Foramen and structures that pass through them

Foramen coecum

Nasal emissary vein

Cribiform plate:

Has 22 lobes. 11 on each side of the crista galli.

Content: Olfactory nerves (CN 1) and branches of the anterior ethmoidal artery, vein and nerve.

On the crista galli, a fold of the dura mater sits

Anterior ethmoid foramen

Content: Anterior ethmoidal artery, nerve and vein.

Posterior ethmoid foramen

Content: Posterior ethmoid artery, vein and nerve.

Opital canal

Content:

1. Optic nerve (CN II)

2. Ophthalmic artery

Chiasmatic groove

Thie crossing of the two optic right and left optic nerve .

Superior orbital fissure

Content: CN III, IV, V1 (first trigeminal nerve) , vi and Superior orbital vein

CN 3- Oculomotor nerve

CN 4- Trochlear nerve

CN V 1- Ophthalmic nerve

CN 6- Abducens nerve

Superio orbital vein

Revision on the Cranial nerves:

There are 12 cranial nerves

CN 1- olfactory nerve

CN 2- optic nerve

CN 3- oculomotor nerve

CN 4- trochlear nerve

CN 5- Trigeminal nerve——— V1: Ophthalmic nerve. V2: Maxillary nerve. V3: Mandibular nerve.

CN 6- abducens nerve

CN 7- Fascial nerve

CN 8- Vestibulocochlear nerve

CN 9- Glossopharyngeal nerve

CN 10- Vagus nerve

CN 11- Accessory nerve

CN 12- Hypoglossal nervd

Foramen Rotundum

Content: Maxillary nerve (CN V/2)

Foramen ovale

Contents: Acronymn : MALE

M- Mandibular nerve (V/3),

A- Accessory menigeal artery

L- Lesser petrosal nerve

E- Emissary vein

Foramen spinosum

Contents:

1. Middle meningeal artery and vein.

2. Meningeal bramch of mandibular nerve.

Foramen Lacerum

1. Greater, lesser and deep petrosal nerve.

Note: This formamen is usually closed (sphenopetrosal synchodrosis)

Carotid canal:

Contents:

1. Internal carotid artery.

2. Internal carotid nerve plexus.

Hiatus os the lesser petrosal canal

Content:

Lesser petrosal nerve

Hiatus for the greater petrosal nerve

Greater petrosal nerve

Hypophysial fossa

Where the pitutary gland sits on

Foramen magnum

Content:

1. vertebral artery

2. Anterior and posterior and spinal arteries.

3. Spinal root of accessory nerve

4. Transition between the medulla oblangata and spinal ord

5. Meninges (dura mater, arachnoid matter, pia matter).

6. Internal vertebral venous plexus.

7. Tectorial membrane and alar ligaments.

Jugular foramen:

Contents: Cranial nerve 9, 10, 11 and Jugular vein

1. CN 9- Glossopharyngeal nerve.

2. CN 10- Vagus nerve.

3. CN 11- Accessory nerve.

Hypoglossal canal:

Hypoglossal nerve (CN 12)

Internal acoustic meatus and canal

1. Facial nerve (CN 7).

2. Vestibulocochlear nerve

3. Labrinthine artery.

Exit to vestibular aqueduct

Endolymphatic duct

Mastoid canal

Emissary vein

Condylar canal

Emissary vein

Petrotympanic fissure

This is where the branch of the facial nerve called the chorda tympani exits the skull through

Fossula petrosa

This is a tiny fossa located between the jugular fossa and the carotid cana;.

Content: The inferior ganglion of the glossopharngeal nerve (CN 9) sits here.

Tympanic canaliculus

This originates at the fossula petrosa, and the tympanic branch of CN 9 passes through it.

Inside the tympanic cavity, it forms the plexus on the inner side of the tympanic membrane (eardrum) called the tympanic plexus. From the tympanic plexus, a branch called the lesser petrosal nerve exits the tympanic cavity through the canal for the lesser petrosal nerve.

The tympanic nerve, which is a branch of the glossopharyngeal nerve CN 9, originates from the inferior ganglion of the glossopharyngeal nerve.

Mastoid canaliculus

auricular branch of CN 10 passes through it

Musclotubarian canal

On the superior half of this canal, the tensor tympani muscle is found.

The inferior half is the eustachian tube.

Jugular fossa

It lodges the bulb of the internal jugular vein and the superior ganglion of the CN 9 and 10.

Stylomastoid foramen

Found between the stylod process and the mastois process.

It is the external opening of the facial canal.

The facial nerve exits sthe skull through it.

Tympanic cavity (Theory)

The ear is split into 3 parts:

1. External

2. Middle ear - also called the TYMPANIC CAVITY.

3. Inner ear

The middle ear lies within the temporal bone and extends from the tympanic membrane (eardrum) to the internal wall of the inner ear.

The main function of the middle ear is to transmit vibrations from the tympanic membrane (eardrum) to the inner ear via the auditory ossicles (malleus, incus and stapes).

TYMPANIC CAVITY:

The tympanic cavity is a narrow air-filled chamber in the petrous part of the temporal bone. This cavity has 2 parts:

1. Tympanic cavity proper.

2. Epitympanic recess- this is the space superior to the tympanic cavity.

Contents of the tympanic cavity

1. Ear ossiscles.

2. Stapedius and tensor tympani muscles

3. Chorda tympani nerve (a branch of the facial nerve CN7).

4. Tympanic plexus of nerve (arises from the CN 9- glossopharyngeal nerve)

Incisive canal

Connects the oral cavity with the nasal cavity.

Content: nasopalatine nerve, artery and vein

Mastoid foramen

Emissary vein