Exam II - Equine Head (& Some Bovine)

Question 1

Which foramen & nerve are covered by the levator labii superioris m. in the horse?

Answer 1

infraorbital foramen & infraorbital nerve

Question 2

Compare the position of the parotid duct of the equine to that of the canine.

Answer 2

In the horse, the parotid duct runs ventrally underneath the masseter m.

In the dog, the parotid gland ran over the middle of the masseter m.

Question 3

What is the only muscle that opens the jaw in the horse?

Answer 3

digastricus m.

(same as canine)

Question 4

What are the muscles of mastication in the horse?

Answer 4

• Masseter m.
• Temporalis m.
• Pterygoid m.
• Digastricus m.

(same as in the canine)

Question 5

What are the borders of Viborg’s Triangle?

Answer 5

1. Sternocephalicus m.
2. Linguofacial v.
3. Caudal border of the ramus (of the mandible)

Viborg’s Triangle can be used to access the salivary glands in this area as well as to access the guttural pouch (to drain infection from it)

Question 6

Describe the difference we observe in the nasolacrimal duct of donkeys vs. that of canines

Answer 6

In donkeys, the opening for the nasolacrimal duct is lateral.

Question 7

What is the the nasolacrimal duct carrying? To where?

Answer 7

The nasolacrimal duct carries tears from the lacrimal sac into the nasal cavity.

Question 8

Which salivary gland in the horse is equivalent to the zygomatic salivary gland in the dog?

Answer 8

Buccal salivary gland

(it is divided into dorsal & ventral buccal salivary glands)

Question 9

How many salivary glands are present in the horse? Name them.

Answer 9

Four (same as in the dog)

1. Mandibular Salivary Gland
2. Sublingual Salivary Gland
   
   • Monostomatic & Polystomatic
3. Parotid Salivary Gland
4. Buccal Salivary Gland
   
   • Dorsal Buccal and Ventral Buccal

Question 10

Which type of salivary gland has only one opening where saliva is expelled?

Answer 10

Monostomatic

Question 11

Which structure(s) is/are present at the root of the tongue on either side that are not present in the canine?

Answer 11

lingual tonsils

Note that these do not replace the palatine tonsils. Horses still have palatine tonsils too.

Question 12

Is the horse a mouth breather or a nasal-breather?

Answer 12

Horses are obligate nasal-breathers.

The epiglottis in the horse lies dorsal to the soft palate. So if the horse tried to breathe through its mouth, it wouldn’t be able to because the epiglottis would close off the trachea when air entered the laryngopharynx.

Question 13

Where would you pass a nasogastric tube in a horse?

Answer 13

Through the **ventral nasal meatus **and down into the esophagus.

Due to the layout of the epiglottis, you cannot pass an orogastric tube in a horse.

Question 14

When the epiglottis gets trapped under the soft palate in the horse, this is referred to as:

Answer 14

dorsal displacement of the soft palate

When this happens, there will be difficulty breathing. If you do an examination of the larynx with a laryngoscope, you won’t see the epiglottis at all.

Question 15

When the epiglottis gets caught under a fold of mucosa in the horse, causing an abnormality in the shape and texture of the epiglottis, this is referred to as:

Answer 15

epiglottic entrapment

Question 16

The large sac-like structure off the caudal aspect of the auditory tube is called the:

Answer 16

guttural pouch

This pouch is bounded laterally by the Pterygoid m. and the Mandibular Salivary Glands

Question 17

The guttural pouches are in close proximity to several important structures. What are those structures?

Answer 17

• CN IX, X, XI, XII
• Sympathetic trunk
• Internal carotid a, External carotid a., & linguofacial a.

Question 18

The two halves of the guttural pouches are reffered to as _______________.

Which is larger?

Answer 18

medial & lateral compartments.

The medial compartment is larger

Question 19

Which sinus is rostral to and continuous with the frontal sinus in the horse?

The two of these sinuses together are called:

Answer 19

Dorsal concha sinus

The Dorsal concha sinus and the frontal sinus together are called the conchofrontal sinus.

Question 20

The hole through which the conchofrontal and maxillary sinuses communicate is called the:

Answer 20

frontomaxillary opening

this is important because if there is an infection in the maxillary sinus, there is a good chance it is also in the frontal sinus

Question 21

Regarding laryngeal structure: What is different about the arytenoid cartilage in the horse vs. that of the dog

Answer 21

There is no cuneiform process of the arytenoid cartilage in the horse

Question 22

Which nerve in the horse passes underneath the cricoarytenoideus dorsalis m. and innervates the intrinsic muscles of the larynx (expect the cricothyroideus)?

Answer 22

caudal laryngeal nerve

Question 23

Which nerve in the horse lies on the lateral surface of the guttural pouch and innervates the cricothyroideus m?

Answer 23

cranial laryngeal n.

It also provides sensory innervation to the mucous membranes of the larynx.

Question 24

What is the only muscle that opens the glottis?

Answer 24

cricoarytenoideus dorsalis

Question 25

The condition caused by partial paralysis in the intrinsic muscles of the larynx is called ____________, and is also known as roaring

Answer 25

Laryngeal hemiplagia

Question 26

Venipuncture in the equine head can be performed using which vein(s)?

Answer 26

external jugular v., transverse facial v., or deep facial v.*

*If using deep facial v, use the facial crest to guide you. Place the needle just under the facial crest and parralel with it.

Question 27

Identify the vessel labeled A

Answer 27

Deep facial vein

Question 28

What is the main muscle used in the Flehmen’s Response?

Answer 28

levator labii superioris m.

Question 29

Name the muscular landmark for finding the infraorbital nerve in the equine

Answer 29

levator labii superioris m.

Question 30

Woah, leg question!

What is the principal artery to the bovine metacarpus?

Answer 30

palmar common digital a.

Question 31

Oh snap, another leg question in the head category!

Which nerve(s) innervate(s) the stifle?

Answer 31

• saphenous n. (from femoral n.)
• common peroneal n. (from sciatic n.)
• tibial n. (from sciatic n.)

Question 32

The **foramen lacerum **in the equine is the equivalent of which foramina in the dog?

Why is this important?

Answer 32

foramen lacerum = oval foramen + jugular foramen

**For facial nerves, the nerves that go through the oval foramen in the dog, for instance, would go through the foramen lacerum in the horse.

Question 33

The foramen orbitorotundrum in ruminants and pigs is the combination of:

Answer 33

orbital fissure & round foramen

Ruminants do NOT have an internal carotid artery. Instead, a branch of the maxillary a. dives into the foramen orbitorotundrum to supply the brain

(foramen orbitorotundrum is shown as ‘R’ in photo)

Question 34

Describe the unique positioning of the alar canal in ruminants compared to that of canines

Answer 34

It it unique because ruminants do not have an alar canal, a rostral alar foramen, or a caudal alar foramen.

Question 35

True or false: the **tympano-occipital fissure **is present in carnivores & herbivores

Answer 35

false.

The tympano-occipital fissure is only present in carnivores.

Question 36

At the base of the bovine horn, there is a transitional epithelium called:

Answer 36

Epiceras

This is tissue that grows and creates the horn (surrounds the cornual process)

When dehorning a cow, you want to make sure you get all of this, otherwise the horn will grow back

Question 37

What is the main nerve providing innervation to the bovine horn?

Answer 37

Cornual n.

Innervation can also come from the infratrochlear n.

Question 38

Which single structure passes through the supraorbital foramen in the bovine?

Answer 38

ONLY the frontal vein passes through the supraorbital foramen in the bovine

(In the horse, the supraorbital a. and n. pass through the supraorbital foramen)

Question 39

In the horse, when you have a laceration to the upper eyelid, which nerve can you block to repair the laceration without sedating the animal?

Answer 39

supraorbital n.

(branch of the opthalmic br. of Trigeminal n.)

Question 40

Identify ‘A’

Answer 40

Cornual n.

Question 41

Which muscle forms the medial border of the jugular groove in the equine?

Answer 41

omohyoideus m.

Question 42

In the equine, the guttural pouches are each divided into medial and lateral compartments by which bone?

Answer 42

stylohyoid bone

Question 43

Identify the muscle tagged in the equine. Which nerve innervates it?

Answer 43

Lateral rectus m.

Abducens n.

Question 44

The hollow space within the cornual process in the bovine is called the:

Answer 44

cornual diverticulum