3) Development of Head & Neck (1) Flashcards
What are the pharyngeal (branchial) arches?
Sequence of ridges that from in the lateral walls of the embryonic pharynx (at cranial end of neural tube)
What are the three regions in the adult pharynx?
Nasal - superior to soft palate
Oral - between soft palate and larynx
Laryngeal - posterior to larynx
How many pharyngeal arches are there?
5, number 1-6
What is superior to the pharyngeal arches?
Frontonasal prominence which is in front of the brain
Describe how the arches are arranged (embryonic tissues):
Mesenchyme core with neural crest cells
Covered by ectoderm on external surface (between arches are clefts)
Covered by endoderm on internal surface (pharyngeal pouches)
What does each arch have associated with it?
Artery, nerve and cartilage bar
What are the three regions of primitive brain?
Forebrain - prosencephalon
Midbrain - mesencephalon
Hindbrain - rhombencephalon
How many pairs of cranial nerves are there?
12
How are the cranial nerves classified?
Function and embryological origin
Where are the cranial nerves derived from?
Apart from I and II, mid or hind brain
Which cranial nerves are associated with the pharyngeal arches?
V, VII, IX and X
Which cranial nerves have a relationship with the pharyngeal arch system?
(not associated with an arch)
CN XI (cranial accessory) and CN XII
What is the facial skeleton derived from?
Frontonasal prominence and 1st pharyngeal arch
What nerve is associated with the 1st pharyngeal arch?
And what is the sensory supply?
CN V, trigeminal nerve
Skin of face
What nerve is associated with the 2nd pharyngeal arch?
And what is the sensory supply?
CN VII, facial nerve
Anterior 2/3rd tongue, taste buds
What nerve is associated with the 3rd pharyngeal arch?
And what is the sensory supply?
CN IX, glossopharyngeal nerve
Posterior 1/3rd tongue
What nerve is associated with the 4th pharyngeal arch?
CN X, vagus nerve (superior laryngeal branch)
What nerve is associated with the 6th pharyngeal arch?
CN X, vagus nerve (recurrent laryngeal branch)
Which muscles are 1st arch derivatives?
Muscles of mastication
digastric, mylohyoid
Which muscles are 2nd arch derivatives?
Muscles of facial expression
Which muscle is a 3rd arch derivatives?
Stylopharyngeus
Which muscles are 4th arch derivatives?
Pharyngeal muscles (constrictors) Cricothyroid
Which muscles are 6th arch derivatives?
Intrinsic muscles of the larynx
What skeletal structures are derived from the 1st arch?
Meckel’s cartilage - template for mandible + malleus and incus
Maxillary and zygomatic bones
What skeletal structures are derived from the 2nd arch?
Reichert’s cartilage - stapes, upper body of hyoid and lesser horn, styloid process and stylohyoid ligament
What skeletal structures are derived from the 3rd arch?
Lower body of hyoid and greater horn
What skeletal structures are derived from the 4th arch?
Thyroid cartilage
Cricoid cartilage
Epiglottis (with 3rd)
What skeletal structures are derived from the 6th arch?
Arytenoid cartilage
Which arteries are associated with the 1st and 2nd arch?
Arteries disappear so none
Which arteries are associated with the 3rd arch?
Internal carotid arteries
Which arteries are associated with the 4th arch?
Arch of aorta (L) and brachiocephalic trunk (R)
Which arteries are associated with the 6th arch?
Pulmonary arch
What is derived from the 1st pharyngeal pouch?
Eustachian tube, tympanic cavity and middle ear cavity
What is derived from the 2nd pharyngeal pouch?
Palatine tonsil
What is derived from the 3rd pharyngeal pouch?
Inferior parathyroid and thymus
What is derived from the 4th pharyngeal pouch?
Superior parathyroid and C cells of thyroid
What happens to the pharyngeal clefts?
1st is all that remains as 2nd arch grows down to cover others
What does the 1st pharyngeal cleft form?
External auditory meatus of ear
What can occur if clefts or cervical sinus remains?
Branchial cysts or fistulae
Where are cysts likely to form?
Anterior border of sternocleidomastoid
