Anatomy of muscles of mastication

Question 1

What are the divisions of the GI tract?

Answer 1

GI tract separates into the:
Upper GI tract: oesophagus, stomach and duodenum of small intestine
Lower GI tract: duodenum, jejunum and ileum of small intestine large intestine, rectum and anus.

Question 2

What are capsules?

Answer 2

Capsules are the somatosensory fibres which detect environment changes like food entering to transmit this information to the brain.to trigger digestion.

Question 3

What are the three salivary glands?

Answer 3

Submandibular
Sublingual
Parotid gland
They all contain acini which secrete saliva containing lingual lipase and amylase. The glands contract to deposit saliva into branched ducts.

Question 4

What is the oropharyngeal isthmus?

Answer 4

The opening at the back of the mouth/oral cavity into the oropharynx.

Question 5

What is the vestibule?

Answer 5

The vestibule is the bony cartilage below the teeth which is connected to the lips and cheeks

Question 6

How is the secretion of the salivary glands regulated?

Answer 6

Rate of secretion is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system. This is located in the medulla obloganta.

Question 7

What is the location of the parotid gland?

Answer 7

Parotid gland is located below the zygomatic arch and above the inferior border of the mandible, in-between the anterior masseter muscle and posterior external ear.

Question 8

What is the mode of secretion of the parotid gland?

Answer 8

Spherical serous acini release serous saliva containing lingual lipase and amylase into the Stensen duct which opens into the oral cavity to the maxillary second molar.

Question 9

What is the innervation for the parotid gland?

Answer 9

It is controlled by the parasympathetic stimulation of the glossopharyngeal nerve.

Question 10

What is the vascularisation and innervation of the parotid gland

Answer 10

Artery supply: The superficial temporal artery and the maxillary artery.

Venous supply: Retromandibular vein which drains the parotid gland.

Innervation: Glossopharyngeal nerve (parasympathetic)

Question 11

How does nerve activation influence salivary gland secretion?

Answer 11

It is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system. Sympathetic activation is the sympathetic ganglion which releases catecholamines which inhibit secretion by acinar cells. It decreases vascular tone to decrease blood flow to the glands. Parasympathetic activation releases acetylcholine which increases secretion by acinar cells. It increases vascular tone to increase blood flow to the glands.

Question 12

What is the location of the sublingual gland?

Answer 12

Beneath the mucosa of the mouth floor below the tongue and superior to the mylohyoid muscle. Found within the sublingual folds at the base of the tongue lateral to the sublingual papilla.

Question 13

What is the mode of secretion of the sublingual gland?

Answer 13

Mixed secretion which is mainly mucous from the acinar cells into the 8-20 Rivinus’ excretory ducts for each salivary gland and partially from the submandibular duct called Wharton’s duct.

Question 14

What is the vascularisation and innervation of the sublingual gland?

Answer 14

External carotid branch: Submental and sublingual arteries

Question 15

What is the location of the submandibular gland?

Answer 15

Inferior border of the mandible, between the bellies of the digastric muscles.

Question 16

What is the mode of secretion of the submandibular gland?

Answer 16

Mixed secretion which is mainly serous from acinar cells into the Wharton’s duct through the sublingual papilla.

Question 17

What is the sublingual papilla?

Answer 17

Membranous tissue immediately inferior to the lingual frenulum which connects the lips to the gums. Sublingual papilla is where the Wharton’s duct of the submandibular gland is found.

Question 18

What is the lingual frenulum?

Answer 18

Web of tissue on the base of the tongue which connects the tongue to the floor of the mouth.

Question 19

What is the vascularisation of the submandibular gland?

Answer 19

Facial artery

Question 20

What are the intrinsic muscles of the tongue?

Answer 20

Superior longitudinal muscle: from submucosa to the anterolateral margin. Elevates tongue apex

Vertical- muscle: tongue root to the lingual aponeurosis. Broadens and elongates tongue

Transverse muscle from lingual septum to lateral: Narrows and elongates tongue

Inferior longitudinal muscle from tongue root to tongue apex. It lowers tongue apex

Question 21

What are the extrinsic muscles of the tongue?

Answer 21

Styloglossus muscle- from styloid process of the temporal bone to the stylomandibular ligament

Hyoglossus muscle- from hyoid bone

Genioglossus- from the symphis menti (medial line) of the mandibular bone

Palatoglossus- from the soft palate

Question 22

What is the innervation of the tongue?

Answer 22

Hypoglossal nerve supplies all the muscles excluding the palatoglossus. Palatoglossus is supplied by the vagus nerve.

Question 23

What is the palatoglossal fold?

Answer 23

Mucosal fold overlying the palatoglossus muscle.

Question 24

What is the palatoglossal arch?

Answer 24

Ridges created by the palatoglossal muscle which separates the oral cavity and the oral pharynx.

Question 25

What is the palatopharyngeal arch?

Answer 25

Recess in the oropharynx posterior to the oral cavity where the palatine tonsil is located.

Question 26

What is the function of the levator pili palatini?

Answer 26

Levator pili palatini muscle contracts to elevate the soft palate and block the opening of the nasopharynx.

Question 27

What is the innervation to the teeth?

Answer 27

Trigeminal nerve has a ganglion with two branches: maxillary nerve branch and mandibular nerve branch.

Question 28

What is the innervation to the maxillary teeth?

Answer 28

Maxillary nerve branches into the superior alveolar nerve which consists of the dental plexus: anterior, middle and posterior superior alveolar nerves.

Question 29

What is the innervation to the mandibular teeth?

Answer 29

Mandibular branch has a tributary of the inferior alveolar nerve.

Question 30

What are the teeth of the mandible?

Answer 30

(On one side) 3 maxillary molars, 3 maxillary premolars, 1 lateral incisor, 1 central incisor
(On one side) 3 mandibular molars, 3 mandibular premolars, 1 lateral incisor, 1 central incisor

Question 31

What is the innervation to the tongue?

Answer 31

Anterior 2/3 has general sensation from the sublingual nerve. This is a tributary of the mandibular nerve branch of the trigeminal nerve. Anterior 2/3 has taste sensation from the chorda tympani. Chorda tympani is a branch of the facial nerve.

Posterior 1/3rd is innervated by the glossopharyngeal nerve for both taste and sensation

Question 32

What are the muscles of mastication?

Answer 32

Masseter, temporalis, lateral pterygoid, medial pterygoid muscle.
Secondary muscle is buccinator.

Question 33

Where is the lateral pterygoid located?

Answer 33

It has two heads. Superior head is from the greater wing of the sphenoid bone. Inferior head is from the lateral pterygoid plate of the sphenoid bone.
Lateral pterygoid attaches to the temporomandibular joint.

Question 34

Where is the medial pterygoid located?

Answer 34

Medial pterygoid plate of the sphenoid bone and attaches to the angle of the mandible.

Question 35

Where is the temporalis muscle located?

Answer 35

Temporal line of the skull to the coronoid process of the mandible.

Question 36

Where is the masseter muscle located?

Answer 36

Zygomatic arch to the mandibular ramus

Question 37

Hypoglossal nerve

Answer 37

Motor innervation to the tongue

Question 38

Lingual nerve

Answer 38

General sensation of the anterior 2/3 of the tongue

Question 39

Chorda tympani

Answer 39

Specialised taste sensation to the anterior 2/3 of the tongue

Question 40

Glossopharyngeal nerve

Answer 40

General and taste sensation to the posterior 1/3 of the tongue