Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah "The musculoskeletal system" The musculoskeletal system is composed of two systems – the skeletal system and the muscular system – but is commonly referred to as 'musculoskeletal' because of the main common functions of the two systems are movement and support. The musculoskeletal system is made up of hard and soft tissues. The hard tissue includes bones and cartilages, while the soft tissues are the muscles, tendons, synovial membranes, joints capsule and ligaments. Skeletal system: Skeletal system is composed of the bones in the body plus the joint where they attached to each others, the skeletal system composed of 206 different bones. The skeletal system is divided into two divisions: 1-The axial skeleton consists of the bones along the axis, or central line, of the human body. The axial skeleton consists of 80 bones comprises the skull, vertebral column and thorax. 2-The appendicular skeleton: contains the bones in the appendages of the body, as well as the structures that connect the appendages to the axial skeleton. The appendicular skeleton consists of 126 bones including the bones of the shoulder girdle; upper limbs, hips and lower limbs. 1 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah Classification of bones 1. Long bones: Long bones are typically longer than they are wide, They are tubular (e.g. the humerus in the arm and femur in leg) 2. Short bones: These bones are generally cube-shaped or round. Examples include the tarsals and carpals, sesamoid bones, which form within tendons, are a special type of short bone 3. Flat bones: these types of bones are mostly thin, flattened and usually curved. They mostly serve protective functions. Examples include most of the skull bones – protecting the brain, and the scapula 4. Irregular bones: These are bones that do not fit into any of the other types of bones. Generally, irregular bones will have a foramen through them. Ex. (the hip bone and vertebrae). 2 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah Types of bone tissue: 1) Compact bone: Compact bone is dense and looks smooth , homogeneous and very strong . 2) Cancellous bone (Spongy bone): Spongy bone is composed of long, needle-like pieces of bone and lots of open space. Cartilage: Cartilage is an important structural component of the body. It is made up of specialized cells called chondrocytes. These chondrocytes produce large amounts of extracellular matrix composed of collagen fibers, proteoglycan, and elastin fibers. There are no blood vessels in cartilage to supply the chondrocytes with nutrients, nutrients diffuse through a dense connective tissue surrounding the cartilage (called the perichondrium) .It's found in many areas of the body including: • Joints between bones ( the elbows, knees and ankles ) • Ends of the ribs • Between the vertebrae in the spine • Ears and nose Functions of cartilage : 1) Supports soft tissues 2) Shock absorbing and sliding area for joints (smooth surface), 3 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah Types of cartilage: 1. Hyaline cartilage Incidence: articular surfaces, wall of large respiratory passages – larynx, trachea, bronchi, ventral ends of ribs, embryonic temporary skeleton 2. Elastic cartilage Incidence: epiglottis, auricle of the ear and Eustachian tube. 3. Fibrocartilage Incidence: intervertebral discs. The joints:- Joints are the areas where two or more bones meet. It made the connection between bones in the body which link the skeletal system into a functional whole Classification of Joints 1. According to the type of tissue at the joint: a) Fibrous joint : uses fibrous connective tissue to articulate bones. b) Cartilaginous joint: uses hyaline cartilage and/or fibrocartilage to articulate bones. c) Synovial joint: uses auricular cartilage, synovial membrane, joint capsule, and ligaments to articulate bones. 2. According to the amount of movement at the joint: a) Synarthrotic joint : immovable joint. 4 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah b) Amphiarthrotic joint: small amount of movement c) Diarthrotic joint: freely movable joint. Functions of skeletal system: The skeletal system serves five important functions in the human body: 1. Support and Protection: the skeletal system surrounds and protects the internal organs. For example, ribs protect the lungs and heart, the bones of vertebral column (spine) protect spinal cord, and the bones of the skull protect the brain 2. Movement :Bones also facilitate movement by serving as points of attachment for your muscles 3. Mineral storage: Calcium and phosphorus, These minerals, incorporated into bone tissue, can be released back into the 5 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah bloodstream to maintain levels needed to support physiological processes. 4. Fat storage : The softer connective tissue that fills the interior of most bone is referred to as bone marrow. There are two types of bone marrow: yellow marrow and red marrow. Yellow marrow contains adipose tissue; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy. 5. Blood cell formation: Red blood cells are manufactured in the red bone marrow. 6 Lecture 8 [ANATOMY AND MEDICAL TERMINOLOGY] Assist. Lec. Nabaa Salah Important medical terminology in skeletal system:- ARTHR- Joint COST- Rib CHONDR- Cartilage cartilage strong flexible connective tissue chondrocyte a cartilage cell OSTEO- Bone osteoblasts immature bone cells osteocytes mature bone cells diaphysis central shaft of bone epiphysis widening at end of bone periosteum connective tissue membrane covering bone sinus hollow cavity within a bone cranium encases the brain articulation where 2 or more bones meet 7 .