Muscle Problems that can Cause a Sore Back

Abnormal pressure, tension or force can injure the muscles of the back. 
Muscular back injuries can be very difficult to diagnose and treat.

The individual muscles will often insert into a number of different bones, or to different places on the same bone.  An injury in a single muscle may therefore cause pain over a wide area, with a wide range of movements, and may affect the ability not only to move the spine, but also to move the limbs.  Treatment is problematic because many of the muscles are either necessary for posture, stability and necessary torso movements, making immobilisation almost impossible.  Many are also very deep within the body, covered by one or more other large muscles, making physical manipulation (osteopathy, massage, physiotherapy) very difficult.  The major muscles in the back region are the:


Trapezius

Runs from the base of the skull down to the thoracic spine and outwards to the scapulae (shoulder blades) and over the top of the torso to the clavicles (collarbones).
Functions in many of the clavicle and scapula movements, and head extension

Latissimus dorsi
Runs from the lower six thoracic vertebrae to the base of the spine and the pelvis and wraps around to the lower ribs.  Overlapped slightly by the trapezius in the thoracic spine region.
Functions in most of the movements of the arms

Gluteal Muscles (maximus, medius and minimus)
The maximus gives the shape of the buttocks, the medius is located directly beneath the maximus, and the minimus directly beneath that.  Maximus runs from the very base of the spine to the pelvis and femur (thigh bone).  Medius and minimus run from the pelvis to the femur.
Work together to control some movements of the thigh


Obliques
Wrap around the sides of the body.  The external obliques run from the lower ribs to the pelvis.  The internal obliques are beneath the external obliques, and run from the pelvis to the lower ribs.
Allow abdominal movements and lateral vertebral movements

Deeper, beneath these large muscles are the spinal muscles that specifically allow spinal movements.  They are long, thin muscles that run up and down the spine, connecting to ribs, vertebrae, the pelvis and the skull.  They are quite numerous, but can be categorised as:

Splenius Muscles

Splenius capitus and cervicus. 
These are associated with movements of the head.

Erector Spinae
Largest muscular mass of the back, comprising the iliocostalis (run outside the other Erector spinae muscles – towards the sides of the body), longissimus (between iliocostalis and spinalis) and spinalis (middle of the back, close to spine) muscles.  All run longitudinally, parallel to each other.
Allow spinal extension and maintain posture

Transversospinalis Muscles
Semispinalis thoracis, cervicus and capitis, as well as Multifidus and Rotatores muscles.
Extension and rotation of the spinal column

Segmental Muscles
Interspinales and Intertransversarii muscles
Extension and lateral flexion (bending over to the side) of the spinal column

Scalene Muscles
Anterior, middle and posterior scalene muscles
Neck flexion and rotation.

Associated Tissues

Muscles and bones are connected by bands of extremely strong fibrous tissue:

Ligament
Fibrous tissue connection between bones (or cartilages).  Provide support and stability over joints and assist in permitting joint movements.

Tendon
Fibrous tissue connection between a muscle and bone.

Muscle Injuries

Injuries to the muscles and tendons include:

Sprain
An injury to a ligament.  Can be a small tear to a complete separation from the bone.

Strain
An injury to a muscle.  Tearing of the muscle tissue will generally result in bleeding and a hematoma.

Tear/Laceration
Generic term, used to describe an injury where muscle fibres, or adjoining anatomical structures are forcibly separated from each other.

Hernia
Where an organ/muscle/tissue protrudes through an abnormal opening in a lining or muscle wall.  In terms of a muscle injury, it can be either that the muscle is the protruding tissue, or the muscle could be damaged by the protrusion of another structure through it.

Atrophy
To waste away.  Can refer to a cell, an organ or a tissue.  Muscles that are unused for extended periods will atrophy, resulting in weakness.

A common back injury today is whiplash, more correctly known as a neck hyperextension injury.  This is the consequence of sudden, forceful jerking of the head forward and backward, often with an equally sudden and forceful stop.  The cervical vertebrae are the smallest and most fragile, as well as being the least well supported by surrounding musculature.  The injury is partially due to the strain on the muscles caused by the extreme range of the movement, as well as the strain on the muscles we instinctively tense up trying to brace our necks and stop the movement.