Intro to GI System

Question 1

Development of Oral Cavity: Stomatodeum

Answer 1

• Primitive oral cavity
• Lined with surface ectoderm
• Forms b/w developing brain and heart
• Derivatives: oral mucose, gingiva, lips, enamel, anterior pituitary gland

Question 2

Development of Oral Cavity: Primitive Pharynx

Answer 2

• Lined with endoderm
• Separated from stomatodeum by the buccopharyngeal membrane (disappears at the end of week 3)

Question 3

Oral fauces

Answer 3

(arches)

Level of ectoderm-endoderm junction in adults

Question 4

Development of the GI tract

Answer 4

• Primitive gut tube–>lined with endoderm
  
  • Portions
    
    • foregut
    • midgut
    • hindgut

Question 5

Functions of GI System

Answer 5

• Ingestion and consumption
• Digestion: breaking down food into smaller particles; mechanical and chemical forms
• Propulsion of food through tract
• Secretion of digestive enzymes and hormones
• Absorption of nutrients into circulatory system
• Elimination of waste products

Question 6

Oral cavity

Answer 6

• From embryo–> stomatodeum
• Ingestion and mechanical digestion of food
• Salivary glands: chemical digestion of food
• Gustation: taste sensation (stimulates digestion)

Question 7

Upper GI Tract

Answer 7

• From embryo–>foregut
• Pharynx: swallowing
• Esophagus: transport/propulsion of bolus

Question 8

The mouth: vestibule

Answer 8

• Vestibule: between the teeth and gums
  
  • Buccal vestibule: between cheeks and gums
  • Labial vestibule: between lips and gums

Question 9

Oral cavity borders

Answer 9

1. anterior border: teeth
2. lateral border: teeth
3. floor: mylohyoid muscle
4. roof: hard and soft palate
5. posterior border: fauces (arches)

Question 10

Fauces

Answer 10

• two arches that separate the oral cavity from the oropharynx
  
  • Palatoglossal arch: palatoglossus m. (CN X)
  • Palatopharyngeus m. (CNX)
  • Palatine tonsil

Question 11

Pharyngeal Lymphoid Ring

Answer 11

• AKA “Waldeyer’s Ring)
• Nasopharynx
  
  • Pharyngeal (adenoid) tonsils
  • tubal tonsils
• Oropharynx
  
  • palatine tonsils
  • lingual tonsils

Question 12

Anatomy of the Tongue

Answer 12

• medial sulcus: divides tongue down the middle
• terminal sulcus: divides oral part (anterior 2/3) from pharyngeal part (posterior 1/3) of tongue
• foramen cecum: depression at the midline of the terminal sulcus; the remnant of the thyroglossal duct
• lingual tonsils: cover the pharyngeal part of the tongue

Question 13

The tongue: GSE

Answer 13

• CN XII
• Extrinsic muscles
  
  • genioglossus
  • hyoglossus
  • styloglossus
  • palatoglossus (CNX)
• Intrinsic muscles
  
  • longitudinal
  • vertial
  • transverse

Question 14

Gustation

Answer 14

• The sense of taste (SVA)
• CN that carry SVA:
  
  • CN VII (oral tongue)
  • CN IX (pharyngeal tongue and vallate papilla)
  • CN X (epiglottis, root of tongue)

Question 15

The tongue: Lingual Papillae

Answer 15

• Filiform papilla: found on the oral part of the tongue; not involved in taste; most numerous type
• Foliate papilla: found on the lateral side of the oral part; taste
• Fungiform papilla: found across the dorsum of the tongue; taste
• Vallate papilla: found in a row anterior to the terminal sulcus; innervated by CN IX; taste

Question 16

What are best at sensing bitter taste?

Answer 16

Vallate papillae

Question 17

Hard Palate Composed of

Answer 17

maxilla and palatine bones

Question 18

Soft palate

Answer 18

• SVE: CN X and XI_C
• Palatoglossus
• Palatopharyngeus
• Musculus uvulae
• Levator veli palatini
• Tensor veli palatini (w/ palatine aponeurosis)-SVE from CN V₃

Question 19

Innervation of the palate

Answer 19

• Somatosensory (GSA)
  
  • Nasopalatine nerve (CN V₂)
  • Greater palatine n. to hard palate (CN V₂)
  • Lesser palatine n. to soft palate (CN V₂)
• Visceromotor (GVE) to palatine mucosa and glands
  
  • Parasympathetic: CN VII through pterygopalatine ganglion
  • Sympathetic through superior cervical ganglion

Question 20

The teeth: Permanent Dentition: What is in each quadrant?

Answer 20

2 incisors (central and lateral)

1 canine

2 premolars

3 molars

Question 21

The teeth: Deciduous dentition: What is in each quadrant?

Answer 21

2 incisors (central and lateral)

1 canine

2 molars

Question 22

The teeth: timepoints

Answer 22

• Deciduous dentition erupts 6-30 months
• Tooth replacement starts around 6 years with M1

Question 23

Salivary glands

Answer 23

• Exocrine glands
• Produces saliva (digestive enzyme)
  
  • Amylase: breaks dowm complex starches/carbohydrates
  • Beginning of chemical digestion
• Heavily vascularized, surrounded by lymph nodes

Question 24

Parotid gland innervation

Answer 24

• GVE innervation from CN IX (otic ganglion)

Question 25

Parotid duct

Answer 25

• (Stensen’s duct)
• Pierces buccinator muscle
• Opens into buccal vestibule at parotid papilla (across from M1)

Question 26

Submandibular and sublingual glands innervation

Answer 26

• GVE innervation from CN VII (submandibular ganglion)

Question 27

Sublingual folds

Answer 27

marks the position of the sublingual gland

Question 28

Submandibular and sublingual glands drain via

Answer 28

• the common submandibular duct (Wharton’s duct)
  
  • opens into the oral cavity at the sublingual caruncle

Question 29

Minor Salivary glands: Submucosal salivary glands

Answer 29

buccal

labial

lingual

palatal

Question 30

Salivary calculi

Answer 30

calcified masses that form within salivary glands or ducts

most common in the submandibular duct

Question 31

Pharynx and esophagus functions

Answer 31

Swallowing (deglutition)

Transport/propulsion of bolus (food)

Question 32

Pharynx and esophagus lines with

(innervation)

Answer 32

• epithelium from foregut endoderm
  
  • Sensory (GVA): CN IX (oro-, naso-), CN X (laryngo-pharynx)
  • Motor (SVE to pharynx, upper esophagus, GVE to lower esophagus: CN X)

Question 33

Innervation of teeth and gingiva diagram

Answer 33