Body of mandible

What parts does the body of the mandible consist of?

• Base of the mandible (Basis mandibulae) is the lower thickened margin of the bone.
• Alveolar part (Pars alveolaris) is the upper margin forming alveolar arch (Arcus alveolaris). It houses dental alveoli (Alveoli dentales) which are separated interalveolar septa (Septa interalveolaria) and interradicular septa (Septa interradicularia). The external surface features alveolar elevations (Juga alveolaria). Posterior to the last molar lies retromolar triangle (Trigonum retromolare) with retromolar fossa (Fossa retromolaris).

Relief of the external and internal surfaces

External (lateral) surface: Along the midline is the mental protuberance (Protuberantia mentalis), on which the paired mental tubercles (Tuberculum mentale) stand out. On the lateral surface opens the mental foramen (Foramen mentale) — this is the end of the mandibular canal (Canalis mandibulae), which runs through the body to the mental foramen.

Internal (medial) surface: Along the midline are two mental spines (Spinae mentales — superior et inferior). Lateral to them lies the digastric fossa (Fossa digastrica). Slightly superior and posterior lies the sublingual fossa (Fovea sublingualis), and inferior and posterior lies the larger submandibular fossa (Fovea submandibularis). These two fossae are separated by the mylohyoid line (Linea mylohyoidea).

Clinical examination and topography

• Bone palpation: performed in strict sequence — from the condylar process down the ramus and then forward along the body of the mandible (Corpus mandibulae).
• Valle's points: the third branch of the trigeminal nerve (n. mandibularis) gives off the terminal nerve n. mentalis, which exits through the foramen mentale. The projection of the foramen mentale is located 0.75 cm above the lower border of the mandible, at the midpoint of the distance from the intersection of the masseter muscle with the inferior border of the mandibular body to the midline.
• Lymph nodes: submandibular nodes are palpable beneath the body of the mandible; submental nodes are palpable in the chin region beneath the body of the mandible.

Clinical significance: pathologies and anesthesia

• Odontogenic cysts: during the growth of a radicular cyst, resorption and remodeling of the surrounding bone occur, increasing the volume of the mandibular body. The thinned bone may spring upon palpation (Dupuytren's sign or 'egg-shell crackling' sign). Large cysts pose a risk of a pathological fracture of the mandibular body.
• Tumors: over 80% of ameloblastoma cases (a benign epithelial tumor) are localized in the body of the mandible (molar, premolar, and angle regions). As it grows, the tumor causes mandibular deformity and appears on radiographs as multilocular areas of destruction resembling 'soap bubbles'.
• Anesthesia: during inferior alveolar nerve block (e.g., Egorov's method), the anesthesia zone covers the alveolar process, part of the body of the mandible, as well as the mucosa of the lower lip and the skin of the chin.

Class and exam questions

What else to study on this topic

• Mandibular ramus (Ramus mandibulae)
• Mandibular canal (Canalis mandibulae)
• Trigeminal nerve (Nervus trigeminus)
• Jaw ameloblastoma

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.