The pharynx is about 12 cm long and extends from the base of the skull to the lower border of the cricoid cartilage. It is divided into 3 parts: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is behind the nasal cavity and opens into the oropharynx. The oropharynx extends from the soft palate to the epiglottis and opens into the oral cavity. The laryngopharynx extends from the epiglottis to the lower border of the cricoid cartilage. Three pairs of constrictor muscles and other muscles like the stylopharyngeus allow the pharynx to

1. Pharynx
Part 1

2. Pharynx
Is about 12 cm long
Extending from base of skull to the lower border of the
cricoid cartilage
Opposite the sixth cervical vertebra where it is
continuous with oesophagus
Divided in to 3 parts : nasopharynx,oropharynx and
laryngopharynx

4. Nasopharynx
Behind the nasal cavity and above the soft palate.
Posterior nasal apertures open into it anterioly
Below it is continuous with oropharynx through
pharyngeal isthmus
The nasopharynx is part of the upper respiratory tract
and does not normally give passage to food or drink

5. Nasopharynx
Auditory tube opens on the lateral wall of nasopharynx
This opening is bounded above and behind by the tubal
elevation produced by underlying medial end of auditory
tube
A collection of lymphoid tissue,the pharyngeal tonsil or
adenoid is located beneath the mucous membrane
The tonsil may become enlarged in chronic infections of
upper respiratory system leading to mouth breathing

6. Nasopharynx
The mucous membrane lining the nasopharynx is of
the respiratory type,covered by ciliated cuboidal
epithilium
Receives its sensory and secretomotor nerve supply
through a branch of pterygopalatine gangilion
It resembles the mucous membrane lining the nose

7. Oropharynx
Extends from soft palate to epiglottis
Oral cavity opens into oropharynx anteriorly through
oropharngeal isthmus ,which is bounded on each side by a
fold of mucous membrane ,the palatoglossal arch
The arch is produced by the underlying palatoglossus
muscle
The lateral wall of oropharynx ,behind the palatoglossal arch
presents a vertical ridge of mucous membrane ,the
palatopharyngeal arch produced by palatopharyngeus
muscle

8. Oropharynx
Between palatoglossal and palatopharyngeal arches is a
depression ,the tonsillar sinus.
The palatine tonsil ,a mass of lymphoid tissue, is situated beneath
the mucous membrane lining the sinus
Laterally the tonsil is enclosed by a fibrous capsule
The tonsil is very variable in size and is frequently the site of
infection which causes it to become enlarged and painful
(tonsillitis)
The oropharynx is lined by stratified squamous epithilium, nerve
supply is from pharyngeal plexus

9. Laryngopharynx
Extends from epiglottis to the lower border of the cricoid
cartilage
Laryngopharynx is lined by stratified squamous epithilium and
innervated by vagus through the internal and recurrent
laryngeal branches
On functional nasopharynx regarded as part of nasal cavity
Unlike oropharynx and laryngopharynx it is respiratory in
function ,lined by respiratory mucosa which receives its
sensory innervation from trigiminal nerve

10. Muscles of pharynx
Three paired of constrictor muscles , meet their
fellows of opposite side in the posterior pharyngeal
wall at the median pharyngeal ligament and raphe
Three other muscles,these are stylopharngeus
,salpinopharyngeus ,palatopharyngeus

12. Superior constrictor
Arises from lower two thirds of posterior border of the medial
pterygoid plate (including hamulus) and from the posterior end of
mylohyoid line on the medial surface of the mandible
Between hamulus and the mandible the fibres arise from the
pterygomandibular raphe where they interdigitate with fibers of
buccinator
Between the upper border of the muscle and the base of the skull
is a gap through which the cartilaginous part of auditory tube and
levator veli palatini muscle pass
The remainder of the gap is closed by pharyngobasilar fascia

13. Middle constrictor
Attached anteriorly to stylohyoid ligament, the lesser
Cornu and upper border of greater Cornu of hyoid
bone
The upper fibers diverge upwards,passing superficial
to the lower part of superior constrictor
The lower fibers run horizontally passing deep to
upper part of inferior constrictor

14. Inferior constrictor
Consists of two parts (thyropharyngeus and cricopharyngeus)
Thyropharyngeus arises from oblique line on the lamina of the
thyroid cartilage and inserted in to pharyngeal raphe
Cricopharyngeus attached anteriorly to the side of the arch of
cricoid cartilage
It encircles the lower most part of pharynx
A weak area called killians dehiscence, is present between
thyropharyngeus and cricopharyngeus giving rise to pharyngeal
pouch

16. Salpinopharyngeus
Arises from the cartilage of auditory tube
It passes downwards beneath the pharyngeal mucous
membrane and raised to form salpinopharyngeal fold
and blends with constrictor muscle

18. Stylopharngeus muscle
Arises from medial surfaces of styloid process
It passes between the internal and external carotid
arteries
It crosses the lower border of superior constrictor
muscle and continues downwards inside the middle
constrictor , beneath the pharyngeal mucous
membrane to be inserted into posterior border of
thyroid cartilage and the side wall of the pharynx

19. Pharyngeal muscles , with exception of
stylopharngeus are innervated by accessory nerve
Stylopharngeus is the only muscle derived from third
pharyngeal arch and supplied by glossopharyngeal
nerve