Head Associated Digestive Structures

Question 1

describe the 3 parts of the tongue

Answer 1

25% root
50% body
25% apex

Question 2

what is the function of the lingual frenulum and where is it found?

Answer 2

it is the flap under the tongue; keeps the tongue from stretching too far

Question 3

describe the sublingual caruncles

Answer 3

two papilla on either side of the lingual frenulum that receive products from the mandibular duct of the mandibular salivary gland and the monostomatic sublingual duct

Question 4

list and describe the 4 major (2 encapsulated and 2 unencapsulated) salivary glands of the dog

Answer 4

Encapsulated:
1. mandibular gland (ice cream scoop) and associated with the monostomatic portion of the sublingual gland
2. sublingual gland: monostomatic portion (ice cream cone) is one gland with one mouth and one duct
polystomatic portion: minor (unencapsulated) salivary glands) have multiple mouths where each tiny gland ducts directly into the oral cavity
Unencapsulated
3. parotid gland: has a parotid duct that drains near the upper 4th premolar (carnassial tooth)
4. zygomatic gland: drains near the last upper molar (M2)

Question 5

what are the 4 muscles of mastication? give origin and insertion and the only species difference for equine

Answer 5

jaw closers (3)
1. temporalis muscle: arises from temporal fossa and inserts on zygomatic arch and mandible
2. masseter muscle: arises from zygomatic arch and inserts on mandible
3. medial and lateral pterygoid muscles: arise from pterygoid fossa and insert on mandible

jaw opener: digastricus muscle: arises from caudal skull and inserts on ventral mandible; in equine has an additional portion (occipitomandibular part) that does not attach to the central tendon; dogs don’t have a central tendon)

Question 6

describe the intrinsic muscles of the tongue

Answer 6

form tongue shape; fascicles are oriented in different planes to provide full range of motion

Question 7

list and describe the 3 extrinsic muscles of the tongue

Answer 7

all insert ON the tongue; important for swallowing since they move the food bolus back for swallowing
1. styloglossus muscle: elevates and retracts tongue (pulls caudally)
2. hyoglossus: depresses and retracts the tongue
3. genioglossus: depresses the tongue/pulls tongue down between mandibles

Question 8

what is another way to describe the rugae of the hard palate?

Answer 8

permanent mucosal folds

Question 9

describe the incisive ducts of the canine; give a species difference for equine

Answer 9

the left and right incisive ducts pass through the two palatine fissures and open at the lateral sides of the incisive papilla, connecting the nasal cavities with the oral cavity; incisive papilla is a bump but is not a tumor!! don’t remove it dumbass!! (vomeronasal organ joins incisive duct)

in equines the incisive ducts do not open on either side of the papilla

Question 10

what is the pharyngoespohageal limen?

Answer 10

the junction between the laryngopharynx and the beginning of the esophagus

Question 11

what two systems share the pharynx? what are the 3 subdivisions of the pharynx?

Answer 11

shared by the digestive and respiratory systems
1. nasopharynx
2. oropharynx
3. laryngopharynx

Question 12

what are the boundaries of the nasopharynx? describe

Answer 12

nasal choanae to the intrapharyngeal ostium (an opening between the nasopharynx and laryngopharynx formed by the caudal border of the soft palate and the left and right palatopharyngeal arches)

Question 13

where is the pharyngeal opening of the auditory tube found? what does it lead to?

Answer 13

found in the nasopharynx; leads to the middle ear cavity inside the tympanic bulla

Question 14

what are the boundaries of the oropharynx? describe

Answer 14

palatoglossal arches to the base of the epiglottis

the palatoglossal arches extend between the body of the tongue and the soft palate

Question 15

where is the palatine tonsil found?

Answer 15

in the oropharynx beneath a semilunar mucosal fold

Question 16

what are the boundaries of the laryngopharynx? describe

Answer 16

intrapharyngeal ostium and the base of the epiglottis to the pharyngoesophageal limen

is basically the region dorsal and lateral to the larynx

Question 17

where are the piriform recesses found? what is their function

Answer 17

found in the laryngopharynx, are laterally positioned pear shaped troughs that channel fluids and possibly aid in vocalization

Question 18

describe the epiglottis

Answer 18

1. valve between airway and oral cavity to the esophagus or larynx
2. elastic cartilage with a fat-filled center in the dog = very flexible
3. movement is passive and based upon forward movement of the hyoid apparatus and backward movement of the tongue

Question 19

describe the prehension of horses and cows

Answer 19

cows: prehensile tongue
horses: prehensile lips
both: use dental pads (cows)/incisors (horses)

Question 20

what are 2 special structures on a cow tongue? describe

Answer 20

1. lingual torus: rounded ridge
2. lingual fossa: valley before the lingual torus and a common entry point for foreign bodies (when infected = woody tongue)

Question 21

describe the major salivary glands of cows

Answer 21

1. parotid: parotid duct opens near 2nd maxillary molar (maxillary M2)
2. mandibular: sublingual caruncles receive ducts for mandibular and monostomatic sublingual glands

Question 22

describe the major salivary glands of equines

Answer 22

1. parotid: parotid ducts open near the 4th maxillary premolar (maxillary PM4)
2. mandibular: sublingual caruncles receive ducts for mandibular glands

Question 23

where does the esophagus move in equines and bovines? clinical application?

Answer 23

begins dorsal to the trachea (like dogs), but moves to the left side of the trachea;

look for visible bulge of the nasogastric tube as it passes through the cervical region on the left side; and can observe food bolus moving up and down the esophagus on the left side in ruminants

Question 24

what is the anatomical pathway traveled by the nasogastric tube when passed from the nostril to the glandular stomach?

Answer 24

1. nostril
2. nasal vestibule
3. nasal cavity via the ventral nasal meatus
4. through the choana into the nasopharynx
5. over the larynx into the esophagus
6. into the glandular stomach

Question 25

when passing a nasogastric tube in cattle via a frick speculum or when using a balling gun, what unique anatomic feature of the cow tongue must be passed over when inserting the instrument into the oral cavity?

Answer 25

lingual torus/torus linguae