The tongue's embryonic orgin is derived from all pharyngeal arches contributing different components. As the tongue ((Latin, lingua; Greek, glossa) develops "inside" the floor of the oral cavity, it is not readily visible in the external views of the embryonic (Carnegie) stages of development. Tongue muscle cells originate from somites, while muscles of mastication derive from the unsegmented somitomeres. This current page gives a brief overview of early tongue development.
The dorsal tongue is covered by a stratified squamous epithelium, with numerous papillae and taste buds. There are also 8 to 12 circumvallate papillae arranged in an inverted V-shape towards the base of the tongue. These notes cover development of the muscular tongue, not the sense of taste.
- Taste Links: Introduction | Student project | Tongue Development | Category:Taste | Gastrointestinal Tract | Category:Tongue
Some Recent Findings
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References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.
Ashraf A El Sharaby, Samir A El-Gendy, Mohamed A Alsafy, Ahmed G Nomir, Satoshi Wakisaka Morphological variations of the vallate papillae in some mammalian species. Anat Sci Int: 2013; PMID:24242871 Xue-Hong Liu, Yong Zhang [Expression of PCNA, C-fos and Bax proteins in human embryonic tongue tissues]. Zhejiang Da Xue Xue Bao Yi Xue Ban: 2013, 42(5);517-22 PMID:24167132 Chandrika Girish Katti, Girish Katti, Ravi Kallur, Srinivas Rao Ghali Magical NiTi expander. BMJ Case Rep: 2013, 2013(); PMID:23867876 Cherie N Billingsley, Jared R Allen, Douglas D Baumann, Samantha L Deitz, Joshua D Blazek, Abby Newbauer, Andrew Darrah, Brad C Long, Brandon Young, Mark Clement, R W Doerge, Randall J Roper Non-trisomic homeobox gene expression during craniofacial development in the Ts65Dn mouse model of down syndrome. Am. J. Med. Genet. A: 2013; PMID:23843306 Tuomas Klockars [Short lingual frenulum]. Duodecim: 2013, 129(9);947-9 PMID:23786107
Pharyngeal Arch Contributions
The tongue has contributions from all pharyngeal arches which changes with time. The tongue initially begins as swelling rostral to foramen cecum, the median tongue bud.
Animation shows the sequence of development of the tongue. The different colours represents the relative contribution from each pharyngeal arch.
The four images below are from the Carnegie Stage 22 human embryo during week 8 of development.
- Tongue muscles originate from the somites.
- Masticatory muscles (MM) originate from the somitomeres. These muscles develop late and are not complete even at birth.
- Tongue muscles develop before masticatory muscles and complete by birth.
Developing muscle fibers within the tongue. Note the multinucleated appearance of each muscle fiber and their overall organization. Muscle goes through the same developmental changes as other skeletal muscle.
See also: Embryonic and postnatal development of masticatory and tongue muscles.
- Links: Skeletal Muscle Histology
The hypoglossal nerve (CN XII) provides the motor innervation of the intrinsic and extrinsic tongue muscles allowing protrusion, retrusion, and changes in the shape of the tongue. Motor units within the hypoglossal motor system can be categorized as predominantly fast fatigue resistant.
The human tongue innervation has been recently analysed histologically and described as extremely dense and complex. The structure of the motor endplate junctions (neuromuscular junctions) was found to be of the multiple en grappe (grapelike cluster) form. The transverse muscle group that comprises the core of the tongue was found to have the most complex innervation. The pattern of innervation of the human tongue also has specializations not found in other mammalian tongues, this allows for fine motor control of tongue shape.
The pathway of the hypoglossal nerve can be imaged using magnetic imaging (MRI) while computer tomography (CT) can show the bony anatomy of the neurovascular foramina of the skull base. Clinically, the nerve pathway can be divided into three regions: intra-axial, cisternal, skull base and extracranial segments.
Frenulum is a general term for a small fold of integument (skin) or mucous membrane that limits the movements of an organ or part. There are several anatomical frenula associated with the genital system, while the lingual frenulum is associated with the inferior side of the tongue.
The lingual frenulum length (short) and position of insertion (anterior) can lead to speech disorders and may affect postnatal feeding. Interestingly, it is the prevalence of pain in mothers breastfeeding infants with ankyloglossia that presents many problems in breastfeeding.
Children with a frenulum length of more than 2 cm do not show these speech problems. Ankyloglossia (tongue-tie) is the general clinical term for the short frenulum which limits the range of movement of the tongue, there is still no accurate classification for this condition. Frenotomy, frenectomy, and frenuloplasty are the main surgical treatment options to release or remove an ankyloglossia.
Term means an abnormally large tongue. Macroglossia is more common than microglossia and can be associated with a number of genetic abnormalities including: trisomy 21 (Down syndrome), acromegaly, Beckwith-Wiedemann syndrome, mucopolysaccharidoses and primary amyloidosis. There is also an association with congenital hypothyroidism and diabetes.
Macroglossia associated with Beckwith-Wiedemann syndrome.
Term means an abnormally small tongue.
Ankyloglossia (tongue-tie) is the general clinical term for the short lingual frenulum (less than 2 cm), that limits the range of movement of the tongue, prevalence ranges between 4.2% and 10.7%. This is associated with speech development disorders and has been suggested as also associated with feeding disorders. There is still no accurate classification for this condition. Frenotomy, frenectomy, and frenuloplasty are the main surgical treatment options to release or remove an ankyloglossia, though there is still discussion about surgical intervention.
A short lingual frenulum is also associated with a number of genetic syndromes such as: ROR2-Related Robinow Syndrome, Dystrophic Epidermolysis Bullosa, Oral-Facial-Digital Syndrome Type I, Opitz Syndrome (X-Linked Opitz G/BBB Syndrome) and Van der Woude syndrome.
- Links: Medline Plus - Tongue tie | ROR2-Related Robinow Syndrome | Dystrophic Epidermolysis Bullosa | Oral-Facial-Digital Syndrome Type I | X-Linked Opitz G/BBB Syndrome
- ↑ PMID 21736745
- ↑ Jae-Young Kim, Min-Jung Lee, Kyoung-Won Cho, Jong-Min Lee, Yeun-Jung Kim, Ji-Youn Kim, Hye-In Jung, Je-Yoel Cho, Sung-Won Cho, Han-Sung Jung Shh and ROCK1 modulate the dynamic epithelial morphogenesis in circumvallate papilla development. Dev. Biol.: 2009, 325(1);273-80 PMID:19014928
- ↑ A Yamane Embryonic and postnatal development of masticatory and tongue muscles. Cell Tissue Res.: 2005, 322(2);183-9 PMID:16041600
- ↑ J Chadwick Smith, Stephen J Goldberg, Mary Snyder Shall Phenotype and contractile properties of mammalian tongue muscles innervated by the hypoglossal nerve. Respir Physiol Neurobiol: 2005, 147(2-3);253-62 PMID:16087149
- ↑ Liancai Mu, Ira Sanders Human tongue neuroanatomy: Nerve supply and motor endplates. Clin Anat: 2010; PMID:20607833
- ↑ Pedro Alves Imaging the hypoglossal nerve. Eur J Radiol: 2010, 74(2);368-77 PMID:20347541
- ↑ Irene Queiroz Marchesan Lingual frenulum: classification and speech interference. Int J Orofacial Myology: 2004, 30();31-8 PMID:15832860
- ↑ Lauren M Segal, Randolph Stephenson, Martin Dawes, Perle Feldman Prevalence, diagnosis, and treatment of ankyloglossia: methodologic review. Can Fam Physician: 2007, 53(6);1027-33 PMID:17872781
- ↑ 9.0 9.1 Valérie G A Suter, Michael M Bornstein Ankyloglossia: facts and myths in diagnosis and treatment. J. Periodontol.: 2009, 80(8);1204-19 PMID:19656020
R Achiron, A Ben Arie, U Gabbay, S Mashiach, Z Rotstein, S Lipitz Development of the fetal tongue between 14 and 26 weeks of gestation: in utero ultrasonographic measurements. Ultrasound Obstet Gynecol: 1997, 9(1);39-41 PMID:9060129
- Clinical Methods The Tongue
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Cite this page: Hill, M.A. (2013) Tongue Development. Retrieved December 5, 2013, from http://embryology.med.unsw.edu.au/embryology/index.php?title=Tongue_Development
- Dr Mark Hill 2013, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G