Chapter 45 - Pharynx Flashcards
What are the three main sections of the pharynx?
Nasopharynx, oropharynx, and laryngopharynx.
What role does the pharynx play during respiration?
It is a musculomembranous tubular structe not supported by bone or cartilaginous matrix and facilitates airflow and pressure changes while preventing communication between the nasopharynx and oropharynx.
How does the soft palate interact with the larynx during respiration?
During respiration,
the caudal free margin of the soft palate intimately contacts the
subepiglottic tissue at the base of the equine larynx
What anatomical structures are attached to the nasopharynx?
Pterygoid, palatine, and hyoid bones, as well as laryngeal, cricoid, and thyroid cartilages.
What intraluminal pressure range must the nasopharynx withstand?
24–50 cm H2O.
What is the maximum airflow velocity the nasopharynx can accommodate?
Up to 90 L/s.
Which muscles are primarily responsible for altering the size and configuration of the nasopharynx?
Muscles that move the tongue, insert on the hyoid apparatus and larynx, and regulate soft palate position.
How is the musculature of the pharynx classified?
Into intrinsic and extrinsic muscles.
What is the primary function of the intrinsic musculature in the nasopharynx?
To stabilize the nasopharynx through muscular contractions.
What structure forms the floor of the nasopharynx?
The soft palate.
What are the components of the soft palate?
Oral mucous membrane, palatine glands, palatine aponeurosis, palatinus and palatopharyngeus muscles, and nasopharyngeal mucous membrane.
How does the palatine aponeurosis contribute to the anatomy of the nasopharynx?
It attaches to the caudal margin of the hard palate and helps maintain structural integrity.
Which 4 muscles coordinate the position of the soft palate?
Tensor veli palatini, levator veli palatini, palatinus, and palatopharyngeus muscles.
What is the innervation of the tensor veli palatini muscle?
Mandibular branch of the trigeminal nerve.
Which muscle elevates the soft palate during swallowing?
Levator veli palatini muscle.
Where does the palatinus muscle originate?
The caudal aspect of the palatine aponeurosis.
What is the function of the palatopharyngeus muscle?
To shorten and depress the soft palate towards the tongue.
How does the tensor veli palatini muscle affect the nasopharynx during inspiration?
It tenses the soft palate and expands the nasopharynx.
What is the role of the stylopharyngeus muscle in the pharynx?
It acts as a pharyngeal dilator to maintain tension in the nasopharynx.
Which nerve innervates the caudal stylopharyngeus muscle?
Glossopharyngeal nerve.
How is the blood supply to the soft palate provided?
By the linguofacial trunk and maxillary artery.
What is the venous drainage pattern for the soft palate?
It occurs via accompanying veins.
Where do lymph vessels from the soft palate drain?
Toward the retropharyngeal lymph nodes.
What type of receptors provide afferent innervation to the nasopharynx?
Pressure, mechanical, and temperature receptors.
What anatomical features separate the nasopharynx from the oropharynx?
The soft palate.
Which muscle has a pulley-like effect on the soft palate?
Tensor veli palatini muscle.
What are the main components of the intrinsic musculature of the nasopharynx?
Muscles of the soft palate and nasopharyngeal muscles.
How does the hyoid apparatus influence the nasopharynx?
Muscles affecting the hyoid can alter the size and stability of the nasopharynx.
what is the anatomical relationship between the soft palate and the larynx?
The caudal margin of the soft palate forms the floor of the nasopharynx, surrounding the larynx.
How is the position of the soft palate dynamically regulated?
Through coordinated contractions of specific muscles during breathing and swallowing.
What anatomical structure extends from the base of the epiglottis to the arch of the cricoid cartilage?
Laryngopharynx.
What anatomical feature provides structural support to the nasopharynx despite the lack of bone?
Muscular contraction and muscle attachments to adjacent bones.
How do the intrinsic muscles affect the configuration of the nasopharynx?
They enable timely contractions that adjust tension and diameter during respiration.
What is the effect of the levator veli palatini muscle on the nasopharynx?
It elevates the soft palate, closing off the nasopharynx during swallowing.
Why is the role of the oropharynx gaining importance in equine pharyngeal disease?
Increased understanding of its anatomy and functions, particularly related to the hypoglossal nerve.
Which muscle fibers continue caudad from the palatine aponeurosis?
The palatopharyngeus muscle fibers.
What anatomical relationship exists between the nasopharynx and the auditory tube?
The levator veli palatini arises from the lateral lamina of the auditory tube.
How do the intrinsic and extrinsic muscles of the pharynx work together?
They coordinate to adjust the size and position of the nasopharynx and oropharynx during various physiological functions.
What is the physiological significance of the nasopharynx’s ability to withstand pressure changes?
It allows effective respiration during varying airflow conditions.
Figure 45-1. The extrinsic structures relevant to equine nasopharynx
stability, showing the definition of the nasopharynx and relative relationships
of the hyoid apparatus, larynx, and extrinsic muscular attachments. a,
Mandible; b, genioglossus muscle; c, geniohyoideus muscle; d, styloglossus;
e, hyoglossus muscle; f, basihyoid bone; g, hyoepiglotticus muscle.
Figure 45-2. The intrinsic structures of the nasopharynx. The nasopharynx forms the passageway that transfers airflow from the caudal aspect of the nasal cavity to the larynx. The floor of the nasopharynx is formed by the soft palate and its relevant structures (a, Palatine aponeurosis; b, oral mucosa; c, glandular layer; d, palatinus muscle) and is normally in a subepiglottic position during respiration. The hamulus (f) of the pterygoid bone, and the tensor veli palatini (e), levator veli palatini (g), and palatopharyngeus (not shown) muscles are underneath the mucosa of the lateral walls of the nasopharynx. The stylopharyngeus (h) with the palatopharyngeus muscles add to the stability of the roof of the nasopharynx.
Figure 45-3. The intrinsic structures of the nasopharynx viewed from the ventral aspect of the nasopharynx, showing the muscles of the soft palate, the palatine aponeurosis (d), and the hamulus of the pterygoid bone (arrow). a, Tensor veli palatini muscle; b, levator veli palatini muscle; c, palatinus muscle.
Figure 45-4. The intrinsic muscles that form the wall and roof of the nasopharynx. Note that contractions of the stylopharyngeus caudalis support the roof of the nasopharynx.
What is the primary structural composition of the pharynx?
The pharynx is a musculomembranous tubular structure unsupported by bone or cartilage.
What are the three anatomical divisions of the pharynx?
The nasopharynx, oropharynx, and laryngopharynx.
How does the soft palate affect communication between the nasopharynx and oropharynx?
The soft palate prevents communication by contacting the subepiglottic tissue.
What is the pressure range (in cm H2O) that the nasopharynx must withstand during respiration?
The nasopharynx withstands pressures from 24 to 50 cm H2O.
What airflow velocity can the nasopharynx accommodate?
The nasopharynx can accommodate airflow velocities up to 90 L/s.
What role do intrinsic muscles play in the nasopharynx?
Intrinsic muscles stabilize the nasopharynx by contracting to tense and dilate its walls.
Which muscle is responsible for tensing the rostral aspect of the soft palate?
The tensor veli palatini muscle.
Which nerve innervates the tensor veli palatini muscle?
The mandibular branch of the trigeminal nerve.
What is the function of the palatinus muscle?
The palatinus muscle shortens and depresses the soft palate toward the tongue.
Which nerve innervates the palatinus and palatopharyngeus muscles?
The pharyngeal branch of the vagus nerve.
What is the role of the extrinsic musculature in the nasopharynx?
Extrinsic muscles increase respiratory patency and stability of the nasopharynx.
What is the primary action of the hyoglossus muscle?
The hyoglossus muscle retracts and depresses the base of the tongue.
Which muscle is primarily involved in the dorsal displacement of the soft palate during exercise?
Dysfunction of extrinsic muscles leads to dorsal displacement of the soft palate.
What anatomical structure do the genioglossus and geniohyoideus muscles attach to?
They attach to the basihyoid bone.
How does the contraction of the thyrohyoideus muscle affect the larynx?
It enhances stability by moving the larynx rostrad during exercise.
Which are the extrinsic muscles?
- geniohyoideus
- thyrohyoideus
- genioglossus
- hyoglossus
- hyoepiglotticus
6.styloglossus - stenohyoideus
- sternothyroideus muscles
What anatomical disorder is characterized by a web of scarring in the nasopharynx?
Nasopharyngeal cicatrix.
Describe the genioglossus
The genioglossus muscle is a fan-shaped extrinsic tongue muscle that originates within the median plane of the tongue and attaches to the oral surface of the mandible, caudal to the symphysis
What happens when genioglossus muscle contracts
Contraction of the genioglossus muscle protracts the tongue and pulls the basihyoid bone rostrally.
The styloglossus muscle lies on the lateral aspect of the tongue, originates on the lateral aspect of the stylohyoid bone and inserts on the tip of the tongue. Its function is
retraction of the tongue (i.e., retruder)
The hyoglossus muscle is located medial to the styloglossus muscle, originates on the
hyoid bones (lingual process, stylohyoid and thyrohyoid bone), and inserts on the median plane of the dorsum of the tongue.
Because local anesthesia of the hypoglossal nerve at the midlevel of the ceratohyoid bone interferes with the action of the___________ and ___________ muscles (protruders of the tongue) at the same time as that of styloglossus and hyoglossus (retruders), the exact function of each paired muscle is not yet known
ceratohyoid bone interferes with the action of the geniohyoideus and genioglossus muscles (protruders of the tongue)
The sternothyroideus muscle inserts on the caudolateral aspect of the thyroid
thyroid cartilage
the sternohyoideus muscle inserts on the basihyoid bone and ________ (1 w) process of the hyoid apparatus.
sternohyoideus muscle inserts on the basihyoid bone and lingual process of the hyoid apparatus.
______________ (1w) muscle, attaches to the hyoid bone at the base of the epiglottis, and during its contraction, pulls the epiglottis ventrad toward the base of the tongue
hyoepiglotticus muscle, attaches to the hyoid bone at the base of the epiglottis, and during its contraction, pulls the epiglottis ventrad toward the base of the tongue
Contraction of sternothyroideus, sternohyoideus results in caudal traction on the________ (1w)apparatus and larynx.
Contraction of these muscles results in caudal traction on the hyoid apparatus and larynx.
What is the only muscle that inserts on the epiglottis
hyoepligotticus muscle
___________________(1w) muscle, which extends from the lateral lamina of the thyroid cartilage to the caudal aspect of the thyrohyoid bone
thyrohyoideus muscle, which extends from the lateral lamina of the thyroid cartilage to the caudal aspect of the thyrohyoid bone
disruption of the thyrohyoideus muscle results in….(1w)
DDSP
The hypoglossal nerve innervates which muscles
geniohyoideus m.(main branch)
genioglossus m. (medial branch)
styloglossus m.
hyoglossus m. (lateral branch)
hyoepiglotticus m. (main granch)
The first and seconde cervical nerves innervate which muscles?
Sternohyoideus
Sternothyroideus
Arterial blood supply to the pharynx is provided by the
- common carotid
- external carotid arteries
- linguofacial trunk
The extrynsic muscles the drainage is from
retropharyngeal and cranial cervical lymph nodes
Which nerves provide sensosry innervation to the nasopharyngeal mucosa?
Trigeminal n.
vagus n.
glossopharyngeal n.
Nasopharyngeal cicatrix has a predisposition for
mares 60%
Figure 45-5. Endoscopic photograph of a nasopharyngeal cicatrix in a horse, characterized by scar formation across the floor of the nasopharynx.
Figure 45-6. Endoscopic photograph of a nasopharyngeal cicatrix affecting the larynx and epiglottic cartilage. Note the deformation of right arytenoid cartilage, as well as scar formation across the floor of the nasopharynx
What percentage of nasopharyngeal cicatrix cases show epiglottic or arytenoid cartilage deformation?
Nearly 95%.
In which climate is nasopharyngeal cicatrix more commonly reported?
Hot climates, especially in the eastern and southern United States.
What is the typical age range of horses affected by nasopharyngeal cicatrix?
Affected horses range from 5 to 29 years.
What is a common clinical sign of nasopharyngeal cicatrix?
Upper respiratory noise.
What types of primary nasopharyngeal masses are mentioned?
Benign lesions, tumors, and ethmoid hematomas.
Figure 45-8. Endoscopic view of a pharyngeal mass in a 20-year-old horse. The mass originated from the root of the tongue
Figure 45-10. Pharyngotomy. The sternohyoideus muscles have been bluntly separated, allowing exposure to the underlying fascia. The basihyoid has been split longitudinally with an osteotome (an optional step), and the superficial fascia is being incised with curved Mayo scissors, exposing the underlying hyoepiglotticus muscle
The skin incision is extended from the rostral aspect of the thyroid cartilage forward toward the basihyoid bone. The sternohyoideus muscles are separated bluntly on the ventral midline, and the incision is extended to the loose fascia between the thyroid cartilage and the basihyoid bone (fig 45-10) The hyoepiglotticus muscle is enclosed in elastic fascia (hyoepiglotticus ligament) deep to the loose fascia. The left and right hyoepiglotticus muscles are separated on the midline, and the incision is extended through multiple layers of loose fascia until the oropharyngeal mucosa is reached. Further exposure is obtained by splitting the basihyoid longitudinally with an osteotome. Malleable or Langenbeck retractors are needed to retract each side of the incision laterad and the root of the tongue rostrad.
Figure 45-9. Pharyngotomy. Schematic shows the view of the ventral cervical area of a horse in dorsal recumbency and illustrates the landmarks for a pharyngotomy. The bold line represents the line of incision extending from the basihyoid to the thyroid cartilage.
Figure 45-13. Thermal rostral palatoplasty. (A) Rostral aspect of the soft palate viewed through the oropharynx immediately before surgery. Note parasagittal longitudinal folds on the oropharyngeal mucosa of the rostral aspect of the soft palate. (B) Appearance of the soft palate immediately after cauterizing.
Figure 45-14. Tension rostral palatoplasty. Schematic drawing shows the location of the elliptical incision (dotted line) on the ventral and rostral aspect of the soft palate as viewed though the oropharynx. This incision leads to resection of the oropharyngeal mucosa and glandular portion of the soft palate in that specific location. a, Hard palate; b, isthmus faucium; c, sagittal fold; d, caudal border of the soft palate.
Figure 45-17. Fenestration of the nasopharynx facilitating rapid equilibration of the airway pressures between the nasopharynx and the guttural pouches. In this horse laser fenestration was made at the nasopharyngeal recess.
Figure 45-19. (A) Palatal granuloma in a 2-year-old Thoroughbred with dorsal displacement of the soft palate. (B) Appearance of the granuloma dorsal to the palate and ventral to the epiglottic cartilage (arrows) with the soft palate replaced
Figure 45-21. Bruising of nasopharynx approximately 12 hours following racing in a 7-year-old Standardbred gelding. This supports a diagnosis of dorsal displacement of the soft palate during racing.
Figure 45-20. Ulcer on the free edge of the soft palate in a 3-year-old Standardbred. This finding supports a diagnosis of DDSP and can also be seen if a subepilgottic mass or lesion is present.
