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Term Paper on Pharynx


Term Paper Contents:

  1. Term Paper on the Introduction to Pharynx
  2. Term Paper on the Parts of Pharynx
  3. Term Paper on the Muscles of  Pharynx
  4. Term Paper on the Blood Supply of Pharynx
  5. Term Paper on the Applied Anatomy of  Pharynx


Term Paper # 1. Introduction to Pharynx:

ADVERTISEMENTS:

The pharynx is a musculo membranous tube. It is a common chamber for digestive and respira­tory system.

Situation:

It is situated posterior to nose, mouth and larynx, but anterior to upper six cervical vertebrae.

Length:

ADVERTISEMENTS:

About 12 to 14 cm.

Transverse Diameter:

In the upper part about 3.5 cm.

In the lower part about 1.5 cm.

ADVERTISEMENTS:

The pharyngo oesophageal junction is the narrowest part of the alimentary system next to the vermiform appendix.


Term Paper # 2. Parts of Pharynx:

1. Naso pharynx

2. Oro pharynx

ADVERTISEMENTS:

3. Laryngo pharynx

Relations:

i. Superiorly- Base of skull.

ii. Interiorly- At the level of lower border of C6 vertebra it becomes oesophagus.

ADVERTISEMENTS:

iii. Anteriorly- Nose, mouth and larynx.

iv. Posteriorly- Upper six cervical vertebrae.

v. Prevertebral muscles and fascia.

Communications:

ADVERTISEMENTS:

(a) Laterally:

It communicates with middle ear cavity via pharyngo tympanic tube.

(b) Anteriorly:

Communicates with cavity of nose, mouth and larynx.

(c) Inferiorly:

It communicates with oesophagus.

Attachments of Pharynx:

From above downwards it is attached to:

1. Medial pterygoid plate.

2. Pterygo mandibular raphe.

3. Mandible.

4. Mucous membrane of the side of tongue.

5. Hyoid bone.

6. Thyroid cartilage.

7. Cricoid cartilage.

I. Naso Pharynx:

This is the upper most part of the pharynx.

Boundaries:

Superiorly: Basi sphenoid and basi occiput.

Anteriorly: Through the posterior nasal aperture it communicates with the nose.

Posteriorly:

1. Arch of adas.

2. Upper half of axis.

Inferiorly:

With oropharynx through pharyngeal isthmus.

Dimensions:

Anteroposteriorly – 2.5 cm.

Transversely- 3.5 cm.

Interior of the Naso Pharynx:

On the lateral wall about 1 cm behind the inferior nasal concha – auditory tube opens.

Behind this opening there is a tubal elevation due to collection of lymphoid follicles called tubal tonsil.

Above and behind the tubal elevation, there is a depression called pharyngeal recess of Rosenmuller which lodges the pharyngeal tonsil (Adenoids).

Mucous membrane of nasopharynx is res­piratory in nature, i.e., lined by ciliated columnar epithelium.

Nerve Supply:

Sensory supply is by pharyngeal branch of pterygo palatine ganglion (maxillary nerve). These fibres are also secretomotor coming from ganglion.

II. Oro-Pharynx:

This is the middle part of pharynx.

Boundaries:

Superiorly- Soft palate.

Inferiorly- Upper border of epiglottis.

Anteriorly- Mouth, tonsillar fossa and dorsum of posterior 1/3 of the tongue.

Posteriorly- Lower 1/2 of 2nd cervical vertebra and 3rd cervical vertebra.

Communications:

Superiorly- It communicates with the naso pharynx via pharyngeal isthmus.

Anteriorly- It communicates with oral cavity via oro­pharyngeal isthmus.

Inferiorly- With laryngo pharynx.

Interior of Oropharynx:

In between palato-glossal and palato pharyngeal arches, palatine tonsil is situated, mucous membrane is of oral type means – it is lined by stratified squamous epithelium.

Nerve Supply:

Sensory, supply is via branches of glossopharyngeal nerve.

Secretomotor:

Fibres coming via lesser palatine nerve branch from pterygo palatine ganglion.

III. Laryngo Pharynx:

This is the lowest part of the pharynx.

It extends from upper border of epiglottis to the level of lower border of cricoid cartilage.

Communication:

Anteriorly- It communicates with larynx via laryngeal inlet.

Inferiorly- It is continuous with oesophagus.

Superiorly- Communication with oropharynx.

Relations:

Posteriorly:

It is related to 4th, 5th and 6th cervical vertebra.

Anteriorly:

Related to:

1. Inlet of larynx.

2. Posterior surface of arytenoid cartilage.

3. Posterior surface of cricoid cartilage.

Boundaries of Laryngeal Inlet:

Antero-superior – Upper border of epiglottis.

Postero-inferior – Inter arytenoids fold of mucous membrane.

Laterally – ary – epiglottic fold of mucous membrane.

Piriform – recess is a depression situated on either sides of laryngeal inlet.

The floor of this recess is supplied by internal laryngeal nerve (X). It is pear shaped fossa.

Boundaries of Piriform Fossa:

Medially – Ary epiglottic fold.

Laterally – Inner surface of lamina of thyroid cartilage and thyrohyoid membrane.

Hard food particles may be lodged with in the fossa accidentally when an instrument is used to remove such foreign particles, it may result in injury to the internal laryngeal nerve and causes anesthesia of the larynx, and considered as surgeons grave yard.

Nerve Supply:

Via internal laryngeal nerve branch of superior laryngeal nerve (X).


Term Paper # 3. Muscles of Pharynx:

Muscles of pharynx are of two types:

A. Constrictors:

Superior, middle and inferior constrictor of pharynx.

They overlap each other from below upwards.

1. Superior Constrictor of Pharynx:

Origin is from:

(a) Posterior border of medial pterygoid plate.

(b) Pterygoid hamulus.

(c) Pterygo mandibular raphe.

(d) Above and behind mylohyoid line of mandible.

(e) Mucous membrane of lateral border of posterior 1/3 of tongue.

Insertion on:

(a) Pharyngeal tubercle of occipital bone.

(b) Median fibrous raphe.

Between the base of skull and upper border of superior constrictor muscle, there is a space called hiatus of morgagni. It is closed by thickened pharyngo basilar fascia and buccopharyngeal fascia.

2. Middle Constrictor of Pharynx:

Origin is from:

(i) Lower part of stylohyoid ligament.

(ii) Greater and lesser horn of hyoid bone.

Insertion on:

Median fibrous raphe of pharynx.

3. Inferior Constrictor of Pharynx:

Origin is from:

(i) Oblique line and inferior horn of lamina of thyroid cartilage.

(ii) Lateral surface of cricoid cartilage.

(iii) Fibrous band extending from thyroid tubercle to cricoid cartilage.

Insertion on:

Median fibrous raphe.

Inferior constrictor has two parts:

(a) Thyropharyngeus part – Arising from thyroid lamina is ascending upwards.

(b) Cricopharyngeus part – Arising from cricoid cartilage is horizontal and acts as sphincter.

The dehiscence of Killian is a weak area between these two parts of inferior constrictor.

Nerve Supply of Constrictors:

Via pharyngeal plexus of nerves containing fibres of vagus and cranial root of accessory nerve.

Action of Constrictors:

During deglutition they contract and relax alternatively causing peristaltic movement of the pharynx. Thyropharyngeus has propulsive function but cricopharyngeus has a sphincteric function. Cricopharyngeal part relaxes during the contraction of the thyropharyngeal part.

Pharyngeal Diverticulum:

When both parts of inferior constrictor are constricted simultaneously, the pressure inside the pharynx is increased. This causes protrusion of the mucous membrane of the pharynx from the weak area between these two parts. This is called pharyngeal diverticulum.

Structures Passing between the Constrictors:

1. Below the inferior constrictors – Recurrent laryngeal nerve (X) and Inferior laryngeal vessels.

2. Between the middle and inferior constrictors – Internal laryngeal nerve (X) and Superior laryngeal vessels.

3. Between the middle and superior constrictors – Stylopharyngeus muscle and Glossopharyngeal nerve (IX).

4. Between the base of skull and superior constrictor – Pharyngotympanic tube and Levator veli palatini

(i) Ascending palatine artery branch of facial artery.

(ii) Palatine branch of ascending pharyn­geal artery.

B. Other Muscles of Pharynx (Longitudinal Muscles):

(i) Stylopharyngeus – arises from styloid process.

(ii) Palatopharyngeus – arises from superior surface of palatine aponeurosis.

(iii) Salpingopharyngeus – arises from lower part of auditory tube.

These muscles descend downward inside the constrictors and inserted on the pharyngeal wall and posterior border of lamina of thyroid cartilage.

Action:

Elevation of the pharynx and larynx.

Nerve Supply:

Palato pharyngeus and salpingo- haryngeus are supplied by pharyngeal plexus of nerves (X and XI).

Stylopharyngeus is supplied by glossopharyngeal nerve (IX).

Nerves forming pharyngeal plexus are branches of:

1. Glossopharyngeal – pharyngeal branch.

2. Vagus nerve containing fibres of cranial root of accessory.

3. Superior cervical sympathetic ganglion – pharyngeal branch.

Pharyngeal plexus of nerves – lies on the surface of middle constrictor of pharynx deep to buccopharyngeal fascia.


Term Paper # 4. Blood Supply of Pharynx:

(a) Dorsalis linguae artery (lingual artery).

(b) Greater and lesser palatine artery, pharyngeal and pterygoid branches of maxillary artery 3rd part.

(c) Tonsillar branch of facial artery.

(d) Ascending palatine branch of facial artery.

(e) Ascending pharyngeal artery branch of external carotid artery.

Venous Drainage:

Via pharyngeal venous plexus drains into internal jugular vein.

Lymphatic Drainage:

Lymphatics go to deep cervical and retropharyngeal group of lymph nodes.

Retropharyngeal Space:

Retropharyngeal space is found behind the pharynx. A mid-line septum divides the space into right and left halves. Space is bounded anteriorly by bucco­pharyngeal fascia and pharyngeal wall. Posteriorly it is bounded by prevertebral muscles and fascia.

Contents of Retropharyngeal Space:

It contains retropharyngeal lymph nodes separated by a septum and drains posterior part of the nose, pharynx, pharyngo tympanic tube, posterior part of palate and tongue and posterior ethmoidal and sphenoidal air sinuses.


Term Paper # 5. Applied Anatomy of Pharynx:

1. Retropharyngeal abscess – due to suppuration of retro pharyngeal lymph nodes – remain unilateral due to septum.

2. Pharyngitis – inflammation of pharynx.

3. Retropharyngeal abscess from the caries of the cervical vertebrae spreads across the midline deep to pre-vertebral fascia, as there is no septum.

4. Diphtheria – occurs on the oropharynx.

5. Hypopharyngeal pouch is formed by herniation of mucous membrane through dehiscence of Killians of the posterior pharyngeal wall.

6. Pharyngeal keratosis – thickening and hardening of the mucous membrane of the pharynx.

7. Pharyngoscopy – examination of interior of pharynx via pharyngoscope.

8. Malignant tumours like – squamous cell carcinoma, lympho-epithelioma etc.