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A Physio’s Guide to Understanding the Anatomy of Muscle and Joint Pain

A Physio’s Guide to Understanding the Anatomy of Muscle and Joint Pain

 Muscles and joints play a fundamental role in human movement, allowing us to stand, mobilise, and perform everyday activities. They are essential for even the most basic functions like breathing. However, they can also be the source of pain and discomfort that limits our movement and well-being. As a physiotherapist, it is our responsibility to comprehend the symptoms, address the root causes, and restore optimal function.

The Anatomy of Muscles

Think of muscles like a bunch of fibres bundled together. Inside these fibres, there are proteins called myosin and actin that make the muscles contract when they're activated by nerves. It's like teamwork: myosin pulls against actin, making the muscle shorter. When the nerve signal weakens, myosin relaxes, and the muscle goes back to its normal length. Most muscles work in pairs, with one contracting while the other relaxes, allowing you to do things like walk or run.

Muscle and Tendon Connection

Muscles are connected to bones by tendons, strong cords of flexible tissue. Inflammation in tendons is often misinterpreted as muscle pain. Tendons typically cross a joint, facilitating joint movement. For example, the quadriceps and hamstrings cross the knee joint, with the hamstrings causing knee flexion when contracted.

Muscle and Tendon connections

Muscle Strength and Flexibility

Muscles must strike a balance between strength and flexibility. Weak muscles can't perform necessary actions, while overly tight muscles can restrict the range of motion. Both issues can be addressed with time and effort.

The Anatomy of Joints

Joints are points where two bones meet, allowing movement in the human body. The joint structure is crucial in understanding joint pain. Joints are held together by ligaments, and strong connective tissue bands, and the ends of bones are covered by smooth cartilage to reduce friction. Most movable joints are surrounded by a membrane that provides lubrication and cushioning. 

Classification of Joints

Joints can be classified based on movement range or type of connective tissue. When addressing joint pain, considering the movement range is most helpful, and joints can be categorised into six types:

  • Shoulder JointBall and socket: Allows movement in all directions (e.g., shoulder, hip).


  • Thumb JointSaddle: Permits back-and-forth and side-to-side movement (e.g., thumb).


  • Knee JointHinge: Enables open and close movement in one direction (e.g., knee, elbow).


  • CJaw Jointondyloid: Facilitates movement without rotation (e.g., jaw, fingers).


  • Gliding: Involves smooth surfaces slipping over each other (e.g., wrist).


  • Axis DiagramPivot: In this type, one bone swivels around a ring formed by another bone (e.g., atlas and axis of the first two vertebrae).


Understanding the type of joint and its expected movements helps diagnose injuries and determine appropriate treatment.

Types of Muscle Pain

Muscle pain can be categorised into different types based on the patient's presentation:

  • Muscle Strain (Overuse/Overload): Results from muscle fatigue to the point of failure, characterised by sharp, localised pain, discolouration, reduced movement, and swelling.
  • Muscle Cramp: Intense, sharp pain, usually of short duration, associated with recent heavy exertion and common in sports like football, rugby, and running.
  • Muscle Tears: Extremely painful with associated swelling, bruising, and loss of range due to muscle overloading and tears in fibre bundles.

Treatment for each type of muscle pain varies, but the primary objective is to protect the muscle and prevent further damage.

Types of Joint Pain

Joint pain can also be classified into different categories:

  • Sprains: Sharp pain accompanied by swelling or bruising after exercise.
  • Osteoarthritis (OA): Continuous, dull ache, typically in the hips or knees, worsened by walking or waking.
  • Rheumatoid Arthritis (RA): Similar to OA but may involve deformities, especially in the hands and fingers. 
  • Bursitis: Characterised by a hot, swollen, and very sharp tender joint, often associated with inflammation of a fluid-filled sac protecting the joint. 
  • Joint Infection: Presents with a hot, swollen joint alongside systemic signs of illness, particularly after surgery.

Treatment for joint pain involves pain relief and joint protection, with specific approaches tailored to each type of joint condition.

The Physiotherapist's Approach

In addressing both muscle and joint pain, physiotherapists must consider the anatomy and nature of the pain. Initial steps involve protecting the injured area and then devising a suitable treatment plan. Remember the adage: "If it’s weak, strengthen it; if it’s tight, stretch it; and if it’s stiff, move it." This mantra is a key guiding principle when evaluating and treating issues related to muscles and joints. 

Rich McBain (BSc), MSK Physiotherapist

Rich McBain

Rich McBain, a qualified MSK physio with over 13 years of experience. Whilst Rich is experienced throughout the MSK field, his specialisms are amputee and orthopaedic rehabilitation and he also has a lot of experience with patient care and evidence-based treatments.
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