Exercise 11 Review Sheet Articulations And Body Movements

Exercise 11 Review Sheet: Articulations and Body Movements

Understanding articulations (joints) and body movements is fundamental to comprehending human anatomy and physiology. This comprehensive review sheet delves into the intricacies of joint classifications, types of movement, and the key anatomical structures involved. We'll explore the different types of fibrous, cartilaginous, and synovial joints, examining their structural features and the range of motion they permit. Furthermore, we'll dissect the various body movements, linking them to specific joint types and providing practical examples. This in-depth guide aims to solidify your understanding of this crucial topic.

I. Classifying Articulations (Joints)

Articulations, or joints, are the points where two or more bones meet. They are classified structurally and functionally, providing a detailed understanding of their capabilities.

A. Structural Classification

Structural classification focuses on the connective tissue binding the bones:

• Fibrous Joints: These joints have bones connected by fibrous connective tissue. There's minimal to no movement (synarthroses or amphiarthroses).

  • Sutures: Found only in the skull, these joints are interlocking, immovable, and highly fibrous. They contribute to the skull's strength and protection. Example: Sagittal suture between parietal bones.
  • Syndesmoses: Bones are connected by a ligament or membrane, allowing slight movement (amphiarthroses). Example: Distal tibiofibular joint.
  • Gomphoses: A peg-in-socket fibrous joint. Example: The articulation between a tooth and its alveolar socket.

• Cartilaginous Joints: These joints have bones connected by cartilage. Movement is limited (amphiarthroses).

  • Synchondroses: Bones are united by hyaline cartilage. They are typically temporary, allowing growth, and eventually ossify. Example: Epiphyseal plates in long bones.
  • Symphyses: Bones are connected by fibrocartilage, providing strength and limited movement. Example: Pubic symphysis.

• Synovial Joints: These joints are characterized by a synovial cavity containing synovial fluid, enabling free movement (diarthroses). They are the most common type of joint in the body. We'll explore these further in the next section.

B. Functional Classification

Functional classification describes the degree of movement at the joint:

• Synarthroses: Immovable joints. Examples include sutures in the skull.
• Amphiarthroses: Slightly movable joints. Examples include intervertebral discs and the pubic symphysis.
• Diarthroses: Freely movable joints. These are all synovial joints.

II. Synovial Joints: A Deeper Dive

Synovial joints are the most complex and freely movable joints. Their key features include:

• Articular Cartilage: Hyaline cartilage covering the articular surfaces of the bones, reducing friction.
• Joint (Synovial) Cavity: A space filled with synovial fluid.
• Articular Capsule: A fibrous capsule enclosing the joint cavity.
• Synovial Fluid: A viscous fluid that lubricates the joint, reducing friction and providing nourishment to the articular cartilage.
• Reinforcing Ligaments: Strengthen the joint and restrict excessive movement.
• Nerves and Blood Vessels: Provide sensation and nourishment.
• Bursae (optional): Fluid-filled sacs that cushion the joint and reduce friction between tendons and bones.
• Tendons sheaths (optional): Elongated bursae that wrap around tendons, reducing friction.

Types of Synovial Joints

Synovial joints are further classified based on their shape and movement:

• Plane (Gliding) Joints: Flat articular surfaces allow for short gliding movements. Example: Intercarpal joints.
• Hinge Joints: Cylindrical projection of one bone fits into a trough-shaped surface on another bone, allowing movement in one plane (flexion and extension). Example: Elbow joint.
• Pivot Joints: A rounded or pointed surface of one bone articulates with a ring formed by another bone and a ligament, allowing rotation. Example: Atlantoaxial joint (between C1 and C2 vertebrae).
• Condyloid (Ellipsoid) Joints: Oval articular surface of one bone fits into a complementary depression of another bone, allowing flexion, extension, abduction, adduction, and circumduction. Example: Metacarpophalangeal joints (knuckles).
• Saddle Joints: Each articular surface has both concave and convex areas, allowing flexion, extension, abduction, adduction, and circumduction. Example: Carpometacarpal joint of the thumb.
• Ball-and-Socket Joints: A spherical head of one bone fits into a cup-like socket of another bone, allowing movement in all three planes (flexion, extension, abduction, adduction, circumduction, and rotation). Example: Shoulder and hip joints.

III. Body Movements

Understanding body movements requires knowledge of anatomical planes and axes:

• Sagittal Plane: Divides the body into left and right halves. Movements in this plane occur around a transverse axis.
• Frontal (Coronal) Plane: Divides the body into anterior and posterior portions. Movements in this plane occur around an anteroposterior axis.
• Transverse Plane: Divides the body into superior and inferior portions. Movements in this plane occur around a longitudinal axis.

Here are the key body movements:

• Flexion: Decreases the angle between bones. Example: Bending the elbow.
• Extension: Increases the angle between bones. Example: Straightening the elbow.
• Hyperextension: Extension beyond the anatomical position. Example: Bending the head back.
• Abduction: Movement away from the midline of the body. Example: Raising the arm to the side.
• Adduction: Movement toward the midline of the body. Example: Lowering the arm to the side.
• Circumduction: A cone-shaped movement involving flexion, extension, abduction, and adduction. Example: Circular movement of the arm.
• Rotation: Movement around a longitudinal axis. Example: Turning the head.
• Supination: Rotating the forearm so the palm faces anteriorly.
• Pronation: Rotating the forearm so the palm faces posteriorly.
• Inversion: Turning the sole of the foot medially.
• Eversion: Turning the sole of the foot laterally.
• Dorsiflexion: Lifting the foot towards the shin (bending the ankle).
• Plantarflexion: Pointing the toes downward (straightening the ankle).
• Protraction: Moving a body part anteriorly. Example: Pushing the jaw forward.
• Retraction: Moving a body part posteriorly. Example: Pulling the jaw backward.
• Elevation: Lifting a body part superiorly. Example: Shrugging the shoulders.
• Depression: Moving a body part inferiorly. Example: Dropping the shoulders.
• Opposition: Touching the thumb to the fingertips.

IV. Clinical Considerations

Understanding joint structure and function is crucial for diagnosing and treating various musculoskeletal conditions. Conditions like osteoarthritis, rheumatoid arthritis, and injuries like sprains and dislocations impact joint mobility and can cause significant pain and disability. Proper diagnosis relies on a thorough understanding of joint anatomy, range of motion, and the specific movements involved.

V. Practical Applications

This knowledge is crucial in various fields:

• Physical Therapy: Physical therapists utilize this understanding to design rehabilitation programs for patients recovering from injuries or surgeries.
• Athletic Training: Athletic trainers assess and treat sports-related injuries involving joints and movements.
• Occupational Therapy: Occupational therapists adapt tasks and environments to suit individual needs based on joint limitations.
• Medical Imaging: Radiologists use their knowledge to interpret images (X-rays, MRI, CT scans) of joints to assess for pathology.

VI. Conclusion

Mastering the concepts of articulations and body movements is a cornerstone of understanding human anatomy and physiology. This review sheet provides a comprehensive overview, enabling you to confidently navigate the intricacies of joint classifications, structural features, types of movement, and their clinical significance. By integrating this knowledge, you can better understand the complex mechanics of the human body and the impact of various conditions and injuries on joint health and function. Remember to consult your textbook and other resources for further in-depth study and clarification. Consistent review and practice will solidify your understanding of this essential topic.