Bones of the orbit

Summary

This educational video script delves into the anatomy of the bony orbit, discussing the bones that comprise it, including the frontal, maxilla, zygomatic, sphenoid, ethmoid, and lacrimal bones. It highlights the concept of blowout fractures, common injuries in the orbit caused by increased pressure from impacts, most frequently affecting the floor of the orbit. The script also touches on the importance of CT radiography in diagnosing these fractures, providing a detailed yet accessible explanation suitable for students and enthusiasts of anatomy.

Takeaways

• 😀 The video discusses the bones that make up the orbit, following a previous session on paranasal sinuses.
• 🦴 The bones of the skull, specifically the orbit, are examined in detail, including the bones' roles and connections.
• 👁️ Blow fractures are highlighted as an interesting type of fracture that can occur in the orbit due to a forceful impact.
• 🔍 The script explains how thin some bones are around the orbit, which can lead to fractures, particularly in the maxillary and ethmoid bones.
• 🧱 The individual bones forming the orbit are identified, including the frontal bone, maxilla, zygoma, sphenoid bone, nasal bones, lacrimal bone, and ethmoid bone.
• 🌈 The script uses color coding on a skull model to differentiate and explain the function of each bone in the orbit.
• 🚫 The zygomatic arch is clarified as a complex structure composed of multiple bones, not just the zygomatic bone.
• 👃 The ethmoid bone's role in the nasal cavity and its connection to the olfactory system via the cribriform plate is discussed.
• 💧 The lacrimal bone's association with tear production and drainage through the nasolacrimal duct is explained.
• 🧊 The video emphasizes the packed nature of the orbit with muscles, nerves, blood vessels, and fat, which can affect the outcome of a blow to the eye.
• 🔬 CT radiography is mentioned as the preferred method for assessing blowout fractures over traditional X-rays due to its enhanced detail.

Q & A

What are the paranasal sinuses?

The paranasal sinuses are air-filled cavities within the bones of the skull that are connected to the nasal passages. They include the maxillary, frontal, sphenoid, and ethmoid sinuses.

What is a blowout fracture?

A blowout fracture is a type of fracture that occurs in the bones surrounding the eye, typically caused by a forceful impact such as a sporting accident. It can cause the thin bone to fracture into the adjacent sinuses.

Which bones are involved in the formation of the orbit?

The bones involved in the formation of the orbit include the frontal bone, maxilla, zygomatic bone, sphenoid bone, ethmoid bone, lacrimal bone, and palatine bone.

Why are the bones around the orbit prone to fractures?

The bones around the orbit are prone to fractures due to their thinness and the pressure increase within the orbit caused by a blow, which can lead to the weakest part of the bone, such as the thin bone of the maxilla, fracturing into the maxillary sinus.

What is the function of the infraorbital foramen?

The infraorbital foramen is a canal through which the infraorbital nerve, artery, and vein pass, providing sensory information and blood supply to the face.

What is the significance of the optic canal?

The optic canal is a tubular canal that houses the optic nerve (cranial nerve II) and the ophthalmic artery, which supplies blood to the retina of the eye.

What is the role of the superior orbital fissure?

The superior orbital fissure connects the middle cranial fossa with the bony orbit, allowing cranial nerves that innervate the extraocular muscles to enter the orbit.

What is the purpose of the periorbital fat mentioned in the script?

The periorbital fat serves to fill the space within the bony orbit, providing cushioning and support to the eye and surrounding structures.

How can a blowout fracture be assessed?

A blowout fracture is commonly assessed using CT radiography, which provides more detailed information than an X-ray and is the preferred method for diagnosis.

What is the nasolacrimal duct and its function?

The nasolacrimal duct is a passageway that drains tears from the lacrimal sac into the nasal cavity, allowing tears to be cleared from the eye.

Why might a blow to the eye cause the eye to appear sunken?

A blow to the eye can cause a blowout fracture, which may result in the eye being pulled back slightly into the orbit due to the increase in pressure within the orbit and subsequent bone displacement.