Skeletal system - Joints and Muscle System

Osteology means

Study of bones

Two parts of the skeletal system

Axial and appendicular

Axial skeleton

Skull, spine, ribs, sternum (body’s central axis)

Appendicular skeleton

Limbs

Trabeculae

Spongy bone structures distributing force

Red bone marrow function

Produces red blood cells

Yellow bone marrow

Stores fat, replaces red marrow with age

Periosteum

Nerve-rich outer bone layer

Osteoblasts

Build bone (generate)

Osteoclasts

Break down bone (absorb)

Bone remodeling cycle happens how often?

Every 10 years

Types of bones (4)

Long, short, flat, irregular

Long bones parts

Epiphysis, metaphysis, diaphysis

Short bones characteristics

Equal length, width, and thickness

Flat bones are

Two layers of compact bone with cancellous inside

Irregular bones characteristics

Mixed characteristics (e.g., spine, face)

Diploe

Spongy bone in skull between compact bone

Bone growth ends at… (age)

Around ages 18–25

Sesamoid bones are found…

Found where tendons need a pull (e.g. fingers)

Bone pain in fracture is sensed due to

Due to periosteum and blood vessel damage

Joint definition

Two bones joined by fibrous connective tissue

Sutures

Fibrous joints in skull; fuse by age 6

Syndesmosis

Movable fibrous joint (e.g. forearm)

Gomphosis

Joint between teeth and jaw via periodontal ligament

Are teeth bones?

No; lack periosteum, don't perform bone functions

Sarcoidosis (in anatomy context)

Temporary joint segment

Cartilaginous joints (symphysis)

Some permanent (e.g. vertebral discs)

Synovial joints

Movable joints with synovial fluid (e.g. knee)

Synovial fluid

Provides nutrients and O₂ to avascular cartilage

Arthritis

Inflammation of joint capsule (autoimmune)

Arthrosis

Degeneration of joint structures (non-inflammatory)

Calcification

Adding calcium

Ossification

Turning into bone

Three types of muscle tissue

Skeletal, cardiac, smooth

Skeletal muscle location

Attached to bones

Cardiac muscle location

Heart walls

Smooth muscle location

Hollow organs (intestines, vessels)

Skeletal muscle control

Voluntary

Cardiac muscle control

Involuntary

Smooth muscle control

Involuntary

Muscle fiber (skeletal) shape

Long cylindrical multinucleated fibers

Cardiac muscle shape

Branched cells with 1-2 nuclei

Smooth muscle shape

Spindle-shaped cells with single nucleus

Intercalated discs

Specialized structures that facilitate connections in cardiac muscle cells.

Striated muscles

Skeletal and cardiac

Non-striated muscle

Smooth

Muscle function

Movement, posture, heat production