Bone Physiology and Articulations

What bones does the shoulder joint connect?

The humerus and scapula.

What is the normal ROM for wrist flexion?

70-90 degrees.

What is the normal ROM for wrist extension?

65-80 degrees.

What are degrees of freedom (DOF)?

The number of axes at which movement occurs in a joint.

How many degrees of freedom does the wrist have?

2; the wrist is biaxial.

What are the 3 structural joint categories?

Fibrous, cartilaginous, and synovial.

What are the 3 functional joint categories?

Synarthrosis, amphiarthrosis, and diarthrosis.

What is a synarthrosis?

An immovable joint.

What is an amphiarthrosis?

A slightly movable joint.

What is a diarthrosis?

A freely movable joint.

In what plane do flexion and extension occur?

Sagittal plane.

What is flexion?

Bending a joint and decreasing the angle between bones.

What is extension?

Straightening a joint and increasing the angle between bones.

What are the special terms for ankle flexion and extension?

Dorsiflexion and plantarflexion.

In what plane do abduction and adduction occur?

Frontal plane.

What planes are involved in circumduction?

Sagittal and frontal planes.

What is rotation?

Movement around the longitudinal axis of the moving segment.

Where can rotation occur?

Head/neck, intervertebral joints, and ball-and-socket joints.

What are pronation and supination?

Specialized rotation at the proximal and distal radioulnar joints.

What are inversion and eversion?

Inversion: Turns the sole of the foot inward

eversion: turns the sole of the foot outward

What is opposition?

Thumb movement to touch any finger in a pincer grasp.

What do sutures connect?

Bones of the skull.

What functional type are sutures?

Synarthroses; they are immovable.

What are fontanels?

Incompletely ossified areas in fetal and infant skulls.

What connects bones in a syndesmosis?

An interosseous ligament.

How much movement does a syndesmosis allow?

A slight shift or 'give' movement.

What is an example of a syndesmosis?

The distal tibiofibular articulation.

What connects bones in a synchondrosis?

Hyaline cartilage.

How movable is a synchondrosis?

Immovable.

What is an example of a synchondrosis?

An epiphyseal plate.

What connects bones in a symphysis?

Fibrocartilage discs.

How movable is a symphysis?

Slightly movable.

What are examples of symphyses?

Pubic symphysis and joints connecting vertebral bodies.

What characterizes a synovial joint?

A joint cavity containing synovial fluid.

How movable are synovial joints?

Freely movable.

Where are synovial joints especially common?

They are the most common joints in the appendicular skeleton.

What are the main shared structures of a synovial joint?

Joint capsule, synovial membrane/fluid, articular cartilage, ligament, and periosteum.

What are the 3 functions of synovial fluid?

Cushion, lubricate, and nourish.

What is a bursa?

A 'pillow' filled with synovial fluid.

What is a tendon sheath?

A 'sleeve' filled with synovial fluid.

How many axes do uniaxial joints have?

1 axis of rotation.

How many movement planes/pairs do uniaxial joints have?

1 plane of movement and 1 movement pair.

What movement pair occurs at a hinge joint?

Flexion and extension.

What shape relationship describes a hinge joint?

A concave surface articulates with a convex surface.

What movement occurs at a pivot joint?

Rotation.

How is a pivot joint structured?

A cylinder rotates within a ring of bone or ligament.

What is an example of a hinge joint?

The elbow.

What is an example of a pivot joint?

The atlantoaxial joint.

How many axes do biaxial joints have?

2 axes of rotation.

What movement pairs occur at biaxial joints?

Flexion/extension and abduction/adduction.

What additional movement can biaxial joints perform?

Circumduction.

How is a condyloid joint shaped?

An ovoid process articulates with a shallow cavity.

What is an example of a condyloid joint?

The wrist.

What is an example of a saddle joint?

The first carpometacarpal joint.

How many axes do triaxial joints have?

3 axes of rotation.

What movements occur at triaxial joints?

Flexion/extension, abduction/adduction, medial/lateral rotation, and circumduction.

How is a ball-and-socket joint shaped?

A spherical surface articulates with a cup-shaped socket.

What is an example of a ball-and-socket joint?

The shoulder.

What are nonaxial gliding joints?

Joints with no identifiable axis of rotation and slight gliding movement.

What surfaces form a gliding joint?

Flat or nearly flat articular surfaces.

What is an example of a gliding joint?

A sternocostal joint.

What are the 5 functions of bone/skeleton?

Support, protection, movement/lever system, Ca and P storage, and hematopoiesis.

What are the 5 classes of bone?

Long, short, flat, irregular, and sesamoid.

What is found in the marrow cavity?

Red marrow (active) or yellow marrow (inactive).

What two bone tissues make up a long bone?

Compact bone and spongy bone.

What are the two major bone coverings/linings?

Periosteum and endosteum.

What structures are associated with growth at the ends of long bones?

The epiphyseal plate and epiphyseal line.

What is another name for the epiphyseal plate?

Growth plate.

What type of cartilage is articular cartilage?

Hyaline cartilage.

Is bone well vascularized?

Yes; bone is very vascularized.

Through what canals do blood vessels enter compact bone?

Volkmann's (perforating) canals.

What are the two types of bone formation (ossification)?

Intramembranous and endochondral ossification.

What forms the early fetal skeleton?

Mesenchyme/connective tissue membranes and hyaline cartilage.

What does intramembranous ossification form bone from?

Mesenchyme.

Which bones are formed by intramembranous ossification?

Membrane bones of skull, clavicle, mandible, and portions of other bones such as scapula.

What are fontanelles in bone formation?

Large areas of dense connective tissue.

What is the function of fontanelles?

They provide flexibility during birth and growth.

What happens during endochondral ossification?

Bone replaces hyaline cartilage.

What does endochondral ossification form?

Most bones of the body.

What allows a long bone to keep increasing in length?

Hyaline cartilage remaining at the epiphyseal plate.

Where does cartilage proliferate during long bone growth?

On the epiphyseal side of the epiphyseal plate.

Where does ossification occur during long bone growth?

On the diaphyseal side of the epiphyseal plate.

When does growth in length stop?

When chondrocytes stop proliferating and the growth plate ossifies.

What is appositional growth?

An increase in bone width.

How does appositional growth increase bone width?

By adding layers while remodeling the marrow cavity.

What strengthens long bone during appositional growth?

Layers of circumferential lamellae thicken compact bone.

Can appositional growth occur in adults?

Yes.

What causes bone remodeling?

Changes in demand, force, or load on bones.

What are examples of conditions that alter bone remodeling?

Weight training and prolonged bed rest.

What is Wolff's Law?

Bones remodel in response to compressive force.

What does PTH do to blood calcium?

Raises blood calcium by stimulating osteoclasts.

What does calcitonin do to bone cells?

Inhibits osteoclasts and stimulates osteoblasts.

What happens to the inorganic/organic matrix ratio in osteoporosis?

It remains normal.

What happens to overall bone density in osteoporosis?

It decreases.

What type of fractures can osteoporosis cause in vertebrae?

Compression fractures, which can cause kyphosis.

What are the stages of bone repair?

Fracture, hematoma, soft callus, bony callus, remodeling.