THE MUSCULOSKELETAL SYSTEM THE TOPICS IN MUSCULOSKELETA SYSTEM a. Skeletal Tissue b. Articulations (Joints)-Arthrology. c. Axial Skeleton d. Appendicular Skeleton e. body muscles SKELETAL TISSUES LEARNING OUTCOMES At the end of this lesson, you should be able to: 1. Describe the structural organization of bone 2. Describe the functions of the skeleton 3. Classify and describe characteristics of skeletal tissue 4. Classify and describe characteristics of bone The skeleton serves as a support or framework of the human body. It is a combination of bones joined together. The two major type of tissue found in the skeletal system are bone and cartilage connective tissue FUNCTIONS OF THE HUMAN SKELETON a. Body Support. The skeletal system provides a framework for the human body, contribute to shape, alignment, and positioning of the body parts b. Protection. Bony boxes protects the delicate structures they enclose. E.g. skull, pelvis, thoracic cavity, vertebral column c. Motion. Bones with their joints constitute levers that move as muscles contract d. Mineral Storage. Bones are the major reservoir for calcium, phosphorus and other minerals e. Formation of Blood Cells (Haemopoiesis). Blood cell formation is carried out by myeloid tissue found in the bone marrow - mainly found in flat bones. BASIC STRUCTURE OF AN INDIVIDUAL BONE The skeleton is made up of 206 individual bones joined together by ligaments. Each bone is an organ made up of various body tissues. Bones can be classified according to structure or shape. According to structure, they are classified into: (1) Compact or Lamella bone or cortical bone - cortex (2) Cancellous or Spongy or woven bone - medulla Individual bones are composed 2 parts: - 1. Cortex - The cortex is the outer layer of the individual bone made up of compact bone 2. Medulla. The medulla is the central portion of the individual bone made up of cancellous bone. Bone marrow There are two types of bone marrow: - 1. Yellow bone marrow - mostly made up of yellow fat tissue. 2. Red bone marrow – made up of haemopoetic tissue which is the only site in adults for the formation of red blood cells (haemopoiesis). TYPES OF BONE Individual bones of the skeleton can be classified into 4 major types depending on their shape. These are: 1. Long bones 2. Short bones 3. Flat bones 4. Irregular bones a. Long Bones. The basic structure of a long bone is made up of 5 major parts e.g. femur. b. Short Bones. The short bones, such as those of the wrist and feet, have a thin layer of compact bone surrounding an inner mass of spongy bone. Example: carpal bones. c.Flat Bones. The flat bones are constructed with two plates of compact bone, which enclose between them a layer of spongy bone. The spongy bone is richly supplied with blood vessels and red marrow. Example: the cranial frontal bone. d. Irregular Bones. The irregular bones are those that do not fit into the three categories above. Example: a vertebra SHORT BONES –HAND FLAT BONES -HUMAN SKULL IRREGULAR BONES –VERTEBRAL COLUMN LONG BONES-HUMERUS Sesamoid Bones Sesamoid bones are small masses of bone that develop in tendons at points where great forces are applied to the tendons. The most obvious and largest sesamoid bone is the patella, or kneecap. Blood Supply of an Individual Bone. • A system of blood vessels enters and spreads out through the periosteum. • Additional blood vessels, called "nutrient vessels," penetrate the cortex of the bone and spread out through the marrow. • The passageways for penetration of these vessels are called the nutrient canals. Osteogenesis Osteogenesis is the process of development of bone from small cartilage or membranous models to adult bone DISEASES AFFECTING THE SKELETAL TISSUE •Malignant tumors (cancers)- Osteosarcoma, Chodrosarcoma •Metabolic diseases – Osteoporosis, Rickets, Osteomalacia, Paget’s disease (osteitis deformans) •Infections – Osteomyelitis. THE AXIAL SKELETON The human skeleton is a collection of individual bones articulated (joined) together. (206 individual bones in total) The major subdivisions of the skeleton are 1.The axial skeleton – 80 bones 2. The appendicular skeleton – 126 bones It is the central framework of the human body, and its composed of the following 3 components: - 1.The skull 2.The vertebral column (spine) 3.The thoracic cage (rib cage) The axial skeleton consists of 80 bones: •29 bones in the head - 8 cranial and 14 facial bones and 7 associated bones (6 auditory ossicles and the Hyoid Bone) •25 bones of the thorax - (the sternum and 24 ribs) •26 bones in the vertebral column (24 vertebrae, the sacrum and the coccyx) THE SKULL The skull is the bony framework (skeleton) of the head region. It has two major subdivisions: the cranium which encases and protects the brain and the facial skeleton which is involved with the beginnings of the digestive and respiratory systems. Cranium, 8 bones 1 Occipital. 2 Parietals. 1 Frontal. 2 Temporals. 1 Sphenoidal. 1 Ethmoidal. In addition, there are 3 pairs of ear ossicles (6 total): –Malleous –Incus –Staples THE VERTEBRAL COLUMN(SPINE) The vertebral column, or spine, is made up of a vertical series of bony blocks called vertebrae. These vertebrae are joined together in such a way as to form a semiflexible rod. The spine is the central support for the trunk, yet allows trunk movements. DIVISIONS OF THE VERTEBRAL COLUMN The vertebral column has 32-33 vertebrae, one on top of the other. These vertebrae are arranged in regions. The vertebrae of each region have a characteristic shape. The regions are as follows: Cervical (neck) region, with 7 cervical vertebrae. (b) Thoracic (chest) region, with 12 thoracic vertebrae. (c) Lumbar (low back) region with 5 lumbar vertebrae. (d) The sacrum, which is a bony fusion of 5 sacral vertebrae. (e) The coccyx ("tail"), with 3-4 coccygeal vertebrae together. The Thoracic (Rib) Cage The rib cage forms a protective enclosure for the vital organs contained within the thorax (chest) such as the heart and lungs. It also allows the movements of breathing to take place. The Rib Cage The rib cage consists of the 12 thoracic vertebrae, 12 pairs of ribs, and the sternum. Each rib is curved laterally from back to front. All 12 pairs of ribs are attached posteriorly to the thoracic vertebrae. The upper seven pairs of ribs (true ribs) are attached directly to the sternum by their costal cartilages. The eighth through tenth pairs of ribs (false ribs) are attached indirectly to the sternum through their costal cartilages (by attaching to the costal cartilage of the rib above). Rib pairs 11 and 12 (floating ribs) do not attach to the sternum. Instead, they are embedded in the trunk wall muscles. The Ribs There are 3 types of ribs: True Ribs – ribs 1-7 ; these are attached directly to the sternum through their own costal cartilages. False Ribs – ribs 8-10; their costal cartilages are joined to the rib just above them so their attachment to the sternum is indirect Floating Ribs – ribs 11-12; these ribs attach to vertebrae, but not to the sternum so they float on one end THE APPENDICULAR SYSTEM Appendicular skeleton refers to the bones of the limbs and the girdles that attach them to the axial skeleton. It is made up of the skeletal elements of the upper and lower members. These members are appended (attached) to the axial skeleton. The appendicular skeleton is made up of a total of 126 bones plus 8 sesamoid bones Functions of the appendicular skeleton 1.Locomotion 2.Protection of major organs of digestive, excretion and reproductive organs 3.Holds and supports the limbs 4.Enables skilled movements of the hands Structural Organization of the appendicular skeleton •The appendicular skeleton is generally organized into upper and lower limbs. •Each limb is made up of the following 4 segments: - 1.Girdle 2.Proximal segment 3.Middle segment 4.Distal segment Carpal Bones – Mnemonic- She Looks Too Pretty Try To Catch Her S: scaphoid L: lunate T: triquetrum P: pisiform T: trapezium T: trapezoid C: capitate H: hamate The Circus Needs More Interesting Little Clowns. T: Talus C: Calcaneus N: Navicular M: Medial cuneiform I: Intermediate cuneiform L: Lateral cuneiform C: Cuboid MUSCLE TISSUE At the end of this lesson, you should be able to: 1.Classify and describe Muscle tissue 2.Describe the structure of skeletal muscle 3.Categorize and describe the muscle organ 4.Describe nomenclature of muscles 5.Describe general arrangement of muscles MUSCLE TISSUES The cellular elements of muscle tissues are specialized to produce motion by contraction. They also produce body heat. a. Smooth muscle tissue is utilized to make up the muscular portion of the various visceral organs b. Cardiac muscle tissue makes up the muscular wall of the heart--the myocardium. c. Striated muscle tissue is used in the makeup of several types of muscles. The main type of muscle is the skeletal muscle. Other types of muscles made with striated muscle tissue are the facial or integumentary muscles and muscles of the jaw apparatus. THE SKELETAL MUSCLE •There are 600 named muscles in a human body •Each skeletal muscle is an individual organ of the human body. •Each is made up of several types of tissues-- mainly, striated muscle fibers and FCT (fibrous connective tissue). •Each is attached to and moves bones. •Bones are parts of the skeleton serving as levers. General Construction of a Skeletal Muscle •The large portion of a muscle is known as its belly or fleshy belly. •This muscle is attached to bones by tendons or aponeuroses. •Tendons and aponeuroses are similar to each other. However, tendons are cord-like and aponeuroses are broad and flat. •The fleshy portion may be directly connected to the bone.