Anatomy of the Upper GI System

Question 1

At what joint does the movement of closing and opening the jaw occur?

Answer 1

Temporomandibular joint (TMJ)

Question 2

What controls the TMJ?

Answer 2

Muscles of mastication

Question 3

State the muscles of mastication and the nerve which supplies them.

Answer 3

Masseter
Temporalis
Lateral pterygoid
Medial pterygoid

Mandibular division of CN V

Question 4

What muscle of mastication connects the coronoid process of the mandible to the temporal fossa?

Answer 4

Temporalis

Question 5

What muscle of mastication connects the angle of mandible to the zygomatic arch?

Answer 5

Masseter

Question 6

What muscle of mastication connects the condyle of mandible to the pterygoid plates of sphenoid bone?

Answer 6

Lateral pterygoid

Question 7

What muscle of mastication connects the angle of mandible to the pterygoid plates of sphenoid bone?

Answer 7

Medial pterygoid

Question 8

What is the overriding course for all cranial nerves?

Answer 8

CNS → Intracranial part → Base of skull foramen → Extracranial part

Question 9

What is the course of the mandibular division of CN V

Answer 9

Pons → Inferior to the edge of tentorium cerebelli → Sphenoid bone & foramen ovale → Structures supplied

Question 10

What is the plane, location and nerve innervation of the anterior two thirds of the tongue?

Answer 10

Plane = horizontal
Location = oral cavity
Nerve innervation = CN VII (taste) and CN V3 (general sensation)

Question 11

What is the plane, location and nerve innervation of the posterior one third of the tongue?

Answer 11

Plane = vertical
Location = oropharynx
Nerve innervation = CN IX

Question 12

State what is found on the surface of the tongue and what they detect

Answer 12

Foliate papillae, vallate papillae and fungiform papillae are all bumps with taste receptors
Filiform papillae are bumps that detect touch and temperature

Question 13

What branch of CN VII contains the taste fibres for the anterior two thirds of the tongue?

Answer 13

Chorda tympani

Question 14

What nerve supplies the superior half of the oral cavity?

Answer 14

CN V2

Question 15

What nerve supplies the inferior half of the oral cavity?

Answer 15

CN V3

Question 16

What is the function of the gag reflex and what nerves carry the sensory and motor parts of the reflex?

Answer 16

The gag reflex is a protective reflex preventing foreign bodies entering the pharynx/larynx.
The sensory fibres are carried by CN IX and the motor fibres are carried by CN IX and CN X.

Question 17

What is the surface anatomy of the three salivary glands?

Answer 17

Parotid = secretes into mouth by upper 2nd molar
Submandibular = enters floor of mouth and secretes via lingual caruncle
Sublingual = lays in floor of mouth

Question 18

What cranial nerves supply the salivary glands?

Answer 18

Parotid are supplied by CN IX

Submandibular and sublingual are supplied by CN VII

Question 19

What do the extrinsic muscles of the tongue do?

Answer 19

They change the position of the tongue during mastication, swallowing and speech

Question 20

Name the four pairs of the intrinsic muscles of the tongue, and their nerve innervation

Answer 20

Palatoglossus - CN X
Styloglossus - CN XII
Genioglossus - CN XII
Hyoglossus - CN XII

Question 21

What is the function of the intrinsic muscles of the tongue?

Answer 21

These muscles modify the shape of the tongue during function

Question 22

What is the function and nerve innervation of the circular muscles of the pharynx?

Answer 22

Contract sequentially to move bolus inferiorly, and innervated by CN X

Question 23

What is the function and nerve innervation of the longitudinal muscles of the pharynx?

Answer 23

Contract to elevate the pharynx and larynx. Innervated by CN IX and CN X

Question 24

List the steps of swallowing

Answer 24

Lips close → tongue pushes food towards oropharynx → pharyngeal constrictor muscles contract to push food towards oesophagus → longitudinal pharyngeal muscles contract to raise larynx and close off laryngeal inlet → food reaches oesophagus

Question 25

What are the sphincters of the oesophagus?

Answer 25

An anatomical upper sphincter (cricopharyngeus muscle) and a physiological lower sphincter

Question 26

Give some of the anatomical relations of the oesophagus

Answer 26

Posterior to trachea and heart

In contact with left atrium

Question 27

What is the function and location of the lower oesophageal sphincter?

Answer 27

The lower oesophageal sphincter helps to prevent reflux
It lies superior to the gastro-oesophageal junction, where there is a change in epithelium from stratified squamous to simple columnar

Question 28

What are the functions of the rugae, cardia and pyloric antrum of the stomach?

Answer 28

Rugae - folds of the stomach that push bolus inferiorly
Cardia - entrance to stomach
Pyloric antrum - where chyme is stored before it is released to duodenum

Question 29

What is the clinical importance of the posterior anatomical relations of the stomach?

Answer 29

Posterior to the stomach is the spleen and its artery. Should a peptic ulcer from the posterior stomach rupture this artery, it will cause massive blood loss