2. Oral cavity and oesophagus

Question 1

How many different teeth do we have?

Answer 1

• Total: 32
• Incisors: 8
• Canines: 4
• Premolars: 8
• Molars: 12

Question 2

Describe the muscles associated with mouth movement

Answer 2

• Positioned on the mandible (jawbone)
• Can widen or close the mandibular joint and swing it side to side
• Masseter muscle - largest jaw muscle, responsible for biting actions

Question 3

Describe the salivary glands

Answer 3

• Secrete lingual lipase and salivary amylase
• Bolus = food + saliva
• Parotid gland - back of mouth
• Sublingual gland - under tongue
• Submandibular gland - under tongue, further into jaw

Question 4

Describe the tongue

Answer 4

• Made of individual muscles
• Intrinsic muscle - fine motor control, sounds, move food around
• Extrinsic muscle - gross movements (up, down, out), aids mechanical digestion by pounding bolus against hard plate

Question 5

What is the epiglottis?

Answer 5

• Covers trachea entrance as bolus moves through pharynx

• Trachea is always open due to cartilage rings

Question 6

What is the upper oesophageal sphincter?

Answer 6

• Relaxes to allow passage into oesophagus

* Oesophagus is closed at rest

Question 7

What 2 muscles (names) in the oesophagus made up of?

Answer 7

• Constrictor pharyngeal medius
- similar to circular layer of GI tract, myenteric plexus (neurones) below this
• Constrictor pharynges inferior
- similar to longitudinal muscle layers

Question 8

How long is the oesophagus and what type of muscle (cells) is it made up of?

Answer 8

• 25cm
• Upper oesophagus - skeletal muscle (not under voluntary control)
• Middle - mixture
• Lower oesophagus - smooth muscle

Question 9

Describe the lower oesophageal sphincters

Answer 9

• Prevents stomach contents from going up
• Simple columnar
• Internal component - built into circular smooth muscle of oesophageal wall
• External component - formed at the right crus of the diaphragm (voluntary control)

Question 10

Compare the pressures of the oesophagus and the stomach?

Answer 10

• Oesophagus - negative

* Stomach - positive

Question 11

What is the lining of the oesophagus made up of?

Answer 11

• Non-keratinising stratified squamous epithelia to endure different temperatures and textures
• Lining goes down to the Z-line (where the LES begins)