Study Notes on the Vertebral Column and Ribs

Introduction

  • Overview of class plans.
  • Reminder of no class on Wednesday and that studying is encouraged.
  • Bones will be accessible outside the room for study purposes.

Structures of the Vertebrae

  • Focus on understanding anatomical structures of vertebrae.
  • Classification based on anatomical features.
  • Importance of distinguishing between cervical, thoracic, lumbar, sacral, and coccygeal vertebrae.

Cervical Vertebrae

  • All mammals have seven cervical vertebrae; examples include: bovine, porcine, equine, canine, feline.
    • C1 is the atlas, C2 is the axis.
    • C1 (atlas) connects the skull at the occipital condyles, allowing for movement of the head (flexion, extension, rotation).
    • C2 (axis) has a prominent spinous process and a projection called the dens.
  • C3 to C7 are similar in appearance; distinguishing characteristics are minimal without specific identifiers.
Distinct Features of Cervical Vertebrae
  • Transverse foramen present in C1-C7.
    • These foramens are holes in the bone unique to cervical vertebrae.
  • Components to identify in C1 & C2 include:
    • Transverse foramen (2 on each side), Central foramen (also known as vertebral foramen).
    • The spinous process and transverse process.
    • The body of the vertebra is extensive, forming the ventral portion.

Thoracic Vertebrae

  • Comprises the region within the chest cavity.
  • Numbered T1 through T18 (e.g., the horse), with most mammals having 13.
  • Identifiable structures:
    • Spinous process (tall in thoracic), Body of the vertebra, Transverse process.
    • Central foramen (veseral canal) remains consistent in size.

Lumbar Vertebrae

  • Typically L1 to L7 in most mammals (except some may have 6).
  • Characteristics:
    • Spinous processes are shorter and broader than in thoracic vertebrae.
    • Longer, flatter transverse processes compared to cervical counterparts.
    • Larger, stout bodies than cervical vertebrae.

Sacrum

  • Consists of fused vertebrae; no numbers assigned individually.
  • Unique function of providing structural support to the pelvis, contributing to a square box structure around the pelvic cavity.
  • Number of fused segments varies by species (e.g. 5-6 depending on the animal).
Differences in Sacrum Structure
  • Positionally distinct from the rest of the vertebrae.
  • Provides multi-functional support.

Coccygeal Vertebrae

  • Individual vertebrae that make up the tail.
  • Number varies typically up to 20, influenced by possible tail docking.
  • Distinct attribute: lack of central foramens.
Relation to the Spinal Cord
  • Spinal cord ends around L4-L5.
  • Below that is the cauda equina: bundle of nerves extending down into the tail.
  • Epidural injections administered at L7-S1 do not risk puncturing the spinal cord due to absence of the true cord.

Ribs

  • Studied in association with thoracic vertebrae, starting rib counting from the cranial border.
  • Total ribs correspond with thoracic vertebra count.
Types of Ribs
  1. True Ribs (in dog and cat): 9
  2. False Ribs: 3
  3. Floating Ribs: 1
  • Counting method: Count from the cranial border downwards.
Rib Structural Junctions
  • Costochondral junction: where rib meets cartilage, critical for rib movement.
  • True ribs attach directly to the sternum; false ribs attach indirectly via cartilage; floating ribs do not attach at all.

Sternum

  • Comprises three structures:
    1. Manubrium: cranial portion, palpable on the animal's chest.
    2. Xiphoid process: terminal point of sternum, also palpable.
    3. Body of sternum: region between manubrium and xiphoid process.
  • Overall structure helps support breathing mechanics; rib count influences sternum structure.

Summary

  • Additional questions encouraged.
  • End of the lecture with the remainder of laboratory time for self-study.