Lecture 2: Bones of the Skull and Orbit

What are the two parts that the skull is divided into?

Cranial and facial bones

Define a suture.

A firm and fibrous joint b/w bones.

Define a sinus.

An air-filled cavity within bones.

Define a foramen.

An opening, hole, or passage in bone.

What structure passes through the stylomastoid foramen?

Facial nerve

What structure passes through the carotid canal?

Internal carotid artery

What important landmarks are found on the temporal bones?

Stylomastoid foramen and carotid canal.

What important landmarks are found on the frontal bone?

Supraorbital foramen, supratrochlear foramen, and foss for lacrimal gland.

What structures does the supraorbital notch/foramen contain?

Supraorbital vessels and nerves

What structures does the supratrochlear notch/foramen contain?

Supratrochlear vessels and nerves.

What is the fossa for lacrimal gland?

It is a temporal depression where the lacrimal gland sits.

What important landmarks does the occipital bone contain?

External occipital protuberance/inion and foramen magnum.

What is the foramen magnum?

The passageway for the spinal cord located at the base of the occipital bone.

What is the sagittal suture?

The suture that separates the two parietal lobes.

What is the coronal suture?

The suture that separates the parietal and frontal lobe

What is the lambdoidal suture?

It is the suture that separates the parietal and occipital lobes.

What is the squamosal suture?

It is the suture that separates the parietal and temporal lobes.

What is the sphenoid bone?

A bone that contains multiple wings and a body.

What is significant about the sphenoid bone?

It has many points of interest like every orbital wall except the floor.

What structures does the lesser wing of the sphenoid contain?

Optic canal/foramen: optic nerve and ophthalmic artery

What structures does the greater wing of the sphenoid contain?

Foramen rotundum: maxillary nerve

Foramen ovale: mandibular nerve

Foramen spinosum: middle meningeal artery

What structures does the body of the sphenoid contain?

Pituitary fossa: pituitary gland

What is the superior orbital fissure (SOF)?

• It is the opening b/w the greater and lesser wings of the sphenoid bone.

• Located b/w orbital roof and lateral orbital wall

• Posterior to common tendinous ring (CTR)

What is the role of the superior orbital fissure?

It is to provide communication b/w the orbit and cranium

What is the inferior orbital fissure (IOF)?

It is the opening between the greater wing of the sphenoid bone and maxilla.

It is located between the orbital floor and lateral orbital wall.

What are some vessels that pass through the SOF and the CTR?

Nasociliary nerve

Oculomotor nerve

Abducens nerve

What are some vessels that pass through the SOF above the CTR?

Lacrimal nerve

Superior ophthalmic vein

Frontal nerve

Trochlear nerve

What vessels pass through the IOF?

Inferior ophthalmic vein

Zygomatic nerve

Infraorbital nerve

Infraorbital artery and vein

What is the ethmoid bone?

The bone that contain areas of the nasal cavity and medial orbital walls.

What landmarks does the ethmoid bone contain?

Cribriform plate: flat portion of bone with cribriform foramina for passage of the olfactory nerves.

Orbital plate: plate portion of the bone which creates the medial and orbital wall.

What are the lacrimal bones?

Its the smallest bones of the face which support the lacrimal apparatus in the orbit. It is located medially near nasolacrimal sac/drainage system.

What do zygomatic bones form?

They form the lateral cheekbone.

What does the zygomatic bones articulate with?

It articulates with the zygomatic process of the frontal bone → zygomatic arches

What does the zygomatic bone contain?

• It contains the lateral/marginal orbital tubercle (Whitnall tubercle).

What does the Whitnall tubercle serve as the site of attachment for?

Site of attachment of various orbital connective tissue structures.

What is the maxilla and what structures does it form?

It is paired bones that form the upper jaw, hard palate, lateral walls of nasal cavity, and floor of orbit.

What landmark does the maxilla contain?

Infraorbital foramen: infraorbital nerve, artery, and vein