The Anatomy of the Spine

The bones of the spine

Vertebral Column: Bones Column of 33 small bones called VERTEBRAE Begin at the cranium and end at the coccyx 5 Divisions: Cervical (7) Thoracic (12) Lumbar (5) Sacrum (5 fused) Coccyx (4 fused)

Functions of Vertebral Column Protection: it encloses the spinal cord, shielding it from damage Support: it carries the weight of the body above the pelvis (below the pelvis, the lower limbs take over) Axis: the vertebral column forms the central axis of the body Movement: it has roles in both posture and movement

The spine is well-designed! Each division of the spine is characterized by a different vertebral structure These differences in vertebral structure allow them to perform their main functions Cervical= Flexibility and movement Thoracic= Stability and protection Lumbar= Power; support weight of body Before looking the differences, we need to look at the general form of a vertebra….

Vertebral Structure While vertebrae have unique regional features, each vertebra has three main parts: Body (purple) Vertebral Arch (green) Processes for muscle attachment (tan)

Vertebral Structure Vertebral Body Anterior part of vertebra Weight-bearing component Size increases as vertebral column descends

Vertebral Structure Vertebral Arch Consists of 2 pedicles and 2 lamina Forms a hole for spinal cord called the VERTEBRAL FORAMEN Vertebral Foramen

Vertebral Structure Processes (7 on each): serve as attachment points for muscles and create joints that allow for movement of the spine Spinous Process Transverse Process (2) Superior Facet (2) Inferior Facet (2)

Inferior Facet would be underneath

Facet Joint Each vertebra has four facet joints: one pair that connects to the vertebra above (superior facets) one pair that connects to the vertebra below (inferior facets)

Intervertebral discs and ligaments

Intervertebral Disc Location: Between each vertebra of the spine Structure: Fibrocartilage Annulus: Tough outer ring Nucleus: Soft gel/liquid center Function: Transmit weight of body and cushion the vertebrae Allow movement between vertebrae

Intervertebral Disc The fluid in the nucleus changes: absorbed during the night as you lie down pushed out during the day as you move upright With age, our discs increasingly lose the ability to reabsorb fluid become brittle and flatter this is why we get shorter as we grow older.

Supraspinous Ligament Spinal Ligaments Major Ligaments Ligamentum Flavum Anterior Longitudinal Ligament (ALL) Posterior Longitudinal Ligament (PLL) Interspinous Ligament Supraspinous LIgament Supraspinous Ligament

Spinal Ligaments Ligamentum Flavum Attaches between the lamina of each vertebra Limits flexion of the spine

Spinal Ligaments Anterior Longitudinal Ligament (ALL) Thick and strong ligament Covers the front and sides of vertebral bodies Runs the whole length of vertebral column Limits extension of the spine

Spinal Ligaments Posterior Longitudinal Ligament (PLL) Runs the whole length of vertebral column Covers the back of the vertebral bodies Helps limit flexion of the spine

Spinal Ligaments Interspinous Ligament: Supraspinous Ligament Connect the lower edge of one spinous process to the upper edge of the next one Supraspinous Ligament Connects the tips of the spinous process Interspinous Ligament Supraspinous Ligament

Spinal cord and spinal nerves

Spinal Cord About 18 inches long and is the thickness of your thumb Runs within the protective vertebral foramen Starts at the brainstem and ends at the 1st lumbar vertebra Then the cord fibers separate into the cauda equina and continue down through the spinal canal to your tailbone before branching off to your legs and feet

Spinal Cord Covered with the same three protective membranes as the brain, called meninges. Inner membrane = pia mater Middle membrane = arachnoid mater Outer membrane = dura mater

Spinal Cord Function: information super-highway, relaying messages between the brain and the body The brain sends motor messages to the limbs and body through the spinal cord allowing for movement. The limbs and body send sensory messages to the brain through the spinal cord about what we feel and touch.

Spinal Cord Sometimes the spinal cord can react without sending information to the brain. These special pathways, called spinal reflexes, are designed to immediately protect our body from harm.

Spinal Cord Any damage to the spinal cord can result in a loss of sensory and motor function below the level of injury.

Spinal Nerves Thirty-one pairs of spinal nerves branch off the spinal cord Act as “telephone lines,” carrying messages back and forth between your body and spinal cord to control sensation and movement Numbered according to the vertebrae above which it exits the spinal canal

Spinal Nerves The spinal nerves innervate specific areas and form a striped pattern across the body called dermatomes Used to diagnose the location of a spinal problem based on the area of pain or muscle weakness

Spinal Nerves Nerves in the cervical spine branch out into your arms This is a neck injury can lead to pain radiating down your arms Nerves in the thoracic branch out into the middle of the body Nerves in the lumbar spine branch out into the legs This is why a low back injury can lead to pain radiating down your legs

Range of Motion of Spine

Muscles of the spine

Spinal Muscles: Deep Closest to the spine is a network of three types of short muscles that help hold the vertebrae together. intertransverse muscles: assist with lateral bending in between transverse processes interspinal muscles: assist flexion and extension In between spinous processes rotator muscles: assist rotation Connect transverse process to spinous process of vertebra above

Spinal Muscles: Deep Multifidus Function = spine stability Connect transverse process to sides of the spinous processes two to four vertebrae above Entire length of spine

Spinal Muscles: Superficial Erector Spinae: One on either side of spine 3 Parts Spinalis Longissimus Iliocostalis Function: Spine extension (when both sides contract) Lateral bending (when only one side contracts)

Spinal Muscles: Abdominal Rectus Abdominis Flex spine External Oblique Flex and rotate spine Internal Oblique Transverse Abdominis Stabilize pelvis

Spinal Muscles: Cervical

Spinal Muscles: Cervical Sternocleidomastoid Functions: Flex neck Rotate neck Laterally bend neck

Spinal Muscles: Cervical Scalenes (Anterior, Middle, and Posterior Parts) Function: Lateral bending of neck

Spinal Muscles: Cervical