Musculoskeletal System.docx

[Musculoskeletal System] Terminology: Muscular systems = "my", "myo", "musc" Skeletal systems = "os", "osteo", "oss" [Skeletal systems:] Function -- support, protection, movement, storage haemopoiesis Classification: Long, flat, irregular (hip), short (wrist), sesamoid (foot) Bone structure:...

[Musculoskeletal System] Terminology: Muscular systems = "my", "myo", "musc" Skeletal systems = "os", "osteo", "oss" [Skeletal systems:] Function -- support, protection, movement, storage haemopoiesis Classification: Long, flat, irregular (hip), short (wrist), sesamoid (foot) Bone structure: Epiphysis -- end of each long bone Metaphysis -- attached to the epiphysis Diaphysis -- long bone (body of bone) Outer layer of Epiphysis has an articular surface / Cartlidge There is also an epiphyseal line which separates the metaphysis and epiphysis parts of the bone Spongy bone is located within the epiphysis and metaphysis Compact bone is within the diaphysis with marrow / medulla cavity Periosteum is the outer layer of the diaphysis Articular Cartlidge -- Smooth slippery surface (20x more slippery than ice), transmission of loads with little friction, devoid of blood vessels, lymphatics and nerves Cavity of bone is filled with compact cortical (less dense) and cancellous spongy trabecular (denser). Compact cortical is within the cavity of the metaphysis and epiphysis whilst compact cortical is located at the diaphysis. Bone section summary: Skull / Cranium Limbs (Arm and Legs) Bony Thorax (Rib cage, protects organs, a part of respiration and muscle attachment) Vertebral column (spine attaching thorax to pelvic girdle) Pelvic / Scapular / Clavicle Girdle (Shoulders and hips) Axial -- Skull / cranium, Vertebral column, Bony thorax Appendicular -- Limbs (Appendages), Pectoral Girdle, Pelvic Girdle The Skull: Made up of many bones Split into 2 regions: - Face is known as the viscerocranium - Head is known as neurocranium Vertebral Column Regions: Cervical = lower head/ neck Thoracis = ribcage Lumbar = stomach Sacral = Hips Coccygeal (Caudals) = below hips Limbs: Upper limbs (humans) Forelimb (quadrupeds): - 1 bone for proximal part - Humerus in arms - Femur in legs Lower limb (human) Hindlimb (quadrupeds): - 2 bones - Radia and Ulna in forearms - Fibula and Tibia in lower legs Hands and Feet are full of short bones Hands = Carpals, Metacarpals and Phalanges Feet = Tarsals, Metatarsals and Phalanges Proximal Attachments: "Origin of muscle belly" Tendons -- Dense regular connective tissue Distal Attachments: "Insertion" Tendons -- Dense regular connective tissue [Muscles:] 1. Muscle 2. Fascicle 3. Muscle fibre cell 4. Myofibril 5. Myofilaments \*Muscles mass is usually proximal to limb and tendon \*Muscles contract by shortening, always pull never push Muscles always span joints or multiple for it to move (1 = Brachialis, pectineus) (2 = Bicep Brachi, Sartorius). Never work alone when prime mover contracts (shortens) the antagonist relaxes and vice versa. Muscle Contractions: 1. Isotonic -- Change in length, no change in tension a. Concentric -- muscle shortens b. Eccentric -- Muscle lengthens, used against force 2. Isometric -- change in tension, no change in length \*Normally muscles are in a state of partial contraction Muscles can also be arranged into compartments but typically have same nerve and blood supply 2 types of muscle fibres: fast twitch (chicken breasts) or slow twitch (duck breasts) Joints: Cavitated -- Synovial (freely moving) Solid: - Fibrous: - Gomphosis (teeth) - Syndesmosis (Tibiofibular) - Suture (Skull) - Cartilages - Primary (Synchondrosis, growth plates) - Secondary (Symphysis, pelvis) [Growth ] Hypertrophy -- increased cell size not number Hyperplasia -- increased cell number not size Types of bone growth: Interstitial -- division of chondroblast from within cartilage Appositional -- differentiation of cells from surface or perichondrium Longitudinal -- indirect growth via interstitial Cartlidge at growth plate and ossification. Ends at skeletal maturity. Circumferential -- occurs directly via oppositional growth at bone surface. Continues through life. Epiphyseal growth plate -- site of indirect bone growth via interstitial Cartlidge. Increase in bone length complete at skeletal maturity Longitudinal bone growth: 1. Starts at bony collar around Cartilage template 2. Blood vessels invade tissue 3. Osteoblasts enter Cartilage shaft and lay down bone matric 4. Osteoblasts enter epiphysis and lay down bone matrix 5. Cartilage is retained between epiphysis and the shaft Endochondral = within cartilage Intramembranous = inside membrane [Hormones:] Gigantism: Onset of excess GH Before closure of epiphysis Tall stature, long bones, delayed puberty Acromegaly: Onset of excess GH After epiphysis closure Height and Gonads unaffected Facial characteristics changed Parathyroid Hormone (PTH): PTH regulates Calcium and Phosphate in body Released from parathyroid glands - Too much causes increase in calcium in blood plasma and decrease in bones - Chance of kidney stones - Osteoporosis / osteopenia - Too little causes decrease in calcium ibn blood plasma - Cause muscle rigidity - Spasms \*Vitamin D works with PTH to help absorb Calcium and Phosphate in GI tract Calcitonin -- Opposes PTH, reduces blood plasma Calcium from thyroid glands Vitamin C -- Involved in collagen synthesis Can cause scurvy (adults) or barlous disease (child) if low Oestrogen -- Reduces bone resorption, stimulates bone development Plays big part in bone maintenance: Testosterone -- Reduces bone resorption, stimulates bone development and increases muscle mass PEDs: Erythropoietin (EPO) -- affects erythropoiesis Anabolic androgen steroid (AAS) -- testosterone Peptide hormones + releasing factors -- GH Growth factors and modulators -- IGF-1, VEGF Hormone and metabolic modulator -- anti-oestrogen Wolff's Law (1869) - Optimisation f bone strength with respect to bone mass - Alignment of trabeculae with principle of stress direction - Self-regulation of bone cells responding to mechanical stimulus \*Basically, increased mechanical loading = Increased bone strength (Greater mineralisation and bone mass and decreased porosity) Osteoarthritis: - Joint degeneration of articular cartilage and bone - Progressive - Joint pain only present when bone is damaged - Not normal aging but very common in older individuals Sarcopenia: - Age related loss of skeletal muscle mass and decline in strength - Decrease in size and quality of muscle - Presence of 50% in 80 yr. olds - More than twice as fast in lower limb than upper limb Kyphosis: - Degeneration of IVDS - Osteoporosis in vertebrae - Lengthening of extensor muscles - Bent over posture