CH 18 Musculoskeletal System

Effects of Aging on the Musculoskeletal System

*Bones* -Bone mass and strength lost; body posture may change, results in osteoporosis and fractures; prevent falls, assess for fractures (particularly of hip) -Calcium is lost (greater in postmenopausal women); bone tissue not replaced quickly, results in hunched posture (kyphosis, humpback, lordosis, swayback), back pain and brittle bones; encourage vit. d and calcium supplements, advise exercise to minimize bone loss, teach safety and prevention of falls, meds and hormone replace therapy may be prescribed -Vertebral column shortens, results in decrease in height (demineralization of bones); encourage preventive diet (protein, minerals, and vit d, encourage exercise) *Joints* Joint degeneration, results in arthritis (degenerative joint disease), Osteoarthropathy, joint stiffness, muscle aches, and back pain; encourage to increase mobility with active and passive R0M. hydrotherapy and external heat often helpful *Muscles* -Muscle cells are lost or atrophy, Muscle cells replaced by fat, elasticity of fibers lost, results in loss of muscle strength, gain of fat tissue, loss of flexibility, easy fatigability, resting tremors may occur; give suggestions on carrying items (groceries) safely, encourage weight control, suggest walking, swimming, physical activity reduces loss of muscle, tissue, tone, and elasticity; increases flexibility, encourage proper nutriiton

Functions of the Skeleton

*Support -Supports the body - Provides framework for body -Gives shape to body *Protection -Protect vital organs -Protects soft tissues *Movement -Provides locomotion (walking, movement) by attachment of muscles, tendons, and ligaments *Hematopoieses -Produces RBC, WBC, and platelets *Storage -Provides calcium and phosphorus

Appendicular Skeleton: Lower Extremities Femur Tibia Fibula Patella

-Femur: thigh bone, bone in the upper leg. The longest and strongest bone. It supports the weight of the body. Lower end is attached to the tibia of the lower leg at knee joint. Upper end, the head, is attached to the pelvic bone in a ball-and-socket joint, where its rounded head fits into a depression., the acetabulum. Head of the femur joins the shaft of the femur by a short length of bone, the neck, called trochanters, serves as points of muscle attachments. -Tibia/Fibula: two bones in the lower leg. Tibia (shin bone) is the long weight beading bone of the lower leg. The upper end is attached to the lower end of the femur at the knee joint. Lower end meets the bones of the ankle and the fibula to form the ankle joint. Protrusion on lower end can be felt on side of ankle; medial malleolus. *Fibula; smaller than tibia, is attached to the tibia at its upper end. Not a weight bearing bone and not part of the knee joint. Lower end is part of the ankle joint. Another projection, "lateral malleolus" located where distal end of fibula meets ankle bones. -Patella (kneecap): sesamoid bone, protects the front of the knee joint and is buried in a tendon passing over the joint. Foot is structured to support entire body weight and still provide flexibility and resilience. -Ankles 7 tarsal bones: compact and shaped irregularly (largest is in heel; calcaneus). Tarsals bones join the 5 metatarsals bones (instep bones) to form two arches:the longitudinal arch; extends from heel to toe, the transverse or metatarsal arch; extends from the foot. Weight of body falls on these arches. -14 bones of the toes, the phalanges, are attached to the metatarsals. The big toe has two phalanges; each of the other toes have three. **Bones of the Hands are more finer and the joints more numerous (27 bones in each wrist and hand, 26 in each ankle and foot). Hands are designed from fine and flexible movements, feet for support.

Bones: Structure -Types of Bone Tissue -Medullary Cavity -Periosteum -Construction of Bones: Diaphysis, Epiphysis

2 types of Bone tissue: -Compact bone: Hard and dense and forms the shaft of long bones and the outer layer of other bones. -Spongy bones(cancellous bone): composed of small bony plates, resembles a sponge and contains more spaces than compact bone. Medullary Cavity: Hollow most inner part of the bone, is lined with endosteum and contains a soft substance called marrow. 2 types: Yellow marrow (seen in soup bones) in the medullary cavity of long bones and is mosty fat and Red marrow found in the ends of long bones, in the bodies of vertebrae, and in flat bones. Responsible for Hematopoiesis (RBC, WBC, platelets) Periosteum: Thin, hard, fibrous, dense connective tissue membrane that covers the outside of the bones. Often merges with tendons and ligaments. Contains blood vessels that supply oxygen and nutrients to bone cells (osteocytes), keeping them alive. Also supplies minerals and other bone building substances that fill intercellular spaces, particularly important in healing of fractures. *2 types of osseous (bony) tissue involved in the construction of long bones of the extremities -Diaphysis: or shaft of the long bone, is hard and compact. -Epiphysis: the end of the long bone, sponge-like and is covered by a shell of harder bone. **The diaphysis and epiphysis do not fuse until adulthood. They meet at the epiphyseal growth plate --Damage to the epiphyseal growth plate by trauma usually causes cessation of growth in long bonds and results in shortening of the limb involved. The younger when injured and the greater the severity, the greater will be the final deficit in length between the injured and uninjured limb

Musculoskeletal System

Also called the locomotive system. It includes the skeleton, joints, ligaments, muscle, tendons, and accessory structures. -The skeleton provides the bony framework for the human body and muscles assist the body to move. System works in coordination with other systems. *Skeleton system= bones and cartilage --offer support and protection *Articular System= joints and ligaments --provide movement sites *Muscular System= muscles and tendons --act to move the bones. Functions: Support (structure), protection, movement (uses bones as levers), hematopoietic (blood formation), and storage.

Axial Skeleton

Axial skeleton contains the bones in the center (axis) of the body; skull, vertebral column, and rib cage. 80 Bones total -Skull >>Cranium 8 bones >>Face 14 bones -Hyoid 1 bone -Auditory ossicles 6 bones -Vertebral column 26 bones -Throax >>Sternum 1 bone >>Ribs 24 bones

Bones

Bones are living, highly specialized connective tissue. The human body has 206 bones. More than half of the bones in the body are found in the hands, wrists, feet, and ankle. (Baby has approx. 300 bones at birth. Fusion is completed at about age 25. - Bones, the marrow within certain bones, and the minerals of which bones are made (primarily calcium and phosphorus) contribute to the homeostatic functioning of the body. *Bones are living tissue and contain blood and lymphatic vessels and nerves. They may shrink (atrophy) if unused or may enlarge (hypertrophy) with excess weight bearing.

Formation of Bone Tissue

Bones develop from embryonic connective tissue called mesenchyme, either directly of via cartilage derived from mesenchyme. -Long bones grow by ossifying the shaft (diaphysis) of the bone. -During bone growth, the epiphyseal plates exist between the diaphysis and epiphyses. These plates are gradually replaced by bone on both sides. When growth is complete, the ends of the bone fuse with the shaft and the seam is shown on x-ray as the epiphysial line -When growth spurts have stopped, new cells form only to replace dead or injured ones and to repair breaks. With age, bone becomes harder and more brittle, breaking more easily. Although they harden due to deposits of calcium and phosphorus, bones are made up of living cells. -Bone building cells are called osteoblasts. Ossification is the formation of bone by osteoblasts, and is the process by which bones become hardened, due to increase in calcified tissue. Ossification progresses from the middle of the shaft outward. The hardened, mature bone cells is the 'osteocyte'. Other cells, 'osteoclasts', assist in resorption or breakdown of bone. Resorption allows bones to grow and change shape, bones continue building up and resorbing throughout life. **Bone growth is rapid during infancy, steady in childhood,and has a rapid spurt in adolescence before the epiphyseal growth plate hardens and growth ceases. Bone growth and maintenance factors: -Heredity: genes, genetic (inherited) tendencies -Nutrition: protein, vitamins (especially A,D,C) and minerals (calcium, phosphorus) -Exercise: weight bearing (provides stress to strengthen bones) (lack of vt. D causes bone malformation in children called rickets, in adults called osteomalacia. -Hormones: affect rate of bone growth, calcium metabolism, energy production, and overall maintenance

Bone: Classifications -Long Bone -Short Bone -Flatbone -Irregular Bone

Classified according the shape. -Long Bones (tubulae): Extended shape and provides the body with support and strength. Acts as levers and support frame (In arms and legs; femur, tibia, radius) -Short Bones(cuboidal): Approx. cube shape, facilitate movement and transfers forces (In wrists and ankles; tarsal, carpals) -Flatbone: Shaped flat and provide broad surfaces for muscle attachments. Serve as muscle attachment and for protection. (In head, chest shoulders and hips; cranial, ribs, pelvis, ilium, sternum) -Irregular bones: Similar to short bones, but are irregular in shape. For attachment of other structures or articulations or for special functions (In face, back, middle ear; facial, vertebrae, bones of middle ear (malleus, incus, stapes) *Irregular bone classification includes small, rounded bones, the sesamoid bones which develop within joints and tendons. Sesamoid (spongy or cancellous) protect tendons from wear, change tendon angle (In knee, foot; patella, first metatarsal) Other special irregular bones are those in the ear. *The smallest bones in the body is the stapes (stirrup) in the middle ear.

Appendicular Skeleton

Contains bones of the pelvic girdle, extremities, and appendages. 126 total bones -Pectoral (shoulder) girdles >>Clavicle 2 bones >>Scapula 2 bones -Upper limbs (extremities) >>Humerus 2 bones >>Ulna 2 bones >>Radius 2 bones >>Carpals 16 bones >>Metacarpals 10 bones >>Phalanges 28 bones -Pelvic (hip) girdle >>Hip, pelvic. or coxal bone 2bones -Lower limbs (extremities) >>Femur 2 bones >>Fibula 2 bones >>Tibia 2 bones >>Patella 2 bones >>Tarsals 14 bones >> Metatarsals 10 bones >> Phalanges 28 bones

Bones: Structure -Contours -Condyle -Tuberosity -Plate -Bony Process -Foramen

Contours of the bone; -Facet: small plane or smooth area. Such as in the vertebrae of spinal column contain facets which are the locations for articulation (joints) with the heads of the ribs -Line(linea): can show up as elevations, as on the tibia -Malleolus: A rounded prominence as the medial and lateral malleoli of the tibia and fibula -Protuberance: projection of the bone, as in the cranium KEY CONCEPT: Layers of the bone from outside in: Periosteum, compact bone (on the epiphysis), cancerous bone (spongy bone), endosteum (tissue lining the medullary cavity), and bone marrow within the cavity (thick, jelly-like; makes blood cells) -Condyle: A large, rounded projection usually for articulation with another bone. (An epicondyle is a structure above a condyle) -Tuberosity: a large, elevated, knob-like projection, usually for muscle attachment. A tubercle is a small, rounded knob or nodule usually for attachment of a tendon or ligament (tibia has condyles and tuberosities on both ends, where it articulates with thigh and ankle bones and connects with muscles and tendons. -Plate: flat projection or area (dental plate; roof of mouth, foot plate; flat portion of stapes bone in middle ear. - Bony process: any prominence or projection of bone(greater trochanter of the femur). >>A spine (spina) is a sharp process (thorn-like, as in veterbrae); pedicle is another process that forms part of the vertebral arch of the vertebral column. >>A ridge or Crest is a thin or narrow process, distinct border or region (iliac creast -Foramen/Foramima: A hole which blood vessels, ligaments, and/or nerves, -Canal: long tube-like hole -Transverse foramen: within the bones of the spinal column through which blood vessels and nerves pass, and vertebral foramina, through which the spinal cord passes. Apical foramen; opening in root of each tooth, sciatic foramen; notch in the the hip bone, allowing passage of the sciatic nerves, carotid canal; through which carotid blood vessels pass into the cranium, infraorbital canal: in eye socket. -Sinus: sponge-like air space within a bone, such as the paranasal sinuses within the skull bones. -Fossa/fossae: A dent, trench, or depression (the cranial or cerebral fossae are depressions in which the brain rests.

Muscle contractions

Contractile filaments of muscles move past each other and change the shape and size of the muscle. -Contractility: ability to shorten and become thicker -Extensibility: Ability to stretch -Elasticity: ability to return to normal length after stretching -Irritability: ability to respond to a stimulus (nerve impulses) An individual muscle fiber cannot partially contract. If stimulus is strong enough to cause contraction, each stimulated fiber will contract as much as it can. If not strong enough, the fiber will not contract. **KEY CONCEPT: Skeletal muscle contraction is stimulated by electrical impulses transmitted by nerves, particularly motor neurons. Cardiac and smooth muscle contractions are caused by internal cells, which stimulate regular contractions. All skeletal muscle contractions and many smooth muscle contractions are facilitated by the neurotransmitter, acetylcholine. Contraction and Relaxation Primer mover; single or set of muscles, initiates movement Antagonist; when the opposite movement to be made, these set of muscles take over Synergic/Synergistic; muscles that assist one another in movement. Flexion; when muscles contracts, hardens, thickens as muscle fibers shorten (flexors) Extension: Muscles relax, lengthen, and pull against front muscles (extensors) Abductors; facilitate movement away from body midline Adductors enable movement away from midline

Thoracic (Rib) Cage

Formed by 12 pairs of flar, narrowed bone, the ribs (costae). Arranged on pairs, 11 on each side. -Ribs form the thoracic or rib cage and protect internal structures (heart, lungs, liver, and great thoracic blood vessels. - From their attachment to the spine at the back, the ribs curve out and to the front like hoops. The relatively elastic cartilage on the ends of ribs allows the chest and abdomen to expand. -Thoracic cage also a supportive structure for the bones of the shoulder girdle. Floor of the thorax is the muscular diaphragm - First 7 pairs "true ribs" or vertebrosternal ribs, are attached posteriorly to the thoracic vertebrae and anteriorly to the sternum. - Next 3 pairs "false ribs" or vertebrocostal ribs, also attached to the vertebrae and are not attached to each other. -Front boundary of the upper thorax is the sternum (breastbone) a flat, sword-shaped bone in the center chest opposite the thoracic vertebrae in the back. Sternum consists of 3 sections: the manubrium at the top, the body in the middle, and the xiphoid process projecting out at the bottom.

The Muscles

Functions of the skeleton include providing the body shape and mobility, using bones as levers. Without muscles, the body would be immobile. Although skeleton determines the size of the body's framework, muscle and fat determine body shape. All muscle tissues have specific characteristics (contractility, extensibility, elasticity, and irritability. -Functions : -Voluntary Movement: > Enable walking, standing, sitting, chewing, etc > Maintain body in upright position > Participate in body balance -Involuntary Movement: > Maintain heartbeat to pump blood > Provide arterial blood flow > Promote lymphatic and venous blood return to heart > Dilate and contract blood vessels to control blood flow > Maintain respiration --the largest muscle of respiration is the diaphragm > Perform digestion processes > Participate in reflexes > Enable all other involuntary actions of body -Protection > Protect body in emergency by reflex action > Cover, surround, and protect internal organs (viscera) > Support Internal organs -Miscellaneous > Produce heat > Assist in maintaining stable body temperature (in shivering, "goose flesh" and muscles give off heat >Provide shape of body

Synovial Joints

Further classified according to their structure and range of movement -Hinge (ginglymus) joints: allow movement in only one plane (flexion and extension), similar to door on hinge ; elbow, knee, and finger and toe joints between phalanges. Jaw, knee, and elbow joints and hinge joints but can move slightly side to side. -Ball-and-socket (spheroidal) joints: consist of rounded end of one bone that moves within a cup-shaped depression (the acetabulum) in the other bone, allowing movement in every direction. (shoulders and hips) -Pivot joints: consist of a bone pivoting or turning within a bony or cartilaginous ring. (wrist joint; turns forearm, in atlas; 1st cervical vertebra, and the head rotating on the axis; 2nd cervical vertebral) -Gliding (arthrodial, plane) joints: bones slide against each other (intervertebral joints, parts of wrists and ankle joints) -Condyloid joints: involve oval shaped head of one bone moving withing an elliptical cavity in another permitting all movements except axial rotation. (radius and carpal bones) -Saddle Joints: allow movements that can be shifted in several directions. these joints allow us to perform movements not present in most animals, picking up small objects (base of the thumb; carpometacarpal joints)

Axial Skeleton: Vertebral Column

Holds the head, allows twisting and bending, stiffens and supports the middle portion of the body and holds it upright and provides attachments for the ribs and pelvic bones. Spine also protects the spinal cord, which passes from the brain down though the vertebral foramina. -In children, vertebral column consists of 33 or 34 bones. Fusions of these bones occur, therefore most adults have 26 vertebrae. **Normal spine has 4 curves that help balance the body but disease, injury, and poor posture distort these curves. -Served by many blood vessels and nerves. -Two major ligaments stabilize vertebral column and help prevent spinal injuries. One extends from pelvic surface of the sacrum to the 1st cervical vertebra (C1, the atlas) and the occipital (skull) bone. Another weaker ligament runs within the vertebral canal and is attached mainly to the intervertebral discs. -Top 7 vertebrae (in the neck) are the cervical vertebrae. -1st cervical vertebrae, the atlas, supports the skull. -2nd cervical vertebra; the axis, has an especially wide surface so the head can turn freely -12 Thoracic vertebrae; directly below cervical vertebrae, which ribs are attached to - 5 lumbar vertebrae; next 5 vertebrae, located in the small of the back. - In adults the sacral vertebrae are fused together (the sacrum) which anchors the pelvis. -The spinal column ends in a single bone in adults, the coccyx (tailbone) **Children have 5 sacral vertebrae which fuse to form the sacrum. The last four vertebrae, the coccygeal vertebrae, are small and incomplete and later fused to form the coccyx.

Exercise Isometric and Isotonic Aerobic and Anaerobic

Isometric exercises do not increase the length of a muscle, but do increase muscle tension. (ex: pushing against immovable object or tensing the muscle, muscles with tighten. This is an isometric contraction/exercise) Isotonic contractions shorten and thicken the muscle, causing movement. (swimming, jogging, bicycling, person in bed can move extremities and move around in bed to exercise muscles) Aerobic exercise (using o2) involves long period of less than maximum exertion. Muscles are used for longer time but not maximally contracted. These exercises use a greater % of slow-twitch muscles; fat, carbohydrates, and protein all used for energy. Very little lactic acid is produced. (running a marathon) Anaerobic exercises (without oxygen) mostly fast twitch muscle fibers are used, at close to maximum contraction strength. ATP and glucose are main energy source, little O2 used, great deal of lactic acid produced, which inhibits ATP production. Anaerobic cannot be sustained for long period of time. (sprinting, weight lifting) -Training increases ability to eliminate waste products and to sustain contractions. Lactic acid can be used for energy or converted back to pyruvate by liver depending on level of training

Joints and Classifications

Joints or articulations are points at which bones join or attach to each other. They determine which motions are possible because of their attachments. Joints have a rich nerve supply which provide information about location in space (proprioception) and impulses to cause muscles to move. Classified according to degree of movement that stay permit: -Synarthroses (synarthrodial, fibrous, or fixed joints; Also called sutural ligaments) Not firmly fixed in infants, fused by adulthood due to interlocking projections and fibrous connective tissue growth. immovable in adults. >Most familiar are the joints between skull bones. Also call sutures because they are so tightly bound as if sewn together. A gomphosis is a fibrous joint in which it conical process is inserted into a socket as is a tooth in bony socket. -Amphiarthroses (amphiarthrodial or cartilaginous joints): slight degree of motion/flexible. (such as articulations between ribs and spinal column, symphysis pubis) >A synchrondosis is a joint in which cartilage is converted to bone by adulthood, as in coccyx. -Diarthroses (synovial joints);freely moveable allowing movement in various directions. Lined with synovial membrane secretes synovial fluid. some synovial joints contain bursa;fluid filled sacs that cushions movements of muscle and tendons. Different types: *Hinge joints: like hinge on door (finger, elbow, and knee joints *Ball-and-socket joints: rotation (shoulders and hips) *Pivot joints: motion like turning doorknob (wrist turns forearm) *Gliding joints: gliding motion (wrist) *Condyloid joints: allow motions in to planes at tight ankles (wrist, foot, hand) *Saddle Joints: fit together lile two saddles with riding surfaces together (thumb)

Power Source

Major function of muscles is to produce force and cause motion. This requires energy. -Foods furnish carbon, hydrogen, and oxygen. Body uses these to make glycogen (sugar), a special form of stored glucose the body uses for fuel. Glucose is metabolized in anaerobic process (without oxygen), glycolysis into materials including lactic acid (latte) and ATP; stored and used for energy. -Aerobic process (using oxygen) creates even more ATP, yielding pyruvate, but no lactic acid. -Muscles break down fatty acids and conserve energy as creatine phosphate, generated from ATP (ATP can be regenerated in body, using creatine kinase) -Muscle fibers also use proteins 'myosin' and 'actin' and other substances to carry out muscle contractions. (ATP powers the myosin) The reaction between these substances creates a contraction. -Blood brings oxygen and ATP, which react with one another (oxidation) to the muscle cells. Resulting from this oxidation (aerobic) is energy and heat. (Most body heats generates from muscle activity) -When muscles are very active, they draw on stored glycogen. When body is cold, muscles can automatically produce heat by general muscles (shivering). To produce great amount of heat in emergency, body produces more violent action of 'total body chilling' -Oxidation also produces waste products: CO2+lactic acid. Blood carries CO2 to the lungs, removed by breathing, and urinary system and sweat glands remove the lactic acid. -Vigorous or prolonged muscle action quickly depletes oxygen. Because they are fast-twitch muscles, skeletal muscles cannot remain contracted for a long time. Gradually due to lack of 02, muscle becomes fatigued and painful, may ache after prolonged use or exercise. **Muscle cell + fuel and oxygen-->heat and energy--> by products: lactic acid and CO2 KEY CONCEPT: -Cardiac muscles can easily use any of the nutrients, protein, glucose, or fat in a aerobic process. This does not require a warm up period and yields maximum ATP. -Lactic acid is rapidly dispersed from muscles via the liver and RBC. Soreness after exercise is usually the result of tiny tears in muscle fibers and 02 depletion.

Muscle Tone

Muscles remain in mild state of contraction to help maintain balance because humans stand erect against gravity's constant pull. These are slow-twitch muscles. Muscle tone (tonus) is the state of slight contraction and the ability to spring into action. -Physical exercise improves muscle tone and increases muscle size. Idle muscles loses tone and wastes away. If not in use, they become flabby and weak (atonic) and may atrophy (waste away)

Structure of Skeletal Muscles

Skeletal Muscles are considered Organs -Posses multinucleated cells and connective tissue framework. Several layers of this connective tissue lie in sheets and cords beneath, the skin, covering the bones. -Muscle fibers are made up of many thin elongated threads called myofilaments (myofibrils). -The contractile unit of the myofibril is the sarcomere, many of which make up one myofibril. -Myosin and actin are the contractile elements of muscle fibers, the basic functional unit of the muscle. (Myosin, principle muscle protein, combines with actin to form actomyosin, to create the contractile property of the muscle. This process is facilitated by ATP) -Each muscle cell is covered by cell membrane; the sarcolemma. This is covered by endomysium. -Individual muscle fibers are bound together by perimysium into bundles called fascicles; # of fascicles form a single muscle. The total muscle covered by epimysium. (In many cases, epimysium extends beyond the muscle as a tendon, which is then attached to a bone. -Each muscle covered by a sheath of connective tissue (fascia), which separates individual muscles or surrounding muscle groups, forming compartments. -The origin; on the end of the muscle, relatively immobile and is attached to more stationary of two bones. the 'insertion' is the part o the muscle attached to the more mobile bones. The leverage strength depends on the origin and insertion of the muscles. (the longer the lever in proportion to the part being moved, the greater the mechanical advantage. -The main part of the muscle is belly. The fibrous muscle tissue that covers that covers bone is periosteum, which is continuous with collagen fivers, forming tendons and ligaments. KEY CONCEPT: Average adult male is 40-50% skeletal muscle, the average female is 30-40%

Ligaments

Strong fibrous bands that hold bones together. -Accessory ligaments do not move move or stretch, but strengthen or support other ligaments to produce stability in a joint. -Some connect bones to muscles or cartilage. -Also support internal organs and structures. Many ligaments allow for great flexibility, stretching, and movement. -Ligament is said to 'arise' or originate in the bone or structure that is more stationary. It is said to 'insert' into the bone that does most of the movement.

Diaphragm and Intercostals

The diaphragm is one of the body's most vital muscles. The intercostal muscles lie between the ribs. The diaphragm and intercostals are the primary muscles for respiration.

Tendons

The ends of muscle fascia lengthen into tough cords called tendons, attaching muscles to bones. -Have sheaths lined with synovial membrane, that permitting smooth gliding movement. Ex: place hand on back of calf and slide down to ankle. A leg and muscles become narrower, the tissues become tough, fibrous, and rope-like. This occurs approx. halfway to the ankle, the muscle is attached to the Achilles tendon, which extends down to heel.

Axial Skeleton: The Skull

The membranous areas between an infant's cranial bones (soft spots) called fontanels. -Anterior (front) fontanel is diamond shaped -Posterior fontanel is triangular. Skull is covered by true scalp, made up of 3 layers Layers of the SCALP S:skin, 1st layer, thin made up of sweat and sebaceous glands and hair follicles. Scalp has good supply and lymphatic drainage. C: connective tissue; middle layer, loose connective tissue including vascular and cutaneous nerves. A: aponeurosis; inner layer, tendinous sheet, also called epicranius. L: loose connective tissue; under true scalp, made up of sponge-like spaces, allowing limited movement of the scalp proper. P: pericranium; dense connective tissue which is the external periosteum of the cranium. -Upper jawbone: two maxilla that fuse together to create. -Lower jawbone: the mandible, the only movable facial bone. Can move up, down. and sideways, as well as forward (protection) and backward (retraction). Hyoid: small horseshoe like shaped bone, lies just behind and below the mandible directly above the larynx. Not directly attached to any skull bone; attached by muscles and ligaments and seems to float. Tongue muscles are attached to the hyoid bone, to assist in swelling and speaking 4 pairs of cavities in cranial bones that make skull lighter and enhance vocal sounds. Frontal, ethmoid, sphenoid, and maxillary. sinuses are lined with mucous membrane continuous with nasal mucosa and drain into nasal cavity.

Muscle Classification -Skeletal Muscle -Smooth Muscle -Cardiac Muscle

Three types of muscle tissue by function skeletal, smooth, and cardiac. -Skeletal muscle and cardiac muscles are striated, consisting of fibers marked by bands and appearing striped. -Smooth muscle is non-striated -Muscle tissue is approx. 18% denser than adipose (fat) tissue. *Skeletal Muscles* -(Voluntary Striated) control skeletal movements and are under voluntary (conscious) control. -There are more than 630 skeletal muscles in the body, approx. 40% of body weight. -Functions: locomotion, facial expression, and posture. Two Types of Voluntary Muscle: -fast-twitch, contract quickly and powerfully, but encounter rapid, fatigue, and -slow-twitch, those which can sustain a contraction, but do not exert force. **Skeletal Muscles are attached to bones. They are voluntary; produces movement at joints; stimulated by nervous system; contracts and relaxes rapidly; produces heat through aerobic production of energy; assists in blood return to heart *Smooth Muscle* - controls involuntary motion inside body organs and structures -Forms parts of walls of blood vessels and hollow internal organs (viscera). Controls involuntary motions and is also known as involuntary or visceral muscle. -Responsible for actions such as propelling urine through urinary tract, moving food in digestive track, dilating pupils, and activating arrector pili in skin. Also controls blood vessel dilation and contraction to assist in circulation and blood pressure maintenance. Smooth muscles are capable of sustained or rhythmic contractions and can also respond to nervous stimulation in emergencies. -Located in wall of hollow organs, vessels, respiratory passageways. Responsible for peristalsis, contracts and release slowly; may sustain contraction; helps maintain blood pressure by regulating size of arteries. *Cardiac Muscle*- responsible for propelling blood through blood vessels. -Involuntary striated -The middle layer of the heart (myocardium), propels blood through blood vessels. -These muscles connect at irregular angles, called intercalated discs. -Cardiac striated muscle works automatically and contracts and relaxes in short, intense bursts. -Structure is similar to skeletal muscle, even though its involuntary. Located in the wall of heart. Pumps blood out of heart; self-excitatory, but influenced by nervous system and hormones.

Appendicular Skeleton: The Pelvic Girdle

Two large, irregularly shaped innominate hip bones (oscoxae) attach posteriorly to the sacrum to form the pelvic girdle or pelvis. -Supports the spinal column and protects parts of the digestive, urinary, and reproductive systems. Pelvic bones spread out at the top and become narrow at their front lower edges -illum: the upper flaring portion of the pelvis, identified as hip bone. -ischium: lower, stronger portion. -Symphysis pubis: where the two pubic bones meet in the front and are joined by a pad of cartilage **Connected to the sacrum and coccyx posteriorly, these bones from the pelvic cavity, which houses the urinary bladder, the rectum, uterus and ovaries(in women), prostate and some glands within penis (males). -Angles of the pelvic opening (pubic arch) is less than 90 degrees in men and greater than 90 degrees in women. In the fetus, pelvic bones develop as 2 separate bones known as the illium, ischium, and pubis, which usually fused by about age 25

Cartilage

Type of connective tissue organized into a system of fibers. Has not blood supply and recieves oxygen and nutrients by diffusion. Soft and flexible, 3 major types: -Articular (hyaline) cartilage: somewhat elastic and semi-transparent, has a bluish tint and covers the ends of long bones (knee and hip joints). Has a slick surface and helps to reduce friction in joints and distribute weight evenly, and absorbs shock to the body. -Fibrous cartilage (fibrocartilage): Strong rigid, as in symphysis pubis. >>Fibrous connective tissue surrounding cartilage (except is joint) is called perichondrium. -Elastic (reticular) cartilage: Opaque and has yellowish tint, most pliable as in auditory canal. **Childrens bones are more pliable than those of adults. Some infant bones at birth are entirely cartilage, some cartilage and bone. childrens bones can bend more easily, helping to prevent fractures. Cartilage slowly replaced by bone as child matures.

Appendicular Skeleton: Upper Extremities

Upper extremities include the shoulders and arms. Four bones form the shoulder girdle, which anchors the arm -Clavicles (collar bones): two long, thin bones attached to the sternum and extend outward at a right angle to it on either sides. -Scapula: opposite the clavicles on each side of the back, also called shoulder blade. It is a flat, triangular bone attached to the outer end of the clavicle on the skeleton. It attaches the trunk of the body medially with manubrium of the sternum. Gives free movement to shoulders and arms. -Humerus: the long bone in the upper arm. Upper end attached to the scapula, and lower end meets the two forearm bones to from the elbow joint. -Ulna: one of two bones in forearm, Larger one, two hollows, or depressions in the upper end of the ulna provide positoning for other bones. One depression holds the lower end of the humerus, other holds the upper end of the radius. -Radius: one of two bones in forearm, smaller one -The 8 carpal bones, wrist bones, are small irregular bones that support the base of palm. They are attached to the radius, the ulna, and five long, slender, and slight curved metacarpal bones forming the palm of the hand. The other ends of the metacarpals attach the phalanges, or finger bones. Three phalanges are in each finger and two in each thumb, with joints between each phalanx; any bone of either a finger or a toe