The Mandible: Anatomy and Muscles (3D Animation)

Summary

This video provides an in-depth exploration of the mandible, the largest and strongest bone of the human skull, detailing its anatomy including the body, rami, condylar and coronoid processes, and key landmarks like the mental and mandibular foramina. It also covers the muscles of mastication—masseter, temporalis, medial and lateral pterygoids—describing their attachments, actions, and innervation. Additionally, the video explains the mandibular nerve (CN V3), its branches, and the sensory and motor functions it provides to the jaw, teeth, tongue, and associated glands, offering a comprehensive overview of mandibular structure, function, and neural control.

Takeaways

• 🦴 The mandible is the largest and strongest bone of the human skull, commonly known as the lower jaw, and forms part of the temporomandibular joint (TMJ).
• 🦷 The body of the mandible has an outer and inner surface, upper (alveolar) and lower (base) borders, and features such as the mental protuberance, mental foramen, and external oblique ridge.
• 🔹 The inner surface of the mandible includes the mylohyoid line, submandibular fossa, sublingual fossa, and genial tubercles, each serving as attachment points or housing glands.
• 📐 The ramus of the mandible has two main processes: the coronoid process (anterior) and condylar process (posterior), with a mandibular notch in between.
• 💪 The masseter muscle is quadrangular with superficial and deep parts, elevates the mandible, and is innervated by the anterior division of the mandibular nerve.
• ⏱ The temporalis muscle is fan-shaped, elevates the mandible with anterior and middle fibers, retracts it with posterior fibers, and is innervated by the anterior division of the mandibular nerve.
• 🔺 The medial pterygoid is quadrangular with deep and superficial heads, elevates the mandible, and is supplied by the trunk of the mandibular nerve.
• ↔️ The lateral pterygoid is triangular with superior and inferior heads, protracts the mandible bilaterally, and produces contralateral movement unilaterally, innervated by the anterior division of the mandibular nerve.
• 🧠 The mandibular nerve (V3), the third branch of the trigeminal nerve, carries both motor and sensory fibers and exits the cranial cavity through the foramen ovale.
• 📍 Key branches of the mandibular nerve include buccal, masseteric, lateral pterygoid, deep temporal, auriculotemporal, lingual, and inferior alveolar nerves, each supplying specific muscles, regions, or glands.
• 🎯 The inferior alveolar nerve gives off the mylohyoid nerve before entering the mandibular foramen and eventually emerges as the mental nerve to supply the lower anterior teeth.

Q & A

What is the mandible and where is it located?

The mandible, commonly known as the lower jaw, is the largest and strongest bone of the human skull, located inferior to the maxilla.

What are the main structural parts of the mandible?

The mandible is composed of a body and a pair of rami, each containing a coronoid process and a condylar process which form the temporomandibular joint.

What is the mental protuberance and where is it found?

The mental protuberance, also known as the chin, is a midline depression on the anterior portion of the mandible formed by the fusion of the left and right halves at the mandibular symphysis.

What is the significance of the mylohyoid line on the mandible?

The mylohyoid line is an oblique ridge on the inner surface of the mandible that serves as the attachment for the mylohyoid muscle and helps form the submandibular and sublingual fossae for their respective glands.

Which processes of the mandible form the temporomandibular joint?

The condylar processes of the mandible articulate with the temporal bone to form the temporomandibular joint.

What are the four main muscles of mastication and their primary functions?

The four main muscles are: Masseter (elevates mandible), Temporalis (elevates and retracts mandible), Medial Pterygoid (elevates mandible), and Lateral Pterygoid (protracts mandible and produces side-to-side movement).

How does the lateral pterygoid muscle contribute to jaw movement?

The lateral pterygoid muscle, acting bilaterally, protracts the mandible, pushing it forward. Acting unilaterally, it produces side-to-side movement, deviating the jaw to the opposite side of the contracting muscle.

Which nerve supplies the mandible and muscles of mastication, and what are its main branches?

The mandibular nerve (V3 of the trigeminal nerve, CN V) supplies the mandible and muscles of mastication. Its main branches include the anterior division (buccal, masseteric, nerve to lateral pterygoid, deep temporal nerves) and posterior division (auriculotemporal, lingual, inferior alveolar nerves).

What is the pathway of the inferior alveolar nerve and what areas does it innervate?

The inferior alveolar nerve runs medial to the mandible, giving off the mylohyoid nerve, enters the mandibular foramen, supplies dental branches to lower molars and premolars, and exits via the mental foramen to supply the lower canine and incisors.

What is the role of the lingual nerve in oral sensation?

The lingual nerve passes medial to the mandible, supplying general sensation to the anterior two-thirds of the tongue, lingual gingiva, and carries taste fibers via the chorda tympani. It also provides parasympathetic fibers to the submandibular and sublingual glands.

Where are the mental and mandibular foramina located and what passes through them?

The mental foramen is located below the second premolar, allowing the mental nerve and vessels to exit. The mandibular foramen is on the inner surface of the ramus, leading into the mandibular canal for the inferior alveolar nerve.