Development of Pharyngeal Arches Flashcards
(36 cards)
Describe when and how the pharyngeal arches appear?
Occurs as the cranial neuropore closes, they appear as tissue bulges separated by clefts. They can also be known as branchial arches. They consist of 3 embryo layers (mesoderm core, ectoderm and endoderm)
What is the stomodeum?
Depression between the developing brain and pericardium in an embryo. Precursor for mouth and anterior lobe of pituitary lobe.
What forms the upper maxillary prominence and lower mandibular prominence?
The 1st pharyngeal arch. In between these is where the stomodeum.
What are somatomeres?
Ill defined segments of paraxial mesoderm in the head region rostral to somites.
What are ectodermal placodes?
Focal thickenings of cranial ectoderm which give rise to sensory ganglia/neurons.
What is does each pharyngeal arch contain?
- Muscle (branchial muscles),
- Cartilage element,
- Artery and,
- Cranial nerve
Where does the majority of the anterior skull develop originate from?
Neural crest cells
Where does the majority of the posterior skull originate from?
Paraxial mesoderm
Name the muscles derived from the first arch “mandibular arch”
- Muscles of mastication,
- Anterior belly of digastric,
- Mylohyoid,
- Tensor tympani,
- Tensor veli palatini. (muscles are also innervated by the nerve of the first asrch)
What are the skeletal derivatives of the first arch? (mandibular arch)
- Maxilla,
- Zygomatic bone,
- Mandible,
- Malleus,
- Incus,
- Meckel’s cartilage (later dissapears)
What is the nerve derived from the 1st pharyngeal arch?
- Trigeminal nerve
So it will supply the skin of the face and the 3rd division will supply the muscles of mastication and others
What artery does the 1st pharyngeal artery form?
Maxillary artery which is the terminal branch of the external carotid artery.
What muscles are derived from the second pharyngeal arch (hyoid arch)
- Muscles of facial expression,
- Stylohyoid,
- Stapedius,
- Posterior belly of digastric
(all will therefore be innervated by the nerve derived from the second pharyngeal arch)
What are the skeletal derivatives of the 2nd pharyngeal arch?
- Stapes,
- Styloid process and stylohyoid ligament,
- Lesser horn of hyoid and upper part of body of hyoid.
What nerve is derived from the second pharyngeal arch?
The CN VII nerve, the facial nerve
What artery is the 2nd pharyngeal associated with?
Hyoid and stapedial arteries
What are the muscles and skeletal (bones) that originate from the 3rd pharyngeal arch
Muscle - Stylopharyngeus,
Skeletal - Greater horn of hyoid and lower part of body of hyoid.
What is the nerve and artery associated with the 3rd pharyngeal arch
Nerve - Glossopharyngeal nerve (IX)
Artery - common carotid arteries and proximal internal carotid.
What are the muscles derived from the 4th pharyngeal arch?
All muscles of the pharynx except stylopharngeus.
All muscles of the palate except tensor veli palatini.
- Cricothyroid.
What are the skeletal derivates of the 4th arch?
Epiglottis, laryngeal cartilages, thyroid, cuneiform, corniculate and arytenoids.
What is the nerve that is derived from the 4th pharyngeal arch
The vagus, more specifically the superior laryngeal branch of the vagus.
What are the arteries associated with the 4th arch?
The 4th left arch gives off the aortic arch. The 4th right gives off the right subclavian artery
What are the muscular and skeletal derivates of the 6th pharyngeal arch?
All of the muscles of the larynx and the cricoid cartilage
What are the nerves and arterial derivates of the 6th pharyngeal arch
Recurrent laryngeal nerve (branch of vagus).
It gives rise to the pulmonary arteries and the ductus arteriosus (which is present on the left)
