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