Anatomy 2 - Equine Head 1

drraythe's version from 2015-06-05 23:29

bones, nose, sinuses

Question Answer
what bones form the roof of the cranium? occipital, parietal, and interparietal bones. Also rostrally by the frontal bones
(in OX, what is the roof of the cranium formed by?)formed by the frontal bone which displaces the parietal bones laterally and caudally
how does the external saggital crest run? forms what?runs cranially, in the midline, diverges to form the temporal line on either side before joining the zygomatic processes of the frontal bone
what does the supraorbital foramen pierce?pierces the root of the zygomatic process of the frontal bone
what forms the nuchal crest? The occipital bone (it forms most of the ca part of the of the skull)
what is a lateral, prominant ridge of the skull which is a major landmark?facial crest
what lies between the nasal and incisive bones?the nasoincisive notch
what are the two divisions of the cranial cavity? (comparitive size, their contents) and what are they separated by?(1) Rostral part-- large. houses the cerebrum. (2) caudal part- smaller. houses the cerebellum. SEPARATED DORSALLY BY THE TENTORIUM CEREBELLI OSSEUM
describe/explain the conchae/ conchal sinusesHave dorsal and ventral conchae. The dorsal is divided into caudal and rostral...the caudal portion of the dorsal conchae forms the DORSAL CONCHAL SINUS and combines with the frontal sinus to form the conchofrontal sinus. The Ventral conchae are ALSO divided into caudal and rostral. The Caudal ventral conchae forms the ventral conchal sinus and this communicates with the rostral maxillary sinus
the osseus support of the nose is formed by which bones?nasal, incisive, maxillary, frontal, lacrimal, zygomatic and palatine bones
What is support of the nose/nasal septum dorsally, medially and ventrally given by? (names of dorsal and ventral portions?)the presence of the alar (wing-like) cartilages (consists of a lamina dorsally and a cornu ventrally) which are attached to the rostral border of the nasal septum
what is the lateral support of the horse nostril? in the horse there is no lateral support for the nostril. The medial accessory cartilage is large and s-shaped while in other species it is small.
how is the nostril divided in the horse? by what? how do these divisions continue?the alar fold divides the nostril into dorsal and ventral passageways. The dorsal leads to the nasal diverticulum (blind cutaneous pouch) and the ventral leads into the nasal cavity.
what are paranasal sinuses? why do we care about them?invaginations of the nasal epithelium into adjacent bones and some nasal conchae. We care because they are infection prone, for dental work, and de-horning
in ox and pig, the frontal sinuses invaginate what?they extend caudally to invaginate the parietal, interparietal , occipital, and temporal bones
in horned animals, what sinus is important to keep in mind?in horned ruminants the corneal process of the frontal bone is also excavated by a diverticulum of the frontal process. *consideration in dehorning procedures.
as the frontal sinus extends rostrally, what happens?extends rostrally into the dorsal turbinate bone - causing the caudal half of the turbinate to have a common cavity with the frontal sinus
what is unique about the equine frontal sinus?The turbinate part of the frontal sinus (it extends into the turbinate bones) makes the equine frontal sinus to extend more rostrally than is the case in other domestic animals.
look at all the damn picturesfack
in most animals, the frontal sinuses communicate directly with the nasal sinuses. In horses, how do they communicate?Frontal-->maxillary--> nasal cavity. (no communication between frontal and nasal)
what is the name of where the frontal sinus opens into the maxillary sinus? where is it situated?frontomaxillary aperture. it is situated in the floor of the frontal sinus between the median plane and the orbit and link the frontal sinus directly with the caudal maxillary sinus
explain how the maxillary sinus is dividedrostral and caudal, with the ventral turbinate bone in the middle (with the infraorbital canal on top of the v.turb.) *the vent. turbinate divides it into the L and M
what are the cheek teeth growing into?the ventral turbinate bone of the maxillary bone
How does the maxillary sinus communicate with the nasal cavity?The rostral and caudal maxillary sinus opens directly into the nasal cavity through the nasomaxillary aperture thus allowing indirect communication of the frontal sinus with the nasal cavity via those sinuses.
which animals have an undivided frontal sinus?horse and cat
aside from the maxillary sinus, what else does the frontal sinus communicate with? to form what? why do we care about this?with the dorsal conchal sinus to form the conchofrontal sinus. It has a single cavity which is incompletely separated into compartments by bony lamellae (this may be trephined to repel the last upper cheek tooth). [basically it's one big space and the one part is frontochoncal]
what is the rostral surgical limit of the FRONTAL SINUS?Mid-way between medial angle (canthus) of the eye and the rostral end of the facial crest (easily seen and/or palpable).
what is the caudal surgical limit of the FRONTAL SINUS?Tranverse plane through zygomatic arch.
what is the lateral surgical limit of the FRONTAL SINUS?A line passing through the supraorbital foramen and parallel to the medial limit.
what is the medial surgical limit of the FRONTAL SINUS?A line about 2 cm parallel to the median plane.
what are the two halves of the MAXILLARY sinus? (two halves on each side of the head)rostral and caudal
how are the rostral and caudal maxillary sinuses divided?COMPLETELY SEPARATED by an OBLIQUE (maxillary) SEPTUM (usually about 5 cm from the rostral end of the facial crest)
is there communication between the rostral and caudal maxillary sinuses?The oblique (maxillary) septum may dissolve proximally, otherwise, NO direct communication between the two sinuses.
how/by what is the ROSTRAL/CAUDAL MAXILLARY sinus SUBdivided? do they communicate?The VENTRAL TURBINATE is incorporated into the rostral/caudal maxillary sinus, which creates two compartments - a lateral, original compartment and a medial, turbinate compartment. they both COMMUNICATE FREELY, dorsally
where does the nasolacrimal canal lie?on the dorsolateral aspect of the maxillary sinus (like on top of it almost)
what does the nasomaxillary opening (slit like) allow communication between?the maxillary sinuses and the middle nasal meatus
describe where the nasomaxillary opening lies?curved slit which lies between the dorsolateral wall of the skull and the curved dorsolateral edge of the ventral turbinate ( like the top of the maxillary sinuses open into a little passage into the middle nasal meatus-- look at pic. its where the nasolacrimal canal is)
problems associated with the nasomaxillary opening?when inflamed, the mucosa will block this slit
what does the frontomaxillary opening connect?the frontal sinus and the caudal maxillary sinuses
which sinus do roots of which teeth project into?the roots of all cheek teeth except the last one project into the MAXILLARY sinus
how MUCH do the cheek teeth roots project into the maxillary sinus?The level of projection varies with the age of the animal. The sockets occupy a greater proportion of the sinus in younger animals. Teeth are gradually extruded as animal ages.
CAUDAL surgical limits of the MAXILLARY sinus?rostral border of the orbit
ROSTRAL surgical limits of the MAXILLARY sinus?a line from the rostral end of the facial crest to the infraorbital foramen
VENTRAL surgical limits of the MAXILLARY sinus?the facial crest.
DORSAL surgical limits of the MAXILLARY sinus?a line from the infraorbital foramen parallel to the facial crest. **the nasolacrimal duct lies just dorsal to this line and must be avoided.
Why would you trephine the maxillary sinus? how would you do it?do it to reach all of the superior cheek teeth for repulsion except the last one. Area entered between TWO LINES: (1) Dorsal limit (to avoid damage to the nasolacrimal duct) is a line between the infraorbital foramen and the medial palpebral commissure of the eye. (2) Ventral limit (to stay above the root of the teeth)- is above the facial crest
In relation to the cheek teeth you are removing, where do you want to trephine?DEPENDS ON THE TOOTH! The hole is made directly above the exposed part of the tooth for the first two cheek teeth and just caudal to the tooth for the third, fourth and fifth ones. The last tooth? You must trephine the conchofrontal sinus 3 cm off the midline directly between the medial palpebral commissures of the eyes (a long pounch is required and a curve one is often useful)
which sinuses communicate directly with the nasal cavity?rostral and caudal maxillary sinuses
Where does the ventral conchal sinus drain? The dorsal?ventral= into the rostral maxillary sinus, but the infraorbital canal and the ventral turbinate can impede this. Dorsal= drains into the frontal (think conchofrontal sinus) and then the frontal drains into the caudal maxillary sinus. (maxillary sinuses drain into nasal cavity)
Why do we want horses to eat with their head at ground level?because the maxillary sinuses' (only ones to drain into nasal cavity) floor is VENTRAL to the nasomaxillary opening (aperture) (slit) (so snot has to move UP to go OUT).
Why would you trephine the frontal sinus? how would you do it?do it to remove the last cheek tooth, OR can examine the caudal maxillary sinus, via the frontomaxillary aperture. Trephine Halfway between the medial angle of the eye and the midline
why would you trephine the rostral maxillary sinus? how would you do it?you can inspect the ventral conchal sinus through this. Trephine 25 mm dorsal to the rostral end of the facial crest.
how do you trephine the caudal maxillary sinus?(he doesnt say why in this slide) toward the caudal end of the facial crest (the maxillary septum lies 5cm from the rostral end of the facial crest)

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