Class notes
Gastrointestinal Anatomy
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GI system anatomy notes and clinical cases
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GASTROINTESTINAL SYSTEMMOUTH TO STOMACH
• Dysphagia: is the difficulty swallowing
• The causes of dysphagia can include: cancer of the mouth, oesophagus, epiglottis, tonsillitis,
stroke/head injury and reduced mobility function
Mouth
• The main boarders of the mouth are described as everything from the lips to palatoglossal arches
and cheeks
• The floor of the mouth is formed by mylohyoid mucles
• The vestibule is the area between the lips and then teeth
• The oral cavity is the area behind the teeth containing the tongue.
Teeth
• Each tooth has a layer of white enamel which covers the tooth. Then dentine which connects the
enamel with the pulp cavity which is filled with the nerves and blood vessels supplying the
tooth. Each tooth is anchored into the alveolar bone with an apical foremen at the bottom of the
roof to allow the nerves and blood vessels to enter the tooth pulp.
• The peridonatyl ligmanet also helps to
anchor teeth roots into the alveoli.
• The teeth and gums - gingivae are supplied
by the superior and inferior alveolar nerves
and vessels which are branches from the
maxillary and mandibular trigeminal nerve
• Hence the supper teeth and gums are
supplies by the superior alveoli nerve which
branches off maxillary
• Lower teeth and gums are supplied by the
inferior alveoli nerve which is a branch of
the mandibular nerve
, • There are 20 deciduous teeth in total 4 incisors, 2canine, 2 molars on the top and bottom. Babies
do NOT have premolars
• Permanent teeth are comprised if 4 incisors, 2 canine, 4 premolars and 6 molars. bringing
adult teeth total to 32
• Incisors are comprised of central and lateral incisors
Tongue
• The tongue is a muscles covered in stratified squamous epithelium as well as papillae which
are taste buds
• It is anchored into the mandible and hyoid bone
• The tongue receives it arterial blood supply from the lingual artery and drains via the lingual
vein
• Additionally lymph from the tongue drains into the deep cervical nodes
• Intrinsic muscles of the tongue move individual parts of the tongue
• Extrinsic muscles more the tongue as a whole
• There are intrinsic muscles dont need to know?) and 4 extrinsic muscles acting on the whole
tongue
• The palatoglossus (extrinsic) is located under the fold of mucosa which makes up the
palatoglossal arches
EXTRINSIC TONGUE MUSCLES
MUSCLE LOCATION ACTION INNERVATION
Genioglossal superior part of the -Inferior fibers protrude Hypoglossal nerve
mandible by the rami the tongue
and inserts into the back -Middle fibers depress
end of the tongue and the centre of the tongue
body of the hyoid bone -Superior fibers draw the
tip of the tongue back
Styloglossus Stems from the styloid Retracts and elevates
process of the temporal tongue
bone and inserts into the
tip and sides of the
tongue
Hyoglossus From hyoid bone to the depresses and retarcts
back sides of the tongue the tongue
Palatoglossus From the palatine Raises the back of the Pharyngeal plexus via
aponeurosis and inserts tongue the branch of the vagus
into the lateral sides of nerve
the tongue superior to
the styloglossus. Forms a
C shape
, EXTRINSIC MUSCLES OF THE TONGUE
Genioglossal
Styloglossus
Hyoglossus
Palatoglossus
Nerve innervation:
• Sensation anterior 2/3 = Lingual nerve (branch of the mandibular trigeminal)
• Sensation posterior 1/3= Glossalpharyngeal
• Specialised taste anterior 2/3 = Facial nerve via the corda tympani
• Specialised taste posterior 1/3 = Glossalpharyngeal
• Motor anterior 2/3 = Hypoglossal except for palatoglassal which is vagus (pharyngeal
plexus)
,Soft and hard palate:
• The soft palate makes up the posterior side of the roof of the mouth via the uvula and palatine
tonsils and the hard palate is the anterior roof to this.
• The palatoglossal arch is the most lateral anterior arch of the mouth (in front of the uvula)
It connect the soft palate with the tongue.
• The palatopharyngeal arch connects the back of the soft palate (behind the uvula) to the
oropharynx
• The palatine tonsils rest in the middle between the palatoglossal and the palatopharyngeal
arches.
• The palatoglossal muscle underlines the infold in mucosal which makes up the palatoglossal
arches (the arch also contains vagus nerve branches)
• During a spot test: if they pin is placed in between the two arches then it is indicative of the
palatine tonsils and the tonsula bed. However these may not actually be seen as the elderly
specimens have degraded tonsils hence may not be seen.
• The hard palate is composed of the palatine process of the maxilla and the horizontal palates
of the palatine bone
• The soft palate however is made up of 5 muscles:
- tensor veli palatine
- levator veli palatine
- Palatoglossus
- palatopharyngeus
- Uvular
• Tensor and levator veli palatine are both found on the roof of the mouth behind the uvula.
The tensor is more anterior to the levator palatine and is in front of the uvula?
• The levator attaches to the end of the soft palate to close it during swallowing so that food
does not go upwards into the naspharynx and nose cavity. It is located behind the uvula
Muscle blood supply sensory nerve supply motor nerve supply
Tensor veli palatine Maxillary artery Maxillary division of Mandibular division of
trigeminal trigeminal
Levator veli Pharyngeal plexus
palatine
Palatoglossus
Palatopharyngeus
Uvular
, Muscles of the pharynx:
• The muscles of the pharynx are comprised of 2 layers,
external and internal layers. The external layers are:
- Superior constrictor
- Middle constrictor
- Inferior constrictor
• The internal layers are:
- Palatopharyngeus
- Salpingopharyngeus
- Stylopharyngeus
• The palatopharangeus makes up the platopharangeal
arch which is behind the uvula and also makes up part
of the soft palate.
• The salpingopharyngeus is the most superior and
anterior, extends higher than the soft palate
• The stylopharyngeus is the most inferior and posterior
and attaches to constrictors at the back of larynx.
• You need to be able to identify where these are on a specimen?
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