Joints and Their Types

Joints

• Joints consist of a minimum of two bones.
• They allow movement.
• Joints are divided into two main groups: Synarthrosis and Diarthrosis.

Synarthrosis

• Fibrous:
  • Sutura: between skull bones.
  • Schindylesis: between the sphenoid and vomer bones.
  • Syndesmosis: distal tibiofibular joint.
  • Gomphosis: between tooth roots and jawbone.
• Cartilaginous:
  • Synchondrosis.
  • Symphysis (e.g., pubic symphysis).

Diarthrosis (Synovial)

• Movements in the transverse axis involve flexion and extension.
• Movements in the vertical axis involve medial and lateral rotation.
• Movements in the sagittal axis involve abduction and adduction.
• Ginglymus (hinge type): Allows only flexion and extension (e.g., interphalangeal joints).
• Bichondylaris: Only allows flexion and extension (e.g., knee joint).
• Spheroidea: Ball and socket joint, allowing all axes of movement (e.g., shoulder and hip joints).
• Plana: Flat articular faces, allowing only gliding movement (e.g., joints between certain wrist bones).

Sternoclavicular Joint

• Located between the sternal end of the clavicle, manubrium, and the first costal cartilage.
• Features a sternal articular surface and a clavicular notch on the sternum.
• A plane or saddle-type joint.
• The articular surfaces fit together with a cartilaginous disc.
• Allows movement in multiple planes: up and down, forward and backward, and some rotation.

Acromioclavicular Joint

• Located between the acromion process of the scapula and the lateral end of the clavicle.
• A plane-type joint.
• Allows gliding movements.
• Clavicle glides on the acromion.
• Scapula rotates on this joint.

Shoulder Joint (Glenohumeral)

• A spheroid (ball and socket) type joint.
• Formed by the head of the humerus and the glenoid fossa of the scapula.

Elbow Joint

• Composed of three joints: humeroulnar, humeroradial, and proximal radioulnar.
• Hinge type joint.
• Allows flexion and extension.

Proximal Radioulnar

• Between the radius and radial notch of the ulna.
• Allows supination and pronation.

Distal Radioulnar

• Between the distal ends of the radius and ulna.
• Can be a trochoide type joint with a disc.

Wrist and Hand Joints

• Numerous joints in the hand, including radiocarpal, carpal, intercarpal, and others.
• Radiocarpal: between distal radius and proximal row of carpal bones. Allows movement in multiple planes.
• Ellipsoid-type joints.
• Carpal Joints: between individual carpal bones. Allow limited gliding movement.

Movements of Radiocarpal Joint

• Flexion
• Extension
• Abduction
• Adduction

Muscles

• Muscles are categorized by structure (smooth, striated, heart).
• Muscles are also categorized by function (abductor, adductor, flexor, extensor).
• Mastication muscles: temporalis, masseter, medial and lateral pterygoids.
• Upper limb muscles: trapezius, latissimus dorsi, pectoralis major, deltoid, biceps brachii, triceps brachii.

Additional Information

• The diaphragm is a parachute-shaped muscle.