Embryology

Front 1

Arch 1 Nerve - Maxillary Process

Back 1

V2 (Trigeminal Nerve)

Also provides sensory innervation to nasal cavity and hard palate muscosa

Front 2

Arch 1 Bones and Ligaments - Maxillary Process

Back 2

From Maxillary Cartilage: Greater wing of Spehnoid Bone, Incus

From Ossification of dermal mesenchyme: Maxilla, Zygomatic, Squamous part of temporal, Palatine, Vomer, Pterygoid Laminae

Front 3

Arch 1 Vascular/Aortic Arches - Maxillary Process

Back 3

Largely disapears, except maxillary a. (and maybe external carotid a. ?)

Front 4

Arch 1 - Nerve - Mandibular Process

Back 4

V3 (Trigeminal Nerve)

Also sensory innervation of oral cavity and anterior 2/3 of tongue, floor of the mouth

Front 5

Arch 1 - Bones and Ligaments - Mandibular Process

Back 5

From Meckel's Cartilage: Malleus, Anterior ligament of malleus, Sphenomandibular ligament

From Ossification of dermal mesenchyme: Mandible, Tympanic part of temboral

Front 6

What are the two parts of the first arch?

Back 6

The Maxillary Process and the Mandibular Process

Front 7

Arch 2 Nerve

Back 7

VII (Facial Nerve)

Also taste buds on anterior 2/3 of tongue, hard palate

Front 8

Arch 2 Muscles

Back 8

Muscles of facial expression, Stapedius, Post. Belly of Digastric, Stylohyoid

Front 9

Arch 2 Bones/Ligaments

Back 9

Reichert's Cartilage:

Stapes
Styloid process
Stylohyoid ligament
Lesser horn of hyoid
Superior part of hyoid body

Front 10

Arch 2 Vascular

Back 10

Proximal part disappears

Distal part - Stapedial artery (embryonic)

Front 11

Arch 3 Nerve

Back 11

IX (Glossopharyngeal nerve)

Also sensory innervation of Pharyngeal cavity mucosa
Posterior 1/3 of tongue

Front 12

Arch 3 Muscles

Back 12

Stylopharyngeus (elevates pharynx during swallowing)

Front 13

Arch 3 Bones/Ligaments

Back 13

Greater horn of hyoid
Inferior part of hyoid body

Front 14

Arch 3 Vascular

Back 14

Proximal part - Common carotid a.

Distal part - Proximal part of internal carotid a.

Front 15

Arch 4 Nerve

Back 15

X (Vagus) - Pharyngeal branch and superior laryngeal branch

Front 16

Arch 4 Muscles

Back 16

(Muscles of Pharynx)
Constrictors, Palatopharyngeus, Levator veli palatini, Musculus uvulae, Palatoglossus

Cricothyroid

(Muscles of Soft Palate)

Front 17

Arch 4 Bones/Ligaments

Back 17

Laryngeal carilages (except epiglottis)

Together with Arch 6

Front 18

Arch 4 Vascular

Back 18

Left - Part of aortic arch

Right - Proximal part of right subclavian a.

Front 19

What happens to Arch 5?

Back 19

Either never forms or quickly regresses

Front 20

Arch 6 Nerve

Back 20

X (Vagus) - Recurrent laryngeal branch

Front 21

Arch 6 Muscles

Back 21

Intrinsic muscles of the larynx (except for cricothyroid which is from Arch 4)

Striated muscle of esophagus (voluntary)

Front 22

Arch 6 Bones/Ligaments

Back 22

Laryngeal Cartilages (except epiglottis)

Together with Arch 4

Front 23

Arch 6 Vascular

Back 23

Proximal Parts - Proximal parts of pulmonary arteries

Distal Parts - Right disappears, left becomes ligamentum arteriousum

Why the reacurrent laryngeal nerves are different on each side

Front 24

Arch 1 Muscles

Back 24

Muscles of Mastication
Mylohyoid
Anterior Belly of digastric
Tensor veli palatini
Tensor tympani

(All innervated by V3)

Front 25

Which aortic arches regress?

Back 25

1, 2 and 5

Front 26

What are the reacurrent laryngeal nerves related to?

Back 26

Right: Right subclavian a.

Left: Aortic arch, Ligamentum arteriousum

Different due to Arch 6 developement

Front 27

Groove 1

Back 27

External auditory meatus (external ear canal)
Outer epithelium of eardrum (from membrane that separates pouch from groove)

Front 28

Pouch 1

Back 28

Retain connection with lumen of pharynx, becomes tympanic (middle ear) cavity.

Tympanic cavity
Mastoid antrum
Auditory tube (connection with pharynx)
Inner epithelium of eardrum

Front 29

Groove 2

Back 29

Cervical sinus (disappears)

Front 30

Pouch 2

Back 30

Palatine tonsil develops adjacent to.

Intratonsillar cleft/sinus (tonsilar fossa)
Surfaces epithelium and lining of crypts of palatine tonsil

Front 31

Groove 3

Back 31

Cervical sinus (disappears)

Front 32

Pouch 3

Back 32

Both migrate caudally

Dorsal part - Inferior parathyroid gland (usually separates from thymus gland and resides posterior to thyroid gland)

Ventral part - Thymus gland

Front 33

Groove 4

Back 33

Cervical sinus (disappears)

Front 34

Pouch 4

Back 34

Dorsal part - superior parathyroid gland (doesn't migrate as far as pouch 3)

Ventral Part - Ultimobranchial body (in thyroid gland) (Become Parafollicular or C Cells - secret calcitonin hormone)

Front 35

Pouch 5

Back 35

When present is rudimentary and become part of Pouch 4

Front 36

Which grooves/pouches never form?

Back 36

Groove 5, Groove 6, Pouch 6

Sometimes Pouch 5

Front 37

What is the first appearance of the tongue?

Back 37

Median tongue bud - swelling in the midline which lies over the 1st pair of arches. Forms no adult derivative.

Forms in the floor of the pharynx.

Later pair of distal tongue buds form on either side, grow, fuse, cover up median tongue buds.

Front 38

What forms the anterior 2/3 of the tongue?

Back 38

The distal tongue buds.

Front 39

What forms the posterior/pharyngeal 1/3 of the tongue?

Back 39

Hypobranchial/Hypopharyngeal eminence. Lies in midline over 3rd and 4th pairs of arches. (Mostly 3rd arch.)

Grows forward, meets distal tongue buds.

Front 40

Sensory innervation to tongue

Back 40

Cranial nerves V3 (anterior)

posteriour - IX (mainly), X (way in back).

Nothing from VII because arch 2 doesn't contribute to mucosa of tongue.

Front 41

Muscular innervation of tongue

Back 41

XII (hypoglossal), grows down with myboblasts.

Front 42

Muscles of tongue

Back 42

From Occipital Myotomes, not arches, except for palatoglossus.

Front 43

Thyroid Gland

Back 43

First endocrine gland to develop, 4th week. Not from an arch but related to floor of pharynx.

Thickening of endoderm called thyroid diverticulum. For a while Thyroid diverticulum retains its connection with the floor for the pharynx, forming the thyroglossal duct.

At 5 weeks of development, the distal end of the TD expands and begins to form a thyroid gland.

At 7 weeks, the adult thyroid has taken shape: two lateral lobes connected by a bar of tissue (isthmus). The connection of the TD had with the floor of the pharynx regresses (the thyroglossal duct atrophies), and sometimes the lower end of the duct persists. If this happens, the thyroglossal duct gives rise to the pyramidal lobe (small, slender strand of thyroid tissue projecting up from the isthmus – a retention of the lower end of the lower end of the thyroglossal duct).

Front 44

Derivatives of Neural Crest Cells

Back 44

All the ganglia of the autonomic nervous system

Medulla of the adrenal gland

All of the Dorsal root ganglion of the spinal cord

Cartilages of at least the 1st 3 pairs of pharyngeal arches.

Important: NCC form the first 3 PA cartilages. The first arch is unique in that certain membrane bones form in relation to this arch. Bones develop either as a cartilage precursor (preform in cartilage and later ossify like the PA cartilages) or they ossify directly through mesenchyme (don’t go through cartilaginous stage). In the case of the first PA, the maxilla and mandible bones ossify directly from the mesenchyme.