Oral and Nasal Cavities

Question 1

What are the two areas which the oral cavity consists of?

Answer 1

1. Vestibule (space between the teeth and the mucosal inner lining of the cheeks and lips)
2. Oral cavity proper (the space contained within the upper and lower dental arches and filled by the tongue)

Question 2

What are the boundaries of the oral cavity?

Answer 2

Roof = the maxilla and palatine

Anterior = maxilla and mandible

Question 3

What are the names of the three muscle on the floor of the mouth?

Answer 3

Mylohyoid muscle
Geniohyoid muscle
Anterior belly of digastric

Question 4

What are the two main muscles of the tongue?

Answer 4

Genioglossus

Geniohyoid

Question 5

What part of the oral cavity does the maxilla make up?

Answer 5

It makes up for the anterior boundary of the upper part of the oral cavity and the anterior 2/3 of the tongue.

Question 6

What folds are the lips described as?

Answer 6

Musculofibrous folds, containing the orbiculares with accompanying nerves and vessels.

Question 7

Where do the nerves suppling the lips and cheeks come from?

Answer 7

From the trigeminal nerve, either the maxillary branch or the mandibular arch.

Question 8

What muscle do the cheeks enclose?

Answer 8

Buccinator muscle

Question 9

What nerves and vessels supply the cheeks?

Answer 9

Blood: buccal arteries (branches of the maxillary)

Nerves: buccal branches (of the mandible)

Question 10

What are the lips covered by internally and externally?

Answer 10

Internally = mucous membrane

Externally = skin

(Zone between the two is called the vermillion border)

Question 11

Does the vermillion border contain glands?

Answer 11

No

Question 12

What is the role of the buccinator muscle?

Answer 12

To push the cheek towards the teeth, preventing food squeezing into the vestibule during chewing

Question 13

What nerve supplies the lateral walls of the oral cavity?

Answer 13

The facial nerve

Question 14

What nerves supply the floor of the cavity?

Answer 14

Geniohyoid supplied by fibres from C1.

The mylohyoid and anterior belly of digastric by the mandibular branch of the trigeminal.

Question 15

What are the mucous membrane of the roof supplied by?

Answer 15

Branches of the maxillary nerve

Question 16

What are the 3 main parts of the tongue?

Answer 16

The root, body and apex.

(The anterior 2/3 of the tongue - the body - rests within the oral cavity while the posterior 1/3 - the root - lies in the oral pharynx)

Question 17

What is the difference in the role fo the intrinsic and extrinsic muscles of the tongue?

Answer 17

Intrinsic muscles change the shape of the tongue while the extrinsic change its position.

Question 18

Explain the nerve supply to the tongue

Answer 18

Innervation of the tongue is rather complex as it needs to consider both its roles in taste and mastication (muscle movement).
All muscles of the tongue except palatoglossus are innervated by the hypoglossal nerve.
The palatoglossus innervated by the pharyngeal plexus.

Nerve supply to tongue for sensory or taste:
The anterior 2/3:
general sensation (touch and temperature) of the anterior 2/3 is via the lingual nerve, a branch of V3
Taste is via the chorda tympani (from nerve 9)
Posterior 1/3 and the vallate papillae:
supplied by lingual branch of nerve 9

Question 19

Explain the blood supply and venous drainage of the tongue

Answer 19

Blood supply to tongue:
the tongue receives blood primarily via the lingual artery, a branch of the external carotid artery and runs underneath the hypoglossus muscle

Venous drainage of the tongue (2 routes)
The dorsal and sides of the tongue are drained by the posterior lingual veins, that leads to the lingual vein. The lingual vein drains to the internal jugular vein.
The remainder is drained by the deep lingual and sublingual veins, that join and lead to the facial vein

Question 20

How is lymph drained from the tongue?

Answer 20

the lymph drains ultimately upwards the deep cervical nodes, that pass it into the general circulation at the venous angles (jugular and subclavian)

Question 21

Where does the duct of the salivary gland enter the mouth?

Answer 21

The duct of the parotid enters the salivary gland near the upper second molar, this is a serious secretion.

Question 22

Give some details on the submandibular and sublingual

Answer 22

The duct of the submandibular gland enters the floor of the mouth, this is a mixed gland (serous and mucin).

The sublingual gland has between 16 and 20 short duct which open into the floor of the mouth. This is mucus secretion.

Question 23

Give the basic information on the nasal cavity:

Answer 23

Forms the upper portion of the respiratory tract. Moistens and warms inspired air, filters the air to remove foreign particles, acts as a resonating chamber for speech.

The external nose is the portion that protrudes out the face, frame is mainly formed from cartilage. All noses have a thick skin covering the cartilage and extend all the way into the nasal opening (nares) where thick hairs help to filter the incoming air.

The nasal cavity is an irregular shaped cavity bordered by:
Floor (the palatine bone that separates it with the oral cavity)
Roof (the cribriform plate of the ethmoid bone separating it from the cranial cavity)

The cavity is high, deep but narrow and divided into left and right by the nasal septum.
The communicates anteriorly with the (external) nose and posteriorly with the nasal part of the pharynx.
The wall is lined by a mucosal later that makes a sticky sheet. This covers the surface and traps duct, bacteria for cilia to propel towards the nasopharynx.

Question 24

Why do we have conchae?

Answer 24

The lateral wall of the nasal cavity shows three circulate tube-like protrusions called conchae.

The conchae force incoming air to swirl around, it slows it down sufficiently to the warmed and also propel the duct and bacteria towards the mucus layer.

Question 25

Explain the parental sinuses

Answer 25

Although empty, the wall of the insures are composed of mucus excreting epithelium.

These are emptied into the nasal cavity and act to help moisten the surface of the nasal cavity and of the incoming air.

Question 26

VAN of the nasal cavity?

Answer 26

Veins: a plexus leading to the ophthalmic, sphenopalatine and facial veins
Arteries: ophthalmic, maxillary and facial arteries
Nerves : ophthalmic (anterosuperiour) and maxillary (postero-inferiour)