Development of Pharyngeal Floor (Exam 1) Flashcards
(40 cards)
What is the Pharyngeal Floor Region?
The floor of the pharynx is the region between pharyngeal walls (pouches) of arches 1-4, 6
What three structures develop from the midline of the pharyngeal floor?
- Tongue
- Larynx
- Thyroid
What is the structure of the Tongue:
It’s a muscular organ located in the floor of the oral cavity
Comprised of skeletal muscle, CT and covered by specialized epithelium that detects taste
What is the function of the Tongue?
Deglutition (swallowing)
Speech
Taste
Mastication
What is the Dorsal surface of the tongue?
Faces the roof of oral cavity
- Oral region= ant 2/3
- Pharyngeal region= post 1/3
What is the Ventral surface of the tongue?
Faces floor of oral cavity
- Oral region (ant 2/3)
Includes: Lingual Frenulum, Plica Fimbriata, Deep lingual vein, and Opening of submandibular duct
What is the Lingual Frenulum?
Area of CT that connects tongue to floor of mouth
Describe the Oral region of the tongue:
It’s the anterior 2/3 of tongue and is moveable.
Anatomical description: Portion of tongue that extends back to palatoglossal folds
Dorsal Surface: (Ectodermal origin) SSK epithelium with lingual papilla; also described as specialized mucosa
Ventral Surface: (Endodermal origin) SSNK epithelium; all described as lining mucosa
Describe the Pharyngeal region:
Posterior 1/3 of tongue. It’s Fixed.
Anatomical description: Portion of tongue that extends from the sulcus terminals and the palatoglossal folds back to the epiglottis
Dorsal surface only: SSNK epithelium (endodermal origin)
Which germ layer does not contribute to the tongue?
Head mesoderm
Describe Pharyngeal Arch 1 related to the development of the Tongue:
Forms ectodermal mucosa of anterior 2/3
Embryonic Structure:
- Lateral lingual swellings (Distal tongue buds)– bilateral structures give rise to mucosa of tongue
- Tuberculum impar (median tongue bud)– central structure between lateral lingual swellings.
Describe Pharyngeal Arch 3 related to the development of the Tongue:
Forms endodermal mucosa of posterior 1/3
Embryonic structure:
Hypobranchial eminence– Midline structure extending from arches 3rd and 4th back to epiglottis
Describe Pharyngeal Arch 4 related to the development of the Tongue:
Froms mucosa for root of tongue (minor contribution) and epiglottis
Embryonic structure:
- Hypobranchail eminence (distal)
- Epiglottic swelling
Which pharyngeal arches do not contribute to the tongue?
- 2nd: The 2nd PA = copula and doesn’t contribute to tongue region. The 2nd PA is overgrown by 3rd
- 6th: PA 6 contributes to larynx forming arytenoid swellings: It doesn’t contribute to the tongue
Innervation region of arch 4:
Vagus (CNX)
Epiglottis (oral side mucosa and taste buds)
*GSA (Pain/Temp)
*SVA (Taste)
Region of arch 3 Innervation:
Glassopharyngeal (CN IX)
Posterior 1/3 mucosa and taste buds (circumvallate papillae)
*GSA (Pain/Temp)
*SVA (Taste)
Region of arch 1:
Trigeminal (CN V3– Mandibular brach)
Anterior 2/3 Mucosa only
*GSA (Pain/temp)
What are the Developmental landmarks on the dorsal surface?
- Sulcus terminalis: V shaped depression posterior to circumvallate papillae (CV)> Point of fusion between 1st arch and 3rd arch
- Foramen Cecum: Located at apex of sulcus terminalis. Represents site of origin for thyroid gland– visible in adult
Innervation pattern and Region of Pharyngeal arch 2:
Branch of Facial (CN VII)
Anterior 2/3
* SVA to taste buds on fungiform and foliate papillae
Describe the Paraxial Mesoderm, Occipital somite region.
Developmental precursors: Skeletal muscle fibers
Adult structure: All skeletal muscle of tongue
Innervation: Hypoglossal (CN XII)
* Motor
Describe the Head/Branchiomeric 4th pharyngeal region
DP: Skeletal Muscle fibers
Adult: Palatoglossus mm
Innervation: Pharyngeal plexus (CN X)
*Motor
What is the Laryngopharynx (LP) Region?
It is the most inferior portion of the pharyngeal tube and is considered a derivative of pharyngeal arches.
It extends from the epiglottis (c3) to cricoid cartilage (c6)
What represents the anterior part of laryngopharynx?
The larynx represents the anterior part of laryngopharynx and develops from the distal hypobranchial eminence/epiglottic swellings of the 4th and arytenoid swellings of the 6th arch.
What is the dividing line between the 4th and 6th arch?
The True vocal cords
