Pharyngeal Arches

Question 1

1. What is the derivative of the first pharyngeal cleft?

2. What two arches makes up the first cleft?

Answer 1

1. External acousic meatus and canal

2. 1st arch (mandibular) and part of second arch (hyoid)

Question 2

What aortic arch comes from the first (mandibular) pharyngeal arch?

Answer 2

Maxillary artery

Question 3

What are the muscles that are derived from the first arch?

Answer 3

Muscles of mastication: Temporalis, Masseter, mylohyoid, ant belly of digastric

Question 4

What are the skeletal derivatives of the first arch?

Answer 4

Malleus, incus, sphenomandibular ligament, Meckel cartilage

Question 5

Derivatives of first pharygeal pouch?

Answer 5

Middle ear and auditory tube (Eustachian/pharyngotympanic tube)
Endoderm of first pouch forms lining of middle ear

Question 6

What is the derivatives of the 2nd, 3rd, and 4th pharyngeal clefts?

Answer 6

The neck; if abnormal, forms persistent cervical sinus found along SCM

Question 7

What aortic arch comes from the second (hyoid) pharyngeal arch?

Answer 7

hyoid artery, stapedial artery

Question 8

What are the muscles that are derived from the second arch?

Answer 8

muscles of facial expression: Buccinator, Orbicularis oris, Post belly of digastric, platysma

Question 9

What are the skeletal derivatives of the second arch?

Answer 9

Stapes, styloid process, stylohyoid ligament, part of hyoid cartilage; Reichert’s cartilage, Lesser cornu and upper part of hyoid bone

Question 10

Derivatives of second pharygeal pouch?

Answer 10

supratonsillar fossa (palatine tonsil) differentiated from tonsillar crypts (mesoderm)

Question 11

What aortic arch comes from the third pharyngeal arch?

Answer 11

Common carotid a and proximal portions of Internal carotid artery

Question 12

What are the muscles that are derived from the third arch?

Answer 12

m. stylopharyngeus

Question 13

What are the skeletal derivatives of the third arch?

Answer 13

parts of hyoid cartilage–Greater cornu and lower portion of hyoid bone

Question 14

Derivatives of third pharygeal pouch?

Answer 14

thymus, inferior paratyroid gland

Question 15

What aortic arch comes from the fourth pharyngeal arch?

Answer 15

IV:
right subclavian artery, aorta
Left side: connects ventral aorta to dorsal aorta;
right side: forms proximal portion of right subclavian a

VI: Proximal develop into right and left pulmonary arteries, while distal portion of left aortic arch artery develops into ductus arteriosus

Question 16

What are the muscles that are derived from the fourth arch?

Answer 16

pharyngeal and laryngeal musculature and levator veli palatini

Question 17

What are the skeletal derivatives of the fourth arch?

Answer 17

Laryngeal cartilage–Thyroid cartilage, cricoid cartilage, corniculate cartilage, arytenoid cartilage

Question 18

Derivatives of fourth pharygeal pouch?

Answer 18

thymus, superior parathyoid gland, ultimobranchial body–forms parafollicular C cells of thyroid gland (5th pouch)

Question 19

Cranial nerve derived from first arch?

Answer 19

Trigeminal nerve (mandibular division?)

Question 20

Cranial nerve from second arch?

Answer 20

Facial nerve

Question 21

Cranial nerve from third arch?

Answer 21

Glossopharyngeal nerve

Question 22

Cranial nerve from fourth arch?

Answer 22

vagus nerve (External laryngeal and Recurrent Laryngeal)

Question 23

Difference between Pharygeal cleft and pharygeal pouch

Answer 23

Cleft: invagination of ectoderm between adjacent arches
Pouch: Invagination of ENDOderm between adjacent arches

Question 24

Between the first pouch and the cleft is the ____

Answer 24

tympanic membrane

Question 25

How does the tongue develop?

Answer 25

Originates from 1st, 2d and 3rd (base) pharyngeal arches; form by fusion of 2 lateral lingual sweillings and overgrow the tuberculum impar

V shaped groove=sulcus terminales

Question 26

Anterior 2/3 of tongue
Sensory innervation?
Innervation of taste buds?

Answer 26

Sensory: Lingual nerve, branch of trigeminal nerve

Taste bud: Facial nerve

Question 27

Posterior 1/3 of tongue
Sensory innervation?
Innervation of taste buds?

Answer 27

Sensory: Glossopharyngeal nerve

Taste bud: Glossopharyngeal, vagus nerve near base

Question 28

Is thyroid gland formed from an arch?

Answer 28

No, formed from midline thyroid diverticulum that fomrs from endoderm at floor of pharynx

opening of thyroglossal duct=foramen cecum found in midline at terminal sulcus

positioned between ant 2/3 and post 1/3 of developing tongue and then migrates anterior into trachea