Ocular Anatomy: Bones of Skull & Orbit (Lecture 2; Exam 1)

What two types of bone makeup the skull?

1. Cranial Bones

2. Facial Bones

Suture

Firm, fibrous joint between bones.

• Most are immovable.

Sinus

Air-filled cavity within bones.

Foramen

Opening, hole, or passage in bone.

How many Cranial Bones are there?

8 bones

How many facial bones are there?

14 bones

What are the 8 cranial bones?

• (2) Parietal

• (2) Temporal

• Frontal

• Occipital

• Sphenoid

• Ethmoid

What are the 14 facial bones?

• (2) Lacrimal

• (2) Nasal

• (2) Zygomatic

• (2) Maxillary

• (2) Palatine

• (2) Inferior conchae

• Vomer

• Mandible

Parietal Bones

Roof and sides of cranium.

Temporal Bones

Sides and base of cranium.

Parts of the Temporal Bones:

• Stylomastoid foramen: facial nerve

• Carotid canal: internal carotid artery

Frontal bone

Anterior skull, superior part of face.

Parts of the Frontal Bone

• Supraorbital notch/foramen

• Supratrochlear notch/foramen

• Fossa for lacrimal gland

Occipital Bone

Posterior skull and floor of cranium.

Parts of the Occipital Bone:

• External occipital protuberance / inion

• Foramen magnum

External occipital protuberance / inion

Bony projection at back of skull that serves as attachment for connective tissue.

Foramen Magnum (occipital bone)

Passageway for spinal cord located at base of occipital bone.

Sagittal Suture

parietal + parietal

Coronal Suture

parietal + frontal

Lambdoidal Suture

parietal + occipital

Squamosal Suture

parietal + temporal

Sphenoid Bone

• Body lies in midline of skull

• Many points of interest for ODs!

• Part of every orbital wall EXCEPT floor.

• Multiple “wings” and a body.

Parts of the Sphenoid Bone

• Lesser wing

• Greater wing

• Body

Sphenoid - Lesser wing

• Optic canal / foramen

  • Optic nerve, ophthalmic artery

Sphenoid - Greater wing

• Foramen rotundum

  • Maxillary nerve

• Foramen ovale

  • Mandibular nerve

• Foramen spinosum

  • Middle meningeal artery

Sphenoid - Body

• Pituitary fossa / sella turcica / hypophyseal fossa

  • Pituitary gland

Sphenoid - Superior Orbital Fissure (SOF)

Opening between the greater and lesser wings of the sphenoid bone.

• Between orbital roof and lateral orbital wall.

• Just posterior to common tendinous ring (CTR)

• Communication between orbit and cranium

Sphenoid - Inferior Orbital Fissure (IOF)

Opening between the greater wing of sphenoid bone and maxilla.

• Between orbital floor and lateral orbital wall.

What vessels pass through the SOF and the CTR?

• Nasociliary nerve

• Oculomotor nerve

• Abducens nerve

What vessels 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

Ethmoid Bone

Bony areas of nasal cavity and medial orbital walls.

What parts make up the ethmoid bone?

• Cribriform plate

• Orbital plate

Ethmoid - Cribriform plate

Flat portion of bone with cribriform foramina for passage of olfactory nerves.

Ethmoid - Orbital plate

Flat portion of bone creating medial orbital wall.

Lacrimal Bones (2)

Smallest bone of face; located medially, that supports the lacrimal apparatus within the orbit.

Nasal Bones (2)

Forms the bridge of the nose.

Zygomatic Bones (2)

Form lateral cheekbone.

• (Articulate with zygomatic process of frontal bone —> zygomatic arches)

Zygomatic Bone

Contains the lateral / marginal orbital tubercle (Whitnall tubercle).

Zygomatic Bone - Whitnall tubercle

• Small prominence ~2-3mm posterior to orbital rim

• Site of attachment of various orbital connective tissue structures (tendons, ligaments, etc.)

Maxilla Bone (2)

Paired bones forming the upper jaw, hard palate, lateral walls of nasal cavity, and floor of orbit.

• Infraorbital foramen: Infraorbital nerve, artery, and vein.

Lacrimal Fossa

Depression where the nasolacrimal sac is located.

Anterior Lacrimal Crest

Anterior boundary of lacrimal fossa; formed by maxillary bone.

Posterior Lacrimal Crest

Posterior boundary of lacrimal fossa; formed by lacrimal bone.

Palatine Bones (2)

L-shaped bones that extend from the hard palate at the back of the mouth, vertically through the nasal cavity and to the orbital floor.

Inferior Conchae (2)

Scroll-like bones along the lateral walls of the nasal cavity.

Vomer

Single bone that forms the posterior part of the nasal septum.

Mandible

Horseshoe-shaped bone that forms the movable lower jaw

• Body + 2 rami (singular : ramus)