Mandible (bone)

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Attachment sites

Foramen Ovale

Mandibular nerve exits the skull via the foramen ovale

Inferior border

Muscular attachments for the inferior border of the mandible¹

Muscle	Origin	Insertion	Nerve	Action
Platysma muscle	/The Archive/Anatomy/Skeletal Muscles/Head and Neck/Muscles of Facial Expression/platysma.html#origin	/The Archive/Anatomy/Skeletal Muscles/Head and Neck/Muscles of Facial Expression/platysma.html#insertion	?var:ref-platysma.nerve	/The Archive/Anatomy/Skeletal Muscles/Head and Neck/Muscles of Facial Expression/platysma.html#action

Mandibular condyle

The mandibular condyle is flattened from front to back, with its medial-lateral length twice as long as its anterior-posterior length². The mandibular condyle and the articular disc form the inferior joint cavity of the TMJ².

• Structure
• The condyle is generally convex
• The medial and lateral poles project short distances from the condyle².
  • The medial pole is more prominent than the lateral pole (tpically)².
• The articular surface of the mandibular condyle is lined with a thin but dense layer of fibrocartilage.
  • Fibrocartilage is better at absorbing mastication forces and has superior healing attributes, which is important for the unqiue demands of the TMJ²

Mandibular Fossa

The mandibular fossa of the temporal bone is divided into two surfaces: articular and nonarticular. The articular surface of the fossa is formed by the articular eminence, occupying the sloped anterior wall of the fossa (see Figs. 11.5 and 11.10). The articular eminence functions as a load-bearing surface and therefore consists of thick compact bone, lined with fibrocartilage. Full opening of the mouth requires that each condyle slides forward across the articular eminence.56 Excessive shear and compression at this interface may eventually cause fragmentation of the fibrocartilage, a common indicator of early degenerative arthritis at the TMJ. The slope of the articular eminence is, on average, 55 degrees from the horizontal plane.36 The steepness of the slope partially determines the kinematic path of the condyle during opening and closing of the mouth. The nonarticular surface of the mandibular fossa consists of a very thin layer of bone and fibrocartilage that occupies much of the superior (dome) and posterior walls of the fossa (see Fig. 11.5). According to Okeson,77 this thin region is not an adequate loadbearing surface. A large upward force applied to the chin can fracture this region of the fossa, possibly even sending bone fragments into the cranium.

References

1.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

2.

Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.