft horn)