Branchial arches Flashcards
Paraxial mesoderm forms
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
Lateral plate mesoderm forms
some of the laryngeal cartilages and connective tissues
Neural crest cells path and form
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
Cells from ectodermal places form
(together with neural crest) form the sensory ganglia of the 5th, 7th, 9th, and 10th cranial nerves
Pharyngeal cleft/groove composition
Initially, they consist of bars of mesenchymal tissue separated by deep clefts externally (ectodermally lined)
Pharyngeal pouches composition
Endodermally lined
How does the cervical sinus form
During the 5th week, the 2nd arch enlarges and overgrows the 3rd and 4th arches which forms an ectodermal depression
Pharyngeal arch composition
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.
Each pharyngeal arch contains:
First pharyngeal arch mainly forms:
Structures of the face and ear
1st arch skeletal derivatives
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
1st arch muscular derivatives
Muscles of mastication (temporalis, masseter, lateral pterygoid, medial pterygoid)
Anterior belly of digastric, mylohyoid, tensor tympani, tensor veli palatini
1st arch artery and nerve derivative
Nerve:
Mandibular division of the trigeminal nerve (CN V3)
Artery:
Maxillary artery
Second pharyngeal arch mainly forms
Contributes to a string of skeletal structures from the body of the hyoid bone to the stapes of the middle ear
2nd arch skeletal derivatives
Forms an area of cartilage called Reicherts cartilagethat forms:
Stapes
Styloid process
Styloid ligament
Lesser horn and body of hyoid bone
2nd arch muscular derivatives
Muscles of facial expression
Stapedius, stylohyoid, posterior belly of the digastric
2nd arch artery and nerve derivative
Nerve:
Facial nerve (CN VII)
Artery:
Hyoid and stapedial arteries
Third pharyngeal arch maily forms:
Contributes to structures of the hyoid bone and upper pharynx
3rd arch skeletal derivatives
Greater horn and body (lower portion) of the hyoid bone
3rd arch muscular derivatives
Stylopharyngeus
3rd arch artery and nerve derivatives
Nerve:
Glossopharyngeal nerve (CN IX)
Artery:
Common carotid and 1st portion of the internal carotid arteries
Fourth arch mainly forms:
Contributes to the structures of the larynx and lower pharynx
4th arch skeletal derivatives
Laryngeal cartilages (4th & 6th arches fuse to form the laryngeal cartilages)
4th arch muscular derivatives
Cricothyroid, levator veli palatini, pharyngeal constrictors
4th arch artery and nerve derivatives
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)
Sixth pharyngeal arch mainly forms
Contributes to structures of the larynx and esophagus
6th arch skeletal derivatives
Laryngeal cartilages (4th & 6th arches fuse to form the laryngeal cartilages)
6th arch muscular derivatives
Intrinsic laryngeal muscles (to be discussed in larynx lecture)
Striated muscles of esophagus
6th arch artery and nerve derivatives
Nerve:
Recurrent laryngeal nerve {branch of Vagus nerve (CN X)}
Artery:
Left side: left pulmonary artery and ductus arteriosus
Right side: right pulmonary artery
First pharyngeal pouch forms:
Second pharyngeal pouch forms:
Third pharyngeal arch forms:
Fourth pharyngeal arch forms:
First pharyngeal cleft forms:
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).
