Paranasal Sinuses

Question 1

Surgical Borders for Equine Frontal Sinus

Answer 1

Caudal: Zygomatic Process of the Frontal Bone
Rostral: 1/2 way between the orbit and the infraorbital foramen
Medial: 2cm from midline
Lateral: Supraorbital foramen to the rostral portion of the medial limit

Question 2

Surgical Borders for the Equine Maxillary Sinus

Answer 2

Caudal: Rostral portion of the orbit (medial canthus of the eye)
Rostral: Rostral end of facial crest/infraorbital foramen
Ventral: Facial crest
Dorsal: Line from infraorbital foramen parallel to the facial crest

Question 3

Surgical Borders for Bovine Frontal Sinus

Answer 3

Caudal: Base of skull
Rostral: Rostral border of orbit

Question 4

Surgical Borders for Bovine Maxillary Sinus

Answer 4

Caudal: Rostral border of orbit
Rostral: Facial tuberosity
Dorsal: Line from medial angle of eye to infraorbital foramen
Ventral: Line from zygomatic arch to facial tuberosity

Question 5

What does the equine frontal sinus communicate with?

Answer 5

Continuous with the dorsal conchal sinus over the ethmoidal labyrinth: together called CONCHOFRONTAL SINUS
Communicates freely with the caudal compartment of the maxillary sinus via FRONTOMAXILLARY OPENING

Question 6

Describe the compartments of the equine maxillary sinus

Answer 6

Divided into rostral and caudal compartments by an oblique septum.
Rostral Compartment is partially divided into medial and lateral parts by the infraorbital canal. Medial part communicates with the middle nasal meatus via the Nasomaxillary opening.
Caudal Compartment divided into medial and lateral parts by the infraorbital canal. Medial part communicates with the sphenopalatine sinus and with the middle nasal meatus via the Nasomaxillary opening.

Question 7

Why does the maxillary sinus increase in size as the horse ages?

Answer 7

Because the last 3-4 upper cheek teeth project into the maxillary sinus and as the horse ages and the teeth are worn and move down there are less teeth in the sinus so the sinus gets larger

Question 8

Describe the divisions of the bovine frontal sinus

Answer 8

Divided into one large caudal frontal sinus and 2 or 3 smaller rostral frontal sinuses.
Caudal portion has 3 blind pockets:
1) Postorbital Diverticulum - caudal and medial to orbit (largest)
2) Cornual Diverticulum - occupies the base of the horn
3) Nuchal diverticulum - caudal and medial end of sinus

Question 9

Why must cattle be dehorned before 6 months of age?

Answer 9

Caudal frontal sinus is continuous with the cornual diverticulum which is within the cornual process.
Before 6 months the sinus has not yet invaded the horn.
If the sinus has invaded the horn you expose the cornual diverticulum to the environment thereby exposing the frontal sinus - BAD

Question 10

Describe the communications between sinuses and nasal passages in the bovine.

Answer 10

There is NO communication between maxillary and frontal sinuses
There is a Nasofrontal opening and a Nasomaxillary opening (there is no nasofrontal opening in the horse)

Question 11

What is the lacrimal bulla in the cow?

Answer 11

Extension of the maxillary sinus (ventral to the orbit) - thin, super breakable