Bone Development and Fractures Quiz

Bone Development

• Infant skeletons are mostly cartilage, a strong and flexible tissue.
• Cartilage is gradually replaced by solid bone, usually completed by the end of growth.
• Not all cartilage is replaced in adults; joints retain cartilage to protect bone ends.

Bone Formation, Growth, and Remodelling

• Bone formation occurs through a process called ossification, on hyaline cartilage models or fibrous membranes.
• Osteogenic cells (osteoprogenitor cells) are mitotically active stem cells found in the periosteum and endosteum.
• Osteoblasts are bone-forming cells that synthesize the matrix.

Bone Fracture

• Fracture: break in a bone.
• Fracture types:
  • Closed (simple): break does not penetrate the skin.
  • Open (compound): broken bone penetrates the skin.
• Fractures are treated by reduction and immobilization.
  • Closed reduction: bones are manually repositioned.
  • Open reduction: bones are secured with pins or wires during surgery.

Bone Strength

• Bone structure makes it both strong and lightweight.
• Bones make up 20% of an adult's weight.
• Bones are composed of two minerals:
  • Calcium
  • Phosphorus

Anatomy of a Long Bone

• Diaphysis: makes up most of the bone length, composed of compact bone.
• Epiphysis (ends: proximal and distal): mostly composed of spongy bone enclosed by a thin layer of compact bone.
• Articular cartilage: covers the external surface of epiphyses, made up of hyaline cartilage, decreases friction at joint surfaces.
• Periosteum: outside covering of the diaphysis, fibrous connective tissue membrane.
• Epiphyseal line: remnant of the epiphyseal plate, seen in adult bones.
• Epiphyseal plate: flat plate of hyaline cartilage found in young, growing bones, causes lengthwise growth of long bones.
• Endosteum: lines the inner surface of the shaft, made of connective tissues.
• Medullary cavity: cavity inside the shaft, contains yellow marrow (fats).
• Red marrow: found in the medullary cavity of infants until age 6 or 7, responsible for blood cell formation.

Central (Haversian) Canal

• Opening in the center of an osteon.
• Carries blood vessels and nerves.

Osteon (Haversian System)

• Contains the central canal and matrix rings.
• Structural and functional unit of compact bone.

Canaliculi

• Tiny canals that form a transport system connecting all bone cells to a nutrient supply.

Perforating (Volkmann’s) Canal

• Canal perpendicular to the central canal.
• Carries blood vessels and nerves

Developmental Aspects of the Skeleton

• Fetal skull:
  • Fontanels are fibrous membranes connecting cranial bones, known as "soft spots".
  • Allow skull compression during birth and brain growth during pregnancy and infancy.
  • Usually ossify by 2 years of age.

Skull

• Paranasal sinuses: hollow portions surround the nasal cavity, lighten the skull and amplify sounds.
• Hyoid bone: the only bone that doesn't articulate with another bone, serves as a movable base for the tongue, aids in swallowing and speech.

Vertebral Column (Spine)

• Provides axial support, extending from the skull to the pelvis.
• 26 vertebral bones separated by intervertebral discs.
• 7 cervical vertebrae in the neck.
• 12 thoracic vertebrae in the chest region.
• 5 lumbar vertebrae associated with the lower back.
• Sacrum: formed by the fusion of 5 vertebrae.
• Coccyx: formed by the fusion of 3-5 vertebrae.

Bony Thorax (Thoracic Cage)

• Protects the organs of the thoracic cavity.
• Consists of three parts:
  • Sternum
  • Ribs:
    • True ribs (pairs 1–7)
    • False ribs (pairs 8- 12)
    • Floating ribs (pairs 11–12)
  • Thoracic vertebrae (T1 – T12)

Primary Curvatures

• Spinal curvatures of the thoracic and sacral regions.
• Present from birth.
• C-shaped curvatures (newborn).

Secondary Curvature

• Spinal curvatures of the cervical and lumbar regions.
• Develop after birth.
• S-shaped (adults)

Parts of a Typical Vertebra

• Body (centrum)
• Vertebral arch
• Pedicle
• Lamina
• Vertebral foramen
• Transverse processes
• Spinous process
• Superior and inferior articular processes

Appendicular Skeleton

• Composed of 126 bones:
  • Limbs (appendages)
  • Pectoral girdle
  • Pelvic girdle

Bones of the Shoulder Girdle (Pectoral Girdle)

• Composed of two bones that attach the upper limb to the axial skeleton:
  • Clavicle
  • Scapula

Bones of the Upper Limbs

• Humerus: upper limb
• Ulna: forearm
• Radius: forearm
• Carpals: wrist
• Metacarpals: hand
• Hand:
  • Carpals: wrist - 8 bones arranged in two rows of 4 bones in each hand.
  • Metacarpals: palm bones - 5 per hand.
  • Phalanges: fingers and thumb - 14 phalanges in each hand, each finger has 3 bones except for thumb which has 2 bones.

Bones of the Pelvic Girdle

• Where the lower limbs attach to the body.
• Composed of three pairs fused bones:
  • Ilium
  • Ischium
  • Pubis
• Pelvic girdle = two coxal bones, sacrum.
• Pelvis = two coxal bones, sacrum, coccyx.

Bones of the Lower Limbs

• Femur: thigh bone - the heaviest and strongest bone in the body.
• Patella: kneecap.
• Tibia: large lower leg.
• Fibula: small lower leg.

Bones of the Foot

• Tarsals: 7 bones - two largest tarsals: Calcaneus and Talus.
• Metatarsals: 5 bones from the sole of the foot.
• Phalanges: 14 bones from the toes.

Joints

• Types of synovial joints based on shape:
  • Plane joint
  • Hinge joint
  • Pivot joint
  • Condylar joint
  • Saddle joint
  • Ball-and-socket joint

Movements at Synovial Joints

• Flexion and Extension:

  • Flexion: reduces the angle of the joint from resting position.
  • Extension: returns joint to resting position.
  • Hyperextension: increases joint angle beyond 180 degrees.
  • Lateral flexion: bending of neck or body toward left or right side.

• Abduction, Adduction, and Circumduction:

  • Abduction: moves a limb, finger, toe, or thumb away from the midline of the body.
  • Adduction: moves a limb, finger, toe, or thumb toward the midline of the body.
  • Circumduction: movement in a circular motion, involves a combination of flexion, adduction, extension, and abduction at a joint.

• Rotation:

  • Rotation: twisting movement.
  • Medial rotation: moves anterior of a limb toward midline.
  • Lateral rotation: moves anterior of a limb away from midline.

• Supination and Pronation:

  • Movements of the forearm.
  • Supination: moves palm toward facing posteriorly.
  • Pronation: moves palm toward facing anteriorly.

• Dorsiflexion and Plantar Flexion:

  • Movements of the ankle joint.
  • Dorsiflexion: moves top of foot toward anterior leg.
  • Plantar flexion: lifts heel away from ground or points toes toward ground.

• Inversion and Eversion:

  • Movements of the foot.
  • Inversion: turns bottom of foot toward midline.
  • Eversion: turns bottom of foot away from midline.

• Protraction and Retraction:

  • Mandible:
    • Protraction: jaw is pushed forward.
    • Retraction: returns jaw to resting position.
  • Scapula:
    • Protraction: shoulder moves forward.
    • Retraction: scapula pulled posteriorly and medially.

• Opposition and Reposition:

  • Opposition: moves tip of thumb in contact with a finger.
  • Reposition: returns thumb to its anatomical position.

Test your knowledge on the process of bone development, growth, and the different types of bone fractures. This quiz covers key concepts related to cartilage, ossification, and fracture treatment methods. Essential for students of anatomy and physiology.