The Tongue

Structure

The tongue is a muscular structure occupying most of the mouth. It is attached to the mandible and the hyoid bone and rests on the geniohyoid and mylohyoid muscles. A "V'-shaped groove separates the tongue into an anterior two thirds and a posterior one third.

Muscles

The tongue has both intrinsic and extrinsic muscles. The intrinsic muscles are arranged in vertical, horizontal and transverse bundles and mainly act to change the shape of the tongue. The extrinsic muscles are genioglossus, hyoglossus, styloglossus and palatoglossus. The extrinsic muscles move the tongue. Palatoglossus is supplied by the pharyngeal plexus (vagus) whereas all the other muscles are supplied by cranial nerve IX.

Nerve Supply (See Figure CA.2)

The lingual nerve supplies the mucous membrane of the anterior two thirds. Taste fibres leave the lingual nerve in the chorda tympani and pass via the facial nerve to the nucleus of the tractus solitarius.

The glossopharyngeal nerve transmits taste and general sensation from the posterior third of the tongue. The salivary glands receive efferent parasympathetic supply from the superior salivary nucleus in the pons.

Blood Supply

The tongue is supplied by the lingual artery and drains via the deep lingual vein into the internal jugular vein.

Lymphatic Drainage

The tip of the tongue drains into the submental nodes, the sides into the submandibular glands and the posterior third drains into the retropharyngeal and jugulodigastric nodes.

EpigloHli

EpigloHli

Figure CA.2 Nerve supply of the tongue

The Nose Structure

The nose may be divided into the external nose, which is made up of bone and cartilage and the nasal cavities. The nasal septum divides the nasal cavity into two separate areas which open anteriorly through the nares and posteriorly through the choanae. The dilated area just within the external nose is termed the vestibule. Each nasal cavity has a roof, floor and two walls.

The roof—The roof is made of the nasal cartilages, nasal bones and frontal bones, the cribriform plate of the ethmoid and the body of the sphenoid. It is arched antero-posteriorly.

The floor—is concave and consists of the horizontal plate of the palatine bone and the palatine process of the maxilla.

The medial wall—is the nasal septum made of septal cartilage with a contribution from the ethmoid and vomer.

The lateral wall—has a bony framework which mainly comprises the ethmoidal labyrinth, the maxilla and the perpendicular plate of the palatine bone. The surface area is increased by the presence of three conchae: superior, inferior and middle each, of which overlies a meatus (Figure CA.3).

The paranasal sinuses and the nasolacrimal duct open onto the lateral wall through orifices. The sphenoid sinus opens into the spheno-ethmoidal recess. The middle ethmoidal cells cause a bulge in the middle meatus onto which they open. This is the bulla ethmoidalis. Below the bulla a semicircular groove, the hiatus semilunaris has the openings of the frontal, ethmoidal and maxillary sinuses (see Figure CA.4).

The nose is lined by vascular mucoperiosteum. Apart from the superior concha and its immediate surrounding area, which is covered by yellow olfactory epithelium, the nose is surfaced by respiratory epithelium.

Figure CA.3 The lateral wall of the left nasal cavity

Blood Supply

The ophthalmic and maxillary arteries supply the nose. Venous drainage is provided by the facial vein and pterygoid venous plexus.

Nerve Supply

The specialised olfactory zone is supplied by the olfactory nerve. The first and second divisions of the trigeminal nerve provide general sensation.

The septum is mainly supplied by the nasopalatine branch of the maxillary nerve.

The lateral wall is supplied by the lateral posterior superior nasal nerve, the anterior superior alveolar nerve and the nasociliary nerve. All are branches of the maxillary nerve.

The floor is supplied by the anterior superior alveolar nerve and the greater palatine nerve.

Lymphatic Drainage

The anterior nasal cavity drains into the submandibular nodes and the posterior into the retropharyngeal lymph nodes.

Lo^ral pleryyoid pVe ftifygCtriijnditiy^r-no phi!

MurvJitilu

Hy^lcssus hyoid

Cricoid CnooiliYfcId

Figure CA.4 Coronal section of the nose and maxillary sinus

Wifljllu Middle iHcifd polole) inferior tor-cho

Wifljllu Middle iHcifd polole) inferior tor-cho

Figure CA.5 The pharynx

The Pharynx

Structure (See Figure CA.5)

The pharynx is basically a wide muscular tube forming the common upper pathway of alimentary and respiratory tracts. It extends from the base of the skull to the level of C6. The pharynx lies posterior to, and communicates with, the nose, mouth and larynx. This relationship divides the pharynx into three sections—naso, oro- and laryngo-pharynx. The posterior surface of the pharynx lies on the pre vertebral fascia and cervical vertebrae. The pharynx has four coats:

Lo^ral pleryyoid pVe ftifygCtriijnditiy^r-no phi!

MurvJitilu

Hy^lcssus hyoid

Cricoid CnooiliYfcId

1) Mucous coat. The mucosa is stratified squamous epithelium excepting the nasopharynx where the lining is ciliated, columnar epithelium.

2) Fibrous coat. This is generally thin, but becomes condensed to form the capsule of the tonsil.

3) Muscular coat. This comprises the three constrictor muscles superior, middle and inferior plus stylopharyngeus salpingopharyngeus and palatopharyngeus. The constrictor muscles have an extensive bilateral origin from mandible, hyoid and larynx. Each constrictor spreads out from its anterior attachment to pass posteriorly joining in the mid-line raphe. The superior constrictor arises from the pterygoid plate, the pterygoid hamulus, the pterygomandibular raphe and the inner aspect of the mandible. The middle constrictor arises from the stylohyoid ligament, and the greater and lesser horns of the hyoid. The inferior constrictor is the largest muscle of the three, arising from the thyroid cartilage, cricoid cartilage and the tendinous arch of cricothyroid. Functionally the muscle has two parts with different muscle fibre orientation. It is between the two that the formation of a pharyngeal pouch may occur.

4) Fascial coat—buccopharyngeal fascia forms the thin fibrous coat of the pharynx. Nasopharynx

The nasopharynx communicates with the oropharynx through the pharyngeal isthmus. The Eustachian tube opens into the nasopharynx just below the inferior nasal concha. The adenoids (nasopharyngeal tonsil) lie on the roof and posterior wall of the nasopharynx. The adenoid is a collection of lymphoid tissue covered by ciliated epithelium positioned against the superior constrictor. The sphenoid sinus lies posterior and slightly above the nasopharynx separating it from the sella turcica.

Was this article helpful?

0 0
Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook


Post a comment