Anatomy of the Back and Vertebral Column Lecture

Question 1

Know the bones, joints and major muscles, ligaments and curvatures of the vertebral column.

Answer 1

Bones
The vertebral column consists of 33 vertebrae, categorized into five regions:

Cervical Vertebrae (7)

C1 to C7 (the first two are the atlas and axis)
Thoracic Vertebrae (12)

T1 to T12
Lumbar Vertebrae (5)

L1 to L5
Sacral Vertebrae (5)

S1 to S5 (fused to form the sacrum)
Coccygeal Vertebrae (4)

Co1 to Co4 (fused to form the coccyx)
Joints
The vertebral column has several types of joints:

Intervertebral Discs: Fibrocartilaginous joints between vertebrae that act as shock absorbers.
Facet Joints: Synovial joints between the articular processes of adjacent vertebrae, allowing for flexibility and movement.
Major Muscles
Key muscles associated with the vertebral column include:

Erector Spinae Group: A group of muscles that help maintain posture and extend the spine.

Iliocostalis
Longissimus
Spinalis
Transversospinalis Group: A group of muscles that aid in rotation and extension.

Semispinalis
Multifidus
Rotatores
Other Muscles:

Rectus Abdominis
External and Internal Obliques
Quadratus Lumborum
Ligaments
Several ligaments support the vertebral column:

Anterior Longitudinal Ligament: Runs along the front of the vertebrae, preventing hyperextension.
Posterior Longitudinal Ligament: Runs along the back of the vertebrae, limiting flexion.
Ligamentum Flavum: Connects the laminae of adjacent vertebrae, providing elasticity.
Interspinous Ligaments: Connect adjacent spinous processes.
Supraspinous Ligament: Runs along the tips of the spinous processes from the sacrum to the cervical region.
Curvatures
The vertebral column has natural curvatures that help with balance and weight distribution:

Cervical Lordosis: A slight inward curve in the cervical region.
Thoracic Kyphosis: A slight outward curve in the thoracic region.
Lumbar Lordosis: An inward curve in the lumbar region.
Sacral Kyphosis: A natural curve in the sacral region.
These curves develop as a person grows and are essential for proper posture and function.

Question 2

Know the main types of bones and joints of the vertebral column.

Answer 2

Types of Bones
Vertebrae: The individual bones that make up the vertebral column. They vary in shape and size based on their location:
Cervical Vertebrae: Small and lightweight, allowing for a greater range of motion in the neck.
Thoracic Vertebrae: Larger than cervical vertebrae, with facets for rib attachment.
Lumbar Vertebrae: The largest and strongest, designed to support the weight of the upper body.
Sacrum: A fused bone formed by the fusion of five sacral vertebrae, connecting the spine to the pelvis.
Coccyx: The small tailbone, formed by the fusion of four coccygeal vertebrae.
Types of Joints
Intervertebral Joints: These are cartilaginous joints formed by intervertebral discs between adjacent vertebrae. Each disc has:

Nucleus Pulposus: The gel-like center that absorbs shock.
Annulus Fibrosus: The tough outer layer that contains the nucleus.
Facet Joints (Zygapophysial Joints): These are synovial joints located between the articular processes of adjacent vertebrae. They allow for limited movement and provide stability while facilitating flexion, extension, rotation, and lateral bending of the spine.

Sacroiliac Joint: A synovial joint that connects the sacrum to the ilium of the pelvis, providing stability and weight transfer between the spine and lower limbs.

Summary
Bones: Composed of individual vertebrae (cervical, thoracic, lumbar, sacral, and coccygeal).
Joints: Includes intervertebral joints (cartilaginous) and facet joints (synovial), with the sacroiliac joint linking the spine to the pelvis.

Question 3

Understand how the back is stabilised to form a framework to which structures from other regions of the body attach.

Answer 3

1. Vertebral Column Structure
   Vertebrae: The stack of vertebrae provides a strong central axis for the body. Each vertebra connects with adjacent vertebrae through intervertebral discs and facet joints, allowing for flexibility while maintaining stability.
   Curvatures: The natural curves (cervical lordosis, thoracic kyphosis, lumbar lordosis, and sacral kyphosis) help distribute mechanical stress and maintain balance.
2. Muscle Support
   Core Muscles: The muscles of the trunk, including the erector spinae, rectus abdominis, and obliques, provide dynamic stability. They work together to control movements, maintain posture, and support the spine during various activities.
   Latissimus Dorsi and Trapezius: These larger muscles attach to the spine and help stabilize the shoulder girdle and upper limb movements.
3. Ligamentous Support
   Anterior Longitudinal Ligament: This ligament runs along the front of the vertebral bodies, preventing excessive extension.
   Posterior Longitudinal Ligament: Located along the back of the vertebral bodies, it prevents excessive flexion.
   Ligamentum Flavum and Interspinous Ligaments: These ligaments connect adjacent vertebrae and provide additional support during movement.
4. Rib Cage
   The thoracic vertebrae articulate with the ribs, forming the rib cage, which protects vital organs and provides additional structural support. The rib cage helps maintain stability in the thoracic region.
5. Pelvic Connection
   The sacrum connects the spine to the pelvis, creating a stable base for the spine. This connection is crucial for weight transfer between the upper body and lower limbs, especially during activities like walking and lifting.
6. Fascia and Connective Tissue
   Thoracolumbar Fascia: This connective tissue structure envelops the lumbar spine and provides additional support, connecting muscles and bones in the lower back.
   Aponeuroses: These are broad, flat tendons that help anchor muscles to the spine and pelvis, contributing to stability.

Question 4

Know the relationship between the vertebral column, the spinal cord and the spinal nerves and appreciate that damage to the vertebral column may lead to nerve damage.

Answer 4

Relationship Overview
Vertebral Column:

The vertebral column consists of individual vertebrae that encase and protect the spinal cord.
It serves as a structural framework for the body and a conduit for the spinal cord.
Spinal Cord:

The spinal cord is a long, cylindrical structure that runs within the vertebral canal, formed by the vertebral foramen of the stacked vertebrae.
It is part of the central nervous system (CNS) and extends from the base of the skull (medulla oblongata) to approximately the level of the first or second lumbar vertebra in adults.
Spinal Nerves:

Spinal nerves emerge from the spinal cord through intervertebral foramina (the spaces between adjacent vertebrae) and branch out to various parts of the body.
There are 31 pairs of spinal nerves, each corresponding to a segment of the spinal cord (cervical, thoracic, lumbar, sacral, and coccygeal).
Each spinal nerve carries both motor and sensory information, enabling communication between the CNS and peripheral body parts.
Implications of Damage to the Vertebral Column
Potential for Injury:

Damage to the vertebral column, such as fractures or dislocations, can directly impact the spinal cord and lead to serious neurological consequences.
The severity of injury can vary based on the level of the vertebra affected and the extent of the damage.
Types of Injuries:

Compression Injuries: Can occur from a fall or impact, leading to vertebral body fractures that may compress the spinal cord.
Herniated Discs: Intervertebral discs may bulge or rupture, pressing on spinal nerves or the spinal cord itself, causing pain, weakness, or numbness.
Consequences:

Nerve Damage: Injury to the spinal cord can result in loss of function below the level of the injury, affecting motor control, sensation, and reflexes.
Paralysis: Depending on the location of the injury, paralysis can be complete (loss of all function) or incomplete (partial loss of function).
Tetraplegia (quadriplegia) occurs with cervical injuries, affecting all four limbs.
Paraplegia occurs with lumbar or thoracic injuries, affecting the lower limbs.
Pain and Discomfort: Damage can lead to chronic pain conditions, such as neuropathic pain, due to the disruption of normal nerve signaling.

Summary
The vertebral column, spinal cord, and spinal nerves work together to protect the central nervous system and enable communication throughout the body. Damage to the vertebral column can have serious consequences, including nerve damage that may lead to paralysis, loss of sensation, and chronic pain. Understanding this relationship highlights the importance of maintaining spinal health and the potential risks associated with spinal injuries.