Cranial Foramina

Question 1

Foramen cecum

Answer 1

Frontal bone

Inferior floor of anterior fossa, central, just anterior to ethmoid bone

Nasal emissary vein (1% of population)

Question 2

Cribiform foramina

Answer 2

Cribiform plate of ethmoid bone

Anterior cranial fossa

Axons of olfactory cells that form olfactory nerves

Question 3

Anterior and posterior ethmoidal foramina

Answer 3

Suture between frontal and ethmoid bones

Anterior cranial fossa, paired, connect with the orbit

Anterior ethmoidal artery vein and nerve
Posterior ethmoidal artery vein and nerve

Question 4

Foramina of anterior cranial fossa

Answer 4

Cecum

Cribiform

Anterior ethmoidal

Posterior ethmoidal

Question 5

Optic canals

Answer 5

Sphenoid bone, either side of prechiasmatic sulcus

Middle cranial fossa, communicate with orbits

Optic nerve, ophthalmic artery

Question 6

Superior orbital fissure

Answer 6

Sphenoid bone, space between the greater and lesser wings

Middle cranial fossa, paired, communicate with orbits

Opthalmic vein, ophthalmic nerve (CN V1), occulomotor nerve trochlear nerve and abducens nerve(CNs III IV and VI, ie all the eye movement nerves), sympathetic fibres

Question 7

Foramen rotundum

Answer 7

Sphenoid bone

Paired, middle cranial fossa, lateral to the hypophyseal fossa and posterior to superior orbital fissure, runs horizontally to pterygopalantine fossa

Maxillary nerve (CN V2)

Question 8

Foramen ovale

Answer 8

Sphenoid bone

Paired, middle cranial fossa, posterior and lateral to foramen rotundum, opens into infratemporal fossa

Mandibular nerve (CNV3), accessory meningeal artery

Question 9

Foramen spinosum

Answer 9

Sphenoid bone

Paired, middle cranial fossa, posterolateral to foramen ovale, opens into infratempotal fossa in relationship to spine of sphenoid

Middle meningeal artery and vein, meningeal branch of CNV3

Question 10

Foramen lacerum

Answer 10

Not part of crescent of foramina, artifact of dried crania and closed by a cartilage plate during life, only a few meningeal artery branches and small veins actually cross it, the internal carotid artery and its accompanying venous and sympathetic plexuses pass across its superior aspect, some nerves transverse it horizontally entering a foramen in its anterior boundary

Sphenoid bone

Posterolateral to hypophyseal fossa

Deep petrosal nerve, some meningeal artery branches and small nerves

Question 11

Grove for greater petrosal nerve

Answer 11

Paired, middle cranial fossa, extends posteriolaterally from foramen lacernum

Greater petrosal nerve, petrosal branch of middle meningeal artery

There is also a groove for the lesser petrosal nerve

Question 12

Foramen magnum

Answer 12

Occipital bone

Single, posterior cranial fossa

Medulla and meninges, vertebral arteries, CN XI (spinal portion), dural veins, anterior and posterior spinal arteries

Question 13

Jugular foramen

Answer 13

Suture between temporal and occipital bones

Paired, posterior cranial fossa, lateral to anterior part of foramen magnum

1-CN IX CN X CN XI (glossopharyngeal, vagus, accessory)
2-superior bulb of internal jugular vein
3-inferior petrosal and sigmoid sinuses
4-meningeal branches of ascending pharyngeal and occipital arteries

Question 14

Hypoglossal canal

Answer 14

Occipital bone

Paired, posterior cranial fossa, sits on lateral walls of foramen magnum

CN XII (hypoglossal)

Question 15

Condylar canal

Answer 15

Occipital bone

Paired, posterior cranial fossa, opens posterior to foramen magnum

Emissary vein passing from sigmoid sinus to vertebral veins in neck

Question 16

Mastoid foramen

Answer 16

Temporal bone

Paired, posterior cranial fossa, opens posterior to mastoid process

Mastoid emissary vein from sigmoid sinus and meningeal branch of occipital artery