This document provides information about the pharyngeal apparatus from a student's notebook. It describes the pharyngeal arches, pouches, and clefts that develop in the pharynx during embryogenesis. It discusses the nerves, arteries, and fate of each pharyngeal arch. It also summarizes the development of structures like the palatine tonsils, thymus, parathyroid glands, and thyroid gland from the pharyngeal pouches and clefts. The document is certified by professors from the S.K.R.P. Gujarati Homeopathy College in Indore, India.

1. S.K.R.P. GUJARATI HOMEOPATHY COLLEGE INDORE (M.P.)
Department Of Anatomy
Batch – 2021 -22
PHARYNGEALAPPARATUS
Guided By :-
Dr. Mukesh Agrawal
{H.O.D. Of Anatomy Department}
Dr. Anukrati Nagori
{Professor Anatomy Department}
Submitted By :-
Jitendra Gurjar
B.H.M.S. First proff.
Batch – 2021-22

2. CERTIFICATE
This is to certify that Jitendra Gurjar, roll no. 30, studying in B.H.M.S. First Proff. In the Year
21-22 to this institute. He has completed practical course based on the syllabus (As per C.C.H.
Regulation 2002 minimum standard of education) and given satisfactory account of it, in this
notebook containing a record of the departmental practical work.
Date:- _____/______/_____
Grade:- __________________
Dr. S.P. Singh
Principal
Dr. Mukesh Agrawal
Professor, Head Of Department
Dr. Anukrati Nagori
Assistant Professor
Seal Of The Institute

3. PHARYNGEAL APPARATUS

4. Contents
1. Introduction
2. Pharyngeal apparatus
3. Pharyngeal arches
4. pharyngeal clefts
5. Pharyngeal Pouches
6. Pharyngeal arches
7. Nerve of Pharyngeal archer
8. Arteries of arches
9. Fate of pharyngeal arches
10. Branchial cyst
11. Branchial fistula
12. External branchial Sinus
13. Development of palatine tonsils
14. Development of thymus
15. Development of parathyroid gland
16. Development of thyroid gland

5. INTRODUCTION
• The pharynx is part of the throat behind the mouth and nose. A Funnel shaped tubular
structure that develops from the foregut.
• On the formation of embryonic folds foregut develops from the part of yolk sac that lies
within the head fold.
• The primitive pharyngeal part has floor, roof and two lateral walls.
RELATIONS OF THE PRIMITIVE PHARYNX
• Cranial :- Forebrain.
• Ventral (floor) :- stomodeum, pericardial bulge, septum transversum.
• Dorsal (roof) :- Notochord and hindbrain vesicles.
• Lateral :- Splanchnopleuric layer of the mesoderm, Surface ectoderm. When the neck was
not present in early developmental stages, the neck was formed in between stomodeum and
pericardial bulge due to mesodermal growth.
• Between stomodeum and pericardial bulge mesoderm shows intermittent thickening. This
thickened mesoderm forms bars on the surface ectoderm.

6. PHARYNGEAL APPARATUS
• Pharyngeal apparatus Consists of pharyngeal arches, pharyngeal pouches and
pharyngeal clefts.
• Pharyngeal arches :-
• Thickened mesodermal bars present in the floor and lateral wall of the primitive
pharynx are called pharyngeal arches.
• Pharyngeal clefts :-
• Depression (grooves) on the surface ectoderm in between adjacent arches are
called pharyngeal clefts.
• Pharyngeal pouches :-
• Endodermal depressions between adjacent pharyngeal arches in the floor and
lateral wall of the primitive pharynx are called pharyngeal pouches.

7. PHARYNGEAL ARCHES
• Horseshoe shaped thickened mesodermal bars in lateral walls & the floor of the
primitive pharynx is called pharyngeal arches. These are six in number.
• Pharyngeal arches begin to develop early in the fourth week as neural crest cells
migrate into the head and neck region.
• The first pair of pharyngeal arches (primordium of jaws) appears as a surface
elevations lateral to the developing pharynx. Soon other arches appear as obliquely
disposed, rounded ridges on each side of the future head and neck regions.
• By the end of the fourth week, four pairs of pharyngeal arches are visible externally.
• The fifth and sixth arches are rudimentary and are not visible on the surface of the
embryo.
• The pharyngeal arches are separated from each other by fissures called pharyngeal
grooves.
• They are numbered in craniocaudal sequence.

8. PHARYNGEAL ARCHES

9. NERVES OF PHARYNGEAL
ARCHES
1. First arch :- Mandibular nerve (pre-trimatic) .
2. Second arch : - Facial nerve
3. Third arch :- Nasopharyngeal nerve
4. Fourth arch: superior Pharyngeal nerve.
5. Sixth arch: Recurrent laryngeal nerve.
ARTERIES OF ARCHES
Each arch contains one arch artery.
These arch arteries connect dorsal aorta with aortic sac (that lies
ventrally).
Aortic arch modify and forms following structures :-
1. First aortic arch artery : A part of maxillary artery.
2. Second aortic arch artery: Stapedial artery, hyoid artery.
3. Third aortic arch artery: A carotid artery from ventral part.
4. Fourth aortic arch artery: On the right side – proximal part of right
subclavian artery.

10. FATE OF PHARYNGEAL ARCHES
• The pharyngeal arches contribute exclusively to the formation the face, nasal cavities,
mouth, larynx, pharynx and neck.
• During the fifth week, the second pharyngeal arch enlarges and overgrows the third and
fourth arches, forming the ectodermal depression called cervical sinus.
• By the end of seventh week the second to fourth pharyngeal grooves and the cervical
sinus have disappeared, giving the neck a smooth contour.
• An Aortic Arch Contains:-
1. An aortic arch, an artery that arises from the truncus arteriosus of the primordial heart.
2. A cartilaginous rod that forms the skeleton of the arch.
3. A muscular component that differentiates into muscles in the head and neck.
4. A nerve that supplies the mucosa and muscles derived from the arch.

11. BRANCHIAL CYST
• Is a congenital cyst in the skin of the lateral part of the
neck.
• It is located along the anterior border of the
sternocleidomastoids muscle, mostly close to the angle of
the mandible.
BRANCHIAL FISTULA
• If the branchial cyst opens both in pharynx and externally
on skin of the neck, it is called complete branchial fistula.
BRANCHIAL CYST
EXTERNAL BRANCHIAL FISTULA
• Branchial cleft fistulae typically open onto the skin at the anterior border of sternocleidomastoid at the
junction of middle and lower 1/3

12. Development of palatine tonsil
Palatine, tonsils develops from two sources :-
Endoderm of second pharyngeal pouch.
Mesoderm (lymphocytes).
Development of thymus
Thymus develops from two source:-
Endoderm of the third pharyngeal pouch.
Mesoderm farms thymocytes & other connective tissue.
Development of parathyroid gland
These are four parathyroid glands :-
Two superior parathyroid glands are derived from fourth pharyngeal
pouch .
Two inferior parathyroid glands, are derived from third pharyngeal
pouch.

13. Development of Thyroid
gland
Thyroid gland develops from the following two sources : -
A. Follicles from thyroglossal duct.
B. Perifollicular cells from ultimo branchial body.
By the end of the third month (12th week) follicular cells
start producing thyroid hormones.
The thyroid gland is the first gland that develops after
fertilisation.

14. BIBLIOGRAPHY
Book Name Author Name
• Human Anatomy B.D. Chaurasiya
• Gray’s Anatomy Henry Gray
• Atlas of human anatomy Frank H. Natter

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