Upper Resp. Passageway Equine Practical

Question 1

The sinuses have been impregnated with silver to highlight their extent and boundaries. Note the extent of the frontal and maxillary sinuses and their relationship to each other. The boney septum which divides the maxillary sinus into a rostral and caudal compartment is also highlighted. Identify 1-4.

Answer 1

1 =infraorbital canal

2 = frontal sinus

3= septum separating caudal maxillary sinus from rostral compartment

4= rostral maxillary sinus

Question 2

Which cheek teeth lie within the rostral maxillary sinus and which lie within the caudal maxillary sinus?

Answer 2

¾ and 5/6

The rostral and caudal maxillary sinuses increase in size with age as the reserve crowns of the cheek teeth move down as the teeth wear.

Question 3

left lateral equine skull

Answer 3

orange: gutteral pouches (left and right)
yellow: pharynx
blue: ethmotrubinates
red: mandibles (left and right)
white: epiglottis

dark blue: styelohyoid bones (left and right)

green: basiphenoid

Question 4

dorsoventral equine skull

https://vetmed.illinois.edu/imaging_anatomy/equine/skull/ex01/skull01-eq%20.html

Answer 4

red: mandibles
blue: nasal turbinates (conchi)
orange: vomer
yellow: maxillary sinus
pink: styelohyoid bones

dark blue: maxillary teeth

Question 5

left-right oblique view equine skull

Answer 5

red: right mandible
orange: left zygomatic arch
grey: hyoid bones
yellow: left mandible and teeth
green: left frontal sinus
blue: left maxilla and teeth

Question 6

identify the paranasal sinuses

Question 7

why doesn’t the nasal vestibule directly lead to the nasal cavity in this species

Answer 7

A blind pouch extends dorsal and caudally as far as the naso-incisive notch (false nostril). The entrance to the nasal cavity lies ventral and medial to this.

Question 8

List two ways the horse can very the amount of oxygen entering the lower respiratory passageways during exercise.

Answer 8

By reducing blood supply to nasal mucosa and abducting the glottis

Question 9

Identify the labelled structures using the specimens and keys provided

Answer 9

1. dorsal meatus
2. middle meatus
3. common meatus
4. ventral meatus
5. frontal sinus
6. rostral maxillary sinus
7. infraorbital canal and nerve

Question 10

The dorsal conchae form a sinus caudally in this species. This is in direct communication with the frontal sinus. How do these sinuses communicate with the nasal cavity?

Answer 10

Indirectly the frontomaxillary opening communicates with caudal maxillary sinus which communicates with the nasal cavity via the nasomaxillary opening.

Question 11

what is the features of the ethmoidal conchae in the equine and where are they

Answer 11

small

confined to the caudal part of nasal cavity

Question 12

The ventral conchae also form a sinus caudally. This communicates with the rostral maxillary sinus. Do the rostral and caudal maxillary sinuses communicate with each other?

Answer 12

No separated by a septum

Question 13

How do the a) rostral and b) caudal maxillary sinuses communicate with the nasal cavity?

Answer 13

Both communicate with the nasal cavity via the nasomaxillary opening which straddles the septum.

Question 14

Precisely where would you locate the nasomaxillary opening?

Answer 14

Middle meatus of the nasal cavity

Question 15

The infraorbital canal carrying the infraorbital nerve travels through the maxillary sinus. What name is given to the foramen in the skull through which this nerve becomes superficial?

Answer 15

Infraorbital foramen

Question 16

sagittal sections of horse head nasal septum intact

Answer 16

1. Nasal septum
2. Frontal sinus
3. Hard palate
4. Soft palate
5. Nasopharynx
6. Oropharynx
7. Opening of auditory tube (large cartilage support)
8. Guttural pouch- the midline septum has been reflected to reveal the medial and lateral compartments of the right pouch
9. The stylohyoid bone cans be seen to divide the pouch into medial and alteral compartments.
10. The oesophagus
11. Larynx
12. The vomer

Question 17

Sagittal sections horse head nasal septum removed to reveal conchae in nasal cavity

Answer 17

1. Leading to nasal vestibule
2. Dorsal concha (scrolled)
3. Dorsal concha (sinus)
4. Frontal sinus – continuous with 3
5. Ventral concha
6. Ethmoidal conchae
7. Opening of auditory tube (large cartilage support)
8. Long soft palate- surrounds aditus of larynx
9. Stylohyoid bone in guttural pouch.
10. Trachea

Question 18

Sagittal section showing the extent of the Paranasal sinuses

Answer 18

1. Frontal sinus
2. Dorsal conchal sinus (communicates with [1]
3. Frontomaxillary opening
4. Caudal maxillary sinus
5. Sphenopalatine sinus (communicates with [4]
6. Rostral maxillary sinus
7. Ventral conchal sinus (communicates with [6]
8. Infraoribital canal and nerve (travels through [6] &[7]

Question 19

Sagittal section showing the extent of the Paranasal sinuses

Answer 19

1. Frontal sinus
2. Dorsal conchal sinus (communicates with [1]
3. Frontomaxillary opening
4. Caudal maxillary sinus
5. Sphenopalatine sinus (communicates with [4]
6. Rostral maxillary sinus
7. Ventral conchal sinus (communicates with [6]
8. Infraoribital canal and nerve (travels through [6] &[7]

Question 20

Guttural pouch transverse section through donkey head (caudal section)

Answer 20

1. Lateral compartment of guttural pouch
2. Septum dividing each guttural pouch
3. Rami of mandible
4. Arytenoid cartilages
5. Oesophagus
6. Cranial cavity

Question 21

name the structures

Question 22

name the sinuses

Answer 22

pink: ventral conchal sinus
yellow: sphenopalatine sinus

light blue: rostral maxillary sinus (left)

purple: caudal maxillary sinus
red: frontal sinus
orange: dorsal conchal sinus

Question 23

name the sinuses

Answer 23

pink: ventral conchal sinus
yellow: sphenopalatine sinus

light blue: rostral maxillary sinus (left)

purple: caudal maxillary sinus
red: frontal sinus
orange: dorsal conchal sinus

Question 24

name the sinuses

Answer 24

pink: ventral conchal sinus
yellow: sphenopalatine sinus

light blue: rostral maxillary sinus (left)

purple: caudal maxillary sinus
red: frontal sinus
orange: dorsal conchal sinus

Question 25

The soft palate which is extremely long in this species. The laryngeal aditus is held within the nasopharynx in the horse by the caudal pillars of the soft palate (palatopharyngeal arches). What are the consequences of this for the horse?

Answer 25

Obligate nasal breather

Question 26

The maxillary sinus is particularly extensive in this old animal- why does the maxillary sinus enlarge with time?

Answer 26

The reserve crowns embedded in the maxillary sinuses gradually move down as the cheek teeth wear down

Question 27

The approximate position of the fronto-maxillary opening is indicated. Which 2 sionus compartments intercommunicate via this opening:

Answer 27

Dorsofrontal and caudal maxillary sinuses

Question 28

What function has been assigned to the guttural pouches of the horse?

Answer 28

Thought to be involved in cooling the blood flowing to the brain via the internal carotid artery during excercise

Question 29

In the horse the paranasal sinuses intercommunicate with each other. What name is given to the opening which links the dorsal conchal/ frontal and caudal maxillary sinuses?

Answer 29

The frontomaxillary opening

Question 30

What name is given to the single opening through which all of the paranasal sinuses communicate with the nasal cavity in the horse?

Answer 30

The nasomaxillary opening

Question 31

Where precisely is this opening located in the nasal cavity?

Answer 31

In the middle meatus (i.e between the dorsal and ventral conchae)

Question 32

what are the clinical landmarks for drainage of the frontal sinus

Answer 32

rostral: transverse line half way between medial canthus of eye and nasoincisive notch caudal: transverse line taken half way along zygomatic arch dorsal: approx 2cm from the midline ventral: dorsal to line from medial canthus of eye to nasoincisive notch

Question 33

what are the clinical landmarks for drainage of the maxillary sinus

Answer 33

rostral: line through infraorbital foramen caudal: transverse line through middle of eye dorsal: line from medial canthus of eye to infraorbital foramen ventral: facial crest and just rostral to its end **position of nasolacrimal duct and infraorbital nerve limit surgical field**

Question 34

why would you nasogastrically intubate a horse

Answer 34

1. diagnostic (colicking horse have reflux) 2. treatment: admin of fluid therapy to dehydrated animal

Question 35

how is a nasogastric tube passed in an equine

Answer 35

1. Clinician stands in front of the horse or at its shoulder (if you are in front of the horse you are at greater risk from the horse striking with a foreleg). Handler should be at the shoulder holding the lead rope. They may also place a hand on the middle of the face to stop the horse raising its head. Some animals will not tolerate the procedure and may require twitching or sedation 2. Mark the tube with the length of the horse’s head. Warm up the end of the tube so it’s more flexible and comfortable. Put one hand at the horse’s nostril and use the other to feed the tube in. Ensure the tube passes into ventral meatus put some downward pressure on it with your thumb. If hard structures are met or tube is difficult to pass it is probably not in ventral meatus (withdraw and redirect) 3. slowly feed tube in until mark reaches the nostril, and you feel soft resistance, so that you know the tube is in the pharynx. The tube is more likely to pass into the trachea with the neck extended, and the oesophagus with it flexed, so put pressure on the face to push the horse’s nose towards its chest. Gentle pressure at the oesophageal opening will stimulate swallowing (twisting the tube 180 degrees can help), when this occurs gently advance the tube 3. Palpation of the tube on the left side of the neck above the jugular (cannot be palpated if in trachea). Suction on the end of the tube (air and no resistance if in trachea – may also cough, negative pressure in oesophagus).If in correct location advance tube gently. Blowing down it inflates the oesophagus in front of the tube. When the stomach is reached there is a reduction in resistance, and borborygmi can be heard through the tube.

Question 36

what is an auriculopalbebral nerve block used for

Answer 36

The upper eyelid of the horse is strong. Even when sedated considerable force is needed to open the eye if the horse does not wish to open it. It is safer to paralyse the upper eyelid with this nerve block than force it open, particularly if the globe may be compromised by injury N.B. block does not provide analgesia/desensitisation

Question 37

what needle is used to perform auriculopalpebral nerve block

Answer 37

5/8” 25G needle, 2ml lidocaine

Question 38

how is a auriculopalpebral nerve block performed

Answer 38

The nerve can be palpated as it passes over the dorsal aspect of the zygomatic arch (above the supraorbital fossa), about halfway between the base of the ear and the lateral canthus of the eye. The needle is inserted subcutaneously so it is parallel to and overlying the nerve.

Question 39

what is the supraorbital nerve block used for

Answer 39

desensitizes the medial two thirds of upper eyelid

Question 40

what is needed for supraorbital nerve block

Answer 40

5/8” 25G needle

Question 41

how is supraorbital nerve block done

Answer 41

If working on the horse’s left eye, use the thumb and second finger of your right hand to grasp the supraorbital process. Your index finger will fall on or near the supraorbital foramen. Inject subcutaneously overlying the foramen.

Question 42

what is a lacrimal nerve block used for

Answer 42

desensitizes the lateral third of upper eyelid

Question 43

what is the zygomaticofacial nerve block used for

Answer 43

Desensitises lateral 3/4 of lower eyelid The above 4 blocks make up a “ring block”

Question 44

what is a retrobulbar nerve block used for

Answer 44

Used for intraocular/corneal surgery and enucleation

Question 45

what are the sinuses exposed

Answer 45

1. frontal sinus and dorsal conchal sinus 2. caudal maxillary sinus 3. rostral maxillary sinus

Question 46

which nerve block is this

Answer 46

auriculopalpebral nerve block

Question 47

what nerve block is this

Answer 47

supraorbital nerve block