Human Anatomy lecture 4The Back2 2024 no video

Anatomy Lecture 4

The Back Part 2: Skeletal Elements

Skeletal Framework

• Main Skeletal Elements

  • Vertebrae comprise the backbone structure.

  • Types of vertebrae:

    • 7 Cervical vertebrae

    • 12 Thoracic vertebrae

    • 5 Lumbar vertebrae

    • 5 fused Sacral vertebrae (Sacrum)

    • 3 to 5 fused Coccygeal vertebrae (Coccyx)

Overview of the Vertebrae

• Total Vertebrae: 33 in total:

  • 7 Cervical (C1-C7)

  • 12 Thoracic (T1-T12)

  • 5 Lumbar (L1-L5)

  • 5 Sacral

  • 4 Coccygeal

Typical Vertebrae

Common Features of Vertebrae

• Parts of a Typical Vertebra:

  • Anterior:

    • Vertebral body

    • Vertebral foramen

  • Posterior:

    • Spinous process

    • Pedicle

    • Lamina

    • Transverse process

    • Articular processes (superior and inferior)

• Distinctive Features:

  • Each type of vertebra (Cervical, Thoracic, Lumbar) has unique traits but shares typical vertebral characteristics.

Cervical Vertebrae (Typical)

Characteristics of C3-C6

• Body: Small, broader laterally than front to back.

• Spinous Process: Short and bifid (forked).

• Vertebral Foramen: Large and triangular.

• Articular Facets: Flat and oval-shaped.

• Transverse Processes: Contain transverse foramen for vertebral artery and vein.

Special Cervical Vertebrae

C1 (Atlas)

• Top vertebra connecting skull and spine.

• Lacks a vertebral body; articulates with occipital condyles.

C2 (Axis)

• Acts as a pivot for the atlas to rotate.

• Features a prominent odontoid process (dens).

C7 (Vertebra Prominens)

• Distinguished by long spinous process; resembles thoracic vertebrae.

• Transverse Foramen: May or may not contain blood vessels. Can be associated with cervical ribs.

Thoracic Vertebrae (Typical)

Structure

• Typical Thoracic Vertebrae: T2-T9

  • Small, circular vertebral foramen.

  • Heart-shaped bodies, spinous processes long and sloped downwards.

  • Have two costal demi-facets for rib articulation (both superior and inferior).

Special Thoracic Vertebrae

• T1: Unique body facilitating rib connections.

• T9-T12: May vary in facets and processes.

Lumbar Vertebrae (Typical)

General Features

• Typical Lumbar Vertebrae: L1-L4

  • Large vertebral bodies; wider side-to-side than front-to-back.

  • Triangular vertebral foramen, larger than in thoracic but smaller than in cervical.

  • Long, slender transverse processes, thick spinous processes.

Special Lumbar Vertebrae

• L5: Notable for massive body and short spinous process.

Sacrum and Coccyx

• Sacrum: Composed of 5 fused vertebrae; triangular, connects to L5 and coccyx.

• Coccyx: Composed of 3-5 vertebral segments; remnant of an evolutionary vestige.

Joints

Types of Joints

1. Synovial Joints: Separated by a cavity; include:

   • Pivot, Ball and Socket, Hinge, Ellipsoidal.

2. Solid Joints: Held together by connective tissue; include:

   • Fibrous and Cartilaginous joints.

Synovial Joints Structure

• Components:

  • Cartilage (hyaline)

  • Joint Capsule: Inner synovial membrane and outer fibrous membrane producing synovial fluid.

Joints in the Back

• Types:

  • Synovial joints between articular processes (zigapophyseal joints).

  • Symphyses between vertebrae (intervertebral discs).

• Vertebral Joints:

  • Composed of 4 synovial and 2 symphyses per typical vertebra, facilitating various movements.

Ligaments in the Back

1. Anterior Longitudinal Ligament (ALL): Runs along the length of the spine.

2. Posterior Longitudinal Ligament (PLL): Runs in the back of the vertebral bodies.

3. Supraspinous Ligament: Connects tips of spinous processes.

4. Interspinous Ligament: Connects adjacent spinous processes.

5. Ligamentum Flavum: Strong ligament safeguarding the spinal cord and nerves.

Test Yourself

• Example questions and features to recognize various vertebrae and structures, including identifiers for cervical ribs, vertebra types, and ligament functions.