23.3 The Mouth, Pharynx, and Esophagus

what are the 3 main organs of the upper alimentary canal

the mouth, pharynx, and esophagus

what are the three associated accessory organs to the main organs of the upper alimentary canal

the tongue, salivary glands, and teeth

what is the oral cavity also called

buccal cavity

what is the oral cavity

mouth

what frame the oral cavity (mouth)

cheeks, tongue, and palate

what are the lips called

labia (labium = plural)

what is the outer covering of the labium

skin

the labium transitions from the skin to

a mucous membrane in the mouth proper

what is a characteristic of the labium

very vascular (consist blood)

the labium contain a layer of

thin layer of keratin making them “red”

why are the labium red

because of the layer of keratin

what muscle does the labium cover

orbicularis oris muscle

what do the orbicularis oris muscles regulate

what comes in and out of the mouth

what is the labial frenulum

a midline fold of mucous membrane that attaches the inner surface of each lip to the gum

what makes up the oral cavity’s sidewalls

the cheeks

what is the inner covering of the cheeks

mucous membrane

what is the outer covering of the cheeks

the skin

what is the mucous membrane made up of

non-keratinized, stratified squamous epithelium

what is between the skin and mucous membranes

connective tissue and buccinator muscles

how does the mouth prevent food from coming out

buccinator muscles of cheeks and orbicularis oris muscle in labium are contracting

what is the oral vestibule

The pocket-like part of the mouth that is framed on the inside by the gums and teeth, and on the outside by the cheeks and lips

what is the fauces

the opening between the oral cavity and throat (oropharynx)

where does the main open area of the oral cavity run from

the gums and teeth to the fauces

what is palate

the arched shape of the roof of your mouth allows you to handle both digestion and respiration at the same time

what does the anterior region of the palate serve as

a wall (or septum) between the oral and nasal cavities as well as a rigid shelf against which the tongue can push food

how is the anterior region of the palate created

by the maxillary and palatine bones of the skull and, given its bony structure, is known as the hard palate

what is the soft palate

posterior region of the bottom portion of the nasal cavity that consists of skeletal muscle

when does the hard palate end

in the posterior oral cavity

what happens to the tissues at the end of the posterior oral cavity

become fleshier

what is the soft palate mainly composed of

skeletal muscle

what does the oral cavity include

labium, tongue, palate, gums, and teeth

what is the uvula

fleshy bead of tissue that drops down from the center of the posterior edge of the soft palate

what happens to the uvula and soft palate when you swallow

move upward, helping to keep foods and liquid from entering the nasal cavity

what contributes to the sound of snoring

uvula

what is on either side of the uvula

two muscular folds extending downward from the soft palate

what is the palatoglossal arch

muscular fold that extends from the lateral side of the soft palate to the base of the tongue

what is the palatopharyngeal arch

muscular fold that extends from the lateral side of the soft palate to the side of the pharynx

what structure is in between the two arches (palatoglossal arch and palatopharyngeal arch)

palatine tonsils

what are the palatine tonsils and purpose

clusters of lymphoid tissue that protect the pharynx

where are the lingual tonsils located

at the base of the tongue

what is the tongue

accessory digestive organ of the mouth, the bulk of which is composed of skeletal muscle

what does the tongue assist with

workhorse, facilitating ingestion, mechanical digestion, chemical digestion (lingual lipase), sensation (of taste, texture, and temperature of food), swallowing, and vocalization

what is the tongue attached to

to the mandible, the styloid processes of the temporal bones, and the hyoid bone

how is the tongue positioned

over the floor of the oral cavity

What divides the tongue into two symmetrical halves?

A medial septum that runs the entire length of the tongue

What lies beneath the mucous membrane covering of the tongue

Each half contains the same number and type of intrinsic and extrinsic skeletal muscles

What are the names of the intrinsic muscles of the tongue?

Longitudinalis inferior, longitudinalis superior, transversus linguae, and verticalis linguae

What do the intrinsic muscles of the tongue allow you to do?

They allow you to change the size and shape of the tongue and to stick it out

Why is it important for the tongue to be flexible?

Flexibility of the tongue helps with swallowing and speech

What are the names of the extrinsic muscles of the tongue?

Palatoglossus, hyoglossus, styloglossus, and genioglossus

Where do the extrinsic tongue muscles originate and insert?

They originate outside the tongue and insert into connective tissues within the tongue

What is the function of the mylohyoid muscle?

It raises the tongue

What does the hyoglossus muscle do?

It pulls the tongue down and back

What does the styloglossus muscle do?

It pulls the tongue up and back

What is the function of the genioglossus muscle?

It pulls the tongue forward

What three digestive functions do the extrinsic tongue muscles perform together?

They position food for optimal chewing, gather food into a bolus, and position food for swallowing

what is the bolus

mass of chewed food

what are the top and sides of the tongue studded with

papillae, extensions of lamina propria of the mucosa, which are covered in stratified squamous epithelium

what covers a large area of the tongue

fungiform papillae

what shape are fungiform papillae and characteristic

mushroom shaped; tend to be larger toward the rear of the tongue and smaller on the tip and sides

what is the characteristic of filiform papillae

long and thin

what does fungiform papillae contain

taste buds

what does filiform papillae contain

touch receptors that help the tongue move food around in the mouth

what do the lingual glands in the lamina propria of the tongue secrete

mucus and a watery serous fluid that contains the enzyme lingual lipase

what is the lingual lipase

digestive enzyme from glands in the tongue that acts on triglycerides

when are lingual lipase activated

in the stomach

what is the lingual frenulum

mucous membrane fold that attaches the bottom of the tongue to the floor of the mouth

what is congenital anomaly ankyloglossia (tongue tie)

condition where lingual frenulum is too short or malformed

what can happen in cases of severe ankyloglossia and treatment

impair speech, surgery

what are the salivary glands

exocrine gland that secretes a digestive fluid called saliva

where are many small salivary glands housed

within the mucous membranes of the mouth and tongue

where are the salivary glands secreting saliva

into the oral cavity or indirectly through ducts, even when sleeping

how many liters of saliva is secreted each day

1-1.5 L

what is the role of saliva

moisten the mouth and teeth

what happens to saliva when you eat and why

secretion is increased bc saliva is essential to moisten food and initiate the chemical breakdown of carbohydrates

where are small amounts of saliva secreted

labial glands in the lips

what glands in the mouth also help to ensure all areas of the mouth are supplied with adequate saliva

buccal glands, palatal glands, and lingual glands

where are the buccal glands located

in the cheeks

where are the palatal glands located

in the palate

where are the lingual glands located

in the tongue

what are the 3 pairs of major salivary glands

submandibular glands, sublingual glands, and parotid glands

what is the do the 3 major salivary glands do

secrete majority of the saliva

where are the submandibular glands located

floor of the mouth

how does the submandibular gland secrete saliva into the mouth

through submandibular ducts

where are the sublingual glands located

below the tongue

how do the sublingual glands secrete saliva into the mouth

the lesser sublingual ducts

where are the parotid glands located

between the skin and the masseter muscle near the ears

how do the parotid glands secrete saliva into the mouth

through the parotid duct

where is the parotid duct located

near the second upper molar teeth

what is saliva

aqueous solution of proteins and ions secreted into the mouth by the salivary glands

what is the saliva mainly composed of

99.4% of water and 0.6% of a complex mixture of ions, glycoproteins, enzymes, growth factors, and waste products

what is the most important ingredient in saliva (from pov of digestion)

the enzyme salivary armylase

what is the salivary amylase

digestive enzyme that is found in the saliva and begins the digestion of carbohydrates in the mouth

why is there not enough time to allow carbohydrates to break down

food does not spend enough time in the mouth

when does salivary amylase get inactivated

by stomach acids

what are the chemical buffers in the mouth

bicarbonate and phosphate ions

what are buffers

solution containing a week acid or a weak base that opposes wide fluctuations in the pH of body fluids

what do bicarbonate and phosphate ions act as and function

chemical buffers and maintains saliva at a pH between 6.35-6.85

what is the pH of saliva

6.35-6.85

what does salivary mucus help with

lubrication of food, facilitate movement in the mouth, form bolus, and swallowing