Intro to GI System Flashcards
Development of Oral Cavity: Stomatodeum
- Primitive oral cavity
- Lined with surface ectoderm
- Forms b/w developing brain and heart
- Derivatives: oral mucose, gingiva, lips, enamel, anterior pituitary gland
Development of Oral Cavity: Primitive Pharynx
- Lined with endoderm
- Separated from stomatodeum by the buccopharyngeal membrane (disappears at the end of week 3)
Oral fauces
(arches)
Level of ectoderm-endoderm junction in adults
Development of the GI tract
- Primitive gut tube–>lined with endoderm
- Portions
- foregut
- midgut
- hindgut
- Portions
Functions of GI System
- 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
Oral cavity
- From embryo–> stomatodeum
- Ingestion and mechanical digestion of food
- Salivary glands: chemical digestion of food
- Gustation: taste sensation (stimulates digestion)
Upper GI Tract
- From embryo–>foregut
- Pharynx: swallowing
- Esophagus: transport/propulsion of bolus
The mouth: vestibule
- Vestibule: between the teeth and gums
- Buccal vestibule: between cheeks and gums
- Labial vestibule: between lips and gums
Oral cavity borders
- anterior border: teeth
- lateral border: teeth
- floor: mylohyoid muscle
- roof: hard and soft palate
- posterior border: fauces (arches)
Fauces
- two arches that separate the oral cavity from the oropharynx
- Palatoglossal arch: palatoglossus m. (CN X)
- Palatopharyngeus m. (CNX)
- Palatine tonsil
Pharyngeal Lymphoid Ring
- AKA “Waldeyer’s Ring)
- Nasopharynx
- Pharyngeal (adenoid) tonsils
- tubal tonsils
- Oropharynx
- palatine tonsils
- lingual tonsils
Anatomy of the Tongue
- 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
The tongue: GSE
- CN XII
- Extrinsic muscles
- genioglossus
- hyoglossus
- styloglossus
- palatoglossus (CNX)
- Intrinsic muscles
- longitudinal
- vertial
- transverse
Gustation
- 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)
The tongue: Lingual Papillae
- 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
What are best at sensing bitter taste?
Vallate papillae
Hard Palate Composed of
maxilla and palatine bones
Soft palate
- SVE: CN X and XIC
- Palatoglossus
- Palatopharyngeus
- Musculus uvulae
- Levator veli palatini
- Tensor veli palatini (w/ palatine aponeurosis)-SVE from CN V3
Innervation of the palate
- 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
The teeth: Permanent Dentition: What is in each quadrant?
2 incisors (central and lateral)
1 canine
2 premolars
3 molars
The teeth: Deciduous dentition: What is in each quadrant?
2 incisors (central and lateral)
1 canine
2 molars
The teeth: timepoints
- Deciduous dentition erupts 6-30 months
- Tooth replacement starts around 6 years with M1
Salivary glands
- Exocrine glands
- Produces saliva (digestive enzyme)
- Amylase: breaks dowm complex starches/carbohydrates
- Beginning of chemical digestion
- Heavily vascularized, surrounded by lymph nodes
Parotid gland innervation
- GVE innervation from CN IX (otic ganglion)
Parotid duct
- (Stensen’s duct)
- Pierces buccinator muscle
- Opens into buccal vestibule at parotid papilla (across from M1)
Submandibular and sublingual glands innervation
- GVE innervation from CN VII (submandibular ganglion)
Sublingual folds
marks the position of the sublingual gland
Submandibular and sublingual glands drain via
- the common submandibular duct (Wharton’s duct)
- opens into the oral cavity at the sublingual caruncle
Minor Salivary glands: Submucosal salivary glands
buccal
labial
lingual
palatal
Salivary calculi
calcified masses that form within salivary glands or ducts
most common in the submandibular duct
Pharynx and esophagus functions
Swallowing (deglutition)
Transport/propulsion of bolus (food)
Pharynx and esophagus lines with
(innervation)
- 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)
Innervation of teeth and gingiva diagram
