6 Bones and Skeletal Tissues

Transcription

1 6 Bones and Skeletal Tissues Cartilage Location and basic structure Found throughout adult body Ear and epiglottis Articular cartilages and costal cartilage Larynx, trachea, and nose Intervertebral discs, pubic symphysis, and articular discs Cartilage Is surrounded by perichondrium Consists primarily of water Resilient tissue it springs back to original shape Types of Cartilage Hyaline cartilage (glassy) Most abundant cartilage Provides support through flexibility Elastic cartilage contains many elastic fibers Able to tolerate repeated bending Fibrocartilage resists strong compression and strong tension An intermediate between hyaline and elastic cartilage Cartilages in the Adult Body Growth of Cartilage Appositional growth Chondroblasts in surrounding perichondrium produce new cartilage Interstitial growth Chondrocytes within cartilage divide and secrete new matrix Cartilage stops growing when the skeleton stops growing

2 Tissues in Bone Bones contain several types of tissues Dominated by bone CT Contain nervous tissue and blood CT Contain cartilage in articular cartilages Contain ET lining blood vessels Function of Bones Support provides hard framework Movement skeletal muscles use bones as levers Protection of underlying organs Mineral storage reservoir for important minerals Blood-cell formation bone contains red marrow Energy metabolism osteoblasts secrete osteocalcin Bone Tissue Bone tissue Organic components cells, fibers, and ground substance Inorganic components mineral salts that invade bony matrix Extracellular Matrix Unique composition of matrix Gives bone exceptional properties 35% organic components Contributes to flexibility and tensile strength 65% inorganic components Provide exceptional harness, resists compression Cells Three types of cells in bone produces or maintain bone Osteogenic cells stem cells that differentiate into osteoblasts Osteoblasts actively produce and secrete bone matrix Bone matrix is osteoid Osteocytes keep bone matrix healthy Cells Osteoclasts Responsible for resorption of bone Are derived from a line of white blood cells Secrete hydrochloric acid and lysosomal enzymes

3 Classification of Bones Long bones longer than wide; a shaft plus ends Short bones roughly cube-shaped Flat bones thin and flattened, usually curved Irregular bones various shapes, do not fit into other categories Gross Anatomy of Bones Compact bone dense outer layer of bone Spongy (cancellous) bone internal network of bone Structure of a Typical Long Bone Diaphysis shaft of a bone Epiphysis ends of a bone Blood vessels well vascularized Medullary cavity hollow cavity filled with yellow marrow Membranes Periosteum, perforating fibers (Sharpey s fibers), and endosteum Structure of a Long Bone Structure of Short, Irregular, and Flat Bones Flat bones, short bones, and irregular bones Contain bone marrow but no marrow cavity Diploë Internal spongy bone of flat bones Gross Anatomy of Bones Bone design and stress Anatomy of a bone reflects stresses Compression and tension greatest at external surfaces Bone Markings Superficial surfaces of bones reflect stresses on them There are three broad categories of bone markings Projections for muscle attachment Surfaces that form joints Depressions and openings Microscopic Structure of Compact Bones

4 Compact Bone Contains passage ways for blood vessels, lymph vessels, and nerves Osteons long cylindrical structures Function in support Structurally resembles rings of a tree in cross-section Microscopic Structure of Compact Bones Osteons contain: Lamellae Central canal Perforating canals Canaliculi Microscopic Structure of Compact Bones Spongy Bone Is less complex than compact bone Trabeculae contain layers of lamellae and osteocytes Are too small to contain osteons 6 Bones and Skeletal Tissues Bone Development Ossification (osteogenesis) bone-tissue formation Membrane bones formed directly from mesenchyme Intramembranous ossification Other bones develop initially from hyaline cartilage Endochondral ossification Intramembranous Ossification Endochondral Ossification All bones except some bones of the skull and clavicles Bones are modeled in hyaline cartilage Begins forming late in the second month of embryonic development

5 Continues forming until early adulthood Stages in Endochondral Ossification Anatomy of Epiphyseal Growth Areas In epiphyseal plates of growing bones: 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 Anatomy of Epiphyseal Growth Areas Older chondrocytes signal surrounding matrix to calcify Older chondrocytes 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 Organization of Cartilage within Epiphyseal Plate of Growing Long Bone Postnatal Growth of Endochondral Bones During childhood and adolescence: Bones lengthen entirely by growth of the epiphyseal plates Cartilage is replaced with bone CT as quickly as it grows Epiphyseal plate maintains constant thickness Whole bone lengthens Hormonal Regulation of Bone Growth Growth hormone produced by the pituitary gland Stimulates epiphyseal plates Thyroid hormone ensures that the skeleton retains proper proportions Sex hormones (estrogen and testosterone) Promote bone growth Later induces closure of epiphyseal plates

6 Postnatal Growth of Endochondral Bones As adolescence draws to an end: Chondroblasts divide less often Epiphyseal plates become thinner Cartilage stops growing Replaced by bone tissue Long bones stop lengthening when diaphysis and epiphysis fuse Bone Remodeling Bone is dynamic living tissue 500 mg of calcium may enter or leave the adult skeleton each day Cancellous bone of the skeleton is replaced every 3 4 years Compact bone is replaced every 10 years Postnatal Growth of Endochondral Bones Growing bones widen as they lengthen Osteoblasts add bone tissue to the external surface of the diaphysis Osteoclasts remove bone from the internal surface of the diaphysis Appositional growth growth of a bone by addition of bone tissue to its surface Bone Remodeling Bone deposit and removal Occurs at periosteal and endosteal surfaces Bone remodeling Bone deposition accomplished by osteoblasts Bone reabsorption accomplished by osteoclasts Remodeling, Spongy Bone Osteoclast A Bone-Degrading Cell A giant cell with many nuclei Crawls along bone surfaces Breaks down bone tissue Secretes concentrated HCl Lysosomal enzymes are released

7 Derived from hematopoietic stem cells Repair of Bone Fractures Simple and compound fractures Treatment by reduction Closed reduction Open reduction Stages of Healing a Fracture Common Types of Fractures Disorders of Bones Osteoporosis Characterized by low bone mass Bone reabsorption outpaces bone deposition Occurs most often in women after menopause Osteoporosis Disorders of Bones Osteomalacia Occurs in adults bones are inadequately mineralized Rickets Occurs in children analogous to osteomalacia Disorders of Bones Paget s disease Characterized by excessive rate of bone deposition Osteosarcoma A form of bone cancer The Skeleton Throughout Life Cartilage grows quickly in youth Skeleton shows fewer chondrocytes in the elderly Bones are a timetable Mesoderm Gives rise to embryonic mesenchyme cells Mesenchyme Produces membranes and cartilage Membranes and cartilage ossify

8 The Skeleton Throughout Life Skeleton grows until the age of years In children and adolescents, bone formation exceeds rate of bone reabsorption In young adults, bone formation and bone reabsorption are in balance In old age, reabsorption predominates Bone mass declines with age 7 Bones, Part 1: The Axial Skeleton The Skeleton Consists of: Bones, cartilage, joints, and ligaments Composed of 206 named bones grouped into two divisions Axial skeleton (80 bones) Appendicular skeleton (126 bones) The Axial Skeleton Formed from 80 named bones Consists of skull, vertebral column, and bony thorax The Axial Skeleton The Skull Formed by cranial and facial bones The Cranium Is the body s most complex bony structure Formed by cranial and facial bones The cranium Encloses and protects brain Provides attachment for head and neck muscles The Face Facial bones serve to

9 Form framework of the face Form cavities for the sense organs of sight, taste, and smell Provide openings for the passage of air and food Hold the teeth in place Anchor muscles of the face Overview of Skull Geography Facial bones form anterior aspect Cranium is divided into cranial vault and the base Internally, prominent bony ridges divide skull into distinct fossae Overview of Skull Geography The skull contains smaller cavities Middle and inner ear cavities in lateral aspect of cranial base Nasal cavity lies in and posterior to the nose Orbits house the eyeballs Air-filled sinuses occur in several bones around the nasal cavity Overview of Skull Geography The skull contains approximately 85 named openings Foramina, canals, and fissures Provide openings for important structures Spinal cord Blood vessels serving the brain 12 pairs of cranial nerves Cranial Bones Formed from eight large bones Paired bones include Temporal bones Parietal bones Unpaired bones include Frontal bone Occipital bone Sphenoid bone Ethmoid bone Parietal Bones and Sutures

10 Parietal bones form superior and lateral parts of skull Four sutures of the cranium Coronal suture runs in the coronal plane Located where parietal bones meet the frontal bone Squamous suture occurs where each parietal bone meets a temporal bone inferiorly Parietal Bones and Sutures Four sutures of the cranium (continued) Sagittal suture occurs where right and left parietal bones meet superiorly Lambdoid suture occurs where the parietal bones meet the occipital bone posteriorly Sutural Bones Small bones that occur within sutures Irregular in shape, size, and location Not all people have sutural bones The Skull Posterior View Frontal Bone Forms the forehead and roofs of orbits Supraorbital margin superior margin of orbits Glabella smooth part of frontal bone between superciliary arches Frontal sinuses within frontal bone Contributes to anterior cranial fossa Occipital Bone Forms the posterior portion of the cranium and cranial base Articulates with the temporal bones and parietal bones Forms the posterior cranial fossa Foramen magnum located at its base Occipital Bone Features and structures Occipital condyles Hypoglossal foramen External occipital protuberance

11 Superior nuchal lines Inferior nuchal lines Inferior Aspect of the Skull Temporal Bones Lie inferior to parietal bones Form the inferolateral portion of the skull Term temporal comes from Latin word for time Specific regions of temporal bone Squamous, temporal, petrous, and mastoid regions Lateral Aspect of the Skull The Temporal Bone The mastoid process Site for neck muscle attachment Contains air sinuses Petrous region Projects medially, contributes to cranial base Houses cavities of middle and internal ear Contributes to the middle and posterior cranial fossae The Temporal Bone Foramina of the temporal bone Jugular foramen At boundary with occipital bone Carotid canal Formane lacerum Internal accoustic meatus 7 Bones, Part 1: The Axial Skeleton The Sphenoid Bone Spans the width of the cranial floor Resembles a butterfly or bat

12 Consists of a body and three pairs of processes Contains five important openings Is the keystone of the cranium The Ethmoid Bone Lies between nasal and sphenoid bones Forms most of the medial bony region between the nasal cavity and orbits The Ethmoid Bone Cribiform plate superior surface of the ethmoid bone Contain olfactory foramina Crista galli attachment for falx cerebri Perpendicular plate forms superior part of nasal septum The Ethmoid Bone Lateral masses contain air cells Superior and middle nasal conchae Extend medially from laterial masses The Ethmoid Bone Facial Bones Unpaired bones Mandible and vomer Paired bones Maxillae Zygomatic bones Nasal bones Lacrimal bones Palatine bones Inferior nasal conchae Facial Bones Mandible The lower jawbone is the largest and strongest facial bone Composed of two main parts Horizontal body Two upright rami

13 Mandible Maxillary Bones Articulate with all other facial bones except the mandible Contain maxillary sinuses largest paranasal sinuses Forms part of the inferior orbital fissure Are the keystone bones of the face Other Bones of the Face Zygomatic bones Form lateral wall of orbits Nasal bones Form bridge of nose Lacrimal bones Located in the medial orbital walls Palatine bones Complete the posterior part of the hard palate Other Bones of the Face Vomer Forms the inferior part of the nasal septum Inferior nasal conchae Thin, curved bones that project medially form the lateral walls of the nasal cavity 7 Bones, Part 1: The Axial Skeleton Special Parts of the Skull Orbits Nasal cavity Paranasal sinuses Hyoid bone Nasal Cavity Nasal Septum

14 Paranasal Sinuses Air-filled sinuses are located within Frontal bone Ethmoid bone Sphenoid bone Maxillary bones Lined with mucous membrane Lighten the skull Orbits The Hyoid Bone Lies inferior to the mandible The only bone with no direct articulation with any other bone Acts as a movable base for the tongue 7 Bones, Part 1: The Axial Skeleton The Vertebral Column Formed from 26 bones in the adult Transmits weight of trunk to the lower limbs Surrounds and protects the spinal cord The Vertebral Column Serves as attachment sites for muscles of the neck and back Held in place by ligaments Anterior and posterior longitudinal ligaments Ligamentum flavum The Vertebral Column Regions and Normal Curvatures The Vertebral column has five major regions 7 cervical vertebrae of the neck region 12 thoracic vertebrae 5 lumbar vertebrae

15 Sacrum five fused bones Inferior to lumbar vertebrae Coccyx inferior to sacrum Regions and Normal Curvatures Curvatures of the spine Cervical and lumbar curvatures Concave posteriorly Thoracic and sacral curvatures Convex posteriority Regions and Normal Curvatures Curvatures increase resilience of spine Thoracic and sacral curvatures Primary curvatures Present at birth Lumbar curvature Develops when baby begins to walk Ligaments of the Spine Major supporting ligaments Anterior longitudinal ligament Attaches to bony vertebrae and intervertebral discs Prevents hyperextension Posterior longitudinal ligament Narrow and relatively weak Attaches to intervertebral discs Intervertebral Discs Are cushion-like pads between vertebrae Composed of Nucleus pulposus Anulus fibrosus Intervertebral Discs Nucleus pulposus Gelatinous inner sphere Absorbs compressive stresses Anulus fibrosus Outer fings formed of ligament

16 Inner rings formed of fibrocartilage Contain the nucleus pulposus General Structure of Vertebrae Common structures to all regions Body Vertebral arch Vertebral foramen Spinous process Transverse process Superior and inferior articular processes Intervertebral foramina 7 Bones, Part 1: The Axial Skeleton Regions Vertebral Characteristics Specific regions of the spine perform specific functions Types of movement that occur between vertebrae Flexion and extension Lateral flexion Rotation in the long axis Cervical Vertebrae Seven cervical vertebrae (C 1 C 7 ) smallest and lightest vertebrae C 3 C 7 are typical cervical vertebrae Body is wider laterally Spinous processes are short and bifid (except C 7 ) Vertebral foramen are large and triangular Transverse processes contain transverse foramina Superior articular facets face superoposteriorly The Atlas C 1 is termed the atlas

17 Lacks a body and spinous process Supports the skull Superior articular facets receive the occipital condyles Allows flexion and extension of neck Nodding the head yes The Axis Has a body and spinous process Dens (odontoid process) projects superiorly Formed from fusion of the body of the atlas with the axis Acts as a pivot for rotation of the atlas and skull Participates in rotating the head from side to side 7 Bones, Part 1: The Axial Skeleton Thoracic Vertebrae (T 1 T 12 ) All articulate with ribs Have heart-shaped bodies from the superior view Each side of the body of T 1 T 10 bears demifacts for articulation with ribs T 1 has a full facet for the first rib T 10 T 12 only have a single facet Thoracic Vertebrae Spinous processes are long and point inferiorly Vertebral foramen are circular Transverse processes articulate with tubercles of ribs Superior articular facets point posteriorly Inferior articular processes point anteriorly Allows rotation and prevents flexion and extension Lumbar Vertebrae (L 1 L 5 ) Bodies are thick and robust Transverse processes are thin and tapered Spinous processes are thick, blunt, and point posteriorly

18 Vertebral foramina are triangular Superior and inferior articular facets directly medially Allows flexion and extension rotation prevented Sacrum (S 1 S 5 ) Shapes the posterior wall of pelvis Formed from 5 fused vertebrae Superior surface articulates with L 5 Inferiorly articulates with coccyx Sacral promontory Where the first sacral vertebrae bulges into pelvic cavity Center of gravity is 1 cm posterior to sacral promontory Ala develops from fused rib elements Sacrum Sacral foramina Ventral foramina Passage for ventral rami of sacral spinal nerves Dorsal foramina Passage for dorsal rami of sacral spinal nerves Coccyx Is the tailbone Formed from 3 5 fused vertebrae Offers only slight support to pelvic organs 7 Bones, Part 1: The Axial Skeleton The Thoracic Cage Forms the framework of the chest Components Thoracic vertebrae posteriorly Ribs laterally Sternum and costal cartilage anteriorly Protects thoracic organs

19 Supports shoulder girdle and upper limbs Provides attachment sites for muscles Sternum Formed from three sections Manubrium superior section Articulates with medial end of clavicles Body bulk of sternum Sides are notched at articulations for costal cartilage of ribs 2 7 Xiphoid process inferior end of sternum Ossifies around age 40 Sternum Anatomical landmarks Jugular notch Central indentation at superior border of the manubrium Sternal angle A horizontal ridge where the manubrium joins the body Xiphisternal joint Where sternal body and xiphoid process fuse Lies at the level of the 9th thoracic vertebra Ribs All ribs attach to vertebral column posteriorly True ribs - superior seven pairs of ribs Attach to sternum by costal cartilage False ribs inferior five pairs of ribs Ribs are known as floating ribs Disorders of the Axial Skeleton Cleft palate A common congenital disorder Right and left halves of palate fail to fuse medially Stenosis of the lumbar spine Narrowing of the vertebral canal Can compress roots of spinal nerves Disorders of the Axial Skeleton Abnormal spinal curvatures

20 Scoliosis an abnormal lateral curvature Kyphosis an exaggerated thoracic curvature Lordosis an accentuated lumbar curvature; swayback The Axial Skeleton Throughout Life Membrane bones begin to ossify in second month of development Bone tissue grows outward from ossification centers Fontanels Unossified remnants of membranes Fontanelles The Axial Skeleton Throughout Life Many bones of the face and skull form by intramembranous ossification Endochondral bones of the skull Occipital bone Sphenoid Ethmoid bones Parts of the temporal bone The Axial Skeleton Throughout Life Aging of the axial skeleton Water content of the intervertebral discs decreases By age 55, loss of a few centimeters in height is common Thorax becomes more rigid Bones lose mass with age 8 Bones, Part 1: The Appendicular Skeleton The Appendicular Skeleton Pectoral girdle Attaches the upper limbs to the trunk Pelvic girdle Attaches the lower limbs to the trunk

21 Upper and lower limbs differ in function Share the same structural plan The Pectoral Girdle Consists of the clavicle and the scapula Pectoral girdles do not quite encircle the body completely Medial end of each clavicle articulates with the manubrium and first rib Laterally the ends of the clavicles join the scapulae Scapulae do not join each other or the axial skeleton The Pectoral Girdle Provides attachment for many muscles that move the upper limb Girdle is very light and upper limbs are mobile Only clavicle articulates with the axial skeleton Socket of the shoulder joint (glenoid cavity) is shallow Good for flexibility, bad for stability Articulated Pectoral Girdle Clavicles Extend horizontally across the superior thorax Sternal end articulates with the manubrium Acromial end articulates with scapula Clavicles Provide attachment for muscles Hold the scapulae and arms laterally Transmit compression forces from the upper limbs to the axial skeleton Scapulae Lie on the dorsal surface of the rib cage Located between ribs 2 7 Have three borders Superior Medial (vertebral) Lateral (axillary) Have three angles

22 Lateral, superior, and inferior The Upper Limb 30 bones form each upper limb Grouped into bones of the: Arm Forearm Hand Arm Region of the upper limb between the shoulder and elbow Humerus The only bone of the arm Longest and strongest bone of the upper limb Articulates with the scapula at the shoulder Articulates with the radius and ulna at the elbow Arm Humerus Many structures of the humerus provide sites for muscle attachment Other structures of the humerus provide articulation sites for other bones Forearm Formed from the radius and ulna Proximal ends articulate with the humerus Distal ends articulate with carpals Forearm Radius and ulna articulate with each other At the proximal and distal radioulnar joints The interosseous membrane Interconnects radius and ulna In anatomical position; the radius is lateral and the ulna is medial Ulna Main bone responsible for forming the elbow joint with the humerus

23 Hinge joint allows forearm to bend on arm Distal end is separated from carpals by fibrocartilage Plays little to no role in hand movement Proximal Part of the Ulna Radius and Ulna Radius Superior surface of the head of the radius articulates with the capitulum Medially the head of the radius articulates with the radial notch of the ulna Contributes heavily to the wrist joint Distal radius articulates with carpal bones When radius moves, the hand moves with it Distal Ends of the Radius and Ulna 8 Bones, Part 1: The Appendicular Skeleton Hand Includes the following bones Carpus wrist Metacarpals palm Phalanges fingers Carpus Forms the true wrist the proximal region of the hand Gliding movements occur between carpals Composed of eight marble-sized bones Carpus Carpal bones Are arranged in two irregular rows Proximal row from lateral to medial

24 Scaphoid, lunate, triquetral, and pisiform Distal row from lateral to medial Trapezium, trapezoid, capitate, and hamate A mnemonic to help remember carpals: Sally left the party to take Carmen home Bones of the Hand Metacarpus Five metacarpals radiate distally from the wrist Metacarpals form the palm Numbered 1 5, beginning with the pollex (thumb) Articulate proximally with the distal row of carpals Articulate distally with the proximal phalanges Phalanges Numbered 1 5, beginning with the pollex (thumb) Except for the thumb, each finger has three phalanges Proximal, middle, and distal Bones of the Appendicular Skeleton Pelvic Girdle Attaches lower limbs to the spine Supports visceral organs Attaches to the axial skeleton by strong ligaments Acetabulum is a deep cup that holds the head of the femur Lower limbs have less freedom of movement Are more stable than the arm Pelvic Girdle Consists of paired hip bones (coxal bones) Hip bones unite anteriorly with each other Articulates posteriorly with the sacrum Bones of the Pelvic Girdle A deep, basin-like structure Formed by: Coxal bones, sacrum, and coccyx

25 The Pelvic Girdle Consists of three separate bones in childhood Ilium, ischium, and pubis Bones fuse, retain separate names to regions of the coxal bones Acetabulum A deep hemispherical socket on lateral pelvic surface Ilium Large, flaring bone Forms the superior region of the coxal bone Site of attachment for many muscles Articulation with the sacrum forms sacroiliac joint Ischium Forms posteroinferior region of the coxal bone Anteriorly joins the pubis Ischial tuberosities Are the strongest part of the hip bone Pubis Forms the anterior region of the coxal bone Lies horizontally in anatomical position Pubic symphysis The two pubic bones are joined by fibrocartilage at the midline Pubic arch inferior to the pubic symphysis Angle helps distinguish male from female pelves Lateral and Medial Views of the Hip Bone True and False Pelves Bony pelvis is divided into two regions False (greater) pelvis bounded by alae of the iliac bones True (lesser) pelvis inferior to pelvic brim Forms a bowl containing the pelvic organs 8 Bones,

26 Part 1: The Appendicular Skeleton Pelvic Structures and Childbearing Major differences between male and female pelves Female pelvis is adapted for childbearing Pelvis is lighter, wider, and shallower than in the male Provides more room in the true pelvis Female and Male Pelves The Lower Limb Carries the entire weight of the erect body Bones of lower limb are thicker and stronger than those of upper limb Divided into three segments Thigh, leg, and foot Thigh The region of the lower limb between the hip and the knee Femur the single bone of the thigh Longest and strongest bone of the body Ball-shaped head articulates with the acetabulum Structures of the Femur Patella Triangular sesamoid bone Imbedded in the tendon that secures the quadriceps muscles Protects the knee anteriorly Improves leverage of the thigh muscles across the knee Leg Refers to the region of the lower limb between the knee and the ankle Composed of the tibia and fibula Tibia more massive medial bone of the leg Receives weight of the body from the femur Fibula stick-like lateral bone of the leg Interosseous membrane Connects the tibia and fibula

27 Leg Tibia articulates with femur at superior end Forms the knee joint Tibia articulates with talus at the inferior end Forms the ankle joint Fibula does not contribute to the knee joint Stabilizes the ankle joint Structures of the Tibia and Fibula The Foot Foot is composed of Tarsus, metatarsus, and the phalanges Important functions Supports body weight Acts as a lever to propel body forward when walking Segmentation makes foot pliable and adapted to uneven ground Tarsus Makes up the posterior half of the foot Contains seven bones called tarsals Body weight is primarily borne by the talus and calcaneus Trochlea of the talus Site of articulation with the tibia Other tarsals are: Cuboid and navicular Medial, intermediate, and lateral cuneiforms Metatarsus Consists of five small long bones called metatarsals Numbered 1 5 beginning with the hallux (great toe) First metatarsal supports body weight Phalanges of the Toes 14 phalanges of the toes Smaller and less nimble than those of the fingers Structure and arrangement are similar to phalanges of fingers Except for the great toe, each toe has three phalanges Proximal, middle, and distal

28 Arches of the Foot Foot has three important arches Medial and lateral longitudinal arch Transverse arch Arches are maintained by Interlocking shapes of tarsals Ligaments and tendons Keystones of arches Talus medial longitudinal arch Cuboid lateral longitudinal arch Lower Limb and Pelvis Disorders of the Appendicular Skeleton Bone fractures Hip dysplasia Head of the femur slips out of acetabulum Clubfoot Soles of the feet turn medially The Appendicular Skeleton Throughout Life Growth of the appendicular skeleton Increases height Changes body proportions Upper/lower body ratio changes with age At birth, head and trunk are 1.5 times as long as lower limbs Lower limbs grow faster than the trunk Upper/lower body ratio of 1 to 1 by age 10 Changes in Body Proportions The Appendicular Skeleton Throughout Life Few changes occur in adult skeleton until middle age, when Skeleton loses mass Osteoporosis and limb fractures become more common 9 Joints

29 Joints Rigid elements of the skeleton meet at joints or articulations Greek root arthro means joint Structure of joints Enables resistance to crushing, tearing, and other forces Classifications of Joints Joints can be classified by function or structure Functional classification based on amount of movement Synarthroses immovable; common in axial skeleton Amphiarthroses slightly movable; common in axial skeleton Diarthroses freely movable; common in appendicular skeleton (all synovial joints) Classifications of Joints Structural classification based on Material that binds bones together Presence or absence of a joint cavity Structural classifications include Fibrous Cartilaginous Synovial Fibrous Joints Bones are connected by fibrous connective tissue Do not have a joint cavity Most are immovable or slightly movable Types Sutures Syndesmoses Gomphoses Sutures Bones are tightly bound by a minimal amount of fibrous tissue Only occur between the bones of the skull Allow bone growth so the skull can expand with brain during childhood Fibrous tissue ossifies in middle age Synostoses closed sutures

30 Syndesmoses Bones are connected exclusively by ligaments Amount of movement depends on length of fibers Tibiofibular joint immovable synarthrosis Interosseous membrane between radius and ulna Freely movable diarthrosis Gomphoses Tooth in a socket Connecting ligament the periodontal ligament Fibrous Joints Cartilaginous Joints Bones are united by cartilage Lack a joint cavity Two types Synchondroses Symphyses Synchondroses Hyaline cartilage unites bones Epiphyseal plates Joint between first rib and manubrium Symphyses Fibrocartilage unites bones; resists tension and compression Slightly movable joints that provide strength with flexibility Intervertebral discs Pubic symphysis Hyaline cartilage present as articular cartilage Symphyses Synovial Joints Most movable type of joint All are diarthroses Each contains a fluid-filled joint cavity General Structure of Synovial Joints

31 Articular cartilage Ends of opposing bones are covered with hyaline cartilage Absorbs compression Joint cavity (synovial cavity) Unique to synovial joints Cavity is a potential space that holds a small amount of synovial fluid General Structure of Synovial Joints Articular capsule joint cavity is enclosed in a two-layered capsule Fibrous capsule dense irregular connective tissue, which strengthens joint Synovial membrane loose connective tissue Lines joint capsule and covers internal joint surfaces Functions to make synovial fluid General Structure of Synovial Joints Synovial fluid A viscous fluid similar to raw egg white A filtrate of blood Arises from capillaries in synovial membrane Contains glycoprotein molecules secreted by fibroblasts Reinforcing ligaments Often are thickened parts of the fibrous capsule Sometimes are extracapsular ligaments located outside the capsule Sometimes are intracapsular ligaments located internal to the capsule General Structure of Synovial Joints Richly supplied with sensory nerves Detect pain Most monitor how much the capsule is being stretched General Structure of Synovial Joints Have a rich blood supply Most supply the synovial membrane Extensive capillary beds produce basis of synovial fluid Branches of several major nerves and blood vessels

32 Synovial Joints with Articular Discs Some synovial joints contain an articular disc Occur in the temporomandibular joint and at the knee joint Occur in joints whose articulating bones have somewhat different shapes 9 Joints How Synovial Joints Function Synovial joints lubricating devices Friction could overheat and destroy joint tissue Are subjected to compressive forces Fluid is squeezed out as opposing cartilages touch Cartilages ride on the slippery film Bursae and Tendon Sheaths Bursae and tendon sheaths are not synovial joints Closed bags of lubricant Reduce friction between body elements Bursa a flattened fibrous sac lined by a synovial membrane Tendon sheath an elongated bursa that wraps around a tendon Bursae and Tendon Sheaths Movements Allowed by Synovial Joints Three basic types of movement Gliding one bone across the surface of another Angular movement movements change the angle between bones Rotation movement around a bone's long axis Gliding Joints Flat surfaces of two bones slip across each other Gliding occurs between

33 Carpals Articular processes of vertebrae Tarsals Angular Movements Increase or decrease angle between bones Movements involve Flexion and extension Abduction and adduction Circumduction Rotation Involves turning movement of a bone around its long axis The only movement allowed between atlas and axis vertebrae Occurs at the hip and shoulder joints Rotation Special Movements Elevation lifting a body part superiorly Depression moving the elevated part inferiorly Special Movements Protraction nonangular movement anteriorly Retraction nonangular movement posteriorly Special Movements Supination forearm rotates laterally, palm faces anteriorly Pronation forearm rotates medially, palm faces posteriorly Brings radius across the ulna Special Movements Opposition thumb moves across the palm to touch the tips of other fingers 9 Joints

34 Special Movements Inversion and eversion Special movements at the foot Inversion turns sole medially Eversion turns sole laterally Special Movements Special Movements Dorsiflexion and plantar flexion Up-and-down movements of the foot Dorsiflexion lifting the foot so its superior surface approaches the shin Plantar flexion depressing the foot, elevating the heel Special Movements Synovial Joints Classified by Shape Plane joint Articular surfaces are flat planes Short gliding movements are allowed Intertarsal and intercarpal joints Movements are nonaxial Gliding does not involve rotation around any axis Plane Joint Synovial Joints Classified by Shape Hinge joints Cylindrical end of one bone fits into a trough on another bone Angular movement is allowed in one plane Elbow, ankle, and joints between phalanges Movement is uniaxial allows movement around one axis only Hinge Joint Synovial Joints Classified by Shape Pivot joints Classified as uniaxial rotating bone only turns around its long axis Examples

35 Proximal radioulnar joint Joint between atlas and axis Pivot Joint Synovial Joints Classified by Shape Condyloid joints Allow moving bone to travel Side to side abduction-adduction Back and forth flexion-extension Classified as biaxial movement occurs around two axes Condyloid Joint Synovial Joints Classified by Shape Saddle joints Each articular surface has concave and convex surfaces Classified as biaxial joints 1st carpometacarpal joint is a good example Allows opposition of the thumb Synovial Joints Classified by Shape 9 Joints Synovial Joints Classified by Shape Ball-and-socket joints Spherical head of one bone fits into round socket of another Classified as multiaxial allow movement in all axes Shoulder and hip joints are examples Ball-and-Socket Joint Factors Influencing Stability of Synovial Joints Articular surfaces Shapes of articulating surfaces determine movements possible Seldom play a major role in joint stability Exceptions that do provide stability

36 Hip joint, elbow joint, and ankle Factors Influencing Stability of Synovial Joints Ligaments Capsules and ligaments prevent excessive motions On the medial or inferior side of a joint prevent excessive abduction Lateral or superiorly located resist adduction Factors Influencing Stability of Synovial Joints Ligaments (continued) Anterior ligaments resist extension and lateral rotation Posterior ligaments resist flexion and medial rotation The more ligaments, usually stronger and more stable Factors Influencing Stability of Synovial Joints Muscle tone Helps stabilize joints by keeping tension on tendons Is important in reinforcing: Shoulder and knee joints Supporting joints in arches of the foot Selected Synovial Joints Sternoclavicular joint Is a saddle joint Four ligaments surround the joint Anterior and posterior sternoclavicular ligaments Interclavicular ligament Costoclavicular ligament Performs multiple complex movements Selected Synovial Joints Temporomandibular Joint Is a modified hinge joint The head of the mandible articulates with the temporal bone Lateral excursion is a side-to-side movement Two surfaces of the articular disc allow Hinge-like movement Gliding of superior surface anteriorly

37 9 Joints Selected Synovial Joints Shoulder (glenohumeral) joint The most freely movable joint lacks stability Articular capsule is thin and loose Muscle tendons contribute to joint stability Glenohumeral Joint Glenohumeral Joint The rotator cuff is made up of four muscles and their associated tendons Subscapularis Supraspinatus Infraspinatus Teres minor Rotator cuff injuries are common shoulder injuries The Shoulder Joint The Shoulder Joint Selected Synovial Joints Elbow joint Allows flexion and extension The humerus articulation with the trochlear notch of the ulna forms the hinge Tendons of biceps and triceps brachii provide stability Wrist Joint Stabilized by numerous ligaments Composed of radiocarpal and intercarpal joint Radiocarpal joint joint between the radius and proximal carpals (the scaphoid and lunate) Allows for flexion, extension, adduction, abduction, and

38 circumduction Intercarpal joint joint between the proximal and distal rows or carpals Allows for gliding movement Selected Synovial Joints Hip joint A ball-and-socket structure Movements occur in all axes Limited by ligaments and acetabulum Head of femur articulates with acetabulum Stability comes chiefly from acetabulum and capsular ligaments Muscle tendons contribute somewhat to stability Selected Synovial Joints Knee joint The largest and most complex joint Primarily acts as a hinge joint Has some capacity for rotation when leg is flexed Structurally considered compound and bicondyloid Two fibrocartilage menisci occur within the joint cavity Femoropatellar joint shares the joint cavity Allows patella to glide across the distal femur Knee Joint Capsule of the knee joint Covers posterior and lateral aspects of the knee Covers tibial and femoral condyles Does not cover the anterior aspect of the knee Anteriorly covered by three ligaments Patellar ligament Medial and lateral patellar retinacula Anterior View of Knee Knee Joint Ligaments of the knee joint Become taut when knee is extended These extracapsular and capsular ligaments are

39 Fibular and tibial collateral ligament Oblique popliteal ligament Arcuate popliteal ligament Posterior View of Knee Joint Knee Joint Intracapsular ligaments Cruciate ligaments Cross each other like an X Each cruciate ligament runs from the proximal tibia to the distal femur Anterior cruciate ligament Posterior cruciate ligament Anterior View of Flexed Knee Knee Joint Intracapsular ligaments Cruciate ligaments prevent undesirable movements at the knee Anterior cruciate ligament prevents anterior sliding of the tibia Posterior cruciate ligament prevents forward sliding of the femur or backward displacement of the tibia Stabilizing function of cruciate ligaments The Unhappy Triad Lateral blows to the knee can tear: Tibial collateral ligament and medial meniscus Anterior cruciate ligament The Unhappy Triad Selected Synovial Joint Ankle joint A hinge joint between United inferior ends of tibia and fibula The talus of the foot Allows the movements Dorsiflexion and plantar flexion only

40 The Ankle Joint Medially and laterally stabilized by ligaments Medial (deltoid) ligament Lateral ligament Inferior ends of tibia and fibula are joined by ligaments Anterior and posterior tibiofibular ligaments Disorders of Joints Structure of joints makes them prone to traumatic stress Function of joints makes them subject to friction and wear Affected by inflammatory and degenerative processes Joint Injuries Torn cartilage common injury to meniscus of knee joint Sprains ligaments of a reinforcing joint are stretched or torn Dislocation occurs when the bones of a joint are forced out of alignment Inflammatory and Degenerative Conditions Bursitis inflammation of a bursa due to injury or friction Tendonitis inflammation of a tendon sheath Inflammatory and Degenerative Conditions Arthritis describes over 100 kinds of joint-damaging diseases Osteoarthritis most common type of wear and tear arthritis Rheumatoid arthritis a chronic inflammatory disorder Gouty arthritis (gout) uric acid build-up causes pain in joints Lyme disease inflammatory disease often resulting in joint pain The Joints Throughout Life Synovial joints develop from mesenchyme By Week 8 of fetal development, joints resemble adult joints Outer region of mesenchyme becomes fibrous joint capsule Inner region becomes the joint cavity The Joints Throughout Life During youth injury may tear an epiphysis off a bone shaft Advancing age osteoarthritis becomes more common

41 Exercise helps maintain joint health 10 Muscle Tissue Muscle Muscle a Latin word for little mouse Muscle is the primary tissue in the: Heart (cardiac MT) Walls of hollow organs (smooth MT) Skeletal muscle Makes up nearly half the body s mass Overview of Muscle Tissue Functions of muscle tissue Movement Skeletal muscle attached to skeleton Moves body by moving the bones Smooth muscle squeezes fluids and other substances through hollow organs Overview of Muscle Tissue Functions of muscle tissue (continued) Maintenance of posture enables the body to remain sitting or standing Joint stabilization Heat generation Muscle contractions produce heat Helps maintain normal body temperature Functional Features of Muscles Functional features Contractility Long cells shorten and generate pulling force Excitability Electrical nerve impulse stimulates the muscle cell to contract Extensibility Can be stretched back to its original length by contraction of

42 an opposing muscle Elasticity Can recoil after being stretched Types of Muscle Tissue Skeletal muscle tissue Packaged into skeletal muscles Makes up 40% of body weight Cells are striated Types of Muscle Tissue Cardiac muscle tissue occurs only in the walls of the heart Smooth muscle tissue occupies the walls of hollow organs Cells lack striations Similarities of Muscle Tissue Cells of smooth and skeletal muscle Are known as fibers Muscle contraction Depends on two types of myofilaments (contractile proteins) One type contains actin Another type contains myosin These two proteins generate contractile force Similarities of Muscle Tissues Plasma membrane is called a sarcolemma Cytoplasm is called sarcoplasm Skeletal Muscle Each muscle is an organ Consists mostly of muscle tissue Skeletal muscle also contains Connective tissue Blood vessels Nerves Basic Features of a Skeletal Muscle Connective tissue and fascicles Sheaths of connective tissue bind a skeletal muscle and its fibers together

43 Epimysium dense regular connective tissue surrounding entire muscle Perimysium surrounds each fascicle (group of muscle fibers) Endomysium a fine sheath of connective tissue wrapping each muscle cell Basic Features of a Skeletal Muscle Connective tissue sheaths are continuous with tendons When muscle fibers contract, pull is exerted on all layers of connective tissue are tendon Sheaths provide elasticity and carry blood vessels and nerves Connective Tissue Sheaths in Skeletal Muscle Basic Features of a Skeletal Muscle Nerves and blood vessels Each skeletal muscle supplied by branches of One nerve One artery One or more veins Basic Features of a Skeletal Muscle Nerves and blood vessels (continued) Nerves and vessels branch repeatedly Smallest nerve branches serve: Individual muscle fibers Neuromuscular junction signals the muscle to contract Basic Features of a Skeletal Muscle Muscle attachments Most skeletal muscles run from one bone to another One bone will move, other bone remains fixed Origin less movable attachment Insertion more movable attachment Basic Features of a Skeletal Muscle Muscle attachments (continued) Muscles attach to origins and insertions by CT Fleshy attachments CT fibers are short

44 Indirect attachments CT forms a tendon or aponeurosis Bone markings present where tendons meet bones Tubercles, trochanters, and crests Microscopic and Functional Anatomy of Skeletal Muscle Tissue The skeletal muscle fiber Fibers are long and cylindrical Are huge cells diameter is µm Length several centimeters to dozens of centimeters Each cell formed by fusion of embryonic cells Cells are multinucleate Nuclei are peripherally located Diagram of Part of a Muscle Fiber Myofibrils and Sarcomeres Striations result from internal structure of myofibrils Myofibrils Are long rods within cytoplasm Make up 80% of the cytoplasm Are a specialized contractile organelle found in muscle tissue Are a long row of repeating segments called sarcomeres (functional unit of Skeletal MT) Sarcomere Basic unit of contraction of skeletal muscle Z disc (Z line) boundaries of each sarcomere Thin (actin) filaments extend from Z disc toward the center of the sarcomere Thick (myosin) filaments located in the center of the sarcomere Overlap inner ends of the thin filaments Contain ATPase enzymes Sarcomere Structure A bands full length of the thick filament Includes inner end of thin filaments H zone center part of A band where no thin filaments occur A bands and I bands refract polarized light differently

45 A bands anisotropic I bands isotropic Sarcomere Structure (continued) M line in center of H zone Contains tiny rods that hold thick filaments together I band region with only thin filaments Lies within two adjacent sarcomeres Sarcomere Structure (continued) Sarcoplasmic Reticulum and T Tubules Sarcoplasmic reticulum A specialized smooth ER Interconnecting tubules surround each myofibril Some tubules form cross-channels called terminal cisternae Cisternae occur in pairs on either side of a t tubule Sarcoplasmic Reticulum and T Tubules Sarcoplasmic reticulum Contains calcium ions released when muscle is stimulated to contract Calcium ions diffuse through cytoplasm Trigger the sliding filament mechanism T tubules deep invaginations of sarcolemma Triad T tubule flanked by two terminal cisterns Mechanism of Contraction Two major types of contraction Concentric contraction muscle shortens to do work Eccentric contraction muscle generates force as it lengthens Muscle acts as a brake to resist gravity Down portion of a pushup is an example Mechanism of Contraction Sliding filament mechanism Explains concentric contraction Myosin head attach to thin filaments at both ends of a sarcomere

46 Then pull thin filaments toward the center of the sarcomere Thin and thick filaments do not shorten Initiated by release of calcium ions from the SR Powered by ATP Sliding Filament Mechanism Contraction changes the striation pattern Fully relaxed thin filaments partially overlap thin filaments Contraction Z discs move closer together Sarcomere shortens I bands shorten, H zone disappears A band remains the same length Microscopic and Functional Anatomy of Skeletal Muscle Tissue Muscle extension Muscle is stretched by a movement opposite that which contracts it Muscle fiber length and force of contraction Greatest force produced when a fiber starts out slightly stretched Myosin heads can pull along the entire length of the thin filaments The Role of Titin Titin a spring-like molecule in sarcomeres Resists overstretching Holds thick filaments in place Unfolds when muscle is stretched Innervation of Skeletal Muscle Motor neurons innervate skeletal muscle tissue Neuromuscular junction is the point where nerve ending and muscle fiber meet Axon terminals at ends of axons Store neurotransmitters Synaptic cleft space between axon terminal and sarcolemma The Neuromuscular Junction

47 Motor Units10 Muscle Tissue Types of Skeletal Muscle Fibers Skeletal muscle fibers are categorized according to two characteristics How they manufacture energy (ATP) How quickly they contract Oxidative fibers produce ATP aerobically Glycolytic fibers produce ATP anaerobically by glycolysis Types of Skeletal Muscle Fibers Skeletal muscle fibers Are divided into three classes Slow oxidative fibers Red slow oxidative fibers Fast glycolytic fibers White fast glycolytic fibers Fast oxidative fibers Intermediate fibers Types of Skeletal Muscle Fibers Slow oxidative fibers Red color due to abundant myoglobin Obtain energy from aerobic metabolic reactions Contain a large number of mitochondria Richly supplied with capillaries Contract slowly and resistant to fatigue Fibers are small in diameter Types of Skeletal Muscle Fibers Fast glycolytic fibers Contain little myoglobin and few mitochondria About twice the diameter of slow-oxidative fibers Contain more myofilaments and generate more power Depend on anaerobic pathways Contract rapidly and tire quickly

48 Types of Skeletal Muscle Fibers Fast oxidative fibers Have an intermediate diameter Contract quickly like fast glycolytic fibers Are oxygen-dependent Have high myoglobin content and rich supply of capillaries Somewhat fatigue-resistant More powerful than slow oxidative fibers Disorders of Muscle Tissue Muscle tissues experience few disorders Heart muscle is the exception Skeletal muscle Remarkably resistant to infection Smooth muscle Problems stem from external irritants Disorders of Muscle Tissue Muscular dystrophy A group of inherited muscle destroying disease Affected muscles enlarge with fat and connective tissue Muscles degenerate Types of muscular dystrophy Duchenne muscular dystrophy Myotonic dystrophy Disorders of Muscle Tissue Myofascial pain syndrome Pain is caused by tightened bands of muscle fibers Fibromyalgia A mysterious chronic-pain syndrome Affects mostly women Symptoms fatigue, sleep abnormalities, severe musculoskeletal pain, and headache Muscle Tissue Throughout Life Muscle tissue develops from myoblasts Myoblasts fuse to form skeletal muscle fibers Skeletal muscles contract by the seventh week of development