Anatomy of pharynx
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Transcript of Anatomy of pharynx
ANATOMY OF PHARYNX
KEERTHI NS2010 BATCH
An overviewPharynx is a conical
fibromuscular tube forming the upper part of air and food passages
12-14cm longWidth :3.5cm at base; 1.5cm at
pharyngo-oesophageal junction
PHARYNX
Division of Pharynx
a)Base of skull(basioociput and basi sphenoid) soft palate
b)Plane of hard palate hyoid bone
c) Hyoid bone lower border of cricoid cartilage
STRUCTURE OF PHARYNGEAL WALL
From outwards:a)Mucus membraneb)Pharyngeal
aponeurosis c)Muscular coat d)Buccopharyngeal
fascia
Mucus membrane• Pseudostratified ciliated
columnar(in nasopharynx)• Stratified squamous epithelium
Pharyngeal aponeurosis• Pharyngobosilar fascia• Fibrous layer lining muscular coat
Muscular coat• Longitudinal muscles(internal
layer) • Constrictors
Buccopharyngeal fascia• Covers pharynx externally • Pharyngeal plexus of nerves
Pharyngeal Muscles
Stylopharyngeus
• O:medial aspect of styloid process
• Gap between middle and superior constrictor
• NS: glossopharyngeal
Palatopharyngeus
• O: upper surface of palatine aponeurosis as 2 fasiculi
• Moves along inner aspect of the constrictor
• NS: pharyngael plexus
Salpingopharyngeus
• O: cartilage of the auditory tube near the pharyngeal opening of it.
LONGITUDINAL MUSCLES
All the 3 are inserted as a conjoint sheet at the post border of thyroid cartilage and lat aspect of epiglottis
Constrictors
Lies in wall of nasopharynx and oropharynx Wide originPost border of med pterygoid plate
&pterygoid hamulusPterygomandibular raphaePost end of mylohyoid line Mucus membrane on side of tongue
Lower part covered by middle constrictor.
Superior Constrictor
Middle Constrictor
HypopharynxO: lower part of stylohyoid ligament lesser and greater cornu of hyoid
Inferiorly overlapped by inferior constrictor.
Inferior Constrictor
Thickest of the 3Thyropharyngeus obliquely displaced O:oblique line of thyroid cartilage inferior cornu of thyroid
Cricopharyngeus transversly displaced O: ant part of cricoid cartilage between attachment of cricothyroid and articulation of inferior cornu
Cricopharyngeus
Muscles of 2 sides act as a sphincterFunction– prevent the entry of air in
to the oesophagus in the interval between swallowing
So sphincter relaxes during swallowing
Contracts between the acts of swallowing.
All of the fibres get inserted into the median fibrous raphae
Extending from Pharyngeal tubercle
oesophagus
Constrictors
Killian’s DehiscencePotential gap b/w weak area of pharyngeal wall
Gateway of Tear perforation can occur at this site during oesophagostomy.
Killian’s Dehiscence
PHARYNGEAL SPACES2 potential spaces in relation to pharynx:Retropharyngeal space:
Situated behind pharynxExtends from base of skull to the bifurcation of
tracheaParapharyngeal space:
Situated on the side of pharynxContains carotid vessels, jugular veins, last
four cranial nerves & cervical sympathetic chain
Pharngeal Plexus of NervesAlmost all of the nerve supply to the pharynx, whether motor or sensory, is derived from the pharyngeal plexus
Formed by the pharyngeal branches of the glossopharyngeal and vagus nerves with contributions from the superior cervical sympathetic ganglion.
The pharyngeal branch of the vagus supplies all the muscles of the pharynx
Excluding stylopharyngeus, which is supplied by the glossopharyngeal nerve
NASOPHARNX / EPIPHARYNX
RoofPost
wallFloor Ant
wall Lat
wall
Nasopharynx Uppermost part Behind nasal cavitiesExtents:Base of skull to soft palateRoof:Basisphenoid and
basiocciputPosterior wall:Arch of atlas vertebraPre vertebral musclesFascia
Nasopharynx (contd)
Floor:Ant:soft palatePost: deficit(nasopharyngeal
isthumus)Ant wall:Posterior nasal apertures or
choanaePosterior ends of nasal
turbinates and meatus are seen
Nasopharynx (contd)Lat wall:Presents pharyngeal opening of eustachian
tube situated 1.25cm behind the posterior end of inferior turbinate
Bounded above and behind by an elevation called TORUS TUBARIUS raised by the cartilage of the tube.◦ Above and behind the tubal elevation is a recess
called fossa of Rosenmuller-commonest site for origin of carcinoma.
◦ Salpingopharyngeal fold-A ridge extending from lower end of the TT to the lateral pharyngeal wall;raised by salpingopharyngeus
NASOPHARYNGEAL TONSIL(ADENOIDS)Subepithelial collection of
lymphoid tissue.At the junction of roof and
posterior wall of nasopharynx.Causes the overlying mucous
membrane to be thrown into radiating folds.
Increases in size up to the age of six years and then gradually disappears.
Epithelial lined median recess found within adenoid massExtends from pharyngeal mucus to periosteum of basiocciput.Represents the attachment of notochord to pharyngeal endoderm during embryonic developmentInfected pharyngeal bursitis post nasal discharge or crustingAbscess in the bursa:Thornwaldt’s disease
Nasopharyngeal Bursa
Rathke’s Pouch
Clinically represented-A dimple above the adenoids
Reminiscent of buccal mucosal invagination to form the anterior lobe of pituitary
Carcinopharyngoima may arise
Tubal tonsilCollection of subepithelial
lymphoid tissueSit. at tubal elevationContinuous with adenoid tissue
and forms a part of Waldeyer’s ring.
CA:When enlarged due to infection,
it causes eustachian tube occlusion.
Sinus of Morgagni:space b/w base of skull & upper free border of sup. constrictor
Pierced by: Eustachian tube Levator veli
palatini Tensor veli
palatini Ascending
palatine artery
FOSSA OF ROSENMULLER
Pharyngeal recessCommonest site of nasopharyngeal
carcinomaMalignant growth may infilterate
adjacent structures
Brain Soft palate Auditory tube nasal cavity
Passavant’s Ridge
A mucosal ridge raised by fibres of palatopharyngeus.
Forms a ring around post and lat walls of nasopharyngeal isthmus.
When soft palate is elevated the muscle band appear as a ridge Passavant’s ridge
During act of swallowing palate and the ridge approximated.
Lymphatic DrainageUpper deep cervical nodes
Retropharyngeal nodesParapharyngeal nodes
Spinal accessory chain of nodes in the posterior triangle of the neck.
FunctionsActs as a conduit for air;b/w nose and
larynx.Ventilates midle ear through eustachian
tube and equalises air pressure on both sides of TM.
Cuts off nasopharynx from oropharynx with the help of Passavant’s ridge.
Acts as a resonating chamber for voice production
Acts as a drainage channel for mucus secreted by nasal and nasopharyngeal glands
OROPHARYNX
Boundaries • Roof • Post wall• Ant wall• Floor • Lat wall
Oropharynx Extends from the plane of hard palate
to the plane of hyoid bone. Lies opposite to the oral cavity, Through oropharyngeal isthmus,it
communicates with oral cavity.
OROPHARYNGEAL ISTHMUS-boundaries.Soft palate above.Upper surface of tongue below.Palatoglossal arch on either sides.
Boundaries of oropharynxPosterior wall Related to retropharyngeal space.Lies opposite the second and upper part
of third cervical vertebrae.Anterior wallDeficient aboveBelow,it presents:
◦Base of the tongue , posterior to circumvallate papillae
◦Lingual tonsils◦Valleculae
Valleculae Cup shaped depressions Lying b/w the base of the tongue
and anterior surface of epiglottis.Bounded medially by the median
glossoepiglottic fold Laterally by pharyngoepiglottic
fold
Boundaries of oropharynx [cont…]Lateral wall presents:
◦Palatine tonsil◦Anterior pillar:palatoglossus muscle◦Posterior pillar: palatopharyngeus
muscleTonsillar fossaA triangular depression b/w the
anterior and the posterior pillars.Lodges palatine tonsils
Lymphatic DrainageUpper jugular chainjugulo-digastric nodes
◦Retropharyngeal and parapharyngeal nodesPosterior cervical group
Function
Conduit passage for air and foodHelps in pharyngeal phase of deglutitionForms part of vocal tracthelp in speechHelps in appreciation of tasteProvide local immunity and defense against
harmful intruders
Laryngopharynx / Hypopharynx
Lowest part of pharynxAbove oropharynx
Below oesophagus
Ant laryngeal cavityLaryngeal inlet
Clinically
Pyriform sinus Post-cricoid Post-pharyngeal (fossa) region wall
Pyriform sinus / fossaBoundariesLat:thyrohyoid memb & thyroid cartilageMed:aryepiglottic fold, postero lateral
surfaces of arytenoid and crocoid cartilage
Forms lateral channel for foodSmuggler’ fossaForeign bodies may get lodged here
Internal laryngeal nerve in submucosa of lateral wall; easily accessible for LA
CA: pain is referred to ear in Ca of pyriform sinus
Pyriform sinus / fossa
ExtentPharyngoeppiglottic fold to upper end of oesophagus
Post-cricoid region
Part of:Ant wall of
laryngopharynx between upper and lower border of cricoid lamina
CA:Commonest site
for carcinoma in females suffering from Plummer-Wilson syndrome
Post-Pharyngeal Wall
EXTENTS FROM:Hyoid bone to the level
of cricoarytenoid joint
Function
Common pathway for air and foodHelp in deglutitionProvides a vocal tract for resonance of certain speech sounds.
Lymphatic Drainage
Pyriform sinus drains intoupper jugular chain
Rich lymphatics high frequency of nodal metastasis in carcinoma of this regionPost cricoid parapharyngeal nodesPost wall parapharyngeal nodes or
lateral pharyngeal nodes
Waldeyer’s RingA ring composed of MALT at
beginning of food and air passage.
Produce B and T lymphocytesLocal defenseAlso produce lymphocytes to
send to other lymph nodes.
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