Notes on Temporal Bone Lecture

Introduction

• Temporal bones are a pair of irregular bones.
• Form part of the lateral wall of the skull and base of the skull.
• Key areas: middle cranial fossa and posterior cranial fossa.

Anatomy of Temporal Bone

Location and Relation

• Positioned between the greater wing of sphenoid (anterior) and occipital bone (posterior).
• Body of sphenoid located between the temporal bones.

External Views

• Norma lateralis view: Shows the left temporal bone.
• Articulated skull correlates with the position of the temporal bone.

Individual Parts of Temporal Bone

1. Squamous Part

   • Flat translucent bony plate.
   • Contains zygomatic process.
   • Forms part of the temporal fossa.

2. Mastoid Part

   • Located posterior to the squamous part.
   • Forms mastoid process.
   • Provides attachment to muscles: sternocleidomastoid, splenius capitis, and longissimus capitis.

3. Tympanic Part

   • Triangular plate contributing to the mandibular fossa and external acoustic meatus.

4. Petrous Part

   • Pyramidal in shape, vital for housing the middle and internal ear.
   • Forms part of middle and posterior cranial fossa.

5. Styloid Process

   • Long, slender bony process directed downward, forward, and medially.
   • Provides attachment to muscles and ligaments: styloglossus, stylohyoid, stylopharyngeus; stylohyoid and stylomandibular ligaments.

Detailed Anatomy of Squamous Part

• Outer Surface: Forms part of temporal fossa; limited by the supramastoid crest.
• Zygomatic Process: Articulates with zygomatic bone to form zygomatic arch.
• Borders: Superior and anteroinferior borders articulate with parietal and greater wing of sphenoid respectively.
• Macewen Triangle: Formed between supramastoid crest and external acoustic meatus; important for identifying tympanic antrum.

Mastoid Part Details

• Outer Surface: Rough, continuous with mastoid process.
• Inner Surface: Forms part of sigmoid sulcus, lodges sigmoid sinus.
• Foramen: Allows passage of emissary vein and meningeal branches.

Tympanic Part Features

• Forms non-articular part of the mandibular fossa.
• Contains squamo-tympanic fissure.
• Medial aspect allows passage of chorda tympani nerve, anterior tympanic branch of maxillary artery.

Petrous Part Features

• Base and Apex: Base merges with squamous and mastoid parts; apex directed forward and medially.
• Contains carotid canal for internal carotid artery.
• Internal Acoustic Meatus: Allows passage of facial nerve, vestibulocochlear nerve, and labyrinthine artery.

Inferior Surface Features

• Related to greater wing of sphenoid and jugular process of occipital bone.
• Jugular fossa lodges superior bulb of internal jugular vein.
• Foramina: Include tympanic canaliculus (for passage of glossopharyngeal nerve) and mastoid canaliculus (for auricular branch of vagus).

Conclusion

• Temporal bone consists of five parts: squamous, mastoid, tympanic, petrous, and styloid.
• Important for understanding cranial anatomy and relations to nearby structures.
• Provides multiple attachments for muscles and ligaments crucial for various functions.

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Key Takeaways

• Understand the anatomy and functions of each part of the temporal bone.
• Recognize the significance of key features like the zygomatic arch, internal acoustic meatus, and jugular fossa.