Chapter 4 – Skeletal System

Question-and-Answer flashcards covering functions, anatomy, joints, bone structure, cell types, common conditions, and movement terminology of the skeletal system.

How many bones are in the adult human skeleton?

206

List the five primary functions of the skeletal system.

Support, Protection, Movement, Blood cell production, Mineral storage

Which part of the skeleton produces blood cells and what type of marrow is involved?

Red marrow in bones of the axial skeleton

What two minerals are principally stored and released by bone?

Calcium and phosphorus

Name the bone that protects the brain.

The skull (cranium)

Which connective tissue attaches muscle to bone?

Tendons

What holds bones together at joints?

Ligaments

What is the medical term for the immovable joints between skull bones?

Sutures

Which suture separates the two parietal bones?

Sagittal suture

What is the common name for the zygomatic bones?

Malars (cheekbones)

Failure of which bones to fuse properly can result in a cleft palate?

Palatine bones

What are fontanelles and when are they present?

Soft fibrous or cartilage joints in an infant’s skull before ossification is complete

How many cervical vertebrae are there and what are the first two called?

Seven; C1 is the Atlas, C2 is the Axis

How many thoracic vertebrae are in the spine?

Twelve

What structure is formed by adjacent vertebral foramina?

The vertebral canal (which houses the spinal cord)

What are intervertebral disks made of and what is their function?

Cartilage; they act as shock absorbers between vertebrae

What happens when an intervertebral disk herniates?

The soft center bulges out, compressing a spinal nerve and causing pain

Name the bones that compose the thoracic cage.

Thoracic vertebrae, sternum, and 12 pairs of ribs

Which bones form the pectoral girdle?

Scapula and clavicle

Which three bones fuse to form a coxal (hip) bone?

Ilium, ischium, and pubis

Why is the female pelvis wider and shallower than the male pelvis?

To accommodate pregnancy and childbirth

Define synarthrosis and give an example.

An immovable joint; example: skull sutures

Define amphiarthrosis and give an example.

A slightly movable joint; example: pubic symphysis

What is another name for a diarthrosis?

Synovial joint

Give two examples of ball-and-socket joints.

Shoulder and hip

Which type of synovial joint is found at the thumb?

Saddle joint

What covers the articulating surfaces of bones in a synovial joint?

Hyaline (articular) cartilage

What structure surrounds a synovial joint and is reinforced by ligaments?

Joint (articular) capsule

What fluid is produced by the membrane lining a joint capsule and what is its function?

Synovial fluid; reduces friction and absorbs shock

What are bursae and what do they do?

Fluid-filled sacs between bone and soft tissues that cushion movement

What happens in rheumatoid arthritis?

The synovial membrane becomes inflamed and thickens

What is the periosteum?

Connective tissue covering each bone; inner layer contains bone-forming cells

Define diaphysis.

The main shaft of a long bone

What is an epiphysis?

The expanded end of a long bone

Where are growth plates (metaphyses) located in children?

Between the diaphysis and each epiphysis

What are osteons (Haversian systems)?

Spindle-shaped structural units of compact bone

Which cells build new bone tissue?

Osteoblasts

Which large cells break down bone matrix?

Osteoclasts

Where are mature bone cells (osteocytes) located?

In lacunae within osteons

What canals carry blood vessels through compact bone?

Haversian canals

Define spongy (cancellous) bone and state where it is commonly found.

Porous bone with trabeculae; found primarily in epiphyses

What type of marrow stores fat and where is it found?

Yellow marrow; in the medullary (marrow) cavity

Differentiate endochondral and intramembranous ossification.

Endochondral: bone develops from cartilage (long bones); Intramembranous: bone develops from connective tissue without cartilage model (flat bones)

What is osteoporosis?

Condition in which bone is broken down faster than it is produced, leading to loss of bone mass

Contrast simple and compound fractures.

Simple: bone does not pierce skin; Compound: bone breaks through skin

What movement term describes decreasing the angle of a joint?

Flexion

What movement term describes increasing the angle of a joint?

Extension

Define abduction.

Movement of a limb away from the midline

Define adduction.

Movement of a limb toward the midline

What is circumduction?

Circular, cone-shaped movement of a limb

Define rotation in joint movement.

Bone turns around its own longitudinal axis

What is pronation of the forearm?

Turning the palm downward or posteriorly

What is supination of the forearm?

Turning the palm upward or anteriorly

Which bones make up the upper limb from proximal to distal?

Humerus, ulna, radius, carpals, metacarpals, phalanges

Name the long bone of the thigh.

Femur

Which small sesamoid bone protects the knee joint?

Patella

List the bones of the lower leg.

Tibia and fibula

What joint connects the two pubic bones anteriorly?

Pubic symphysis

What are transverse processes and where are they located?

Lateral projections on a vertebra for muscle and rib attachment