Development of the Tongue

Summary

The tongue's development begins at week four of intrauterine life, originating from the first four pharyngeal arches. The anterior two-thirds form from the first arch's mesenchyme, creating the tuberculum impar and lateral lingual swellings, which merge to form the median sulcus. The posterior one-third arises from the second, third, and fourth arches, developing as the copula and hypobranchial eminence. Taste buds emerge around week 8 to 13, with cranial nerves providing sensory and motor innervation.

Takeaways

• 👅 The tongue begins developing around week four of intrauterine life.
• 📏 It consists of an anterior two-thirds and a posterior one-third, separated by the terminal sulcus.
• 🦐 At week four, the embryo resembles a shrimp more than a baby, with the tongue starting to form.
• 🧠 The neural tube expands to form the primitive forebrain, which is part of the early development of the tongue.
• 🌱 Six mesodermal bulges sprout to become the branchial or pharyngeal arches, crucial for tongue development.
• 🔄 The first pharyngeal arch gives rise to the anterior two-thirds of the tongue.
• 🔄 The second, third, and fourth pharyngeal arches contribute to the posterior one-third of the tongue.
• 🤚 The tongue's muscles develop from the occipital somites, which migrate into the developing tongue.
• 👅 Taste buds begin to form around week 8 and finish differentiating by week 11 to 13.
• 🤖 The tongue's sensory innervation comes from cranial nerves, including the trigeminal, glossopharyngeal, and vagus nerves.

Q & A

What is the tongue and when does its development begin?

The tongue is a muscular structure and sensory organ that starts developing around week four of intrauterine life.

How is the tongue divided into parts?

The tongue consists of two parts: the anterior two-thirds and the posterior one-third, which is called the root of the tongue.

What is the terminal sulcus and how does it relate to the tongue's development?

The terminal sulcus is a shallow V-shaped groove that separates the anterior two-thirds and the posterior one-third of the tongue.

What causes the tongue's two parts to develop separately?

The two parts of the tongue develop separately due to the folding of the embryo along the rostrocotyl axis and the lateral axis.

What is the significance of the stomadeum in tongue development?

The stomadeum is a small pit that forms between the frontal prominence and the developing cardiac bulge and eventually becomes the oral cavity.

What are the branchial arches and how do they contribute to tongue development?

Branchial arches are six little bulges of the mesoderm that sprout from the primitive pharynx and contribute to the development of the tongue.

From which pharyngeal arches does the anterior two-thirds of the tongue develop?

The anterior two-thirds of the tongue develops from the first pharyngeal arch.

What is the role of the tuberculum impar in the development of the tongue?

The tuberculum impar is a midline swelling that develops from the mesoderm of the first pharyngeal arch and is part of the anterior two-thirds of the tongue.

How does the posterior one-third of the tongue develop?

The posterior one-third of the tongue develops from the second, third, and fourth pharyngeal arches.

What is the origin of the sensory innervation of the tongue?

The sensory innervation of the tongue comes from the lingual branch of the mandibular division of the trigeminal nerve for the anterior two-thirds and the glossopharyngeal nerve for the posterior one-third.

How do the taste buds develop and when do they finish differentiating?

Taste buds start to sprout over the surface of the tongue around week 8 and finish differentiating into different types around week 11 to week 13.