Advertisements help pay for this website. Thank you for your support.
Last updated 30 March 2006
This page was contributed by David Boshell
Pharynx and Craniofacial Development
Pharyngeal arches
The pharynx is a chordate
adaptation for feeding and respiration, a derivative of the branchial
arches and gill slits of primitive chordates.
Pharyngeal arch cartilages
Pharyngeal arch arteries
Pharyngeal arch muscles
Pharyngeal arch innervation
Derivatives of the Pharyngeal Arches and their tissues of origin |
||||
Arch |
Arch Artery |
Skeletal Elements |
Muscles (SVE) |
Cranial Nerve |
1 |
Terminal branch of maxillary artery | Derived from arch cartilages (originating from
neural crest):
Derived by direct ossification from arch dermal mesenchyme: maxilla, zygomatic, squamous part of temporal bone, mandible |
Muscles of mastication (temporalis, masseter, pterygoids), myelohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini (originate from cranial somitomere 4) | Maxillary (V2), mandibular (V3) divisions of trigeminal nerve (V), for each respective swelling |
2 |
Stapedial artery (embryonic), corticotympanic artery (adult) | Stapes, styloid process, stylohyoid ligament, lesser horns and upper rim of hyoid (derived from the 2nd arch [Reicherts] cartilage; originate from neural crest) | Muscles of facial expression (orbicularis oculi, risorius, platysma, auricularis, fronto-occipitalis, buccinator), posterior belly of digastric, stylohyoid, stapedius (originate from cranial somitomere 6) | Facial nerve (VII) |
3 |
Common carotid artery, root of internal carotid | Lower rim and greater horns of hyoid (derived from the 3rd arch cartilage; originate from neural crest) | Stylopharyngeus (originates from cranial somitomere 7) | Glosso-pharyngeal nerve (IX) |
4 |
Arch of aorta, Right of subclavian artery, original sprouts of pulmonary arteries | Laryngeal cartilages (from 4th arch cartilage, originate from lateral plate mesoderm) | Constrictors of pharynx, cricothyroid, levator veli palatini (originate from occipital somites 2-4) | Superior laryngeal branch of vagus nerve (X) |
6 |
Ductus arteriosus, roots of definitive pulmonary arteries | Laryngeal cartilages (derived from the 6th arch cartilage; originate from lateral plate mesoderm) | Intrinsic muscles of larynx (originate from occipital somites 1-2) | Recurrent laryngeal branch of vagus nerve (X) |
Larson, W. Human Embryology 2nd ed., Churchill Livingstone, 1997, p357: Table 12-1.
Pharyngeal Clefts
Pharyngeal Pouches
Cranial Development
Parasagittal cartilages |
|
Embryological cartilages |
Adult bones |
Prechordal |
Part of ethmoid bone |
Hypophyseal |
Body of sphenoid |
Parachordal |
Base of occipital bone |
Primitive sensory capsules |
|
Capsule |
Adult bones |
Olfactory |
The nasal turbines, portions of ethmoid and nasal bones |
Optic |
Lesser wings of sphenoid |
Otic |
Periotic (petromastoid) portion of temporal bone |
Facial development
Paranasal sinuses |
|
Sinus |
Description |
Maxillary sinuses |
Appear in 3rd month, enlarge throughout childhood |
Ethmoid sinuses |
Appear in 5th month, enlarge until puberty |
Sphenoid sinuses |
Extensions of ethmoid sinuses |
Frontal sinuses |
Appear at 5-6 years, grow throughout adolescence |
Development of the tongue, thyroid and salivary glands
Innervation of the tongue |
||
. |
Anterior third |
Posterior third |
Sensory |
Mandibular n. (CN V3), lingual branch |
Glossopharyngeal n. (CN IX) |
Taste (SVA) |
Facial n. (CN VII), chorda tympani branch |
|
Motor |
Hypoglossal n. (CN XII), all muscles except palatoglossus (pharyngeal plexus) |