Seet 10

Question 1

What we can see during week 4 embryo

Answer 1

✓ stomodeum
✓ Five facial swelling surrounding it
✓ Buccopharyngeal membrane

Question 2

Week 5 in utero

Answer 2

stomodeum
frontonasal process
maxillary process
nasal pit
optic placode
second pharyngeal (hyoid arch).

Question 3

nasal placode

Answer 3

is a local thickening of the epithelium (ectoderm) at the site where the nasal pits start to appear.
✓ Nasal placodes sink into the mesenchyme forming 2 nasal pits.

Question 4

Historyof the nasal cavity

Answer 4

it starts as nasal placodes→ then becomes nasal pits→ then the pits become orifices when they dig deeper→ to make the nasal cavity.

Question 5

From which membrane you can indicate that you are in week 5

Answer 5

oronasal membrane

Question 6

maxillary isthmus

Answer 6

is a bridge of mesenchyme that joins the maxillary and medial nasal processes

Question 7

nasal fin

Answer 7

sheet of epithelium in front of each nasal pit

Question 8

nasal fin

Answer 8

sheet of epithelium in front of each nasal pit

Question 9

muscular contributions or muscular derivatives of The first pharyngeal arch

Answer 9

muscles of mastication, 
anterior belly of digastric muscle,
 mylohyoid, 
tensor tympani, 
tensor veli palatini muscles

Question 10

Blood and nerve supply for the first pharyngeal arch

Answer 10

blood supply from the maxillary artery and nerve supply from the trigeminal nerve

Question 11

Second pharyngeal arch Muscular derivatives

Answer 11

Muscles of facial expression, 
buccinator,
 platysma, 
stapedius, 
stylohyoid, 
poster belly of digastric muscle.

Question 12

Nerve and blood supply of the 2nd pharyngeal nerve

Answer 12

facial nerve (VII)
stapedial artery.

Question 13

embryologically mosaic: a structure that’s derived from more than one pharyngeal arch or process
Mention the muscle and structure that is embryologically mosaic

Answer 13

1)digastric muscle is derived from two pharyngeal arches. The anterior belly is derived from the first arch, and the posterior belly is derived from the second arch.
2)the hyoid bone part of it derived from second arch, and the remainder from the third arch.
3) The upper lip is another example of an
embryological mosaic structure; part of it is derived from the medial nasal process and part of it is derived from the maxillary process.

Question 14

stapes, styloid process, lesser horn and upper parts of the body all derived from

Answer 14

Reichert’s cartilage

by a process called endochondral ossification.

Question 15

Skeletal contributions of the second pharyngeal arch

Answer 15

Stapes,temporal styloid process,hyoid bone(lesser hornsand upper part of body),stylohyoid ligament,[14]Reichert’s cartilage

Question 16

Skeletal contributions of the first pharyngeal arch

Answer 16

Premaxilla,maxilla,mandible(only as a model for mandible not actual formation of mandible),zygomatic bone, part of thetemporal bone,[16]theincus, and themalleusof the middle ear, alsoMeckel’s cartilage

Question 17

There is a ligament connecting the styloid process with the lesser horn of the hyoid bone called stylohyoid ligament. This ligament is derived from

Answer 17

perichondrium of Reichert’s cartilage.

Question 18

Third arch

Answer 18

only one muscle called stylopharyngeus.
Skeletal contribution: the remainder of the hyoid bone: the greater horn and the lower part of the body
Nerve supply is the glossopharyngeal nerve (IX)
Blood supply is from common carotid and internal carotid arteries.

Question 19

Forth arch

Answer 19

➢ Muscular contribution: intrinsic muscles of the soft palate.
➢ Skeletal contribution: thyroid cartilage and epiglottic cartilage.
➢ Nerve supply from the vagus nerve (X) which is the tenth cranial nerve, specifically the superior laryngeal branch of the vagus nerve.
➢ Blood supply the right side from the right subclavian artery, the left side from the aortic arch.

Question 20

Sixth arch

Answer 20

➢ Muscular contribution: intrinsic muscles of the larynx.
➢ Skeletal contributions: cricoid cartilage, arytenoid cartilage, corniculate cartilage; these are some of the cartilages of the larynx called laryngeal cartilages.
➢ Nerve supply the recurrent laryngeal branch of the vagus nerve.
➢ Blood supply: the right side gets blood supply from the right pulmonary artery the left side gets its supply from pulmonary artery and ductus arteriosus.

Question 21

The origin of the formation of the laryngeal cartilages.

Answer 21

the fourth and the sixth arch together contribute to the formation of the laryngeal cartilages. The fourth gives rise to the thyroid cartilage which is Adam’s apple, and the epiglottis cartilage. The remainder of the cartilage of the larynx (cricoid, arytenoid, corniculate cartilage) are derived from the 6th arch.

Question 22

medial nasal process give rise to

Answer 22

philtrum
mid (central) region of the nose
the central region of the nasal cavity,
the premaxilla

Question 23

Each pharyngeal arch is supported by primary cartilage before bone starts to be formed. The cartilage that provides support for the maxillary process is called………. cartilage and the cartilage that provides support for the mandibular process is called…………… .

Answer 23

pterygopalatoquadrate

Meckel’s cartilage

Question 24

You can see in week 7+8

Answer 24

nasal cavity
secondary nasal septum, 
lateral palatal shelves, 
Meckel’s cartilage, 
mandibular bone,
 tooth germs.

Question 25

What is the type of ossification that take place in the maxillary and the Palatine bone and when does it start

Answer 25

Intramembranous ossification which means that the bone is formed directly from mesenchymal cells without going through the cartilage stage Ossification of the hard palate starts once the fusion of the palatal shelves is complete (after week 12).