Skeletal System and Bone Biology

Flashcards covering skeletal histology, long bone anatomy, ossification, fracture pathology, joint kinematics, and axial versus appendicular skeletal anatomy.

What is osteology?

The study of bone structure and treatment of bone disorders.

What are the six primary functions of bone tissue?

Support, protection, movement, mineral homeostasis, blood cell production (hemopoiesis) in red marrow, and energy storage.

What are the four general classifications of bones by shape?

Long, short, flat, and irregular bones.

What are common examples of flat bones?

Pelvis, sternum, and ribs.

What are common examples of irregular bones?

Vertebrae, cranial bones, and facial bones.

In long bone anatomy, what is the diaphysis?

The shaft, which is the long, main portion of the bone.

What is the metaphysis of a long bone?

The region where the diaphysis joins the epiphysis (containing the epiphyseal plate).

What are the two layers of the periosteum and their components?

1. Fibrous layer: contains blood vessels and nerves.
2. Osteogenic layer: contains blood vessels and bone cells.

What is the function of the nutrient foramen in a long bone?

A hole in the bone that allows nutrient arteries to enter and supply the diaphysis and metaphysis.

What is the chemical composition of bone matrix?

$25\%$ water, $25\%$ protein fibers, and $50\%$ mineral salts.

What are osteoprogenitor cells and where are they located?

Unspecialized cells that undergo mitosis to become osteoblasts; they are found in the inner portion of the periosteum, the endosteum, and in canals.

What is the function of osteoblasts?

They are bone-forming cells that secrete collagen needed to build bone.

What role do osteoclasts play in bone tissue?

They settle on the bone surface and are responsible for bone resorption, aiding in bone development, growth, and repair.

What is calcification and how does it occur in bone tissue?

The crystallization of mineral salts deposited in the matrix between collagen fibers, leading to the hardening of bone tissue.

Why is collagen essential to the structure of bone?

It acts like reinforcing metal rods in concrete, providing the bone with tensile strength.

What are the structural components of a Haversian system (osteon) in compact bone?

Volkman’s canals, a central Haversian canal, concentric lamellae, osteocytes, and canaliculi.

How does spongy bone differ structurally from compact bone?

Spongy bone lacks true Haversian systems; its lamellae are arranged in an irregular latticework of thin plates called trabeculae, with spaces filled with red marrow.

When does embryonic ossification begin?

During the 6th to 7th week of embryonic life.

What are the two types of ossification?

Intramembranous ossification (within fibrous connective tissue membranes) and endochondral ossification (within a hyaline cartilage model).

What are the four anatomical zones of the epiphyseal plate?

1. Zone of resting cartilage
2. Zone of proliferating cartilage
3. Zone of hypertrophic cartilage
4. Zone of calcified cartilage

What four factors affect bone growth?

Heredity (genetics), nutrition (calcium, vitamin D), hormones (GH, PTH), and exercise (mechanical stress).

What is a comminuted fracture?

A fracture where the bone has splintered at the site of impact.

What is a Colles’ fracture?

A fracture of the distal end of the lateral forearm bone (radius) in which the distal fragment is displaced.

Which type of fracture is depicted in this illustration?

An impacted fracture, where one fragment is firmly driven into the other.

What is a Pott’s fracture?

A fracture of the distal end of the lateral leg bone (fibula).

Which type of fracture is depicted in this diagram?

A greenstick fracture, a partial break where one side bends and the other breaks (seen only in children).

What are the four main steps in the repair of a bone fracture?

1. Formation of a fracture hematoma (6–8 hours after injury)
2. Formation of a fibrocartilaginous procallus
3. Formation of spongy bone trabeculae (bony callus)
4. Remodeling of the callus by osteoclasts and osteoblasts

How does parathyroid hormone (PTH) regulate blood calcium in a negative feedback loop?

When blood calcium drops, PTH is secreted by the parathyroid glands; it stimulates the kidneys to retain calcium in the blood, increasing blood calcium levels.

At what ages does calcium loss typically begin in women and men?

In women it begins after age $30$ (associated with decreased estrogen production), and in men it begins after age $60$.

What are the three functional classes of joints based on movement?

Synarthrosis (immovable), amphiarthrosis (slightly movable), and diarthrosis (freely movable).

What instrument is used to measure range of motion angles at joints?

A goniometer.

What is the difference between flexion and extension?

Flexion is bending that decreases the angle of the joint, whereas extension is unbending that increases the angle.

What is the difference between dorsiflexion and plantar flexion?

Dorsiflexion is bending the foot toward its upper surface; plantar flexion is bending the foot in the direction of the sole.

Which division of the human skeleton is highlighted in blue in this diagram?

The axial skeleton, which comprises bones primarily responsible for protection.

Which division of the human skeleton is highlighted in red in this diagram?

The appendicular skeleton, which consists of the bones required for movement.

What are the four prominent sutures of the human skull?

1. Coronal suture (between frontal and parietal bones)
2. Sagittal suture (between parietal bones)
3. Lambdoidal suture (between parietal and occipital bones)
4. Squamous suture (between parietal and temporal bones)

What are the six cranial bones and their respective counts?

Frontal bone (1), parietal bones (2), temporal bones (2), occipital bone (1), sphenoid bone (1), and ethmoid bone (1).

What passes through the foramen magnum of the occipital bone?

The medulla oblongata, vertebral arteries, and spinal arteries.

Why is the sphenoid bone referred to as the keystone of the cranial floor?

It is located in the middle base of the skull, where it joins and holds together all other cranial bones.

What are the names and quantities of the bones of the face?

Nasal bones (2), maxillae (2), zygomatic bones (2), mandible (1), lacrimal bones (2), palatine bones (2), and vomer (1).

What are the five regions of the vertebral column and the number of bones in each?

Cervical ($7$), thoracic ($12$), lumbar ($5$), sacrum ($1$), and coccyx ($1$).

Which two specialized cervical vertebrae and projection are shown in this diagram?

The atlas (C1 vertebra, which supports the head) and the axis (C2 vertebra) with its dens (odontoid process).

How do true ribs, false ribs, and floating ribs differ?

True ribs (pairs 1–7) connect directly to the sternum; false ribs (the last 5 pairs) do not connect directly; floating ribs (pairs 11 and 12) have no connection to the sternum at all.

What are the three parts of the sternum?

Manubrium, body, and xiphoid process.

What two bones compose the pectoral girdle?

The clavicle (collarbone) and the scapula (shoulder blade).

How do the radius and ulna compare in length?

The ulna is longer than the radius; the radius is shorter than the ulna.

What are the three regions of the hand and the bone counts in each?

Carpals ($8$ wrist bones), metacarpals ($5$ palm bones), and phalanges ($14$ finger bones).

What three fused components make up a hip (coxal) bone?

The ilium (superior, largest), ischium (inferior, posterior), and pubis (inferior, anterior).

What sesamoid bone is shown in this image?

The patella (kneecap), which protects the knee joint.

Which two bones of the foot bear the majority of body weight during walking?

The talus and the calcaneus.