Musculoskeletal System Introduction and Histology PDF

Musculoskeletal System Introduction and Histology Histology: Interpret micrographs by recognizing important components of cells and tissues to more fully understand how organs and organ systems function. Muscular System: Identify the muscles of the body and re...

Musculoskeletal System Introduction and Histology Histology: Interpret micrographs by recognizing important components of cells and tissues to more fully understand how organs and organ systems function. Muscular System: Identify the muscles of the body and recall their basic actions to link body mechanics and aid in future diagnoses. Skeletal System: Identify bones of the body and their major landmarks by examining 2-D and 3-D representations to understand the functionality of the skeletal system and to build a foundation for terminology used in other organ systems.  Learning Objectives 1. Recall the components of bone that 6. Recall the microscopic organization provide strength and flexibility. of skeletal muscle based on the 2. Describe the gross anatomical connective tissue components structure of bone including the variety of shapes, components of 7. Describe muscle contraction by long bones, and organizational types. comparing the types of 3. Recall the microscopic organization of contraction, motor units, and bone including the cells and tissues origin and insertion sites that support it and their functions. 4. Visually identify bone, cartilage, and 8. Recall muscle categories, linking their related structures histologically. their names to the direction of 5. List the components and their fibers, function, and/or shape characteristics of cartilage and the 9. Using the provided histology slides, attributes of each type to relate them to their location and function in the visually identify the skeletal muscle body. and associated features  Musculoskeletal System Support Movement Isotonic contraction- muscle length changes Concentric- muscle fibers shorten Eccentric- controlled lengthening Insertion and origin sites Origin site is fixed on bone Insertion site moves Insertion and origin sites and the direction of muscle fibers allow us to predict muscle action Movement controlled by efferent nervous system- motor neurons; reflexes  Musculoskeletal System Stability Isometric- contraction without change in muscle length Stabilize joints; maintain upright posture Involves proprioceptors Shape Create spaces; provides protection; shape Communication Muscles of the face convey mood; allow for speech and hearing The Skeletal System  LO 1 Bone Composition and Function Living connective tissue Organic component- Cells, osteoid, and collagen fibers provide flexibility Location for hemopoiesis Storage Reserve for calcium for muscle contraction, blood clotting, and impulse transmission and phosphates important in APT utilization Without inorganic component Lipids in yellow bone marrow are a source of potential energy Inorganic component- hydroxyapatite Without organic component crystals provide strength Support and protection Movement  LO 2 Classification and 2 Anatomy of Bones 1. Long bones- tubular, 1 elongated with expanded ends 2. Flat bones- provide protection for underlying soft tissue 3. Short bones- cuboidal bones of ankle and wrist 4. Irregular bones- complex shapes 4 3 Sesamoid bones- develop in tendons throughout life Gray's Basic Anatomy (2018), Drake et al. and Netter’s Images  LO 2 Gross Anatomy of Long Bones Draw it out Diaphysis Metaphysis (present only during development) Epiphysis Epiphyseal line/plate* Marrow cavity Nutrient foramen  LO 2 Anatomy of Long Bones Lone bone anatomy Diaphysis Metaphysis (present only during development) Epiphysis- covered in hyaline cartilage Epiphyseal line/plate* Marrow cavity Red bone marrow- blood cell and platelet formation Yellow bone marrow- fatty Nutrient foramen- opening in the diaphysis for vessels and nerves  LO 2 Anatomy of Bone- Types of bone Compact/cortical Outer layer that provides strength Trabecular/cancellous Inner bone composed of flat or needle-like trabeculae Ratio of compact to spongy bone will be related to function Based on their function, compare and contrast the difference between a rib and a femur.  LO 3 Draw it out a. Osteons (Haversian system) b. Central canal c. Concentric lamellae d. Osteocytes e. Lacunae f. Canaliculi g. Perorating (Volkmann’s) canals h. Interstitial lamellae  LO 3 Compact Bone- Microscopic Anatomy Osteons (Haversian system) Central canal - holds blood vessels and nerves Concentric lamellae- layers of bone matrix Lacunae- spaces between lamellae that hold osteocytes Canaliculi – hold cellular extensions of osteocytes; allow for communication Perforating (Volkmann’s) canals- connect central canals Circumferential lamellae- adjacent to peri- and endosteum Interstitial lamellae- fill gaps/left over from remodeled osteons Junqueira's Basic Histology (2018), Mesher  LO 3 Trabecular Bone Located deep to compact bone Named for the needle-like projections called trabeculae that comprise it Comprised of lamellae that are not formed around central canals Nutrients diffused via canaliculi that connect to capillaries in the endosteum surrounding trabeculae Junqueira's Basic Histology (2018), Mesher  LO 3 Osteoid Related Tissue Periosteum- 2 layered CT membrane outside 1. Fibrous outer layer- dense Marrow spaces irregular CT Trabeculae with Anchor for tendons and ligaments Trabecular bone hematopoietic cells and fat 2. Osteogenic inner layer- osteogenic cells Endosteal surface Contains/creates bone cells Attached to bone via Sharpey’s Periosteum fibers Endosteum- internal CT membrane lining medullary cavity Compact bone  LO 3 Bone Cells Osteogenic (osteoprogenitor) cells Mitotically active stem cells in periosteum and endosteum Can differentiate into osteoblasts (osteocytes) or bone lining cells Osteoblasts Bone building cells located on bone surface Synthesize and secrete osteoid of bone matrix Become osteocytes when surrounded by matrix Junqueira's Basic Histology (2018), Mesher  LO 3 Bone Cells Osteocytes Bone maintenance cells React to strain or stress though deformation, loading, and weightlessness Stimulate osteoblasts and osteoclasts Located in lacunae Connect and communicate with to other osteocytes, osteoblasts, and bone lining cells via protoplasmic projections Bone lining cells Flat cells on bone surface where remodeling is not occurring Help maintain bone matrix Called periosteal cells on external bone surface, endosteal cells on internal surface Osteoclasts (osteophages) Bone eating cells- resorb bone- osteolysis Large, motile, multinucleated cells Originate from bone marrow, fusion of monocytes Enzymes from osteoclasts break down bone matrix Junqueira's Basic Histology (2018), Mesher Bone Histology 1. Osteon Compact Bone a. Osteon LO 4 b. Central canal 2. Interstitial lamellae c. Lamellae 3. Perforating canal d. Osteocytes e. Canaliculi  LO 4 Cancellous/ Osteocytes Trabecular Lacunae Bone Periosteum  LO 4 Bone Cells LO 7 Osteocyte Osteoblast Osteoclast Cartilage  LO 5 Cartilage Tough durable form of supporting connective tissue ideal for mechanical and protective roles in the body Functions: Provides flexibility Provides smooth, low friction, gliding surfaces on articular surfaces Components Gelatinous extracellular matrix (EMC) and abundant fibers Chondrocytes Within ECM in cavities called lacunae Perichondrium Dense CT covering that supplies nutrients via diffusion Characteristics Avascular Obtains nutrients by diffusion Lacks nerves Junqueira's Basic Histology (2018), Mesher  LO 5 Cartilage Types A. Hyaline- movement and support Most common type Sparse chondrocytes, collagen fibers Juvenile- Forms scaffolding for developing bone, allows for longitudinal bone growth Adults- Ends of bones in many joints, respiratory tract, and connects ribs to sternum B. Elastic- flexibility and stretching Ear, epiglottis in the upper respiratory tract More elastin fibers compared to hyaline C. Fibrocartilage- strength and cushioning Intervertebral discs, and menisci of knee, pelvic girdle Organized rows of chondrocytes between rows of collagen fibers Junqueira's Basic Histology (2018), Mesher  LO 4 Perichondrium Hyaline Cartilage Lacunae Chondrocytes  LO 4 Perichondrium Lacunae Elastic Cartilage Chondrocytes  LO 7 Lacunae Chondrocytes Fibrocartilage  Muscular System: Types, Shapes, Contraction, Organization  Muscle Tissue Categorized by Long and narrow Voluntary or involuntary contractile muscle cells = Appearance: striated or muscle fibers smooth/nonstriated Location: Somatic (body wall or Surrounded by CT that limbs) or visceral (hollow organs carries nerve and vessels or blood vessels) and binds them into fascicles (bundles) Types of muscle Skeletal muscle- voluntary, somatic, striated Cardiac muscle- involuntary, visceral, striated Smooth muscle- involuntary, visceral, nonstriated Clinically Oriented Anatomy (2018), Moore et al.  Skeletal Muscle One or more contractile portions (bellies) Often have associated tendons- Noncontractile CT that link muscle to bone Attach to Bone Cartilage Ligaments (bone to bone/cartilage) Fascia Function: Movement Support Form Heat Posterior view  LO 6 Muscle Organization Thin layers of CT surround and organize muscle tissue 1. Epimysium Dense irregular CT Surrounds entire muscle Carries larger nerve and vessels in septa 2. Perimysium Thin CT Surrounds each fascicle (bundle) Nerves and vessels penetrate to supply each fascicle 3. Endomysium Very thin, delicate CT of reticular fibers and fibroblasts Surrounds external lamina of each muscle fiber (cell) Nerve fibers and capillaries penetrate  LO 7 Describing Muscle Contraction Skeletal muscles always pull, never push Muscles contract, shorten Attachment site (origin site) remains fixed Insertion site moves Attachment sites of muscles provide movement information; move joints they cross Flex, extend, abduct, adduct  LO 7 Describing Muscle Contraction A. Tonic contraction Muscle tone- slight contraction while relaxed Does not produce movement or active resistance Joint stability, maintain posture, at- the-ready B. Reflexive contraction Automatic contractions due to stimulus E.g., myotatic reflex, movement of diaphragm Plantar grasp reflex  LO 7 Describing Muscle Contraction C. Phasic (active) contraction a. Isotonic contraction- muscles changes in length, movement Concentric contraction- muscle shortening Eccentric contraction- controlled muscle lengthening b. Isometric contraction- no change in length, increased force Resist gravity or antagonistic force  LO 7 Describing Muscle Contraction Motor Unit-motor neurons and muscle fibers that it controls Prime mover- muscle responsible for movement Synergist- complements prime mover Antagonist- opposes action of another muscle Fixator- steadies/stabilizes Shunt muscle- contracts to resist dislocating forces at joints Spurt muscle- capable of rapid and effective movement  Draw muscle shape and/or fiber direction. LO 8 Muscle Shape Circular Fusiform Muscle shape depends on arrangement of muscles fibers and associated CT Most muscles are named for their function, the bone they attach, position, length, or shape Flat Pennate Circular (sphincteral)- controlled opening and closing of opening or orifice Fusiform- spindle shape, tendonous attachments Flat- parallel fibers with aponeurosis; stabilizers Pennate- feather like, diagonal fibers Quadrate Convergent Quadrate- 4 equal sides Convergent- cover broad areas but form single tendon Multiheaded or multibellies  LO 8 Skeletal Muscle Muscle shape depends on arrangement of muscles fibers and associated CT Most muscles are named for their function, the bone they attach, position, length, or shape Circular (sphincteral)- controlled opening and closing of opening or orifice Fusiform- spindle shape, tendonous attachments Flat- parallel fibers with aponeurosis; stabilizers Pennate- feather like, diagonal fibers Quadrate- 4 equal sides Convergent- cover broad areas but form single tendon Multiheaded or multibellies Clinically Oriented Anatomy (2018), Moore et al. Skeletal Muscle Histology  LO 4 Muscle Histology Skeletal muscle Cardiac muscle Smooth muscle  Fascicle LO 9 Muscle fibers Epimysium Perimysium Endomysium  LO 9 Muscle fiber Skeletal muscle (longitudinal) Nucleus of muscle fiber Endomysium Striations (not testable)  LO 9 1. Muscle fiber Skeletal muscle (cross-section) 2. Nucleus of muscle fiber 3. Endomysium