Foramina of the Skull and Their Contents

In this final section, we return to the foramina of the skull. As a reminder, you are responsible for knowing the names of the foramina, what bone they’re in, and what travels through them.

Frontal Bone

Supraorbital notch/foramen: for passage of the supraorbital nerve (branch of the ophthalmic nerve, CN V1)

Mandibular Bone

Mental foramen: for the passage of the mental nerve, a branch of the mandibular nerve (CN V3)
Mandibular foramen: in the inner surface of the mandible; allows passage of the inferior alveolar nerve and vessels Maxilla
Infraorbital foramen: for passage of the infraorbital nerve, a branch of the maxillary nerve (CN V2)
Incisive fossa: allows for passage of the nasopalatine nerves and sphenopalatine vessels, which innervate and supply blood to the roof of the mouth

Figure 2.1 Supraorbital notch contents

HELPFUL HINTS

Remember, the Trigeminal nerve (CN V) divides into three major branches which we denote V1, V2 and V3. CN V1 is the ophthalmic n., CN V2 is the maxillary n., and CN V3 is the mandibular n.

Maxilla

Infraorbital foramen: for passage of the infraorbital nerve, a branch of the maxillary nerve (CN V2)
Incisive fossa: allows for passage of the nasopalatine nerves and sphenopalatine vessels, which innervate and supply blood to the roof of the mouth
Greater and lesser palatine foramina: allow passage of the greater and lesser palatine nerves and vessels, which innervate and supply blood to the roof of the mouth

Figure 2.2 Foramina of the maxilla

Figure 2.3 Infraorbital foramen

Ethmoid bone

Foramina of the cribiform plate: small holes that allow passage of bundles of the olfactory nerve (CN I)

Figure 2.4 Features of the ethmoid bone

Sphenoid bone

Optic canal: transmits the optic nerve (CN II) and the ophthalmic artery (first branch of the internal carotid artery)
Superior orbital fissure: a space that separates the lesser and greater wings of the sphenoid bone; contains the occulomotor nerve (CN III), trochlear nerve (CN IV), abducent nerve (CN VI) and the following branches of the ophthalmic nerve (CN V1): lacrimal, frontal and nasocilliary nn. It also contains the superior ophthalmic vein.
Foramen rotundum: maxillary nerve (CN V2)
Foramen ovale: mandibular nerve (CN V3) and lesser petrosal n.
Foramen spinosum: middle meningeal a. and v.; meningeal branch of the mandibular n.

Foramen lacerum: sits between the sphenoid, occipital and temporal bones; the greater petrosal nerve passes through the connective tissue the closes off the foramen lacerum

Temporal bone

Carotid canal: winds its way through the bone, allowing passage of the internal carotid a. and the internal carotid nerve plexus (post-ganglionic sympathetic axons from the superior cervical ganglion)
Internal acoustic meatus: allows passage from the inside of the skull to the internal ear. Carries the vestibulocochlear nerve (“auditory” nerve, CN VIII) and the labrynthine a. Also carries the facial nerve (CN VII) though the facial nerve is not going to the ear, just passing through.
External acoustic meatus: the ear hole; allows sound waves to travel to the tympanic membrane (eardrum)
Stylomastoid foramen: sits between the styloid and mastoid processes of the temporal bone, and allows passage of the facial nerve (CN VII)
Jugular foramen: a space between the temporal and occipital bones. It contains the glossopharyngeal nerve (CN IX), the vagus nerve (CN X), accessory nerve (CN XI). It also allows for passage of the posterior meningeal artery and the sigmoid sinus (which becomes the internal jugular vein after exiting the skull).

Occipital bone

Hypoglossal canal: contains the hypoglossal nerve (CN XII)
Foramen magnum: contains the medulla oblongata, meninges, vertebral arteries, meningeal branches of the vertebral arteries, spinal roots of the accessory nerve (CN XI)

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