Small Animal Answer Key

1. a. Identify this structure. The serratus ventralis muscle.
b. What is its insertion? The dorsomedial scapula.
c. What is its innervation? The serratus ventralis m. is innervated by
ventral branches of the cervical spinal nerves
and
The long thoracic nerve (C7).
d. What is its innervation? The serratus ventralis m. creates
a "sling" in which the trunk is supported.
This muscle also depresses the scapula.
2. a. Identify this bone, and indicate if the specimen comes from a cat or a dog. This is a canine humerus.
b. How can the humerus of the cat be differentiated from that of the dog? The feline humerus has a supracondylar foramen in its medial epicondyle. This foramen is not present the dog.
c. What is important about this difference? The external iliac artery continues on as the femoral artery into the pelvic limb.
3. a. Identify this bone. The femur.
b. What originates in the darkened area? The vastus lateralis and
the vastusintermedius muscles
originate in the darkened area.
4. a. Identify at least one muscle that originates here? The biceps femoris, semitendinosus, the semimembranosus originate on the ischiatic tuberosity. The biceps femoris also originates from the sacrotuberous ligament.
b. What is(are) the action(s) of the muscle(s) identified? The biceps femoris extends the hip, stifle, and hock. The semitendinosis extends the hip, flexes the stifle and extends the hock. The semimembranosus extends the hip and both flexes and extends the stifle.
5. a. Identify the superficial structure that drains blood from this region? The lateral saphenous vein.
b. How is this arrangement different in the cat? In the cat, the region is drained by the medial saphenous vein, not the lateral.
6. a. Name the four muscles that comprise the Quadriceps.

The four muscles are:
1. The rectus femoris
2. The vastus lateralis
3. The vastus intermedius
4. The vastus medialis

b. Name the nerve(s) that innervate(s) these muscles. The femoral nerve innervates all four.
7. Name the sensory nerve that innervates the indicated area. The radial nerve innervates the dorsal aspect of the paw.
8. a. Identify. The trapezius muscle.
b. What nerve innervates this muscle? The accessory nerve innervates the trapezius.
c. Where does this muscle insert? The trapezius inserts on the spine of the scapula.
9. A lesion on what nerve would cause a cat to be unable to bear weight on its left leg? The lesion would be on the radial nerve. The radial nerve provides motor innervation for all the extensors of the lower front limb. Without this nerve, these muscles would be unable to bear weight.
10. a. Identify. The extensor carpi radialis muscle.
b. What action does it perform? The extensor carpi radialis extends the carpus.
11. Identify this structure. The long head of the triceps.
12. Use the top image to get your bearings. Then, identify the indicated structure in the bottom image. The middle gluteal muscle.
13. a. Identify. Parietal serous pericardium.
b. Identify. Parietal mediastinal pleura.
14. a. Identify. (If you need a hint, you are viewing a canine thoracic limb!) The biceps brachii muscle.
b. Name the insertion and origin of this muscle. The biceps brachii arises from the supraglenoid tubercle of the scapula, and inserts on the ulnar and radial tuberosities. It is one of the few muscles that spans two joints.
15. Identify. The ligament of the femoral head.
16. Identify (be specific). The right middle lung lobe.
"Lung" was not enough of an answer to be correct.
17. a. Identify this structure. The esophagus.
b. Where does this structure pass through the diaphragm, and what other structure runs along with it? The esophagus passes through the diaphragm at the esophageal hiatus, along with the dorsal and ventral vagal trunks.
18. a. Name the bone that forms this prominence. The calcaneus.
b. Name at least two muscles that insert on this bony prominence. The biceps femoris, the gracilis, the semitendinosus, the superficial digital flexor, and the Gastrocnemius all insert on the calcaneus.
19. a. Name this joint. The stifle joint.
b. Name at least three structures that stabilize this joint.
1. The medial & lateral collateral ligaments.
2. The cranial & caudal cruciate ligaments.
3. The medial & lateral menisci.
4. The patellar ligament.
Additional structures could include:
5. The tendon of the quadriceps.
6. The tendon of the quadriceps.
7. The tendon of the popliteus
8. The tendon of the long digital extensor
20. a. Identify (Hint:   this is a ventral view of the pelvis ). The external iliac artery.
b. This artery has one branch before continuing into the pelvic limb.  Name the branch, and the significance of the branch. The branch of the external iliac artery is the deep femoral artery.
The pudendoepigastric trunk branches off the deep femoral. The external pudendal artery branches off of the pudendoepigastric trunk and courses through the inguinal ring.
c. What does this artery become when it continues into the pelvic limb? The external iliac artery continues on as the femoral artery into the pelvic limb.
21. How does the feline pelvic limb differ from its canine counterpart? The cat has an additional muscle - the soleus.
22. a. Name this bone. The tibia.
b. What inserts on the indicated area? The patellar ligament attaches in the specified spot.
23. a. Use the top image to get you bearings, then identify A in the bottom image. Testes.
b. Identify. Tail of the epididymis.
24. a. What structures compose the deep inguinal ring? The deep inguinal ring is made up of the external abdominal oblique, the internal abdominal oblique, and the rectus abdominis.
b. Name two structures that pass through it. The spermatic cord, the ductus deferens, the testicular artery and vein, the external pudendal artery and vein, the vaginal tunic, and the genitofemoral nerve all travel through the inguinal canal.