Branchial arches

Question 1

Paraxial mesoderm forms

Answer 1

a large portion of the membranous and cartilaginous components of the neurocranium, all voluntary muscles of the craniofacial region, and dermis and connective tissues in the dorsal region of the head

Question 2

Lateral plate mesoderm forms

Answer 2

some of the laryngeal cartilages and connective tissues

Question 3

Neural crest cells path and form

Answer 3

migrate into the pharyngeal arches and rostrally around the forebrain to form the entire viscerocranium (face) and parts of the membranous and cartilaginous regions of the neurocranium (skull). They also form all other tissues in these regions including cartilage, bone, dentin, tendon, dermis, pia and arachnoid, sensory neurons, and glandular connective tissue

Question 4

Cells from ectodermal places form

Answer 4

(together with neural crest) form the sensory ganglia of the 5th, 7th, 9th, and 10th cranial nerves

Question 5

Pharyngeal cleft/groove composition

Answer 5

Initially, they consist of bars of mesenchymal tissue separated by deep clefts externally (ectodermally lined)

Question 6

Pharyngeal pouches composition

Answer 6

Endodermally lined

Question 7

How does the cervical sinus form

Answer 7

During the 5th week, the 2nd arch enlarges and overgrows the 3rd and 4th arches which forms an ectodermal depression

Question 8

Pharyngeal arch composition

Answer 8

Each pharyngeal arch consists of a core of mesenchymal tissue covered on the outside by surface ectoderm and on the inside by epithelium of endodermal origin.

Question 9

Each pharyngeal arch contains:

Answer 9

Question 10

First pharyngeal arch mainly forms:

Answer 10

Structures of the face and ear

Question 11

1st arch skeletal derivatives

Answer 11

Maxillary process gives rise to the premaxilla, maxilla, zygomatic bone, and part of the temporal bone through membranous ossification

Mandible

Incus and malleus

Sphenomandibular ligament

Question 12

1st arch muscular derivatives

Answer 12

Muscles of mastication (temporalis, masseter, lateral pterygoid, medial pterygoid)

Anterior belly of digastric, mylohyoid, tensor tympani, tensor veli palatini

Question 13

1st arch artery and nerve derivative

Answer 13

Nerve:

Mandibular division of the trigeminal nerve (CN V3)

Artery:

Maxillary artery

Question 14

Second pharyngeal arch mainly forms

Answer 14

Contributes to a string of skeletal structures from the body of the hyoid bone to the stapes of the middle ear

Question 15

2nd arch skeletal derivatives

Answer 15

Forms an area of cartilage called Reicherts cartilagethat forms:

Stapes

Styloid process

Styloid ligament

Lesser horn and body of hyoid bone

Question 16

2nd arch muscular derivatives

Answer 16

Muscles of facial expression

Stapedius, stylohyoid, posterior belly of the digastric

Question 17

2nd arch artery and nerve derivative

Answer 17

Nerve:

Facial nerve (CN VII)

Artery:

Hyoid and stapedial arteries

Question 18

Third pharyngeal arch maily forms:

Answer 18

Contributes to structures of the hyoid bone and upper pharynx

Question 19

3rd arch skeletal derivatives

Answer 19

Greater horn and body (lower portion) of the hyoid bone

Question 20

3rd arch muscular derivatives

Answer 20

Stylopharyngeus

Question 21

3rd arch artery and nerve derivatives

Answer 21

Nerve:

Glossopharyngeal nerve (CN IX)

Artery:

Common carotid and 1st portion of the internal carotid arteries

Question 22

Fourth arch mainly forms:

Answer 22

Contributes to the structures of the larynx and lower pharynx

Question 23

4th arch skeletal derivatives

Answer 23

Laryngeal cartilages (4th & 6th arches fuse to form the laryngeal cartilages)

Question 24

4th arch muscular derivatives

Answer 24

Cricothyroid, levator veli palatini, pharyngeal constrictors

Question 25

4th arch artery and nerve derivatives

Answer 25

Nerve:

Superior laryngeal nerve {branch of Vagus nerve (CN X)}

Artery:

Left side: arch of aorta from the left common carotid to the left subclavian arteries

Right side: right subclavian artery (proximal portion)

Question 26

Sixth pharyngeal arch mainly forms

Answer 26

Contributes to structures of the larynx and esophagus

Question 27

6th arch skeletal derivatives

Answer 27

Laryngeal cartilages (4th & 6th arches fuse to form the laryngeal cartilages)

Question 28

6th arch muscular derivatives

Answer 28

Intrinsic laryngeal muscles (to be discussed in larynx lecture)

Striated muscles of esophagus

Question 29

6th arch artery and nerve derivatives

Answer 29

Nerve:

Recurrent laryngeal nerve {branch of Vagus nerve (CN X)}

Artery:

Left side: left pulmonary artery and ductus arteriosus

Right side: right pulmonary artery

Question 30

First pharyngeal pouch forms:

Answer 30

Question 31

Second pharyngeal pouch forms:

Answer 31

Question 32

Third pharyngeal arch forms:

Answer 32

Question 33

Fourth pharyngeal arch forms:

Answer 33

Question 34

First pharyngeal cleft forms:

Answer 34

The dorsal part of the 1st cleft penetrates the underlying mesenchyme and gives rise to the external auditory meatus (external ear canal).

The epithelial lining at the bottom of the meatus participates in the formation of the tympanic membrane (eardrum).