Bones & Skeletal Tissue - Big Lecture Note

University:
North Idaho College
Course:
NURS 201 | Fundamentals Of Nursing
Academic year:

2021
Views:

126

Pages:

100
Author:

MichGar

Bones & Skeletal Tissue INTRODUCTION The skeletal system includes: Bones Cartilages Joints Ligaments Other connective tissues Composition of Bone (Extracellular) Matrix Inorganic components hydroxyapatites calcium and phosphate deposits 65% of bone by mass responsible for bone hardness Fibers collagen provides an ability of bone to ﬂex slightly without fracturing FUNCTIONS Support Movement: muscles attach by tendons and use bones as levers to move body Protection Skull – brain Vertebrae – spinal cord Rib cage – thoracic organs Mineral storage Calcium and phosphorus Released as ions into blood as needed Blood cell formation and energy storage Bone marrow: red makes blood, yellow stores fat TYPES OF THE SKELETON Axial skeleton - forms long axis of body Skull Vertebral column Thoracic cage Appendicular skeleton – appendages and what they attach to Upper limbs (arms) Pectoral girdle (shoulder) Lower limbs (legs) Pelvic girdle Axial Skeleton Skull Sternum Ribs Vertebral Column Skull Divided into two parts: a) Calvaria =8 bones b) Face =14 bones Cranial bones frontal parietal temporal occipital parietal parietal _______sphenoid _____ethmoid occipital Facial bones: Mandible Vomer Maxillae (paired) Zygomatics (paired) Nasal (paired) Lacrimal (paired) Palatines (paired) Inferior nasal conchae (paired) Hyoid bone Only bone which does not articulate with any other bone Moveable base for the tongue Points of attachment for neck muscles that raise and lower the larynx during swallowing Vertebral Column 7 Cervical Vertebrae (of the neck) Lumbar vertebra, lateral view 12 Thoracic Vertebrae (of the chest) Lumbar vertebra, superior view 5 Lumbar Vertebrae (of the lower back) Sacrum (mid-line region of buttocks) Coccyx (4 or 5 fused vertebrae of the tail bone) Structure of a typical vertebra Cervical vertebrae (C1-C7) C1 (atlas) C2 (axis) Cervical Vertebrae Smallest Lightest Most ﬂexible Triangular vertebral foramen Transverse processes have foramina (transverse foramen) Spinous process biﬁd (forked) except for C7 Thoracic Vertebrae T1-T12 Heart shaped body Additional small costal facets (costal=ribs) Round or oval vertebral foramen Form posterior part of rib cage Lumbar Vertebrae L1-L5 Massive blocklike bodies Short, thick hatchet-shaped spinous processes Limited mobility The Sacrum Shapes posterior wall of pelvis Composite bone of 5 fused vertebrae Sacral foramina allow passage of vessels & nerves Coccyx (the tailbone) The Thoracic Cage Sternum Ribs Manubrium True ribs 1-7 Body False ribs 8-12 Xiphoid process Floating ribs 11,12 The Ribs Manubrium Sternal Body True Ribs (1-7) Xiphoid Process Costal Cartilages False Ribs (8-10) Floating Ribs (11-12) Sternum Mid-line breast bone The clavicles and ribs one to seven articulate with the sternum Sternum – comprised of the manubrium, sternal body and xiphoid process Ear Bones Malleus (2): the hammer Incus (2): the anvil Stapes (2): the stirrup Appendicular skeleton Consists of: ▪ 1. The pectoral gridle (chest) ▪ 2. Pelvic girdle (hip) ▪ 3. The upper limbs ▪ 4. The lower limbs Clavicle 1.Pectoral Girdle Consists of: Scapula (shoulder blade) Scapula Clavicle (collar bone) ■ ■ Allows the upper limb great mobility The sternoclavicular joint is the only point of attachment between the axial skeleton and the pectoral girdle 2. Pelvic Girdle Formed by pair of os coxae (hip bones) supports the bladder and abdominal contents Attachment: Posteriorly – join with the sacrum Anteriorly - join to each other anteriorly Laterally – join to the head of thigh bone through a cup-shaped acetabulum 3. Upper Limb Humerus Humerus The arm bone shoulder to elbow Radius and Ulna The forearm bones elbow to wrist Radius Ulna Upper Limb Cont. Carpals Proximal Phalanx Metacarpals Phalanges Distal Phalanx Middle Phalanx Upper Extremities Humerus: upper arm Radius: thumb side of forearm Ulna: little ﬁnger side of forearm Carpals (8): wrist bones Metacarpals (5): hand bones Phalanges (14): ﬁnger bones 4. Lower Limb Femur thigh bone Femur from hip to knee Patella knee cap sesamoid bone in the tendon of the quadriceps muscles (thigh) Patella Lower Limb Cont’d Tibia and Fibula leg bones From knee to ankle Tibia is medial and ﬁbula is lateral Fibula Medial malleolus and Lateral malleolus The distal ends of the tibia and ﬁbula, respectively commonly referred to as the "ankle bones" can be easily palpated Tibia Lat. malleolus Med. malleolus Lower Limb Cont’d Talus Tarsals ankle bones calcaneus or the heel bone talus Metatarsals Calcaneus 5 bones of the foot Tarsals unite with the toes Phalanges toe bones three per toe except the big Metatarsals toe - proximal, middle and distal Phalanges Lower Extremities Femur: thigh bone Patella: kneecap Tibia: shin bone Fibula: lateral bone of lower leg Tarsals (7): ankle bones; talus and calcaneus Metatarsals (5): foot bones Phalanges (14): toe bones; great toe = halux Divisions of the Skeletal System Copyright 2009, John Wiley & Sons, Inc. CLASSIFICATIONS OF BONES 1.Classiﬁcation according to the shape. 2.Structural Classiﬁcation. 3.Developmental Classiﬁcation. 4.Regional classiﬁcation. Classification of bones by shape Long bones Short bones Flat bones Irregular bones Pneumatized bones Sesamoid bones Accessory bones Heterotopic bones. (Short bones include sesmoid bones) Classification of Bones 1.Long bones ∙ Typically longer than wide ∙ Have a shaft with heads at both ends ∙ Contain mostly compact bone • Examples: Femur, humerus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.4a Classification of Bones 2.Short bones ∙ Generally cube-shape ∙ Contain mostly spongy bone ∙Examples: Carpals, tarsals Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.4b Classification of Bones on the Basis of Shape Figure 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.4c Classification of Bones 3.Flat bones ∙ Thin and flattened ∙ Usually curved ∙ Thin layers of compact bone around a layer of spongy bone ∙Examples: Skull, ribs, sternum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.5a 4.Irregular bones ∙ Irregular shape ∙ Do not fit into other bone classification categories ∙Example: Vertebrae and hip Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.5b 5.Pneumatic Bones have air spaces within them which makes them lighter than more solid bone. They are only found in the skull. An example of a pneumatic bone is the Sphenoid bone. Maxilla 6.Sesamoid bones • Sesamoid bones are small • • • • more or less rounded masses embedded in certain tendons and usually related to joint surfaces. Their functions probably are to modify pressure to diminish friction, and occasionally to alter the direction of a muscle pull Example:patella,pisiform.fabella 8.Accessory bones. • They are not always present. • These may occur as ununited epiphyses developed from extra centres of ossiﬁcation. • Example:sutural bone,os trigonum,os vesalianum 8.Heterotopic bones irregular nodules of bone may appear as the result of intermittent pressure in certain regions, e.g., the “rider’s bone,” which is occasionally developed in the Adductor muscles of the thigh. Bone Classification(structural) According to the degree of porosity, bone can be classiﬁed into two general categories:MACROSCOPICALLY Cortical bone (low porosity) Spongy or cancellous bone (high porosity) Bone Composition Bone is very strong for its relatively light weight The major components of bone are: Cortical Bone Spongy Bone Calcium carbonate Calcium phosphate Collagen Water Medullary (marrow) cavity Gross Anatomy of Bones Compact bone – dense outer Spongy bone – internal layer of bone. It texture like ivory They have adaption for bending and twisting force network of bone Made up of meshworks of trabeculae of rods and plates. They adapt for compressive force. Body of Mandible Histology of Compact Bone Osteon – the structural unit of compact bone Lamellae – column-like matrix tubes composed of collagen and crystals of bone salts Central canal - (Haversian canal) canal containing blood vessels and nerves The Structure of Spongy Bone No osteons Lamellae as trabeculae Arches, rods, plates of bone Branching network of bony tissue Strong in many directions Red marrow (blood forming) spaces Cancellous bone Compact Bone •Porosity •High (Low mineral content and high collagen) •Low (High mineral content and low collagen) •Structure •Honey comb •Compact •Characteristic •Provides more flexibility but is not as stress resistant •Stiffer and can resist greater stress but less flexible •Function •Shock absorption due to its better ability to change shape are important •Withstanding stress in body areas that are subject to higher impact loads •Location •e.g., vertebrae •Long bones (e.g., bones of the arms and legs) Bone markings reﬂect the stresses MICROSCOPICALLY I. II. III. IV. V. Lamellar bone Woven bone Fibrous bone Dentine Cement Developmental Classification Membranous(dermal): ossify in Somatic bone Cartilaginous: ossify in Visceral bone: They develop from pharengeal arches,example:Hyoid bone,ear ossicles. membrane(intramembranous or mesenchymal ossiﬁcation)e.g.,facial bones. cartilage(intracartilaginous or endochondral ossiﬁcation)e.g.,vertibral column Membrano Cartilaginous: ossify partly in membrane and partly in cartilage.e.g.,clavicle,madible,occi pital,temporal,sphenoid. MOCST Gross Anatomy of a Long Bone ∙ Diaphysis ∙ Epiphysis ∙ Metaphysis Figure 5.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.6 Diaphysis It is the elongated shaft of a long bone which ossifies from a primary centre. TYPES OF EPIPHYSIS There are four types of epiphysis: 1.Pressure epiphysis: the region of the long bone that forms the joint is a pressure epiphysis (e.g. the head of the femur, part of the hip joint complex). Pressure epiphyses assist in transmitting the weight of the human body and are the regions of the bone that are under pressure during movement or locomotion. Another example of a pressure epiphysis is the head of the humerus which is part of the shoulder complex Traction epiphysis: the regions of the long bone which are non-articular, i.e. not involved in joint formation. Unlike pressure epiphyses, these regions do not assist in weight transmission. However, their proximity to the pressure epiphysis region means that the supporting ligaments and tendons attach to these areas of the bone. Traction epiphyses ossify later than pressure epiphyses. Examples of traction epiphyses are tubercles of the humerus (greater tubercle and lesser tubercle), and trochanters of the femur (greater and lesser). Atavistic epiphysis: These types of fused bones are called atavistic; e.g. the coracoid process of the scapula which has been fused in humans but is separate in four-legged animals. ABERRANT EPIPHYSIS: these epiphyses are deviations from the norm and are not always present. For example, the epiphysis at the head of the first metacarpal bone. METAPHYSIS Epiphysis end of diaphysis is called metaphysis. Hair pin bend formed by end arteries. Common site for osteomyelitis in childrean Adult no more end arteries STRUCTURES OF A LONG BONE ∙ Periosteum ∙ Outside covering of the diaphysis ∙ Fibrous connective tissue membrane ∙ Sharpey’s fibers ∙ Secure periosteum to underlying bone ∙ Arteries ∙ Supply bone cells with nutrients Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5.2c Slide 5.7 STRUCTURES OF A LONG BONE ∙ Articular cartilage ∙ Covers the external surface of the epiphyses ∙ Made of hyaline cartilage ∙ Decreases friction at joint surfaces Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5.2a Slide 5.8a STRUCTURES OF A LONG BONE ∙ Medullary cavity ∙ Cavity of the shaft ∙ Contains yellow marrow (mostly fat) in adults ∙ Contains red marrow (for blood cell formation) in infants Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5.2a Slide 5.8b Epiphysial plate of cartilage It separates epiphysis from metaphysis. Proliferation of cell in cartilage growth plate is responsible for growth of bones. BLOOD SUPPLY OF LONG BONES Terms (examples) chondro refers to cartilage chondrocyte endochondral perichondrium osteo refers to bone osteogenesis osteocyte periostium blast refers to precursor cell or one that produces something osteoblast cyte refers to cell osteocyte Formation of the Skeleton Before week 8, the skeleton of a human embryo consists of ﬁbrous membanes and hyaline cartilage Intramembranous ossiﬁcation – bone develops from a ﬁbrous connective tissue membrane. The ﬂat bones of the skull (frontal, parietal, temporal, occipital) and the clavicles are formed this way. Endochondral ossiﬁcation – bone forms by replacing hyaline cartilage, uses hyaline cartilage “bones” as patterns Bone Formation in 16-Week-Old Fetus Bone Formation and Growth Intramembranous Ossiﬁcation Ossiﬁcation—Process of converting other tissues to bone Forms ﬂat bones of skull, mandible, clavicle Stem cells diﬀerentiate to osteoblasts Produces spongy bone, then compact bone Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Intramembranous Ossification An ossiﬁcation center appears in the ﬁbrous connective tissue membrane Osteoblasts secrete bone matrix within the ﬁbrous membrane Osteoblasts mature into osteocytes Intramembranous Ossification The bone matrix develops into trabeculae. The trabeculae formed from various ossiﬁcation centers fuse with one another to create spongy bone. Eventually the spaces between trabeculae ﬁll with red bone marrow. Bone Formation and Growth Endochondral Ossiﬁcation Most bones formed this way Cartilage model replaced by bone Replacement begins in middle (diaphysis Replacement follows in ends (epiphyses) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Endochondral Ossification Chondrocytes at the center of the growing cartilage model enlarge and then die as the matrix calicifies. Newly derived osteoblasts cover the shaft of the cartilage in a thin layer of bone. Blood vessels penetrate the cartilage. New osteoblasts form a primary ossification center. The bone of the shaft thickens, and the cartilage near each epiphysis is replaced by shafts of bone. Blood vessels invade the epiphyses and osteo-blasts form secondary centers of ossification. Articular cartilage Enlarging chondrocytes within calcifying matrix Epiphysis Diaphysis Bone formation Marrow cavity Primary ossification center Blood vessel Marrow cavity Blood vessel Epiphyseal cartilage Secondary ossification center Cartilage model Figure 6-5 1 of 6 Longitudinal Bone Growth Longitudinal Growth (interstitial) – cartilage continually grows and is replaced by bone Bones lengthen entirely by growth of the epiphyseal plates Cartilage is replaced with bone as quickly as it grows Epiphyseal plate maintains constant thickness Epiphyseal Plate Cartilage is organized for quick, eﬃcient growth Cartilage cells form tall stacks Chondroblasts at the top of stacks divide quickly Pushes the epiphysis away from the diaphysis Lengthens entire long bone Older chondrocytes signal surrounding matrix to calcify, then die and disintegrate Leaves long trabeculae (spicules) of calciﬁed cartilage on diaphysis side Trabeculae are partly eroded by osteoclasts Osteoblasts then cover trabeculae with bone tissue Trabeculae ﬁnally eaten away from their tips by osteoclasts Appositional Bone Growth Growing bones widen as they lengthen Appositional growth – growth of a bone by addition of bone tissue to its surface Bone is resorbed at endosteal surface and added at periosteal surface Osteoblasts – add bone tissue to the external surface of the diaphysis Osteoclasts – remove bone from the internal surface of the diaphysis Figure 6-6 Medicolegal and anthropological aspects Whether the bones are human of not Whether they belong to one or more persons The age of individual The sex The stature THE TIME AND CAUSE OF DEATH Factors regulating bone growth Vitamin D: increases calcium from gut Parathyroid hormone (PTH): increases blood calcium (some of this comes out of bone) Calcitonin: decreases blood calcium (opposes PTH) Growth hormone & thyroid hormone: modulate bone growth Sex hormones: growth spurt at adolescense and closure of epiphyses CLINICAL ANATOMY Oblique Comminuted Spiral Compound Bone Fractures Treatment is reduction Closed--set in place by physical manipulation from outside body Open--surgical placement of pins or screws Healing Hematoma Fibrocartilaginous callus Bony calllus Remodeling by osteoclasts/osteoblasts Types of Fractures Repair of bone fractures (breaks) Simple and compound fractures Closed and open reduction Osteoporosis- bone reabsorption outpaces bone deposit; bones become lighter and fracture easier Factors: • age, gender (more in women) • estrogen and testosterone decrease • insufficient exercise (or too much) • diet poor in Ca++ and protein • abnormal vitamin D receptors • smoking 29 40 84 92 Bone grafts and artificial bone Widely used cutting-edge technologies Bone cells highly regenerative and move into any suitable matrix Use bone pieces from same body—ﬁbula Use crushed bone from cadavers Use bone substitutes—coral, synthetics—”nanotechnology” Applications are numerous Jaw bone ﬁller for dental work Birth defects Osteoporosis Bone repair Vertebral Column and Spinal Curvatures Alternating concave and convex curves Abnormal curvatures Kyphosis Lordosis Scoliosis Spinal Deformities Abnormal curvatures • Rickets- vitamin D deficiency • Osteomalacia- soft bones, inadequate mineralization in bones, lack of vitamin D • Pagets Disease- spotty weakening in the bones, excessive and abnormal bone remodeling Clinical manifestations Advanced rickets: Head: early signs is craniotabes, Like a derby hat or ping pong ball . Thorax: -Harrison’s groove Pigen breast deformity children are late in standing and walking THANK YOU