Sinuses & Horn

Question 1

Explain the structure of the paranasal sinuses, their drainage and interconnection in the horse and dog

Question 2

Explain the structure of the paranasal sinuses

Answer 2

Blind ending pouches (diverticles), between external and internal lamina of the bones of the skull, which communicate with the nasal cavity

Arise as invaginations into each bone

Contain respiratory epithelium in common with nasal cavities:

Innervated from ophthalmic and maxillary branches of the trigeminal nerve (details in 
     neuroscience module)

Common sensory nerve of the face

Question 3

Explain the function of the paranasal sinuses

Answer 3

Resonating cavities (voice).

Insulation / cooling (brain).

Light weight construction.

Increased insertion surfaces, space for teeth.

Question 4

What are the different types of paranasal sinuses?

Answer 4

Rostral and Caudal Maxillary
Dorsal and Ventral Conchal
Ethmoidal
Frontal
Sphenopalatine (PS)

Question 5

Outline the structure of the frontal sinus

Answer 5

Located between nasal and cranial cavities,

Usually drains into ethmoidal meatus: (Different in the horse which drains into the frontomaxillary aperture)

Can be 3-5 compartments depending on species which remain unconnected

Question 6

Outline the frontal sinus in cattle

Answer 6

5 compartments:

One larger caudal compartment leads to cornual process and pneumatises the horn.

Question 7

Outline the frontal sinus in dogs

Answer 7

3 compartments:

Lateral compartment largest. May include the zygomatic process.

Question 8

Outline the frontal sinus in a pig

Answer 8

One very extensive cavity

Question 9

Describe the Maxillary sinus structure

Answer 9

Located at the caudolateral aspect of upper jaw. Around cheek teeth (molars and premolars).

Huge species variability (dog – simplest; horse most complex).

Invagination into maxillary bone from the middle meatus:

Drains into middle meatus:
Naso-maxillary opening
Usually a narrow slit dorsal to the bulk of the sinus so natural drainage is difficult
Contains the roots of some of the upper cheek teeth

Question 10

Outline some species differentiation of cattle and carnivores in relation to the structure of the maxillary sinuses

Answer 10

In cattle extends into palatine bone:
Palatomaxillary sinus

In carnivores very large opening - becomes the nasomaxillary recess

Question 11

What additional paranasal sinuses do horses have?

Answer 11

sphenopalatine (cant be reached whilst horse is alive)
ethmoidal

Question 12

What additional paranasal sinuses do cattle have?

Answer 12

lacrimal sinus within the medial orbit
sphenoidal sinuses which lie past the orbit
within the conchae themselves are the conchal sinuses

Question 13

What additional paranasal sinuses do pigs have?

Answer 13

lacrimal, sphenoid and conchal

Question 14

What are the paranasal sinuses in birds

Answer 14

The infraorbital sinus is the only paranasal sinus in birds and is located lateral to the nasal cavity and surrounding the eyes ventrally.

Question 15

Outline the drainage of the equine paranasal sinus system

Answer 15

Frontal sinus and dorsal conchal sinus communicate together and drain through the frontomaxillary aperture into the caudal maxillary sinus.

The Sphenopalatine communicates witht he caudal maxillary sinus.

From the Caudal maxillary sinus the drainage continues to the middle meatus through the nasomaxillary opening.

The rostral maxillary sinus drains straight in the middle meatus after passing to through nasomaxillary opening

Question 16

Outline the cutaneous landmarks for preparation of surgical drainage on the frontal sinus

Answer 16

Half way between medial canthus and rostral end of facial crest - to - half way along zygomatic arch:

Surgical access: Half way between dorsal midline and dorsal rim of bony orbit.

Question 17

Outline the cutaneous landmarks for preparation of surgical drainage on the maxillary sinus

Answer 17

Infraorbital foramen - to - middle of eye.
Stay below so not to damage nerve and cause facial paralysis

Facial crest - to - line from infraorbital canal to medial canthus of eye.

Rostral:
Surgical access: 2.5cm dorsal to facial crest (medial compartment) or further ventral (lateral compartment).
Avoiding nasolacrimal duct (runs from medial canthus to nasoincisive notch).

Caudal:
5cm caudal.

Question 18

Outline the cutaneous landmarks for preparation of surgical drainage on the infraorbital sinus

Answer 18

Triangular cavity under the skin rostroventral to the eye

Question 19

List the other cranial structures associated with the paranasal sinuses

Answer 19

Nasolacrimal duct
Horn

Question 20

Describe the relationship between the paranasal sinuses and nasolacrimal duct

Answer 20

Drainage from medial canthus to nasal cavity:
Nasal punctae
Runs within maxilla and maxillary sinus

	Ends within nostril (easy to see the punctum):
		Horse
	
	Within nasal cavity:
		Dogs

Question 21

Describe the interconnection between the sinuses and horn

Answer 21

Continuous with sinuses
NOT ANTLERS – these are bone

Frontal sinus communicates with horn:
Caudal compartment in cattle

During removal of horn in adults the sinus is exposed:
	Animal will ‘breathe’ through its horn base
	Predisposed to infection and nasal discharge

Horns receive nervous sensory innervation from variety of sources:
Variable and species differences

Question 22

Describe the neuronal supply to the horns of cows and goats

Answer 22

Most arise from the trigeminal nerve:
The 5th cranial nerve of the head
Major sensory nerve of the face

Cornual nerve - all animals:
Located halfway between lateral canthus and horn base - along ridge of frontal bone

Cornual branch of Infratroclear nerve:
Located between medial canthus and medial horn base - 90% of animals

Frontal nerve (15% of animals)

Frontal sinus nerve (5% of animals) - within sinus

Cutaneous branches from 1st and 2nd cervical vertebrae – caudally

Question 23

Describe the vascular supply to the horns of cows and goats

Answer 23

Ruminants:
Branch off maxillary a.
Superficial temporal a.
Cornual a.

Very vascular – dehorning can produce a lot of bleeding if the fetotomy wire is not moved quickly

Can tie off with figure-8 around both horn stumps using twine

Question 24

Outline the process of dehorning

Answer 24

Calves:
Burn off under local (only cornual n.block needed)

Cattle:
Needs cornual n. and cornual br of infratrochlear n. blocks
May also need to block region caudal to horn
Wire/saw (work quickly- to reduce bleeding)
Opens the frontal sinus (don’t do when flies are abundant)

Goat kids:
Be careful since frontal sinus very small and xs heat can damage the brain

Question 25

Outline some clinically relevant causes of nasal discharge

Answer 25

Ventral conchal bulla fenestration

Unilateral:
Usually represents upper respiratory tract infection (bacterial or fungal
Nasal disease
Sinus disease (sinuses drain into nasal cavities)

Bilateral:
Bilateral upper airway disease

Or lower airway disease - caudal to pharynx / larynx
    Lung, trachea