Cranial Bones: Ethmoid, Sphenoid, and Temporal

1. 📌 Essentials

• Ethmoid bone: unpaired; forms part of skull base, nasal septum, medial orbit wall; contains olfactory foramina.
• Sphenoid bone: centrally located; articulates with all cranial bones; houses sella turcica, sphenoidal sinuses.
• Temporal bone: lateral skull base; includes squamous, mastoid, petrous parts; contains structures for hearing and balance.
• Cribriform plate: allows olfactory nerve (CN I) passage.
• Sella turcica: houses pituitary gland.
• Stylomastoid foramen: facial nerve (CN VII) exits.
• Carotid canal: internal carotid artery enters skull.
• Foramina: key for cranial nerve and vessel passage (e.g., rotundum, ovale, spinosum).
• Key landmarks: crista galli, pterygoid hamulus, mandibular fossa.
• Clinical relevance: fractures impact nerves and vessels; pathology can cause sensory/motor deficits.

2. 🧩 Key Structures & Components