FSHP Academy
Human Anatomy — all lessons

Foundations of Anatomy

Anatomical terminology, planes, axes and movement directions

The Skeletal System

Skeletal system: structure and functionsBone structure, remodelling and adaptation to loading

Joints and the Muscular System

Joint types and classificationJoint mechanics: arthrokinematics and stabilityThe muscular system: organisation and major muscle groupsMuscle architecture: pennation, length and cross-sectional areaMuscle fibre types

Regional Functional Anatomy

Spine and postureThe shoulder complexThe hip complexThe knee complexThe ankle and foot complexCore and pelvic stabilityElbow and wrist functional anatomyCervical and thoracic spine functional anatomy

Joint types and classification

Fibrous, cartilaginous and synovial joints — how structure determines how much a joint moves, and the six types of synovial joint.

Beginner Evidence: Established consensus 3 min read Reviewed 2026-10-31 Status: draft

Learning objectives

  • Classify joints structurally (fibrous, cartilaginous, synovial) and functionally (synarthrosis, amphiarthrosis, diarthrosis)
  • Describe the components of a synovial joint
  • Identify the six synovial joint types, their degrees of freedom and examples
  • Relate joint type to the movements an exercise can use

Before this lesson

Why this matters

Every exercise is a combination of joint actions. Knowing what each joint is built to do explains which movements are possible, which are risky, and why the shoulder dislocates far more often than the hip.

Fundamental concepts

Structural classification (what connects the bones) [openstax2022joints]:

ClassConnectionMovementExamples
FibrousDense connective tissueNone to slightSkull sutures, distal tibiofibular syndesmosis, tooth sockets
CartilaginousHyaline or fibrocartilageSlightIntervertebral discs, pubic symphysis, first sternocostal joint
SynovialJoint cavity with fluidFreeKnee, hip, shoulder, elbow, wrist

Functional classification: synarthrosis (immovable), amphiarthrosis (slightly movable), diarthrosis (freely movable — all synovial joints).

The synovial joint

Synovial joint structure and the six types of synovial joint Left: a synovial joint in section. Two bone ends are covered with articular cartilage and enclosed by a fibrous joint capsule lined by synovial membrane; the joint cavity contains synovial fluid, and a ligament reinforces the capsule. Right: a table of the six synovial joint types with their degrees of freedom and examples. Bone Articularcartilage Synovial fluid in cavity Fibrouscapsule Synovialmembrane Ligament Six synovial joint types Hinge 1 DOF Elbow (humero-ulnar), knee*, ankle Pivot 1 DOF Atlanto-axial, proximal radio-ulnar Condyloid 2 DOF Wrist (radiocarpal), MCP joints Saddle 2 DOF Thumb carpometacarpal Ball & socket 3 DOF Hip, glenohumeral Plane (gliding) small glides Intercarpal, facet joints DOF = degrees of freedom. *Knee: modified hinge; rotates when flexed.
Figure 1. Components of a synovial joint (left) and the six types of synovial joint with degrees of freedom (right). — Original diagram, FSHP Academy (schematic, not to scale).
  • Articular cartilage — smooth hyaline cartilage reducing friction and spreading load. It has no blood supply; it relies on synovial fluid pumped in and out with loading and movement.
  • Joint capsule — an outer fibrous layer, often thickened into capsular ligaments.
  • Synovial membrane — lines the capsule and produces synovial fluid.
  • Accessory structures — extracapsular and intracapsular ligaments (e.g., cruciates), menisci and labra (deepen sockets), bursae and fat pads.

Synovial joint types

The shape of the articular surfaces determines the degrees of freedom (DOF) — the number of planes in which rotation can occur [neumann2017]:

  • Hinge (1 DOF) — flexion/extension; elbow (humero-ulnar), ankle (talocrural), interphalangeal joints.
  • Pivot (1 DOF) — rotation about a longitudinal axis; atlanto-axial joint (head rotation), proximal radio-ulnar joint (pronation/supination).
  • Condyloid/ellipsoid (2 DOF) — flexion/extension and abduction/adduction; wrist, knuckles (MCP).
  • Saddle (2 DOF) — thumb CMC; allows opposition.
  • Ball-and-socket (3 DOF) — hip and glenohumeral.
  • Plane (gliding) — small translations; intercarpal and spinal facet joints.

The knee is often called a hinge but is better described as a modified hinge: it allows axial rotation when flexed.

Practical application

Common mistakes and misconceptions

  • Calling every joint “a hinge or a ball-and-socket”. Many joints combine motions; the elbow complex, for instance, includes a hinge and a pivot.
  • Ignoring cartilaginous joints. Intervertebral discs are joints that allow and transmit spinal movement.

Case study

A swimmer and a weightlifter both ask why their shoulders “feel loose”. The trainer explains the trade-off between glenohumeral mobility and stability, screens for symptoms, and builds rotator cuff and scapular strength into both programmes, referring the swimmer to a physiotherapist because of episodes of the shoulder “slipping”.

Further learning: video lessons

Video links are only marked “verified” after a human has watched them. Unverified entries open a YouTube search for that channel and topic rather than a guessed link.

Introductory needs verification — opens a YouTube search

Joints: classification and synovial joint types

Crash Course

You will understand: the three structural classes and six synovial types

Why: Concise beginner overview.
Technical needs verification — opens a YouTube search

Synovial joints explained with models

Kenhub

You will understand: joint components and degrees of freedom

Why: Anatomy educator using labelled models.

Knowledge check

Knowledge check · 0/5

1. The pubic symphysis is an example of a…

Answer B. It is a fibrocartilaginous (symphysis) joint with slight movement.

2. Which joint has three degrees of freedom?

Answer C. Ball-and-socket joints (glenohumeral, hip) allow motion in all three planes.

3. What produces synovial fluid?

Answer B. The synovial membrane lining the capsule secretes fluid that lubricates and nourishes cartilage.

4. The thumb carpometacarpal joint is a…

Answer A. Its saddle shape allows two degrees of freedom and opposition.

5. Why is articular cartilage dependent on joint movement?

Answer B. Cartilage is avascular; cyclic loading and movement help move nutrients through it.

Short-answer & application questions

  1. Compare the hip and shoulder in terms of mobility and stability, and explain the structural reasons.
  2. Which synovial joint types are involved in a push-up? Name them.
  3. Explain why prolonged immobilisation may be harmful to articular cartilage.

Key takeaways

  • Joints are classified by structure (fibrous, cartilaginous, synovial) and by how much they move.
  • Synovial joints have articular cartilage, a fibrous capsule, a synovial membrane and synovial fluid.
  • Hinge and pivot joints have one degree of freedom; condyloid and saddle two; ball-and-socket three.
  • More mobility generally means less inherent bony stability.

Connected topics

anatomy

Joint mechanics: arthrokinematics and stability

anatomy

The shoulder complex

anatomy

The hip complex

anatomy

The knee complex

References

  1. Betts JG, Young KA, Wise JA, et al. (2022). Anatomy and Physiology 2e — Chapter 9: Joints. OpenStax, Rice University. · Link Textbook check pending
  2. Neumann DA (2017). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation (3rd ed.). Elsevier. Textbook check pending

Educational content only — not medical advice. Consult a qualified clinician for diagnosis or treatment.