The Skeletal System - Lecture Flashcards

A focused set of flashcards covering key concepts from the skeletal system lecture notes. Each card presents a question (term) and its answer (definition).

What tissues combine to form a bone?

Osseous (bone) tissue, cartilage, dense connective tissue, epithelium, adipose tissue, and nervous tissue.

When is the fetal skeleton first completely formed as cartilage, and what begins afterward?

At about three months of gestation; ossification and growth begin afterward.

At what ages does longitudinal growth end for girls and boys, and by what age does bone maturation typically finish?

Longitudinal growth ends at about 15 years for girls and 16 years for boys; bone maturation completes around age 21.

What are the four primary roles of the skeletal system in maintaining homeostasis?

Support, protection, blood cell production, and storage of minerals (plus triglyceride storage).

What structures connect bones to bones, muscles to bones, and cover bone ends?

Cartilage covers the ends of bones at joints; ligaments connect bones to bones; tendons connect muscles to bones.

What are the two subdivisions of the adult skeleton and the total number of bones?

Axial skeleton (80 bones) and Appendicular skeleton (126 bones); total 206 bones.

What are the three types of skeletal cartilage and a key feature of each?

Hyaline cartilage (most abundant; fine collagen fibers); Elastic cartilage (more elastic fibers, bends easily); Fibrocartilage (highly compressible and very strong).

Where are cartilage remnants typically found in the adult skeleton?

In regions requiring flexibility, such as joints, intervertebral discs, nose, trachea, and parts of the rib cage.

What are the four bone cell types and their primary roles?

Osteoprogenitor cells (osteogenic) – origin; Osteoblasts – bone formation; Osteocytes – mature bone cells; Osteoclasts – bone resorption.

Which minerals and vitamins are crucial for bone growth and remodeling, and what do they do?

Minerals: calcium, phosphorus, magnesium, fluoride, manganese. Vitamins: A (osteoblast activity), C (collagen synthesis), D (calcium absorption), K and B12 (bone protein synthesis).

Which hormones influence bone growth and calcium homeostasis?

Insulin-like growth factors (IGFs); Calcitonin; Parathyroid hormone (PTH); Thyroid hormones (T3/T4); Insulin; Estrogens and Androgens.

What is the epiphyseal plate and what happens when growth stops?

A hyaline cartilage growth plate that enables lengthwise bone growth; after growth stops it becomes the epiphyseal line.

What is the medullary (marrow) cavity, and what marrow does it contain in adults vs infants?

A cavity inside the shaft (and in epiphyses) that contains yellow marrow in adults and red marrow in infants.

What is the periosteum and what is its function?

The outer fibrous membrane covering the diaphysis; Sharpey’s fibers anchor it to bone; arteries in the periosteum nourish bone cells.

What is articular cartilage and its function?

Hyaline cartilage covering the ends of long bones at joints; provides a smooth, friction-reducing surface.

What are the main parts of a long bone anatomy (diaphysis, epiphysis, periosteum, medullary cavity)?

Diaphysis – the central shaft made of compact bone; Epiphysis – ends with a thin layer enclosing spongy bone; Periosteum – outer covering of the diaphysis; Medullary cavity – hollow interior with marrow.

What are the two main bone tissue types?

Compact bone (dense, smooth, homogeneous) and spongy bone (trabeculae with open spaces).

What are the four bone shapes and provide an example for each?

Long bones (e.g., femur, humerus); Short bones (carpals, tarsals); Flat bones (skull, sternum, ribs); Irregular bones (vertebrae, hip bones).

In a flat bone, what is the diploë?

The spongy bone layer sandwiched between two thin layers of compact bone.

Describe an osteon (Haversian system) and its components.

A cylindrical unit with a central (Haversian) canal, concentric lamellae, and osteocytes in Lacunae connected by canaliculi.

What are Sharpey’s fibers?

Perforating fibers that secure the periosteum to the underlying bone.

What happens to the growth plates during puberty?

Hormones inhibit long bone growth, leading to closure of the epiphyseal plates.

Where is red marrow located in adults, and where is it most commonly found?

Red marrow is confined mainly to the central axis of the body and the most proximal epiphyses of the limbs.

What are the major components of the axial skeleton?

Skull (cranium and facial bones), vertebral column, and thoracic cage (sternum and ribs).

What bones make up the pectoral (shoulder) girdle?

Clavicle (collarbone) and scapula (shoulder blade).

What bones form the upper limb?

Humerus; ulna; radius; carpals; metacarpals; phalanges.

What bones form the pelvic girdle?

Two coxal (ossa coxae) bones: ilium, ischium, and pubis.

What bones form the lower limb?

Femur; patella; tibia; fibula; tarsals; metatarsals; phalanges.

What are the arches of the foot and their components?

Medial longitudinal arch (calcaneus, talus, navicular, three cuneiforms, three medial metatarsals); Lateral longitudinal arch (calcaneus, cuboid, two lateral metatarsals); Transverse arch (across base of metatarsals).

What are the six types of synovial joints?

Plane, hinge, pivot, condyloid, saddle, ball-and-socket.

What structures are associated with synovial joints and their function?

Bursae and tendon sheaths cushion; synovial fluid lubricates; joint capsule encloses the joint.