Ch. 7 – The Skeletal System

Introduction  Bones are ALIVE  They have many functions  There are a total of 206 bones in the human body

Functions of Skeletal System  Provide a surface for muscles to attach  Protect and support softer tissues and organs  Produce blood (hematopoeisis)  Store salts  Contains passageways for blood vessels and nerves

5 Tissues found in Bone  Bone (osseous) tissue  Cartilage  Dense connective tissue  Blood  Nervous tissue

2 Bone (Osseous) Tissues  1. Compact Bone – wall of the bone (along diaphysis); solid and strong  2. Spongy Bone – softer, porous bone; found in ends of bones (epiphyses)

Bone Structure 1.EPIPHYSIS - ends of bone; forms a joint with another bone. 2. DIAPHYSIS - shaft of the bone 3. ARTICULAR CARTILAGE - hyaline cartilage covering ends of bones 4. PERIOSTEUM - tough membrane-like covering over entire bone 5. MEDULLARY CAVITY - hollow chamber within the diaphysis, contains bone marrow - Red Marrow - mainly in spongy bone in adults, produces blood cells - Yellow Marrow - fat storage

Microscopic Structure - MATRIX – where all of the bone cells live - OSTEOCYTES - mature bone cells are enclosed in tiny chambers called LACUNAE -OSTEOCYTES form concentric rings called LAMELLA which surround HAVERSIAN CANALS that houses blood vessels -Volkmann’s Canals run horizontally connecting the vessels between OSTEONS

Bone Development Bones first form as hyaline cartilage, then gradually changes into bone tissue - a process called OSSIFICATION. OSTEOBLASTS produce bone cells called OSTEOCYTES OSTEOCLASTS - dissolve bone tissue to release minerals - a process called RESORPTION

Bone Structures  Long bones (Humerus, Femur)  Longer than they are wide  Short bones (Carpals, Tarsals)  Approximately as wide as they are long  Flat bones (Scapula, Cranium)  Irregular bones (Mandible, Vertebra)

The skeleton is divided into two portions: 1. AXIAL SKELETON 2. APPENDICULAR SKELETON

Axial skeleton  Supports and protects organs of the head, neck, and trunk  Skull  Hyoid  supports tongue for speaking and swallowing  Vertebral column  Thoracic cage (sternum and ribs)

Appendicular skeleton  Upper and lower limbs AND bones that hold those limbs to the axial skeleton  Upper limbs (arms) – Humerus, radius, ulna, carpals, metacarpals, phalanges  Pectoral girdle - scapula, clavicle  Lower limbs (legs) – Femur, fibula, tibia, patella, tarsals, metatarsals, phalanges  Pelvic girdle (hip bones) – 2 coxa

Vertebral column 1)Cervical (7) – neck curvature 2)Thoracic (12) – attached to rib cage 3)Lumbar (5) – lower back curvature 4) Sacrum and Coccyx (fused) **The ATLAS vertebrae is the 1 st vertebrae (C1) ** The AXIS vertebrae is the 2nd (C2)

Abnormal spine curvature 1.Lordosis – “Swayback”; the spine curves significantly inward at the lower back

Abnormal Spine Curvature 2. Kyphosis - “Humpback”; abnormally rounded upper back

Abnormal Spine Curvature 3. Scoliosis – sideways or “S- shaped” curve to the spine

Types of Fractures 1. Simple/Closed – bone breaks, but does not damage surrounding tissue 2. Compound/Open – bone breaks and breaks through the skin 3. Greenstick – incomplete break and the bone bends 4. Comminuted – fragmented and shattered break 5. Stress/hairline – small crack caused by repeated impact

Joints  Unions between two or more bones  A.k.a.— articulations

3 Types of Joints 1. Fibrous joint – found between bones that closely contact one another; connected with dense, fibrous tissue Ex: sutures between bones in the skull Least movable joint

3 Types of Joints 2. Cartilagenous joint – connected by hyaline cartilage Ex: vertebral column and pubic symphysis Limited movement

3 Types of Joints 3. Synovial Joint Complex joints that allow free movement

6 Synovial Joints 1. Ball-and-socket—ex: shoulder 2. Condyloid—ex: metacarpals and phalanges 3. Gliding—ex: carpals 4. Hinge—ex: elbow 5. Pivot—ex: atlas and axis vertebra (head movement) 6. Saddle—ex: thumb