The Skeletal System: Bone Structure chp 6 AND 9 JOINTS add more bone stuff

Comprehensive vocabulary flashcards covering the axial skeleton, skull markings, vertebral regions, bone tissue histology, ossification, calcium regulation, and fractures.

Sutural Bones (Wormian Bones)

Small, flat, oddly shaped bones with jigsaw puzzle-like borders found embedded along sutures between the flat bones of the skull.

Interstitial growth

– growth in length

Bone growth

Bone development begins six weeks after fertilization

Bone growth stops around age 25

•Parathyroid hormone (P T H)

–Increases blood calcium ion levels by

▪Stimulating osteoclast activity to promote bone resorption and release of calcium

▪Increasing intestinal absorption of calcium by enhancing calcitriol secretion by the kidneys

Decreasing calcium excretion by the kidneys

Osteopenia

– inadequate ossification (reduction of bone mass)

Begins between ages 30 and 40

Osteoporosis

•– loss of bone mass sufficient to compromise normal bone function

–Bones become brittle and fragile

–In women, —- accelerates after menopause

sequence of endochondral ossification

Step 1+ cartilage model

At the primary ossification center at center of shaft, chondrocytes increase in size

The reduced matrix begins to calcify

Chondrocytes die

Step 2

Blood vessels grow around the cartilage

Cells from the perichondrium (membrane of cartilage) differentiate into osteoblasts

Shaft become ensheathed in bone-this area is called bone collar

Step 3 +spongy bone formation in the center

Blood vessels enter the primary ossification center

Fibroblasts migrate in, differentiate into osteoblasts, and start producing spongy bone

Both formation spreads from center toward both ends

Step 4 +remodel

The spongy bone in the center of shaft remodels and a marrow cavity opens +just below the bone collar, compact bone forms

Step 5

Blood vessels and osteoblasts migrate into the epiphyses to create secondary ossification centers

Step 6

Epiphyses become filled with spongy bone

Epiphyseal cartilage (epiphyseal plate) in the metaphysis separates diaphysis from epiphyses

Ossification continues on diaphyseal side, while new cartilage is produced on epiphyseal side

Step 7

At puberty, rate of ossification becomes faster than rate of cartilage production

Epiphyseal closure – epiphyseal cartilage(in the metaphysis) become narrower and ultimately disappears(as it gets replaced by bone

An epiphyseal line remains after epiphyseal growth has ended

concentric lamellae

form osteons (central canal)

Interstitial lamellae

fill the spaces between osteons

Circumferential lamellae

are at outer and inner bone surfaces

Spongy bone structure

• No osteons +no central cannal

• Matrix arranged as a network of trabeculae

• No blood vessels in matrix, but plenty of blood vessels run right through the open spaces

• Supports and protects red bone marrow

• Produces blood cells

• Some —- bone contains yellow bone marrow

• Stores fat

•Bone matrix +minerals and organic matter

Two thirds of the matrix is made of calcium phosphate

One third is made of collagen fiber; strong flexible

-found as hydroxyapatite crystals, which resist compression

-▪A bone lacking a calcified matrix looks normal, but is very flexible

irregular bones

▪Have complex shapes

▪Examples: spinal vertebrae, pelvic bones

•Structure of a flat bone

–Consist of core of spongy bone between two layers of compact bone (cortex)

CHARACTERISTICS of bone

–Dense matrix made of protein fibers and deposits of calcium salts

Within the cranium, the core of spongy bone is called

diploe

Short bones

Boxy

Examples: carpal bones and tarsal bones

Flat bones

▪Thin with parallel surfaces

▪Examples: bones of skull roof, sternum, ribs, and scapulae

–Long bones

▪Long and slender

▪Found in arms, legs, palms, soles, fingers, toes

–Sesamoid bones

▪Small, round, and flat

▪Found within tendons near joints of knees, hands, and feet

Major functions of the skeletal system:

Structural support for body

Storage of minerals and lipids

Blood cell production

Protection of soft tissues and organs

Leverage for movement

Fibrous

– held together by dense —connective tissue or a — ligament

Suture

joint between the bones of the skull

Gomphosis

joint between a tooth and its bony socket

Syndesmosis

bones connected by a ligament

Example: distal joint between tibia and fibula

Cartilaginous

held together by cartilage

Synchondrosis

– rigid cartilaginous connection between two bones

ie: vertebrosternal joint of the first rib

Symphysis

– bones connected by a pad of fibrocartilage

Example: pubic symphysis

Bony

rigid ossified joint

Synostosis

two bones fuse and the boundary between them disappears

Synovial

enclosed by a capsule filled with synovial fluid

Example: knee

Synarthrosis

– immovable joint

Examples: suture, gomphosis, synostosis, synchondrosis

Amphiarthrosis

– slightly movable joint

Examples: syndesmosis, symphysis

Diarthrosis

– freely movable joint

All synovial joints

Synovial joints (diarthroses

–Surrounded by joint capsule (articular capsule) continuous with periosteum

Contains inner —- membrane and outer fibrous capsule

fluid from the synovial membrane fills the joint cavity

Articular cartilage

covers articulating surfaces and prevents direct contact between bones

Synovial fluid

Resembles interstitial fluid, but contains proteoglycans with a high concentration of hyaluronan

functions:

▪Lubrication between articulating surfaces

Nutrient distribution for chondrocytes in articular

Meniscus

fibrocartilage pad between opposing bones

Fat pads

– localized masses of adipose tissue covered by synovial membrane

Ligaments

support and strengthen joints

Extracapsular outside the joint and intracapsular inside the joint

Tendons

– attach muscles to and stabilize the joint

Bursae

small pockets filled with synovial fluid

Bursitis

– inflammation due to repetitive motion, pressure, infection or trauma that results in swollen bursae with excess synovial fluid

Gliding movement

when two flat surfaces slide past each other

Angular movements

change an angle

Flexion

– decreases the angle between articulating bones in the anterior-posterior plane

Extension

increases angle between articulating bones in the anterior–posterior plane

Hyperextension

extension past the normal anatomical limit

Abduction

movement away from longitudinal axis of the body in the frontal plane

Adduction

movement toward the longitudinal axis of the body in the frontal plane

Circumduction

a complete circular movement without rotation

Rotational movement (twist)

Rotation in reference to anatomical position

–Example: left or right rotation of head

Medial rotation

– internal rotation toward longitudinal axis of the trunk

Lateral rotation

external rotation away from the longitudinal axis of the trunk

Pronation

palm faced posteriorly

rotates forearm so that radius rolls across ulna and

Supination

palm turns anteriorly

Special movements

movements at specific joints

Inversion

– twists the sole of the foot medially

Eversion

– twists the sole of the foot laterally

Dorsiflexion

– flexion at the ankle (lifting toes

Plantar flexion

extension at the ankle (pointing toes)

Opposition

movement of the thumb toward palm or other fingers

Reposition

– returns thumb and fingers from opposition

Protraction

movement of a body part anteriorly in the horizontal plane (forward)

ie: mandible

Retraction

opposite of protraction (pulling back

ie: mandible

Depression

moving a structure inferiorly (down)

Elevation

moving a structure superiorly (up)

Lateral flexion

bending the vertebral column to the side

Plane joint

gliding joint) – flattened or slightly curved surfaces that slide against one another

Hinge joint

– permits angular motion in a single plane (monaxial, angular

Condylar joint

oval articular face nested within a depression on the opposite surface

Saddle joint

articular faces fit together like a rider in a saddle

example: first carpometacarpal joint

Pivot joint

– permits rotation: monaxial

▪Examples: atlanto-axial joint

Ball-and-socket joint

round head of one bone fits in a cup-shaped depression in another

Examples: shoulder and hip joints

Intervertebral joints

joints between adjacent vertebral bodies and adjacent vertebral articular processes

–Adjacent vertebral bodies are connected by symphyses (Intervertebral disc)

–The first two cervical vertebrae are joined by a pivot diarthrosis synovial joint (atlanto-axial joint)

Anulus fibrosus

tough outer layer of fibrocartilage that attaches the disc to the vertebrae

Nucleus pulposus

– soft, elastic, gelatinous core that works as a shock absorber

Bulging disc

– bulge in the anulus fibrosus invades the vertebral canal

Herniated disc

– the nucleus pulposus breaks through the anulus fibrosus and compresses spinal nerves

Posterior longitudinal ligament

connects the posterior surfaces of vertebral bodies

Anterior longitudinal ligament

– connects the anterior surfaces of vertebral bodies

Flexion

– bend anteriorly

Extension

bend posteriorly

Lateral flexion

–– bend laterally

Joints (articulations)

where two bones connect

Allow for movement to occurs

Sesamoid Bones

Small, round, and flat bones that develop within tendons near joints of the knees, hands, and feet, universally exemplified by the patellae.

Diaphysis

The center extended, tubular shaft of a long bone with walls of compact bone surrounding a hollow medullary cavity.

Arthritis

– joint inflammation

Hip joint

strong ball-and-socket diarthrosis between the head of the femur and the acetabulum of the hip bone

Shoulder joint

– ball-and-socket diarthrosis between the head of the humerus and the glenoid cavity of the scapula

Greatest range of motion of any joint

Gouty arthritis

crystals of uric acid form within synovial fluid

Epiphysis

The expanded articular end of a long bone consisting primarily of spongy bone surrounded by a thin layer of compact bone.

Metaphysis

The narrow region of a mature long bone that connects the diaphysis with the adjacent epiphysis.

Hydroxyapatite

Hard, brittle mineral crystals with the formula $Ca_{10}(PO_4)_6(OH)_2$ formed from calcium phosphate, comprising roughly two-thirds of the bone matrix to resist compression.

Osteoid

The organic components of the bone matrix secreted by osteoblasts before it undergoes calcification.

Osteogenic Cells (Osteoprogenitor Cells)

Mesenchymal stem cells

- located in the inner cellular layers of the periosteum and endosteum -

-divide to produce daughter cells differentiating into osteoblasts.

imporant for fracture repair

Osteoblasts

Immature bone cells responsible for osteogenesis

(the production of new bone matrix) by secreting osteoid

and promoting calcium salt deposition.

surrounded by bone matrix, osteoblasts become osteocytes

Osteocytes

• Mature, non-dividing bone cells in lacunae

• have cytoplasmic extensions that pass

• maintain the matrix

Osteoclasts

Large, multinucleated cells remove bone matrix in a process called osteolysis

secrete acids and protein digesting enzymes dissolve bone matrix and release stored minerals(such as Calcium)

monocytes fused to make oestoclasts