The Skeletal System The skeletal system includes connective tissues such as bone, cartilage, tendons, and ligaments. These tissues are combined with the various types of muscle tissue to form the Musculo-Skeletal System.
The Musculo-Skeletal System Osteology Articular System Myology
Osteology a study of the skeleton
The human skeleton
Functions of the Skeletal System A. Support - a framework and structural support for the whole body
Functions of the Skeletal System B. Protection - enclose delicate and vital organs
Functions of the Skeletal System C. Movement 1. Muscles are attached to bones 2. Muscles pull bones to produce movement
Functions of the Skeletal System D. Storage 1. Calcium is stored in the bones 2. The skeletal system has an important role in the homeostatic maintaince of blood calcium levels.
Functions of the Skeletal System E. Hemopoiesis 1. Definition: The process of blood cell formation. 2. Occurs in red bone marrow
A. 1. 2. Types of Bones Long bones Femur Humerus B. Short bones 1. 2. Tarsals Carpals - provide levers for movement - develop by replacement of hyaline cartilage - have structurally distinct regions
Types of Bones C. Flat bones (squamous) 1. Frontal 2. Scapula - generally serve protective or reinforcement functions - develop by replacement of connective tissue - Diploe spongy bone structure between two plates of compact bone (lamina vitrea)
Types of Bones D. Irregular bones - Vertebrae (26 bones)
Types of Bones F. Sesamoid bones o Patella o Pisiform bone - develop within tendon - change the attrition of the tendon - increase the volume of the movement
Types of Bones G. Pneumatic bones -bones which contain air spaces lined with mucous membrane -typically skull bones -make the skull light -impart resonance to voice -act as conditioning chambers for inspired air
Chemical Composition of the Bones
Osteogenesis imperfecta (OI) (brittle bone disease, Lobstein syndrome) deficiency of type I collagen - defective connective tissue (or without the ability to make it)
1. Diaphysis a. Shaft: made of hard compact bone 2. Medullary cavity a. Hollow area inside diaphysis b. Contains yellow bone marrow (inactive, fatty marrow) 3. Epiphyses a. Ends of long bone b. Inside contains red, spongy bone marrow Long Bone Structure
Long Bone Structure 4. Articular Cartilage a. Thin layer of cartilage cover each epiphyses (bone ends) b. Act as a cushion at the joint 5. Periosteum a. Fibrous membrane covering a long bone (except the ends) 6. Endosteum a. Fibrous membrane lining medullary cavity
Microscopic Structures 1. Compact bone a.outer layer of bone that is hard and dense 2. Spongy (trabecular) bone a. Porous bone in the end of a long bone
Compact bone: Matrix composed of Osteons or Haversian systems Calcium matrix arranged in rings Each ring = concentric lamella Central canal contain blood vessels
Osteocytes = bone cells that lie between lamellae in space called lacunae Canaliculi= passageways that connect the lacunae with each other and the central canal
Blood vessels from the outer periosteum enter bone and pass through the central canal of an Osteon (or Haversian Canal). Nutrients pass from the blood vessel through the canaliculi to the osteocytes.
Bone Growth Bone begins as cartilage and fibrous structures in the fetus.
a. Primary center (Punctum ossificatum primum) - middle of long bone b. Secondary centers (Punctum ossificatum secundum) - in both epiphyses at ends of long bone c. Epiphyseal plate - cartilage between epiphysis and diaphysis
Growth will continue to occur as long as any cartilage in epiphyseal plate remains. An x-ray will show if any remains. Epiphyseal line is all that is left after growth ceases and the epiphyseal plate disappears.
Equilibrium lever (First Class) Power lever (Second Class) Speed lever (Third Class)
Anatomic planes Posterior Medial Lateral Anterior Lateral Superior Inferior
Divisions of the Human Skeleton Axial division Skull bones Vertebral column Appendicular division Pectoral girdle Pelvic girdle
Skull bones
Skull bones a. Cranial bones (7 bones): Frontal ( 1 ) Parietals ( 2 ) Temporals ( 2 ) Occipital ( 1 ) Sphenoid ( 1) Face bones (14 bones): Maxilla ( 2 ) Mandible ( 1 ) Zygomatic ( 2 ) Nasal ( 2 ) Palatine ( 2 ) Lacrimal ( 2 ) Vomer ( 1 ) Inferior choncha ( 2 )
Vertebral column a. Cervical vertebrae (7) b. Thoraic vertebrae (12) True ribs (first 7 pairs of ribs attached to T-1 through T-7) False ribs (last 5 pairsof ribs attached to T-8 through T-12) Note: True ribs are directly attached to the sternum and false ribs are not directly attached. c. Lumbar vertebrae (5 ) d. Sacrum (5 bones fused into 1 bone) e. Coccyx ( found as 3 to 5 separate vertebrae in a child while in the adult they are fused into 1 bone)
Pectoral girdle
Pelvic girdle In a young child each coxal bone consists of three bones: ilium, ischium and pubis. In adults they grow together into 1 bone.
Endochondral ossification Punctum ossificatum primum Punctum ossificatum secundum