NOTES part 5 : Joints and Types of Movements (Ch 7)

*Joints are functional junctions between bones.

Functions of Joints They hold the skeletal bones together Allow the rigid skeleton some flexibility so that gross movements can occur.

TYPES OF JOINTS Joints are classified by structure & by function Functional classification is based on the amount of movement allowed at the joint Synarthroses Amphiarthroses Diarthroses Structural classification focuses on the material binding the bones together Fibrous Cartilaginous Synovial

FUNCTIONAL TYPES OF JOINTS Synarthroses: immovable joints Amphiarthroses: slightly movable Diarthroses: freely movable

STRUCTURAL TYPES OF JOINTS **These joints can be classified according to the type of tissue that binds the bones together.**

 FIBROUS JOINTS (Synarthroses): • Bones at fibrous joints are tightly joined by a layer of dense connective tissue. •Little or no movement occurs at a fibrous joint • Example: the sutures between the flat bones of the skull synarthroses!

3 types of fibrous joints 1) Syndesmoses- fibrous bands connect 2 bones (radius and ulna) 2) Sutures- teethlike projections from adjacent bones fit together with a thin layer of fibrous tissue between them. Becomes fully ossified in older adults only found in the skull 3) Gomphoses- joint that occurs between the root of a tooth and the alveolar process Periodontal membrane- fibrous tissue between tooth’s root and alveolar process

FYI

 CARTILAGINOUS JOINTS (Amphiarthroses): • A layer of hyaline cartilage, or fibrocartilage, joins bones of cartilaginous joints • Allow limited movement • Example: the joints that separate the vertebrae amphiarthroses!

2 types of cartilaginous joints 1) Synchondroses- have hyaline cartilage between the articulating bones Articulation between first rib and sternum Epiphyseal plate present during growth 2) Sympheses- fibrocartilage disks between articulating bones Fibrocartilage disk will only allow slight movement when pressure is applied to bones Found in vertebral column and symphysis pubis

 SYNOVIAL JOINTS: • Most joints in the body are synovial joints • Allow free movement Synovial joints have 7 characteristic structures • Bones at synovial joints are covered with hyaline cartilage (“articular cartilage”) and held together by a fibrous JOINT CAPSULE. diarthroses!

 SYNOVIAL JOINTS: • The joint capsule consists of an outer layer of ligaments and an inner lining of synovial membrane (which secretes synovial fluid to lubricate the joint). • Some synovial joints have flattened, shock-absorbing pads of fibrocartilage called MENISCI between the articulating surfaces of the bones

 SYNOVIAL JOINTS: • Some synovial joints may also have BURSAE, which are fluid-filled sacs located between the skin and the underlying bony prominences. • Example: at the knee joint, the patella is sandwiched between 2 bursae.

 SYNOVIAL JOINTS: Most synovial joints also have ligaments, which are strong cords of dense, white fibrous connective tissue which grow between bones and bind them together (makes the joint more stable than with a joint capsule alone) Ex. Knee joint Anterior Cruciate Ligament (ACL) - attaches anterior part of tibia to posterior part of lateral condyle of the femur Posterior Cruciate Ligament (PCL) - attaches posterior part of tibia and lateral meniscus to the femur’s medial condyle Medial Collateral Ligament (MCL)- located on the medial side of the knee Lateral Collateral Ligament (LCL)- located on the lateral side of the knee

TYPES OF SYNOVIAL JOINTS: • Ball-and-socket: Head of 1 bone articulates with cuplike socket of another (shoulder, hip) • Condyloid (Ellipsoidal): oval articular surface of 1 bone fits into a concavity in another (occipital condyle and atlas) • Gliding: allow only short slipping or gliding movements (carpals, tarsals)

TYPES OF SYNOVIAL JOINTS: • Hinge: cylindrical projection of 1 bone fits into a trough-shaped surface of another (knee, elbow) • Pivot: rounded end of 1 bone protrudes into a ring of bone of another (ex: atlas & dens of axis) • Saddle: resemble condyloid joints but allow greater freedom of movement (thumb)

MOVEMENTS ALLOWED BY SYNOVIAL JOINTS • Muscles fastened on either side of a joint produce movements of synovial joints. • Typically, one end of a muscle is attached to a relatively immovable or fixed part on one side of a joint, and the other end of the muscle is fastened to a movable part on the other side

 SYNOVIAL JOINT MOVEMENTS INCLUDE… • Flexion • Extension • Dorsiflexion • Plantar flexion •Hyperextension

 JOINT MOVEMENTS (cont.) • Abduction • Adduction • Rotation • Circumduction

 JOINT MOVEMENTS (cont.) • Pronation • Supination • Eversion • Inversion

 JOINT MOVEMENTS (cont.) • Retraction • Protraction • Elevation • Depression