Joints and Their Types

Joints

• Joints are where two or more bones, or a bone and cartilage, meet.
• Three main types of joints: fibrous, cartilaginous, and synovial.

Fibrous Joints

• Bones connected by fibrous tissue.
• Three classifications: Suture, Syndesmosis, and Gomphosis.
• Sutures: Found in the skull, allow little movement.
• Syndesmosis: Joined by interosseous ligament, allows very little movement. Example: inferior tibiofibular joint.
• Gomphosis: Joint between a tooth and the mandible or maxilla, allows no movement (only pathological movement should occur).

Cartilaginous Joints

• Bones united by cartilage.
• Two types: primary and secondary cartilaginous.

Primary Cartilaginous Joints

• Joined by hyaline cartilage.
• Found in the epiphyseal plate, ribs and costal cartilage.
• Typically ossify over time.

Secondary Cartilaginous Joints

• Covered by hyaline cartilage.
• Joined by fibrocartilage.
• Slightly movable.
• Examples: symphysis pubis, between vertebral bodies, sternum.

Synovial Joints

• Most common type.
• Bones covered by hyaline cartilage.
• Bones separated by joint cavity.
• Cavity is surrounded by a fibrous capsule.
• Capsule lined by synovial membrane.
• Capsule supported by ligaments.
• Can also contain ligaments, cartilage, and tendons.

Classification of Synovial Joints

• Classified by number of axes: uniaxial, biaxial, multi-axial (polyaxial).

Uniaxial Synovial Joints

• Hinge: Allows flexion and extension. Example: elbow joint.
• Pivot: Allows rotation around a vertical axis. Examples: Superior radioulnar joint, Atlantoaxial joint.

Biaxial Synovial Joints

• Ellipsoid: Allows flexion, extension, adduction, and abduction (no rotation). Examples: Wrist joint.
• Saddle: Allows flexion, extension, adduction, abduction, and slight rotation. Example: Carpometacarpal joint of thumb.

Polyaxial Synovial Joints

• Ball and socket: Allows all movements. Examples: Shoulder joint, hip joint

Factors Supporting Joints

• Shape of articulating bones
• Supporting ligaments
• Tone of surrounding muscles

Muscles

• Three main muscle types: Skeletal, Smooth, Cardiac.
• Skeletal muscles: voluntary, rapid contractions, make up the majority of muscles in the limbs.
• Smooth muscles: involuntary, found in organs like GI tract, urinary bladder, uterus, and blood vessels.
• Cardiac muscles: involuntary, capable of rhythmic contractions, controlled by the autonomic nervous system and hormones.

Classification of Skeletal Muscles by Shape and Line of Pull

• Parallel fibers: wide range of movement, less force.
• Quadrilateral: Example: Quadratus lumborum
• Fusiform: Example: Biceps
• Strap: Example: Sartorius
• Strap-like with tendinous intersection: Example: Rectus abdominus
• Oblique fibers: less range of movement, more force.
• Pennate:
  • Unipennate: Examples: Flexor pollicis longus, Dorsal interossei.
  • Bipennate: Example: Rectus femoris.
  • Multipennate: Examples: Deltoid.
• Triangular: Fibers converge from a wide attachment to a narrow tendon. Example: Temporalis
• Cruciate fibers: muscle fibers in two planes running in different directions. Example: Sternomastoid.
• Circular fibers: muscle fibers in a complete circle. Example: Orbicularis oculi.

Attachment of Skeletal Muscles

• Proximal attachment is called the origin.
• Distal attachment is called the insertion.
• Muscles can act from either their origin or insertion depending on the needed movement.

Actions of Muscles

• Prime mover: initiates movement.
• Antagonist: opposes movement.
• Synergist: prevents unwanted movements.

Nervous System

• Two main parts: Central nervous system (CNS) and Peripheral nervous system (PNS).
• CNS: Includes the brain and spinal cord.
• PNS: Includes the cranial nerves, spinal nerves, and autonomic nervous system (ANS).
• Somatic Nervous System (SNS): Part of the PNS, carries sensation and controls skeletal muscles.
• ANS: Part of the PNS, controls smooth muscles, heart, and glands.
• ANS is subdivided into sympathetic and parasympathetic systems.

The Brain

• Composed of: Cerebrum, brain stem, cerebellum.

The Spinal Cord

• Divided into 31 segments, giving rise to 31 pairs of spinal nerves.
• Cervical segments: 8
• Thoracic segments: 12
• Lumbar segments: 5
• Sacral segments: 5
• Coccygeal segments : 1

Peripheral Nervous System

• Includes 12 pairs of cranial nerves.

This quiz explores the different types of joints in the human body, including fibrous, cartilaginous, and synovial joints. Learn about their structures, classifications, and movements associated with each type. Test your knowledge on the specifics of each joint category.