Sinuses & Horn Flashcards
Explain the structure of the paranasal sinuses, their drainage and interconnection in the horse and dog
Explain the structure of the paranasal sinuses
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
Explain the function of the paranasal sinuses
Resonating cavities (voice).
Insulation / cooling (brain).
Light weight construction.
Increased insertion surfaces, space for teeth.
What are the different types of paranasal sinuses?
Rostral and Caudal Maxillary
Dorsal and Ventral Conchal
Ethmoidal
Frontal
Sphenopalatine (PS)
Outline the structure of the frontal sinus
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
Outline the frontal sinus in cattle
5 compartments:
One larger caudal compartment leads to cornual process and pneumatises the horn.
Outline the frontal sinus in dogs
3 compartments:
Lateral compartment largest. May include the zygomatic process.
Outline the frontal sinus in a pig
One very extensive cavity
Describe the Maxillary sinus structure
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
Outline some species differentiation of cattle and carnivores in relation to the structure of the maxillary sinuses
In cattle extends into palatine bone:
Palatomaxillary sinus
In carnivores very large opening - becomes the nasomaxillary recess
What additional paranasal sinuses do horses have?
sphenopalatine (cant be reached whilst horse is alive)
ethmoidal
What additional paranasal sinuses do cattle have?
lacrimal sinus within the medial orbit
sphenoidal sinuses which lie past the orbit
within the conchae themselves are the conchal sinuses
What additional paranasal sinuses do pigs have?
lacrimal, sphenoid and conchal
What are the paranasal sinuses in birds
The infraorbital sinus is the only paranasal sinus in birds and is located lateral to the nasal cavity and surrounding the eyes ventrally.
Outline the drainage of the equine paranasal sinus system
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
Outline the cutaneous landmarks for preparation of surgical drainage on the frontal sinus
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.
Outline the cutaneous landmarks for preparation of surgical drainage on the maxillary sinus
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.
Outline the cutaneous landmarks for preparation of surgical drainage on the infraorbital sinus
Triangular cavity under the skin rostroventral to the eye
List the other cranial structures associated with the paranasal sinuses
Nasolacrimal duct
Horn
Describe the relationship between the paranasal sinuses and nasolacrimal duct
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
Describe the interconnection between the sinuses and horn
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
Describe the neuronal supply to the horns of cows and goats
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
Describe the vascular supply to the horns of cows and goats
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
Outline the process of dehorning
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
Outline some clinically relevant causes of nasal discharge
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
