Inferior Skull Neuroanatomy > Cranial Nerves & Skull Base > Cranial Nerves & Skull Base INFERIOR SKULL KEY DEFINITIONS • Foramina are holes that allow neurovascular structures to pass through the bone. • Processes serve as muscle attachment sites. Maxilla: • Palatine process - Portion of the maxilla that extends posteriorly, towards the palatine. • Incisive foramen - A small opening for neurovascular structures; its name reflects its location posterior to the incisors (the front teeth). - The nasopalatine nerve and sphenopalatine artery (and vein) pass through the incisive foramen to serve the palate and associated structures. • Alveolar margin (aka, ridge) - The border of the maxilla where the upper teeth reside. Sphenoid: • Pterygoid process - Gives rise to the medial and lateral pterygoid plates, which are extensions where muscles of mastication (aka, chewing) attach. • Foramen ovale - Petrosal nerve, mandibular nerve, and accessory meningeal artery. 1 / 3 • Foramen spinosum - Middle meningeal artery and meningeal branch of the mandibular nerve. Temporal bone: • Mandibular fossa - Shallow depression where the mandible (the bone of the lower jaw) articulates with the cranium. • External auditory meatus - External opening of the ear. • Styloid process - A pointy projection for attachment of muscles. • Mastoid process - Larger, roughened cone-shaped projection for muscle attachment (sternocleidomastoid). • Opening of the carotid canal - Internal carotid artery enters the cranium to supply the brain via this opening. • Stylomastoid foramen - Lies between the styloid and mastoid processes. - CN VII (facial nerve). Occipital bone: • Foramen magnum - A large hole where the spinal cord enters the cranium to become the brainstem. - The brainstem, vertebral arteries, and CN XI (accessory nerve) pass through the foramen magnum; • Occipital condyles - Lie on either side of the foramen magnum; these rounded surfaces articulate with the vertebral column. 2 / 3 • Hypoglossal canal - A small opening near the foramen magnum and the occipital condyles. - CN XII (hypoglossal nerve) • External occipital crest - Extends from the posterior edge of the foramen magnum, and terminates at the external occipital protuberance • External occipital protuberance - A roughened elevation; it serves as a muscle attachment site and is usually larger in adult males. • Inferior and superior nuchal lines - Extend horizontally from the crest; they serve as muscle attachment sites. • Foramen lacerum - Lies between the occipital, sphenoid, and temporal bones; it is irregularly shaped. - Greater petrosal nerve; it is a branch of the facial nerve (CN VII). • Jugular foramen - Lies between occipital and temporal bones; it is named for the jugular vein, which exits through this space. - CNs IX (glossopharyngeal nerve), X (vagus), and XI (accessory), and the jugular vein Powered by TCPDF (www.tcpdf.org) 3 / 3.