Equine Head Flashcards
What are the 3 external features of the skull?
Nasoincisive notch
Facial crest
Mandibular notch
What are the foramina of the skull?
Supraorbital
Infraorbital
Mental
Mandibular
What are the nerve blocks of the face?
Infraorbital
Mental
Mandibular
What are the nerve blocks of the eye?
Supraorbital (trigem, opthalmic)
Auriculopalpebral (Facial, palpebral)
Lacrimal (trigem and opthalmic)
Zygomaticofacial (trigeminal, zygomatic)
Infratrochlear (trigem, opthalmic)
Which nerve blocks comes from the trigeminal nerve (7)?
Infraorbital, mental and mandibular alveolar
How do you locate the infraorbital nerve block?
Three finger method: nasoincisive, infraorbital f. and rostral end of facial crest
Lift the levator labii superioris muscle to locate
What does the infraorbital nerve block desensitize?
Upper lip
Nose
First upper 2 cheek teeth
How do you locate the mental nerve block?
Palpate caudal to the canines
Covered by the depressor labii inferioris muscle
What does the mental nerve block desensitize?
Lower lip
Canine and incisors
Mandibular alveolar nerve block
Intersection point between a line parallel to the masticatory surface of the cheek teeth and lateral canthus
Lower cheek teeth blocked
Subpalpebral lavage system
Used for medication
To avoid the eye
Anesthetize the upper eyelid
Supraorbital nerve block
Supraorbital branch of the opthalmic nerve
Portions of palpebral branches of the auriculopalpebral n.
3 fingers= dorsal surface of eyelid, supraorbital foramen, supraorbital fossa
Purpose of the supraorbital nerve block
Prevents sensation to the upper eyelid
Auriculopalpebral nerve block
Located @ the dorsal edge of the zygomatic arch
Prevents blepharospasm (blinking)
Lacrimal nerve block
Located along the dorsolateral third of the orbit
Zygomaticofacial nerve block
Located laterally along the ventral margin of the orbit
Medial to the zygomatic process of the frontal bone
False Nostril (diverticulum)
Blind sac (closed)
CS: block with thumb to help navigate the nasogastric tube
True nostril
Opening for breathing
CS: nasogastric intubation and endoscopy
How can the nasolacrimal duct be blocked?
Can be blocked by polyps (excessive lacrimation)
How do you test the nasolacrimal duct?
With the patency of the NLD Jones Test
Postive (good): dye put in eye and comes out of duct
Neg (bad): corneal ulcers
Nasal septum
Sits in the vomer bone
CS: NS deviation
Hyaline cartilage that separates the left and right nostrils
What are the 3 nasal conchae?
Dorsal
Ventral
Ethmoidal
Which meatus does the nasogastric tube or endoscope go into?
Ventral nasal meatus
Ethmoid conchae
Highly vascularized
CS: Ethmoid Hematoma, nasal bleeding that could be fatal (if hit by nasogastric tube)
Sinusitis
Other than dental, most important cases
Enlargement, infected sinus with a large amount of exudate (pus)
Fix: trephination and bone flap
Paranasal sinuses
Gas filled cavities between the internal and external plates of the flat bones that comprise the skull
Diverticula, lined by ciliated glandular epithelium
What is the function of the sinuses?
Reduce the weight of the skull and provide expanded spaces for the teeth
What are the 3 paranasal sinuses?
Conchofrontal
Maxillary (rostral and caudal)
Sphenopalatine
What does the CAUDAL DORSAL concha communicates with and what does it form?
Communicates with the frontal sinus to form the conchofrontal sinus
What does the CAUDAL VENTRAL concha communicates with the what is it over?
With rostral maxillary sinus over the infraorbital canal
What does the CAUDAL MAXILLARY sinus communicate with?
Dorsally with the conchofrontal sinus and caudally with the sphenopalatine sinus
Where do the sinuses drain?
Into the nasal cavity via the nasomaxillary fissure then passes to the middle nasal meatus
How are the rostral and caudal portions of the maxillary sinus separated?
Bony septum located 5 cm caudal to the rostral end of the facial crest
What are the borders for the maxillary sinus
Cr: rostral end of the facial crest to the infraorbital foramen
Cd: Rostral part of the bony orbit of the eye
Ventral: Facial crest
Dorsal: Infraorbital foramen to medial canthus of the eye
Why is the dorsal border of the maxillary sinus important?
Surgical access
Border covers the infraorbital canal (nerve) and nasolacrimal duct
Don’t want to injure, so you go below the border
Molar roots
Roots of the last 3 cheek teeth are in maxillary sinus
As a surgeon: use the borders to access a tooth abscess or remove a tooth
PM4 partially located in the rostral maxillary sinus
Sphenopalatine sinus location
Cd to ethmoidal concha
Dor to guttural pouches and nasopharynx
Cr to physis between the basisphenoid and basioccipital bones
Clin. Sig. of the Sphenopalatine sinus
Young animal gets an infection –> infection goes through the bone plate and to the brain –> neurological signs
How does the Sphenopalatine sinus drain?
Rostrally into the caudal maxillary sinus –> nasal cavity via the middle nasal meatus
How do you get into the nasal sinuses?
Trephination (making an opening)
Bone Flap (cutting skin around the bone)
Guttural pouches
Extensions of ear of the horse (2)
Air-filled diverticula from the auditory tube separated by a thin septum on the midline
Lined with ciliated pseudostrat. epithelium (goblet and mucus cells)
What are the functions of the guttural pouch?
Influence BP in the internal carotid
Cerebral blood-cooling mechanism during racing
Balace system
What are the components of the GP?
Medial compartment (larger)
Lateral compartment
Stylohyoid bone (divides the compartments)
Capacity: 300-500 ml
Stylohyoid bone
Largest bones of the hyoid apparatus
Incompletely divide the guttutal pouches into medial and lateral
What are the guttural pouches drained by?
Medial retropharyngeal LN
When does the physis between the basioccipital bone and basisphenoid bone close?
@ 2-3 years of age
What muscle attaches to the basioccipital bone and basisphenoid bone and is involved in guttural pouch diseases?
Longus capitis muscle
What are the natural entrances to the GP?
Nasopharynx (via endoscopy)
Lateral Canthus
Dorsal to Pouch
Lymphoid Hyperplasia
Pharyngitis or sore throat (bumps)
Normal in the pharynx
What diseases are associated with the GP?
Tympani
Empyema
Mycosis
Exostosis of the styloid bone
Tumors (melanoma)
GP tympani
Enlargment of the GP with air
Needs to be drained
GP emypema
GP filled with pus (infection and bacteria)
Dried pus= chondroid formation, surgically remove
GP Mycosis
Fungus living in GP
Fungus grows on walls of BVs –> weakens and ruptures them
Leads to GP bleeding
Exostosis of the stylohyoid bone
Excessive bone formation on the stylohyoid bones
Surgical approaches of the GP
Viborg Triangle
Modified Whitehouse (enter through medial compartment)
Viborg Triangle
Landmarks: ramus of the mandible (cr)
Linguofacial vein (ven)
Tendon of the sternocephalicus (dor)
Parotid ducts are at risk
Whitehouse technique
NOT midline
Cutting beside the midline (couple inches)
Larynx
Box that separates the oral cavity from the respiratory system
CS: laryngeal hemiplegia (roaring)
Epiglottis
Shutter for breathing/ swallowing
CS: epiglottic entrapment (by excessive mucous membrane due to inflammation of the area)
Soft Palate
Root of the tongue, shutter also
CS: Dorsal displacement of the soft palate (SP sits on top of the epiglottis)
Cricoarytenoideus dorsalis
Supplied by recurrent laryngeal nerve (stimulation –> contraction –> muscle opens –> air comes)
CS: Laryngeal hemiplegia (roaring)
F: Abduct arytenoid
Laryngeal prosthesis (tie back)
Solution for hemiplegia
#1 site: dorsal aspect of cricocartilage (most caudal point)
#2 site: muscular process of the arytenoid cartilage
What is another procedure surgeons do with the tie back?
Ventriculectomy/ Sacculectomy
Burr inside and cut mucous membrane lining ventricle to increase diameter (also done with laser)
