Skeletal System PDF

SKELETAL SYSTEM o Two thin layers of compact bone surround a layer of spongy bone Components of the Skeletal System ▪ Ex. SKULL, RIBS, - Bones...

SKELETAL SYSTEM o Two thin layers of compact bone surround a layer of spongy bone Components of the Skeletal System ▪ Ex. SKULL, RIBS, - Bones and STERNUM - Cartilages - Tendons - Ligaments Two (2) Subdivisions of the Skeleton - AXIAL - APPENDICULAR Functions of the Skeletal System 1. Support 2. Movement - Irregular bones 3. Protection o Irregular shape 4. Blood cell formation o Do not fit into other bone 5. Storage classification categories o Minerals ▪ Ex. VERTEBRAE o Triglyceride storage and HIP BONES Bones of the Human Body - Skeleton has 206 bones - Two basic type of bone tissue o Compact bone ▪ Dense and looks smooth ▪ Homogenous o Spongy bone ▪ Small needle-like - Long bones pieces of bones o Typically, longer that they ▪ Has many open are wide spaces o Shaft with heads situated at both ends o Contains mostly compact bone o Bones of the Limbs (except: wrist, ankle, and kneecap bones) ▪ Ex. FEMUR and Classifications of Bones (shape) HUMERUS - Flat bones o Thin, Flattened, and usually Curved - Short bones Bone Strength o Generally, cube-shaped - The structure of the bones makes it o Contains mostly spongy both strong and light weight bone - (adult) 20% of the weight is bones o Includes bones in the wrist - Bones are made up of two (2) and ankles minerals o Sesamoid bones in the o CALCIUM tendons o PHOSPHORUS ▪ Ex. CARPALS and TARSALS Anatomy of a LONG BONE - Diaphysis o Makes up most of the bone length o Composed of compact bones - Epiphysis (ends: proximal and distal) o Mostly composed of spongy bone enclosed by a - Sesamoid bones (in joints) thin layer of compact bone o Found in: ▪ The knee- patella (the largest sesamoid bone) ▪ The hand- distal portions of the first metacarpal and second metacarpal bone. ▪ The wrist- pisiform of the wrist ▪ The foot- first metatarsal bone - Articular cartilage o Covers the external surface of epiphyses o Made up of hyaline cartilage o Decreases friction at joint surfaces - Periosteum o Outside covering of the diaphysis o Fibrous connective tissue membrane  - Epiphyseal line - Central (Haversian) canal o Remnant of the epiphyseal o Opening in the center of an plate osteon o seen in adult bones o Carries blood vessels and - Epiphyseal plate nerves o Flat plate of hyaline - Osteon (haversian system) cartilage seen in young, o Contains central canal and growing bones matrix rings o Causes lengthwise growth o Structural and functional of long bones unit of compact bone - Endosteum - Canaliculi o lines the inner surface of o Tiny canals the shaft o Forms a transport system o made of connective tissues connecting all bone cells to - Medullary cavity a nutrient supply o Cavity inside the shaft - Perforating (volkmann’s) canal o Contains yellow marrow o Canal perpendicular to the (fats) central canal o Contains red marrow for o Carries blood vessels and blood cell formation in nerves infants until age 6 or 7. Structure of Bone How bones DEVELOP - (infant) most skeleton is cartilage - Cartilage: strong and flexible tissue - Over time, cartilage is replaced by solid bone, usually completed by the end of growth. - Not all cartilage is replaced in adults; many joints retain cartilage. - Cartilage protects the ends of bones, such as in the ears and joints. Bone Formation, Growth, and Bone Fractures Remodelling - Fracture: break in a bone - Occurs on hyaline cartilage models - TYPES: or fibrous membranes o Closed (simple) - Long bone growth involves two ▪ a break that does not major phases penetrate the skin - Ossification o Open (compound) o the process of bone ▪ a broken bone that formation penetrates the skin - Bone fractures are treated by reduction and immobilization - Osteogenic cell or osteoprogenitor o Closed reduction cells ▪ bones are manually o mitotically active stem cells coaxed into position found in the membranous by physician’s periosteum and endosteum. hands. o Stem cell o Open reduction - Osteoblasts ▪ bones are secured o bone forming cells with pins or wires o matrix-synthesizing cell during surgery. responsible for bone - Healing time is 6–8 weeks growth - Repair of bone fractures involves - Osteocytes four major events: o mature bone cells; monitor 1. Hematoma (blood-filled and maintain the bone swelling) is formed matrix. 2. Break is splinted by - Osteoclasts fibrocartilage to form a o giant bone-destroying callus cells 3. Fibrocartilage callus is o Break down bone matrix replaced by a bony callus for remodelling 4. Bony callus is remodelled o Bone remodelling is to form a permanent patch performed by both osteoblasts and osteoclasts o Bone-resorbing cell  o only the mandible is attached by a freely movable joint o 8 cranial bones protect the brain ▪ 1 Frontal bone ▪ 2 Occipital bone ▪ 3 Ethmoid bone ▪ 4 Sphenoid bone AXIAL SKELETON ▪ 5, 6 Parietal bones (pair) - Forms the longitudinal axis of the ▪ 7, 8 Temporal bones body (pair) - Divided into three parts: o 14 facial bones o Skull ▪ 1, 2 Maxillae (pair) o Vertebral Column ▪ 3, 4 Palatine bones o Bony Thorax (pair) ▪ 5, 6 Lacrimal bones (pair) ▪ 7, 8 Zygomatic bones (pair) ▪ 9, 10 Nasal bones (pair) ▪ 11 Vomer bone ▪ 12, 13 Inferior nasal conchae (pair) ▪ 14 Mandible SKULL - Two sets of bones form the skull o Cranium bones ▪ Encloses the brain o Facial bones ▪ Hold eyes in anterior position ▪ Allow facial muscles to express feelings o bones are joined by sutures  - Growth of cranium after birth is related to brain growth o Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways “The growth of the skull in harmony with the brain. As the brain grows, the skull (Developmental Aspects of the Skeleton) must grow in response to accommodate - FETAL SKULL extra volume while providing a tight fit.” o Fontanels are fibrous - Size of cranium in relationship to membranes connecting the body cranial bones o 2 years old—skull is three- ▪ Known as “soft fourths the size of adult spots” skull ▪ Allow skull o 8 or 9 years old—skull is compression during near adult in size and birth proportion ▪ Allow the brain to o Between ages 6 and 11, the grow during later face grows out from the pregnancy and skull infancy - Skeletal changes ▪ Usually ossify by 2 o At birth, the head and trunk years of age are proportionately much longer than the lower limbs o During puberty: ▪ Female pelvis broadens ▪ Entire male skeleton becomes more robust SKULL VERTEBRAL COLUMN (Spine) - Paranasal sinuses - Provides axial support o Hollow portions of bones o Extends from skull to surrounding the nasal cavity pelvis - Functions of paranasal sinuses - 26 vertebral bones are separated o Lighten the skull by intervertebral discs o Amplify sounds made as o 7 cervical vertebrae are in we speak the neck o 12 thoracic vertebrae are in the chest region o 5 lumbar vertebrae are associated with the lower back o Sacrum (formed by the fusion of 5 vertebrae) o Coccyx (formed by the fusion of 3-5 vertebrae) - Hyoid bone o The only bone that does not articulate with another bone o Serves as a movable base for the tongue o Aids in swallowing and speech - Primary curvatures BONY THORAX (Thoracic Cage) o Spinal curvatures of the - Protects the organs of the thoracic thoracic and sacral region cavity o Present from birth - Consists of three parts: o C-shaped curvatures o Sternum (newborn) o Ribs - Secondary curvature ▪ True ribs o Spinal curvatures of the (pairs 1–7) cervical and lumbar ▪ False ribs regions (pairs 8- 12) o Develop after birth ▪ Floating ribs o S-shaped (adults) (pairs 11–12) o Thoracic vertebrae - Parts of a typical vertebra ▪ T1 – T12 o Body (centrum) o Vertebral arch o Pedicle o Lamina o Vertebral foramen o Transverse processes o Spinous process o Superior and inferior articular processes APPENDICULAR SKELETON BONES OF THE UPPER LIMBS - Composed of 126 bones - Humerus: upper limb o Limbs (appendages) - Ulna: forearm o Pectoral girdle - Radius: forearm o Pelvic girdle - Carpals: wrist - Metacarpals: hand BONES OF THE SHOULDER GIRDLE - Hand - Also called pectoral girdle o Carpals- wrist - Composed of two bones that attach ▪ 8 bones arranged in the upper limb to the axial skeletal two rows of 4 bones o Clavicle in each hand o Scapula o Metacarpals- palm bones ▪ 5 per hand o Phalanges- fingers and thumb ▪ 14 phalanges in each hand ▪ Each finger= 3 bones ▪ Thumb= 2 bones BONES OF THE PELVIC GIRDLE - Where lower limbs attach to the body - Composed of three pairs fused bones: o Ilium o Ischium o Pubis - Pelvic girdle = two coxal bones, sacrum - Pelvis = two coxal bones, sacrum, coccyx - Foot o Tarsals- 7 bones ▪ Two largest tarsals: Calcaneus Talus o Metatarsals- 5 bones from the sole of the foot o Phalanges- 14 bones from the toes BONES OF THE LOWER LIMBS - Femur: thigh bone o The heaviest and strongest bone in the body - Patella: kneecap - Tibia: large lower leg - Fibula: small lower leg JOINTS o bending of neck or body toward left or right side - Types of synovial joints based on shape o Plane joint o Hinge joint o Pivot joint o Condylar joint o Saddle joint o Ball-and-socket joint Abduction, Adduction, and Circumduction - (e) Abduction: o Moves a limb, finger, toe, or thumb away from the midline of the body. - Adduction: o Moves a limb, finger, toe, or thumb toward the midline of the body. - Circumduction: o Movement in a circular motion. o Involves a combination of flexion, adduction, extension, and abduction at a joint. MOVEMENTS AT SYNOVIAL JOINTS Flexion and Extension - (a) Flexion o reduces the angle of the joint from resting position - (b) Extension o returns joint to resting position - (c) Hyperextension o increases joint angle beyond 180 degrees - (d) Lateral flexion Rotation Dorsiflexion and Plantar Flexion - (f) Rotation - Movements of the ankle joint o twisting movement - (h) Dorsiflexion - Medial rotation o moves top of foot toward o moves anterior of a limb anterior leg toward midline - Plantar flexion - Lateral rotation o lifts heel away from o moves anterior of a limb ground or points toes away from midline toward ground Inversion and Eversion - (i) Inversion o movement that turns bottom Supination and Pronation of foot toward midline - Movements of the forearm - Eversion - (g) Supination o movement that turns bottom o moves palm toward facing of foot away from midline posteriorly - Pronation o moves palm toward facing anteriorly Protraction and Retraction - (j) Mandible o Protraction ▪ jaw is pushed forward o Retraction ▪ returns jaw to resting position - Scapula o Protraction ▪ shoulder moves forward o Retraction ▪ scapula pulled posteriorly and Opposition and Reposition medially - (l) Opposition o moves tip of thumb in contact with a finger - Reposition o returns thumb to its anatomical position AMEN. Depression and Elevation - (k) Mandible o Depression ▪ downward movement o Elevation ▪ upward movement - Scapula o Depression ▪ downward movement o Elevation ▪ upward movement o Think “shrugging shoulders”