Q&A - Cases 1-8 Flashcards
A horse has left laryngeal hemiplegia, what nerve is responsible for this condition?
left recurrent laryngeal nerve
Which muscle is responsible for the abduction of the left arytenoid cartilage?
cricoarytenoideus dorsalis
Which portion of the arytenoid cartilage is visible by endoscopic examination of the larynx in the horse?
corniculate process
What are the cartilaginous structures that make up the larynx?
cricoid, thyroid, epiglottic and pair arytenoid cartilages
Which muscles of the larynx are involved in left laryngeal hemiplegia in addition to the cricoarytenoideus dorsalis?
crycoarytenoideus lateralis, vocalis, ventricularis, and arytenoideus transverses
What intrinsic muscles of the larynx are innervated by the cranial laryngeal nerve?
cricothyroideus
Where does the cranial laryngeal nerve originate?
the vagus nerve
Why is the horse an obligate nasal breather?
basically the soft palate blocks the horse from breathing through its mouth; the soft palate forms a continuous sheet of tissue that extends from the hard palate to the dorsal caudal pharyngeal wall, completely separating the oral and nasopharynx. The larynx protrudes through the palate in the intrapharyngeal ostium.
In the endoscopic photo of the horse with epiglottic entrapment, what anatomical structure is responsible for entrapping the epiglottis?
the aryepiglottic fold
When performing a laryngeal prosthesis procedure to correct left laryngeal hemiplegia, a large diameter non-absorbable suture is used to hold the arytenoid cartilage in abduction, describe the surgical approach to the larynx and the placement of the suture.
the surgeon makes an incision on the left lateral side below the lingual facial vein, and the larynx is exposed via blunt dissection. The suture is passed around the caudal edge of the cricoid cartilage and then underneath the cricopharyngeus and thyropharyngeus muscles. It then is passed through the muscular process of the arytenoid cartilage and is tied under tension which mimics the pull of the cricoarytnoideus dorsalis muscle and holds the cartilage in permanent abduction
In general which vessels could be involved as a source of hemorrhage in guttural pouch epistaxis?
internal carotid artery, external carotid artery, maxillary artery and vein, possibly the linguofacial, caudal auricular, superficial temporal, and occipital arteries
What does the internal carotid artery pass through in the horse to get to the guttural pouch?
the foramen lacerum
What nerves are closely associated with the guttural pouch?
facial, glossopharyngeal, vagus, accessory, sympathetic trunk, cranial cervical ganglion, and hypoglossal nerve
What foramina does the facial nerve pass through?
the stylomastoid foramen
What foramina does the glossopharyngeal, vagus, accessory, sympathetic trunk, and cranial cervical ganglion pass through?
the foramen lacerum
What nerves are associated with dysphagia and pharyngeal paralysis/paresis?
the glossppharyngeal and pharyngeal branch of the vagus
What nerves are associated with Horner’s syndrome?
sympathetic innervation from the cranial cervical ganglion
What are symptoms of Horner’s syndrome?
constricted pupil, enophthalmos, ptosis, protrusion of the third eyelid, vasodilaton
What is the cranioventral border of Viborg’s triangle?
the lingofacial vein
What is the caudodorsal border of Viborg’s triangle?
the tendinous insertion of the sternocephalicus or sternomandibularis
What is the cranial border of Viborg’s triangle?
the caudal border of the ramus of the mandible
What structure divides each guttural pouch into a large medial compartment and a small lateral compartment?
stylohyoid bone
Which artery is most likely to be involved with GP mycosis and the source of hemorrhage?
internal carotid artery
What is hyperkalemia caused by?
a continued intake of potassium in the diet and lack of excretion of potassium in the urine
What is hyponatremia and hypochloremia caused by?
volume dilution from water retention
What is increased plasma BUN and creatine caused by?
failure to excrete these waste products from the body
Why is the peritoneal fluid creatine higher than the plasma creatine while the BUN in both is more similar in concentration?
creatine is a larger molecule and therefore diffuses across membranes more slowly than the smaller urea molecule which equilibrates rapidly
What is persistent patent ductus arteriosis?
when the ductus arteriosis, a fetal vessel, does not close after birth leading to a left to right shunt from the aorta to the pulmonary artery
What mechanisms bring about the conversion of the fetal circulation to that of the neonatal foal?
the closure of the ductus arteriosus and the closure of the foramen ovale
What is the affect of hyperkalemia on resting membrane potentials?
it will decrease the resting membrane potential
What organs or organ systems are most severely affected by hyperkalemia?
hyperexcitability and uncontrolled muscular contractions, nerve dysfunction, and arrhythmia in the heart followed by cardiac arrest
How does blood flow through the fetus (right atrium route)?
Umbilical vein (high O2) to either (a) through the mass of the liver or (b) through the ductus venosus to the caudal vena cava (low O2) to the right atrium, through the oval foramen, between septum 1 and 2, through foramen 2, into the left atrium, to the left ventricle, out of the aorta, to the head, back to the aortic arch to the umbilical artery
If the blood does not go to the right atrium in the fetus, how does the blood flow?
to the right ventricle, joined by the blood returning from the cranial vena cava, to the pulmonary trunk to the ductus arteriosus to the aorta to the aortic arch to the umbilical artery
How does oxygenated blood get from the placenta of a mare to the fetal tissues?
diffusion
What factors increase the rate at which tubular potassium secretion occurs?
aldosterone, tubular flow rate, and plasma potassium concentration
Where is parathyroid hormone produced?
in chief cells of the parathyroid gland
What organs/structures does the parathyroid hormone target?
bone, kidney, and salivary glands
What is the effect of the parathyroid hormone in bone?
stimulates the proliferation of osteoclasts - increased bone resorption
What is the effect of the parathyroid hormone in the kidney?
it increases the absorption of calcium in the distal convulated tubules and decreases phosphate re-absorption in the proximal tubules; it also activates vitamin D
What is the effect of the parathyroid hormone in salivary glands?
it increases the secretion of phosphorus
What is the overall effect of parathyroid hormone on serum calcium and phosphorus?
it effectively raises serum calcium and lowers phosphorus
Where is calcitonin produced?
in the parafollicular C cells of the thyroid gland
What organs/structures does calcitonin target?
bone, kidney, and the GI tract
What is the effect of calcitonin in bone?
it stimulates bone deposition and inhibits resorption
What is the effect of calcitonin on the kidney?
it decreases tubular reabsorption of phosphorus
What is the effect of calcitonin on the GI tract?
it inhibits gastrin secretion and reduces calcium absorption
What is the overall effect of calcitonin on serum calcium and phosphorus?
it decreases serum calcium and phosphorus
Where is vitamin D produced?
cholecalciferol is ingested in the diet and can be synthesized in the skin when exposed to UV light, vitamin D is further hydroxylated in the kidney to calcitriol
What organs/structures does vitamin D target?
the GI tract, bone, and the kidneys
What is the effect of vitamin D on the GI tract?
increases calcium and phosphorus absorption