Skeletal System PDF

The Skeletal System The Skeletal System ▪ Parts of the skeletal system ▪ Bones (skeleton) ▪ Joints ▪ Cartilages ▪ Ligaments ▪ Two subdivisions of the skeleton 1. Axial skeleton 2. Appendicular skeleton Functions of the Bones ▪ Support the body ▪ Protect soft organs ▪ Skull and v...

The Skeletal System The Skeletal System ▪ Parts of the skeletal system ▪ Bones (skeleton) ▪ Joints ▪ Cartilages ▪ Ligaments ▪ Two subdivisions of the skeleton 1. Axial skeleton 2. Appendicular skeleton Functions of the Bones ▪ Support the body ▪ Protect soft organs ▪ Skull and vertebrae protect brain and spinal cord ▪ Rib cage protects thoracic cavity organs ▪ Attached skeletal muscles allow movement ▪ Store minerals and fats ▪ Calcium and phosphorus ▪ Fat in the internal marrow cavity ▪ Blood cell formation (hematopoiesis) Classification of Bones ▪ The adult skeleton has 206 bones ▪ Two basic types of osseous (bone) tissue 1. Compact bone ▪ Dense, smooth, and homogeneous 2. Spongy bone ▪ Small needlelike pieces of bone ▪ Many open spaces Figure 5.1 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Spongy bone Compact bone Classification of Bone ▪ Bones are classified on the basis of shape into four groups ▪ Long ▪ Flat ▪ Short ▪ Irregular Figure 5.2 Classification of bones on the basis of shape. (b) Flat bone (sternum) (a) Long bone (humerus) (d) Irregular bone (vertebra), right lateral view (c) Short bone (talus) Classification of Bones ▪ Long bones ▪ Typically longer than they are wide ▪ Shaft with enlarged ends ▪ Contain mostly compact bone; spongy bone at ends ▪ All of the bones of the limbs (except wrist, ankle, and kneecap bones) are long bones ▪ Examples: ▪ Femur ▪ Humerus Figure 5.2a Classification of bones on the basis of shape. (a) Long bone (humerus) Classification of Bones ▪ Flat bones ▪ Thin, flattened, and usually curved ▪ Two thin layers of compact bone sandwich a layer of spongy bone between them ▪ Examples: ▪ Most bones of the skull ▪ Ribs ▪ Sternum Figure 5.2b Classification of bones on the basis of shape. (b) Flat bone (sternum) Classification of Bones ▪ Short bones ▪ Generally cube-shaped ▪ Contain mostly spongy bone with an outer layer of compact bone ▪ Sesamoid bones are a type of short bone that form within tendons (patella) ▪ Examples: ▪ Carpals (wrist bones) ▪ Tarsals (ankle bones) Figure 5.2c Classification of bones on the basis of shape. (c) Short bone (talus) Classification of Bones ▪ Irregular bones ▪ Irregular shape ▪ Do not fit into other bone classification categories ▪ Examples: ▪ Vertebrae ▪ Hip bones Figure 5.2d Classification of bones on the basis of shape. (d) Irregular bone (vertebra), right lateral view Structure of Bone ▪ Long bone anatomy ▪ Diaphysis (shaft) ▪ Makes up most of bone’s length ▪ Composed of compact bone ▪ Periosteum ▪ Outside covering of the diaphysis ▪ Fibrous connective tissue membrane ▪ Perforating (Sharpey’s) fibers secure periosteum to underlying bone Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Figure 5.3c The structure of a long bone (humerus of arm). Endosteum Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries (c) Structure of Bone ▪ Long bone anatomy (continued) ▪ Epiphysis (ends) ▪ Composed mostly of spongy bone enclosed by thin layer of compact bone ▪ Articular cartilage ▪ Covers the external surface of the epiphyses ▪ Made of hyaline cartilage ▪ Decreases friction at joint surfaces Figure 5.3b The structure of a long bone (humerus of arm). Articular cartilage Compact bone Spongy bone (b) Structure of Bone ▪ Long bone anatomy (continued) ▪ Epiphyseal line ▪ Remnant of the epiphyseal plate ▪ Seen in adult bones ▪ Epiphyseal plate ▪ Flat plate of hyaline cartilage seen in young, growing bone ▪ Causes lengthwise growth of a long bone Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Structure of Bone ▪ Long bone anatomy (continued) ▪ Endosteum ▪ Lines the inner surface of the shaft ▪ Made of connective tissue ▪ Medullary cavity ▪ Cavity inside the shaft ▪ Contains yellow marrow (mostly fat) in adults ▪ Contains red marrow for blood cell formation in infants until age 6 or 7 Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Structure of Bone ▪ Bone markings ▪ Sites of attachments for muscles, tendons, and ligaments ▪ Passages for nerves and blood vessels ▪ Categories of bone markings ▪ Projections or processes—grow out from the bone surface ▪ Terms often begin with “T” ▪ Depressions or cavities—indentations ▪ Terms often begin with “F” Table 5.1 Bone Markings (1 of 3) Table 5.1 Bone Markings (2 of 3) Table 5.1 Bone Markings (3 of 3) Structure of Bone ▪ Microscopic anatomy of spongy bone ▪ Composed of small, needlelike pieces of bone called trabeculae and open spaces ▪ Open spaces are filled by marrow, blood vessels, and nerves Figure 5.4a Microscopic structure of bone. Trabeculae of spongy bone Osteon (Haversian Perforating system) (Volkmann’s) canal Blood vessel continues into medullary cavity containing marrow Blood vessel Lamellae Compact bone Central (Haversian) canal Perforating (Sharpey’s) fibers Periosteum Periosteal blood vessel (a) Structure of Bone ▪ Microscopic anatomy of compact bone ▪ Osteocytes ▪ Mature bone cells situated in bone matrix ▪ Lacunae ▪ Cavities in bone matrix that house osteocytes ▪ Lamellae ▪ Concentric circles of lacunae situated around the central (Haversian) canal Structure of Bone ▪ Microscopic anatomy of compact bone (continued) ▪ Central (Haversian) canal ▪ Opening in the center of an osteon (Haversian system) ▪ Runs lengthwise through bone ▪ Carries blood vessels and nerves ▪ Osteon (Haversian system) ▪ A unit of bone containing central canal and matrix rings ▪ Structural and functional unit of compact bone Figure 5.4b Microscopic structure of bone. Lamella Osteocyte Canaliculus Lacuna Central Bone matrix (Haversian) canal (b) Figure 5.4c Microscopic structure of bone. Osteon Interstitial lamellae Lacuna Central (Haversian) canal (c) Structure of Bone ▪ Microscopic anatomy of compact bone (continued) ▪ Canaliculi ▪ Tiny canals ▪ Radiate from the central canal to lacunae ▪ Form a transport system connecting all bone cells to a nutrient supply ▪ Perforating (Volkmann’s) canal ▪ Canal perpendicular to the central canal ▪ Carries blood vessels and nerves Figure 5.4b Microscopic structure of bone. Lamella Osteocyte Canaliculus Lacuna Central Bone matrix (Haversian) canal (b) Structure of Bone ▪ Bone is relatively lightweight and resists tension and other forces ▪ Organic parts (collagen fibers) of the bone make bone flexible and have great tensile strength ▪ Calcium salts deposited in the bone make bone hard to resist compression Bone Formation, Growth, and Remodeling ▪ Bone formation and growth ▪ Ossification is the process of bone formation ▪ Occurs on hyaline cartilage models or fibrous membranes ▪ Long bone growth involves two major phases Bone Formation, Growth, and Remodeling ▪ Two major phases of ossification in long bones 1. Osteoblasts (bone-forming cells) cover hyaline cartilage model with bone matrix 2. In a fetus, the enclosed cartilage is digested away, opening up a medullary cavity Figure 5.5 Stages of long-bone formation in an embryo, fetus, and young child. Articular cartilage Hyaline Spongy cartilage bone New center of bone growth New bone Epiphyseal forming plate cartilage Growth Medullary in bone cavity width Bone starting Invading to replace Growth blood cartilage in bone vessels length New bone Bone collar forming Hyaline Epiphyseal cartilage plate cartilage model In an embryo In a fetus In a child Figure 5.6 Growth and remodeling of long bones. Slide 4 Bone growth Bone grows in length because: 1 Cartilage Articular cartilage grows here. Epiphyseal plate 2 Cartilage is replaced by bone here. 3 Cartilage grows here. © 2018 Pearson Education, Ltd. Bone Formation, Growth, and Remodeling ▪ By birth, most cartilage is converted to bone except for two regions in a long bone 1. Articular cartilages 2. Epiphyseal plates ▪ New cartilage is formed continuously on external face of these two cartilages ▪ Old cartilage is broken down and replaced by bony matrix Figure 5.6 Growth and remodeling of long bones. Slide 8 Bone remodeling Growing shaft is remodeled as: Articular cartilage Epiphyseal plate 1 Bone is resorbed by osteoclasts here. 2 Bone is added (appositional growth) by osteoblasts here. 3 Bone is resorbed by osteoclasts here. © 2018 Pearson Education, Ltd. Bone Formation, Growth, and Remodeling ▪ Appositional growth ▪ Bones grow in width ▪ Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis ▪ Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis ▪ Bone growth is controlled by hormones, such as growth hormone and sex hormones Bone Formation, Growth, and Remodeling ▪ Bones are remodeled throughout life in response to two factors 1. Calcium ion level in the blood determines when bone matrix is to be broken down or formed 2. Pull of gravity and muscles on the skeleton determines where bone matrix is to be broken down or formed Bone Formation, Growth, and Remodeling ▪ Calcium ion regulation ▪ Parathyroid hormone (PTH) ▪ Released when calcium ion levels in blood are low ▪ Activates osteoclasts (bone-destroying cells) ▪ Osteoclasts break down bone and release calcium ions into the blood ▪ Hypercalcemia (high blood calcium levels) prompts calcium storage to bones by osteoblasts Bone Fractures ▪ Fracture: break in a bone ▪ Types of bone fractures ▪ Closed (simple) fracture is a break that does not penetrate the skin ▪ Open (compound) fracture is a broken bone that penetrates through the skin Bone Fractures ▪ Bone fractures are treated by reduction and immobilization ▪ Closed reduction: bones are manually coaxed into position by physician’s hands ▪ Open reduction: bones are secured with pins or wires during surgery ▪ Healing time is 6–8 weeks Bone Fractures ▪ Repair of bone fractures involves four major events ▪ Hematoma (blood-filled swelling, or bruise) is formed ▪ Fibrocartilage callus forms ▪ Cartilage matrix, bony matrix, collagen fibers splint the broken bone ▪ Bony callus replaces the fibrocartilage callus ▪ Osteoblasts and osteoclasts migrate in ▪ Bone remodeling occurs in response to mechanical stresses Figure 5.7 Stages in the healing of a bone fracture. Hematoma External Bony callus callus of spongy bone New Internal blood callus vessels Healed (fibrous fracture tissue and Spongy cartilage) bone trabecula 1 Hematoma 2 Fibrocartilage 3 Bony callus 4 Bone remodeling forms. callus forms. forms. occurs. Table 5.2 Common Types of Fractures Axial Skeleton ▪ Forms the longitudinal axis of the body ▪ Divided into three parts 1. Skull 2. Vertebral column 3. Bony thorax Figure 5.8a The human skeleton. Cranium Skull Facial bones Clavicle Thoracic cage Scapula (ribs and Sternum sternum) Rib Humerus Vertebra Vertebral Radius column Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges (a) Anterior view Figure 5.8b The human skeleton. Cranium Bones of pectoral Clavicle girdle Scapula Sternum Upper Rib limb Humerus Vertebra Radius Bones of Ulna pelvic Carpals girdle Phalanges Metacarpals Femur Lower Tibia limb Fibula (b) Posterior view Skull ▪ Two sets of bones form the skull 1. Cranium bones enclose the brain 2. Facial bones ▪ Hold eyes in anterior position ▪ Allow facial muscles to express feelings ▪ Bones are joined by sutures ▪ Only the mandible is attached by a freely movable joint Skull ▪ 8 cranial bones protect the brain 1 Frontal bone 2 Occipital bone 3 Ethmoid bone 4 Sphenoid bone 5, 6 Parietal bones (pair) 7, 8 Temporal bones (pair) Skull ▪ 14 facial bones 1, 2 Maxillae (pair) 3, 4 Palatine bones (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 Figure 5.9 Human skull, lateral view. Coronal suture Frontal bone Parietal bone Sphenoid bone Temporal bone Ethmoid bone Lambdoid Lacrimal bone suture Squamous suture Nasal bone Occipital bone Zygomatic process Zygomatic bone Maxilla External acoustic meatus Mastoid process Alveolar processes Styloid process Mandible (body) Mental foramen Mandibular ramus Figure 5.10 Human skull, superior view (top of cranium removed). Frontal bone Cribriform plate Ethmoid Crista galli bone Sphenoid bone Optic canal Sella turcica Foramen ovale Temporal bone Jugular foramen Internal acoustic meatus Parietal bone Occipital bone Foramen magnum Figure 5.11 Human skull, inferior view (mandible removed). Maxilla Hard (palatine process) Incisive fossa palate Palatine bone Maxilla Zygomatic bone Sphenoid bone Temporal bone (greater wing) (zygomatic process) Foramen ovale Vomer Mandibular fossa Carotid canal Styloid process Mastoid process Jugular foramen Temporal bone Occipital condyle Parietal bone Foramen magnum Occipital bone Figure 5.12 Human skull, anterior and posterior views. Coronal suture Frontal bone Parietal bone Nasal bone Superior orbital fissure Sphenoid bone Optic canal Ethmoid bone Temporal bone Lacrimal bone Zygomatic bone Infraorbital foramen Middle nasal concha of ethmoid bone Maxilla Inferior nasal concha Vomer Mandible Alveolar processes Mental foramen Sagittal suture Anterior view Parietal bone Lambdoid suture Occipital bone Mastoid process of temporal bone Posterior view Skull ▪ Paranasal sinuses ▪ Hollow portions of bones surrounding the nasal cavity ▪ Functions of paranasal sinuses ▪ Lighten the skull ▪ Amplify sounds made as we speak Figure 5.13a Paranasal sinuses. Frontal sinus Ethmoid sinus Sphenoidal sinus Maxillary sinus (a) Anterior view Figure 5.13b Paranasal sinuses. Frontal sinus Ethmoid sinus Sphenoidal sinus Maxillary sinus (b) Medial view Skull ▪ Hyoid bone ▪ Closely related to mandible and temporal bones ▪ The only bone that does not articulate with another bone ▪ Serves as a movable base for the tongue ▪ Aids in swallowing and speech Figure 5.14 Anatomical location and structure of the hyoid bone. Greater horn Lesser horn Body Vertebral Column (Spine) ▪ Vertebral column provides axial support ▪ Extends from skull to the pelvis ▪ 26 vertebral bones are separated by intervertebral discs ▪ 7 cervical vertebrae are in the neck ▪ 12 thoracic vertebrae are in the chest region ▪ 5 lumbar vertebrae are associated with the lower back ▪ Sacrum (formed by fusion of 5 vertebrae) ▪ Coccyx (formed by fusion of 3–5 vertebrae) Figure 5.15 The vertebral column. Anterior Posterior 1st cervical vertebra (atlas) Cervical curvature 2nd cervical (concave) 7 vertebrae, vertebra (axis) C1 – C7 1st thoracic vertebra Transverse process Spinous Thoracic curvature process (convex) 12 vertebrae, T1 – T12 Intervertebral disc Intervertebral foramen 1st lumbar vertebra Lumbar curvature (concave) 5 vertebrae, L1 – L5 Sacral curvature (convex) 5 fused vertebrae Coccyx 4 fused vertebrae Vertebral Column (Spine) ▪ Primary curvatures ▪ Spinal curvatures of the thoracic and sacral regions ▪ Present from birth ▪ Form a C-shaped curvature in newborns ▪ Secondary curvatures ▪ Spinal curvatures of the cervical and lumbar regions ▪ Develop after birth ▪ Form an S-shaped curvature in adults Figure 5.16 The C-shaped spine typical of a newborn. Vertebral Column (Spine) ▪ Parts of a typical vertebra ▪ Body (centrum) ▪ Vertebral arch ▪ Pedicle ▪ Lamina ▪ Vertebral foramen ▪ Transverse processes ▪ Spinous process ▪ Superior and inferior articular processes Figure 5.17 A typical vertebra, superior view. Posterior Lamina Vertebral arch Transverse Spinous process process Superior articular process and facet Pedicle Vertebral foramen Body Anterior Figure 5.18a Regional characteristics of vertebrae. (a) ATLAS AND AXIS Transverse Posterior process arch Anterior arch Superior view of atlas (C1) Spinous Transverse process process Facet on superior articular process Dens Body Superior view of axis (C2) Figure 5.18b Regional characteristics of vertebrae. (b) TYPICAL CERVICAL VERTEBRAE Facet on superior Spinous articular process process Vertebral foramen Transverse Transverse process foramen Superior view Superior articular Body process Spinous process Transverse process Facet on inferior articular process Right lateral view Figure 5.18c Regional characteristics of vertebrae. (c) THORACIC VERTEBRAE Spinous process Transverse Vertebral process foramen Facet Facet on for rib superior articular process Body Superior view Facet on Body superior articular process Facet on transverse process Costal facet Spinous for rib process Right lateral view Figure 5.18d Regional characteristics of vertebrae. (d) LUMBAR VERTEBRAE Spinous process Vertebral foramen Transverse process Facet on superior Body articular process Superior view Superior Body articular process Spinous Facet on inferior process articular process Right lateral view Figure 5.19 Sacrum and coccyx, posterior view. Superior Auricular Ala Sacral articular surface canal process Body Median Sacrum sacral crest Posterior sacral foramina Sacral Coccyx hiatus Thoracic Cage ▪ Bony thorax, or thoracic cage, protects organs of the thoracic cavity ▪ Consists of three parts 1. Sternum 2. Ribs ▪ True ribs (pairs 1–7) ▪ False ribs (pairs 8–12) ▪ Floating ribs (pairs 11–12) 3. Thoracic vertebrae Figure 5.20a The bony thorax (thoracic cage). T1 vertebra Jugular notch Clavicular notch Manubrium Sternal angle Body Xiphisternal Sternum True joint ribs Xiphoid (1–7) process False ribs (8–12) Intercostal spaces L1 Floating vertebra Costal cartilage ribs (11, 12) (a) Figure 5.20b The bony thorax (thoracic cage). T2 Jugular T3 notch T4 Sternal angle Heart T9 Xiphisternal joint (b) Appendicular Skeleton ▪ Composed of 126 bones ▪ Limbs (appendages) ▪ Pectoral girdle ▪ Pelvic girdle Figure 5.8a The human skeleton. Cranium Skull Facial bones Clavicle Thoracic cage Scapula (ribs and Sternum sternum) Rib Humerus Vertebra Vertebral Radius column Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges (a) Anterior view Figure 5.8b The human skeleton. Cranium Bones of pectoral Clavicle girdle Scapula Sternum Upper Rib limb Humerus Vertebra Radius Bones of Ulna pelvic Carpals girdle Phalanges Metacarpals Femur Lower Tibia limb Fibula (b) Posterior view Bones of the Shoulder Girdle ▪ Also called pectoral girdle ▪ Composed of two bones that attach the upper limb to the axial skeletal 1. Clavicle 2. Scapula ▪ Light, poorly reinforced girdle ▪ Allows the upper limb a exceptional flexibility Figure 5.21a Bones of the shoulder girdle. Acromio- clavicular Clavicle joint Scapula (a) Articulated right shoulder (pectoral) girdle showing the relationship to bones of the thorax and sternum Figure 5.21b Bones of the shoulder girdle. Posterior Sternal (medial) end Acromial Anterior (lateral) end Superior view Acromial end Sternal end Anterior Posterior Inferior view (b) Right clavicle, superior and inferior views Figure 5.21c Bones of the shoulder girdle. Coracoid process Suprascapular notch Superior Acromion angle Glenoid cavity at lateral angle Spine Medial border Lateral border (c) Right scapula, posterior aspect Figure 5.21d Bones of the shoulder girdle. Acromion Suprascapular notch Superior border Coracoid process Superior angle Glenoid cavity Lateral angle Lateral (axillary) Medial border (vertebral) border Inferior angle (d) Right scapula, anterior aspect Bones of the Upper Limbs ▪ Humerus ▪ Forms the arm ▪ Single bone ▪ Proximal end articulation ▪ Head articulates with the glenoid cavity of the scapula ▪ Distal end articulation ▪ Trochlea and capitulum articulate with the bones of the forearm Figure 5.22a Bones of the right arm and forearm. Greater Head of tubercle humerus Lesser tubercle Anatomical neck Intertubercular sulcus Deltoid tuberosity Radial fossa Medial epicondyle Coronoid fossa Capitulum Trochlea (a) Figure 5.22b Bones of the right arm and forearm. Head of humerus Anatomical neck Surgical neck Radial groove Deltoid tuberosity Medial epicondyle Olecranon fossa Lateral Trochlea epicondyle (b) Bones of the Upper Limbs ▪ The forearm has two bones 1. Ulna—medial bone in anatomical position ▪ Proximal end articulation ▪ Coronoid process and olecranon articulate with the humerus 2. Radius—lateral bone in anatomical position ▪ Proximal end articulation ▪ Head articulates with the capitulum of the humerus Figure 5.22c Bones of the right arm and forearm. Trochlear notch Olecranon Head Coronoid process Neck Radial Proximal tuberosity radioulnar joint Radius Ulna Inter- osseous membrane Ulnar Radial Distal styloid styloid process process radioulnar joint (c) Bones of the Upper Limbs ▪ Hand ▪ Carpals—wrist bones ▪ 8 bones arranged in two rows of 4 bones in each hand ▪ Metacarpals—palm bones ▪ 5 per hand ▪ Phalanges—fingers and thumb ▪ 14 phalanges in each hand ▪ In each finger, there are 3 bones ▪ In the thumb, there are only 2 bones Figure 5.23 Bones of the right hand, anterior view. Distal Middle Phalanges (fingers) Proximal 4 3 2 Metacarpals 5 (palm) 1 Hamate Trapezium Carpals Pisiform Trapezoid (wrist) Triquetrum Scaphoid Lunate Capitate Ulna Radius Bones of the Pelvic Girdle ▪ Formed by two coxal (ossa coxae) bones ▪ Composed of three pairs of fused bones 1. Ilium 2. Ischium 3. Pubis ▪ Pelvic girdle = two coxal bones, sacrum ▪ Pelvis = two coxal bones, sacrum, coccyx Bones of the Pelvic Girdle ▪ The total weight of the upper body rests on the pelvis ▪ Pelvis protects several organs ▪ Reproductive organs ▪ Urinary bladder ▪ Part of the large intestine Figure 5.24a The bony pelvis. Iliac crest Sacroiliac joint llium Coxal bone Sacrum (or hip bone) Pelvic brim Pubis Coccyx Ischial spine Acetabulum Ischium Pubic symphysis Pubic arch (a) Figure 5.24b The bony pelvis. Ilium Iliac crest Posterior superior iIiac Anterior superior spine iliac spine Posterior inferior Anterior inferior iIiac spine iliac spine Greater sciatic notch Acetabulum Ischial body Body of pubis Ischial spine Pubis Ischial tuberosity Inferior pubic ramus Ischium Obturator Ischial ramus foramen (b) Bones of the Pelvic Girdle ▪ The female’s pelvis ▪ Inlet is larger and more circular ▪ Shallower, on the whole, and the bones are lighter and thinner ▪ Ilia flare more laterally ▪ Sacrum is shorter and less curved ▪ Ischial spines are shorter and farther apart; thus, the outlet is larger ▪ Pubic arch is more rounded because the angle of the pubic arch is greater Figure 5.24c The bony pelvis. False pelvis Inlet of true pelvis Pelvic brim Pubic arch (less than 90º) False pelvis Inlet of true pelvis Pelvic brim Pubic arch (more than 90º) (c) Bones of the Lower Limbs ▪ Femur—thigh bone ▪ The heaviest, strongest bone in the body ▪ Proximal end articulation ▪ Head articulates with the acetabulum of the coxal (hip) bone ▪ Distal end articulation ▪ Lateral and medial condyles articulate with the tibia in the lower leg Figure 5.25a Bones of the right thigh and leg. Surgical neck Head Inter- trochanteric line Lesser trochanter Lateral epicondyle Medial epicondyle Patellar surface (a) Figure 5.25b Bones of the right thigh and leg. Greater Head trochanter Inter- trochanteric Lesser trochanter crest Gluteal tuberosity Intercondylar fossa Medial Lateral condyle condyle (b) Bones of the Lower Limbs ▪ The lower leg has two bones 1. Tibia—shinbone; larger and medially oriented ▪ Proximal end articulation ▪ Medial and lateral condyles articulate with the femur to form the knee joint ▪ Distal end articulation ▪ Medial malleolus forms the inner part of the ankle 2. Fibula—thin and sticklike; lateral to the tibia ▪ Has no role in forming the knee joint ▪ Distal end articulation ▪ Lateral malleolus forms the outer part of the ankle Figure 5.25c Bones of the right thigh and leg. Intercondylar eminence Lateral Medial condyle condyle Head Tibial tuberosity Proximal tibiofibular joint Interosseous membrane Anterior border Fibula Tibia Distal tibiofibular joint Medial Lateral malleolus malleolus (c) Bones of the Lower Limbs ▪ Foot ▪ Tarsals—7 bones ▪ Two largest tarsals are the: ▪ Calcaneus (heel bone) ▪ Talus ▪ Metatarsals—5 bones form the sole of the foot ▪ Phalanges—14 bones form the toes Figure 5.26 Bones of the right foot, superior view. Phalanges: Distal Middle Proximal Tarsals: Medial Metatarsals cuneiform Tarsals: Intermediate cuneiform Lateral cuneiform Navicular Cuboid Talus Calcaneus Bones of the Lower Limbs ▪ Arches of the feet ▪ Bones of the foot are arranged to form three strong arches ▪ Two longitudinal ▪ One transverse Figure 5.27 Arches of the foot. Medial longitudinal arch Transverse arch Lateral longitudinal arch Joints ▪ Joints are articulations ▪ Occur where two or more bones meet ▪ Functions of joints ▪ Hold bones together securely ▪ Allow for mobility ▪ Two ways joints are classified ▪ Functionally ▪ Structurally Joints ▪ Functional joint classifications ▪ Synarthroses ▪ Immovable joints ▪ Amphiarthroses ▪ Slightly movable joints ▪ Diarthroses ▪ Freely movable joints Joints ▪ Structural joint classifications ▪ Fibrous joints ▪ Generally immovable ▪ Cartilaginous joints ▪ Immovable or slightly movable ▪ Synovial joints ▪ Freely movable Joints ▪ Fibrous joints ▪ Bones are united by fibrous tissue ▪ Types ▪ Sutures ▪ Immobile ▪ Syndesmoses ▪ Allow more movement than sutures but still immobile ▪ Found on the distal ends of tibia and fibula ▪ Gomphoses ▪ Immobile ▪ Found where the teeth meet the facial bones Figure 5.28a Types of joints. Fibrous joints Fibrous connective tissue (a) Suture Figure 5.28b Types of joints. Fibrous joints Tibia Fibula Fibrous connective tissue (b) Syndesmosis Joints ▪ Cartilaginous joints ▪ Bones are connected by fibrocartilage ▪ Types ▪ Synchrondrosis ▪ Immobile ▪ Found in epiphyseal plates of growing long bones ▪ Symphysis ▪ Slightly movable ▪ Found in the pubic symphysis, intervertebral joints Figure 5.28c Types of joints. Cartilaginous joints First rib Hyaline cartilage Sternum (c) Synchondrosis Figure 5.28d Types of joints. Cartilaginous joints Vertebrae Fibrocartilage (d) Symphysis Figure 5.28e Types of joints. Cartilaginous joints Pubis Fibro- cartilage (e) Symphysis Joints ▪ Synovial joints ▪ Articulating bones are separated by a joint cavity ▪ Synovial fluid is found in the joint cavity ▪ Four distinguishing features of synovial joints 1. Articular cartilage 2. Articular capsule 3. Joint cavity 4. Reinforcing ligaments Figure 5.28f Types of joints. Synovial joints Scapula Articular capsule Articular (hyaline) cartilage Humerus (f) Multiaxial joint (shoulder joint) Figure 5.28g Types of joints. Synovial joints Humerus Articular (hyaline) cartilage Articular capsule Radius Ulna (g) Uniaxial joint (elbow joint) Figure 5.28h Types of joints. Synovial joints Ulna Radius Articular capsule Carpals (h) Biaxial joint (intercarpal joints of hand) Joints ▪ Synovial joints (continued) ▪ Bursae—flattened fibrous sacs ▪ Lined with synovial membranes ▪ Filled with synovial fluid ▪ Not actually part of the joint ▪ Tendon sheath ▪ Elongated bursa that wraps around a tendon Joints ▪ Types of synovial joints based on shape ▪ Plane joint ▪ Hinge joint ▪ Pivot joint ▪ Condylar joint ▪ Saddle joint ▪ Ball-and-socket joint Figure 5.29 General structure of a synovial joint. Acromion of scapula Ligament Joint cavity containing Bursa synovial fluid Ligament Articular (hyaline) Tendon cartilage sheath Synovial membrane Tendon of Fibrous layer of the biceps muscle articular capsule Humerus Figure 5.30a Types of synovial joints. Nonaxial Uniaxial Biaxial Multiaxial (f) (a) Plane joint (b) (c) (a) (e) (d) Figure 5.30b Types of synovial joints. Nonaxial Uniaxial Biaxial Multiaxial (f) (b) Humerus (c) Ulna (a) (e) (b) Hinge joint (d) Figure 5.30c Types of synovial joints. Nonaxial Uniaxial Ulna Biaxial Radius Multiaxial (f) (c) Pivot joint (b) (c) (a) (e) (d) Figure 5.30d Types of synovial joints. Nonaxial Uniaxial Biaxial Multiaxial (f) Metacarpal (b) Phalanx (c) (d) Condylar joint (a) (e) (d) Figure 5.30e Types of synovial joints. Nonaxial Carpal Uniaxial Metacarpal #1 Biaxial Multiaxial (f) (e) Saddle joint (b) (c) (a) (e) (d) Figure 5.30f Types of synovial joints. Nonaxial Uniaxial Biaxial Multiaxial (f) Head of humerus (b) (c) Scapula (f) Ball-and-socket joint (a) (e) (d) Developmental Aspects of the Skeleton ▪ Birth to adulthood ▪ First “long bones” of a fetus are hyaline cartilage ▪ Earliest “flat bones” of the fetal skull are fibrous membranes ▪ As fetus grows, all bone models are converted to bone Figure 5.31 Ossification centers in the skeleton of a 12-week-old fetus are indicated by the darker areas. Parietal bone Frontal bone of skull Occipital bone Mandible Clavicle Scapula Radius Ulna Humerus Femur Tibia Ribs Vertebra Hip bone Developmental Aspects of the Skeleton ▪ Fetal skull ▪ Fontanels are fibrous membranes connecting the cranial bones ▪ Known as “soft spots” ▪ Allow skull compression during birth ▪ Allow the brain to grow during later pregnancy and infancy ▪ Usually ossify by 2 years of age Figure 5.32a The fetal skull. Anterior fontanel Frontal bone Parietal bone Posterior fontanel Occipital (a) bone Figure 5.32b The fetal skull. Anterior fontanel Sphenoidal Parietal bone fontanel Frontal Posterior bone fontanel Occipital bone Mastoid fontanel Temporal bone (b) Developmental Aspects of the Skeleton ▪ Growth of cranium after birth is related to brain growth ▪ Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways Developmental Aspects of the Skeleton ▪ Size of cranium in relationship to body ▪ 2 years old—skull is three-fourths the size of adult skull ▪ 8 or 9 years old—skull is near adult in size and proportion ▪ Between ages 6 and 11, the face grows out from the skull Developmental Aspects of the Skeleton ▪ Skeletal changes ▪ At birth, the head and trunk are proportionately much longer than the lower limbs ▪ During puberty: ▪ Female pelvis broadens ▪ Entire male skeleton becomes more robust ▪ By the end of adolescence: ▪ Epiphyseal plates become fully ossified Figure 5.33a Differences in the growth rates for some parts of the body compared to others determine body proportions. Human newborn Human adult (a) Figure 5.33b Differences in the growth rates for some parts of the body compared to others determine body proportions. Newborn 2 yrs. 5 yrs. 15 yrs. Adult (b) Developmental Aspects of the Skeleton ▪ Older adults ▪ Osteoporosis ▪ Bone-thinning disease afflicting: ▪ 50 percent of women over age 65 ▪ 20 percent of men over age 70 ▪ Disease makes bones fragile, and bones can easily fracture ▪ Vertebral collapse results in kyphosis (also known as “dowager’s hump”) ▪ Estrogen aids in health and normal density of a female skeleton Figure 5.34 Osteoporosis. Figure 5.35 Vertebral collapse due to osteoporosis. Age 40 Age 60 Age 70