SKELETAL TISSUES AND THE SKELETAL SYSTEM

Chapter 7 /8 pgs. 189- 250

Skeletal Tissue Introduction

Bone and cartilage are a specialized types of connective tissue

Individual Bones are considered separate organs

Articulations (joints) – contact points between bones that make movement possible

Bone Tissue

Two types:

1. Compact Bone – dense and solid in appearance.

2. Cancellous or Spongy Bone – characterized by open space partially filled with needle-like structures

Types of bones (4)

Bones are classified based on shape

1. Long Bones

2. Short Bones

3. Flat Bones

4. Irregular Bones

Long Bones

Characterized by a long longitudinal axis

Uniquely shaped articular (joint) ends

EX: Humerus, femur, tibia

Short Bones

Described as cube or box shaped

About as wide (broad) as they are long

Ex: bones of the wrist and ankle

Flat Bones

Generally broad and thin with flattened and curved surface

Ex: shoulder blades (scapulae), certain skull bones, ribs and breastbone (sternum)

Irregular Bones

Often clustered into groups

Come in various shapes and sizes

Ex: vertebral bones, facial bones, and kneecap (patella)

Part of a long bone

1. Diaphysis – main shaft of the bone. Hollow, cylindrical, and made of compact bone

2. Epiphyses – the ends of a long bone. Bulbous in shape for muscle attachment, made of spongy bone and filled with red marrow.

Epiphyseal Plate – layer of caritlage between diaphysis and epiphyses

Parts of a Long Bone

3. Articular Cartilage – layer of hyaline cartilage that covers the surface of the epiphyses

4. Periosteum- dense white membrane that covers the bone except for the joint surfaces. Contains blood vessels, and bone forming/destroying cells

Parts of a Long Bone

5. Medullary Cavity – hollow space inside of the diaphysis which is filled with fatty yellow marrow

6. Endosteum – thin membrane that lines the medullary cavity

Microscopic Structure of Compact Bone

Compact bone is made of many cylinder-shaped structures called osteons which are made of 4 parts:

Lamellae- cylinder shaped layers of calcified matrix

Lacunae – small spaces containing fluid in which the cell lies imprisoned

Canaliculi – small canals radiating in all directions from the lacunae

Haversian canal – extends lengthwise throughout the center of each osteon, contains blood vessels, lymphatic vessels, and nerves – moves nutrients and oxygen through osteon

Microscopic Structure of Compact Bone

Microscopic Structure of Cancellous *(spongy bone) No osteons in spongy bone

Instead contain trabeculae – needle- like bony spicules

Types of Bone Cells

3 types of cells

1. Osteoblasts – (bone forming cells) small cells that make organic matrix called osteoid. Collagen lies up around the osteiod and serves as a framework for the deposition of calcium

2. Osteoclasts – very large multinucleate cells responsible for the active erosion of bone minerals

3. Osteocytes – mature, non-dividing osteoblasts that have become surrounded by matrix and now lie within the lacunae

Bone Marrow - specialized type of soft tissue that serves as the

site of blood production

Found in the medullary cavities of long bones and in the spaces of some spongy bone

2 types 1. Red Marrow – produces red blood cells

- virtually all of a child bones are filled with red marrow that becomes yellow marrow as the individual ages

- adult bone w/ red marrow – ribs, vertebrae, pelvis, femur, thigh bone

2. yellow marrow – cells have been saturated with fat and are inactive in blood cell production

Functions of Bone

Support – framework of the body, contribute to shape and alignment

Protection – protect structures they enclose like skull - brain, ribs- lungs and heart

Movement – joints constitute levers, muscles are attached to bones; pull on bones producing movement

Mineral Storage – serves as a reservoir for calcium, phosphorus, and other minerals

Hematopoiesis – (blood cell formation) carried out by red marrow

Cartilage

Connective tissue consisting of 3 types: Hyaline, Elastic, Fibrocartilage

Hyaline – most common type of cartilage, glassy in appearance, covers the ends of bone, connects anterior and posterior ribs to the sternum, forms cartilage rings in the trachea, and bronchi of lungs, and the tip of the nose

Cartilage

Elastic – gives form to the external ear, the epiglottis, and the auditory tubes that connect middle ear to the nasal cavity

Fibrocartilage – characterized by small quantities of matrix, very strong and rigid. Found in the pubis, intervertebral disks, and points of attachment of some large tendons to bones

Divisions of the Skeleton

Two Main divisions: Axial and Appendicular Skeleton

Axial – 80 bones that form the upright axis of the body

Appendicular – 126 bones form the appendages

Axial/ Appendicular Skeleton

Axial/ Appendicular Skeleton

Axial

Cranium/Skull (28)

Face (14)

Ear (3)

Hyoid Bone (1)

Spinal Column (26)

Sternum and Ribs (25)

Appendicular

Upper Extremities (64)

Lower Extremities (62)

Skull and Facial Bones

Skull and Facial Bones

Frontal – forehead bone

Parietal – lateral and top of the skull

Mandible – Lower Jaw

Maxilla- Upper Jaw

Temporal – Temple

Occipital – back of the head

Palatine- hard palate ( roof of mouth)

Nasal – Bridge of nose

Lacrimal – tear duct

Vomer – in between nostrils (close to lip)

Ethmoid – extends from the temporal into the eye socket and into the nostrils

Hyoid Bone

Single bone in the neck

U-Shaped just above the larynx

Only bone in the body that does not articulate (connect with any other bone in the body)

Attaches the tongue to the

floor of the mouth

Vertebrae Bones

Spinal column in flexible rather than rigid

Consists of 24 bone plus the sacrum and coccyx

Joints between vertebrae permits forward, backwards, and side to side movement

Separated into segments:

Cervical Vertebrae (7) – make up the neck

Thoracic Vertebrae (12) – make up the chest (thoracic region)

Lumbar Vertebrae (5) – make up the lower back

Sacrum – single bone resulting from 5 fused vertebrae

Coccyx – single bone resulting from 4 fused vertebrae

Vertebrae Bones

Bones of the Rib Cage and sternum

Sternum (breast plate) – middle part of the chest; dagger-shaped bone made of 3 parts:

1. manubrium – upper part

2. body – middle

3. xiphoid process – end

tip

Bones of the Rib Cage and sternum

12 pairs of ribs make up the rib cage First 7 pairs known as true ribs because the

connect to the spine and to the cartilage that attaches to the sternum

Last 5 pairs known as false ribs because the do not attach directly to the sternum. The cartilage of pairs 8,9, and 10 attach to the cartilage of the rib above it

Last 2 pairs of the false ribs are known as floating ribs because they do not attach at all to the sternum, even indirectly

Bones of the Rib Cage

Bones of the upper Extremities

-Upper extremities consist of the shoulder girdle, upper arm, wrist, and hand

2 bones – scapula and clavicle make the shoulder girdle

Bones of the upper Extremities

The humerus is the upper arm bone and the radius (on the thumb side) and ulna (on the little finger side) make up the lower arm

Bones of the upper Extremities

8 carpal bones make up the wrist

5 metacarpal bones make up the hand

Phalanges – bones of the fingers

Lower Extremity Bones

Bones of the lower extremities include the hip, thigh, lower leg, and foot.

The hip bone or pelvis can be separated is made of 3 bones:

- 1. ilium – largest and uppermost

bone

-2. ischium - strongest and

lowermost bone

-3. pubis - anterior

Lower Extremity Bones

Femur – thigh bones; longest and heaviest bones in the body

Patella – kneecap

Tibia – larger and stronger of the two lower leg bones

Fibula – smaller of the two lower leg bones

Lower Extremity Bones Tarsals – bones of the

ankle

Calcaneus – heel bone

Metatarsals – bones of the foot

Phalanges – bones of the toes