Large Animal Quiz Answer Key
1. a. What organ occupies the majority of the left side of the abdominal cavity? The Rumen.
b. What is an important application of this knowledge? Knowing the anatomy is important when considering a surgical approach to the abdomen. A common approach is from the left side because the rumen helps to block the intestines within the abdominal cavity.
2. a. Identify this joint. This is the carpal joint of the thoracic limb.
3. a. What is the reciprocal apparatus? The reciprocal apparatus consists of two parts.  The caudal aspect is composed of the superficial digital flexor, while the cranial portion is composed of the peroneus tertius.
b. What is its function? These two elements provide a mechanism whereby the stifle and tarsus flex/extend in sync with one another.   Therefore, when the horse flexes its stifle, the tarsus also flexes and lifts the distal limb.  This mechanism is important  in the movement of the limb.
4. a. Identify. Radial Carpal Bone.
b. Identify. Fourth Carpal Bone.
5. What comprises the jugular groove? The jugular groove is formed ventrally by the sternomandibularis, dorsally by the cleidomastoideus and medially by the omohyoideus muscles in the horse or the sternomastoideus in the ruminant.
6. a. Identify. Laminar part of the nuchal ligament.
b. Identify. Funicular part of the nuchal ligament.
7. a. Into what space does the epiploic foramen open?

The epiploic foramen opens into the omental bursa.

b. In which species does this structure play a clinical role? In the horse, a loop of jejunum can pass through the opening of the epiploic foramen and become strangulated.
8. Identify. The scapular cartilage.
9. What attaches at the labeled site? The sternomandibularis muscle.
10. a. Based on your recognition of this region of the skeleton, is this a thoracic limb or a pelvic limb? The talus tells all -- a pelvic limb.
b. Identify this joint. The distal intertarsal joint.
11. a. What is this organ? The rumen.
b. Identify the indicated structure. The cranial pillar of the rumen.
12. Identify (be specific). The spiral loop of the ruminant
ascending colon.
13. a. Identify this compartment. The rumen.
b. Identify this compartment. The abomasum.
c. Identify this compartment. The reticulum.
d. Identify this compartment. The omasum.
14. a. Name the two parts of the greater omentum. The greater omentum
has a superficial leaf and a deep leaf.
b. What lies between these? The space between the superficial and deep leaves is the omental bursa.
c. The greater omentum is associated with what structures? The greater omentum is associated with the rumen, reticulum, and abomasum.
d. The lesser omentum covers what structure(s)? The lesser omentum covers the omasum.
15. a. Identify this structure.

This structure is the straight ligament.

b. Name the attachments of this structure. Its attachments include the proximal sesamoids and the complementary fibrocartilage of P2.
16. a.

Along the dorsal aspect of the hoof, there are 2 structures that interdigitate. Name these structures (only one is shown in this image).

One of these structures is the laminar epidermis (insensitive laminae), which is shown in the image extending from the hoof wall. The other structure, the laminar corium (sensitive laminae) is not shown, but interdigitates with the laminar epidermis.
b. What condition is associated with the separation of these two structures? Laminitis is associated with the
separation of these laminae.

Identify this ligament below the carpus.

The accessory ligament of the deep digital flexor (also known as the distal check ligament).

18. a. Identify this structure. The deep digital flexor.
b. What structures prevent tarsal flexion when the stay apparatus is locked? The components of the stay apparatus that
prevent tarsal flexion include the interaction between the locking mechanism associated with the medial patellar ligament, the fibrous tendon of the superficial digital flexor and its attachments to the calcaneus and phalanges. This interaction prevents both stifle and tarsal flexion when the stay apparatus is locked.
19. a. Identify this structure. The frog.
b. Identify this structure. The bulb of the heel.
20. Identify this structure. The intermediate patellar ligament.
How can you distinguish the medial side from the lateral side? The trochlear tubercle of the medial condyle (of the femur) forms a large prominence that allows the medial patellar ligament to lock into place.
21. a. Identify the artery and nerve on this thoracic limb (ignoring medial and lateral). The palmar digital artery and nerve.
b. What is the origin of each of these? The digital artery originates from the median artery.  The digital nerves arise from both the median nerve and the palmar branch of the ulnar nerve.
c. What nerve in the horse differs from that in other animals, and how is it different? The radial nerve does not extend past the carpus in the horse.
22. a. Identify this structure. The pararectal fossa.
b. Identify this structure. The vesicogenital pouch.
c. Identify this structure. The pubovesical pouch.
23. a. Identify this structure. Broad ligament of the uterus.
b. Identify this structure. Median ligament of the bladder.
24. a. Identify this structure. The intersection of the common digital extensor and the extensor branch of the interosseous.
b. Identify this structure. The deep digital flexor.
25. a. What is the function of the suspensory apparatus? To prevent muscle fatigue.   The suspensory apparatus transfers tension from the muscle bellies to bones.
b. When comparing the biceps brachii of the horse, the dog, and the ruminant, what additional structure do you see in the horse? The horse has the lacertus fibrosus.  It connects the biceps brachii to the extensor carpi radialis muscle. This structure is part of the stay apparatus of the thoracic limb.