Joints and Movements: Key Terms and Structures

Joints and Movements

Overview of Joint Movements

Joints, also known as articulations, are points where two or more bones meet. They allow for a variety of movements essential for daily activities and complex motions. Understanding the terminology of joint movements is fundamental in anatomy and physiology.

• Flexion: Decreasing the angle between two bones, typically bending a limb at a joint (e.g., bending the elbow).

• Extension: Increasing the angle between two bones, straightening a limb (e.g., straightening the knee).

• Abduction: Moving a limb away from the midline of the body (e.g., raising the arm sideways).

• Adduction: Moving a limb toward the midline of the body (e.g., lowering the arm to the side).

• Rotation: Turning a bone around its own long axis (e.g., turning the head side to side).

• Circumduction: Moving a limb in a circular motion, combining flexion, extension, abduction, and adduction (e.g., arm circles).

• Depression: Lowering a body part (e.g., dropping the shoulders).

• Elevation: Raising a body part (e.g., shrugging the shoulders).

• Protraction: Moving a body part forward (e.g., jutting the jaw forward).

• Retraction: Moving a body part backward (e.g., pulling the jaw back).

• Supination: Rotating the forearm so the palm faces up.

• Pronation: Rotating the forearm so the palm faces down.

• Inversion: Turning the sole of the foot inward.

• Eversion: Turning the sole of the foot outward.

• Opposition: Moving the thumb to touch the tips of other fingers.

Major Joints and Their Structures

Each joint in the body has unique anatomical features and supporting structures that allow for specific movements and stability. Below are key joints and their associated ligaments and components.

Shoulder Joint

• Articular capsule: Encloses the joint, providing stability and containing synovial fluid.

• Glenohumeral ligament: Strengthens the front of the capsule.

• Coracohumeral ligament: Supports the upper part of the joint.

• Coracoacromial ligament: Forms a protective arch over the shoulder.

• Coracoclavicular ligament: Connects the coracoid process to the clavicle; includes:

  • Conoid ligament

  • Trapezoid ligament

• Acromioclavicular ligament: Connects the acromion to the clavicle.

• Transverse scapular ligament: Bridges the scapular notch.

Elbow Joint

• Allows flexion and extension of the forearm.

Hand Joints

• Metacarpophalangeal joints (1-5): Knuckle joints, allow flexion, extension, abduction, and adduction.

• Interphalangeal joints: Hinge joints between phalanges.

  • Proximal interphalangeal joints (2-5): Between first and second phalanges.

  • Distal interphalangeal joints (2-5): Between second and third phalanges.

  • Interphalangeal joint 1: Thumb joint.

Hip Joint

• Iliofemoral ligament: Strongest ligament, prevents hyperextension.

• Ischiofemoral ligament: Reinforces the posterior aspect.

• Pubofemoral ligament: Prevents excessive abduction.

Knee Joint

• Medial meniscus & Lateral meniscus: Cartilage pads that absorb shock.

• Medial collateral ligament (MCL): Stabilizes the inner knee.

• Lateral collateral ligament (LCL): Stabilizes the outer knee.

• Anterior cruciate ligament (ACL): Prevents forward movement of tibia.

• Posterior cruciate ligament (PCL): Prevents backward movement of tibia.

• Patellar ligament: Connects patella to tibia.

• Quadriceps tendon: Connects quadriceps muscle to patella.

Ankle Joint

• Medial deltoid ligament: Provides medial stability.

• Lateral calcaneofibular ligament: Provides lateral stability.

Foot Joints

• Metatarsophalangeal joints (1-5): Allow flexion, extension, abduction, and adduction of toes.

• Interphalangeal joints: Hinge joints between toe phalanges.

  • Proximal interphalangeal joints (2-5): Between first and second toe phalanges.

  • Distal interphalangeal joints (2-5): Between second and third toe phalanges.

  • Interphalangeal joint 1: Big toe joint.

Temporomandibular Joint (TMJ)

• Connects the jawbone to the skull, allowing opening, closing, and side-to-side movement of the mouth.

Joints of the Vertebral Column

• Allow for flexion, extension, lateral flexion, and rotation of the spine.

Rib Joints

• Costovertebral joints: Connect ribs to vertebrae.

• Costotransverse joints: Connect ribs to transverse processes of vertebrae.

• Sternocostal joints: Connect ribs to sternum.

• Intercondral joints: Connect cartilage of ribs.

Summary Table: Major Ligaments and Their Functions

Joint	Ligament/Structure	Main Function
Shoulder	Glenohumeral, Coracohumeral, Coracoacromial, Coracoclavicular, Acromioclavicular, Transverse scapular	Stabilize and support shoulder movement
Hip	Iliofemoral, Ischiofemoral, Pubofemoral	Prevent hyperextension, excessive abduction, and reinforce joint
Knee	Medial/Lateral meniscus, MCL, LCL, ACL, PCL, Patellar ligament, Quadriceps tendon	Shock absorption, stability, prevent abnormal movement
Ankle	Medial deltoid, Lateral calcaneofibular	Medial and lateral stability
Rib	Costovertebral, Costotransverse, Sternocostal, Intercondral	Allow rib movement for breathing

Example: Knee Joint Injury

Damage to the anterior cruciate ligament (ACL) is a common sports injury, often resulting in instability of the knee and requiring surgical repair.

Additional info: The above notes expand on the provided list of terms by including definitions, functions, and examples for each joint and movement, making the content suitable for exam preparation in an anatomy and physiology course.