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Ch. 5 THE SKELETAL SYSTEM Copyright © 2010 Pearson Education, Inc. Five Functions of Bones • Support • For the body and soft organs • Protection • For brain, spinal cord, and vital organs • Movement • Levers for muscle action Copyright © 2010 Pearson Education, Inc. Functions of Bones • Storage • Minerals (calcium and phosphorus) and growth factors; Triglyceride (energy) storage in bone cavities • Blood cell formation (hematopoiesis) in marrow cavities Copyright © 2010 Pearson Education, Inc. Classification of Bones by Shape • Long bones • Longer than they are wide • All limb bones except carpals and tarsals, patella • Short bones • Cube-shaped bones (in wrist and ankle) • Sesamoid bones (within tendons, e.g., patella) Copyright © 2010 Pearson Education, Inc. Classification of Bones by Shape • Flat bones • Thin, flat, slightly curved • Examples: Sternum, scapulae, ribs most skull bones • Irregular bones • Complicated shapes • Examples: coxal, vertebrae Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Figure 6.2 Bone Textures • Compact bone • Dense outer layer of bone • Composed of osteons • Spongy bone • Internal to compact bone & composed of trabeculae • No osteons • Spaces between trabeculae are filled with bone marrow Copyright © 2010 Pearson Education, Inc. Membranes of Bone • Periosteum • Surrounds entire outer surface of compact bone, except joint surfaces • Contains: Osteoblasts and osteoclasts • Secured to compact bone by Sharpey’s fibers • Endosteum • Lines internal surfaces of bone and also contains osteoblasts and osteoclasts Copyright © 2010 Pearson Education, Inc. Structure of a Long Bone • Diaphysis (shaft) • Compact bone collar surrounds medullary (marrow) cavity Copyright © 2010 Pearson Education, Inc. Structure of a Long Bone • Epiphyses • Expanded ends • Spongy bone interior • Epiphyseal line (remnant of growth plate) • Articular (hyaline) cartilage on joint surfaces Copyright © 2010 Pearson Education, Inc. Articular cartilage Proximal epiphysis Compact bone Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) (b) Diaphysis Distal epiphysis (a) Copyright © 2010 Pearson Education, Inc. Figure 6.3a-b Structure of Short, Irregular, and Flat Bones • Endosteum covered spongy bone surrounded/sandwiched by compact bone covered in periosteum Copyright © 2010 Pearson Education, Inc. Spongy bone (diploë) Compact bone Trabeculae Copyright © 2010 Pearson Education, Inc. Figure 6.5 Chemical Composition of Bone: Organic • Bone cells (osteoblasts, osteocytes, osteoclasts) • Osteoid—organic bone matrix secreted by osteoblasts Copyright © 2010 Pearson Education, Inc. Chemical Composition of Bone: Inorganic • Hydroxyapatites (mineral salts) • 65% of bone by mass • Mainly calcium phosphate crystals • Responsible for hardness and resistance to compression Copyright © 2010 Pearson Education, Inc. Bone Formation, Growth and Remodeling • Ossification- bone tissue formation • Stages • Bone formation—begins in the 2nd month of development • Postnatal bone growth—until early adulthood • Interstitial ( in length of long bones)and appositional ( in bone width & continues after adulthood) • Bone remodeling and repair—lifelong Copyright © 2010 Pearson Education, Inc. Month 3 Week 9 Birth Childhood to adolescence Articular cartilage Secondary ossification center Epiphyseal blood vessel Area of deteriorating cartilage matrix Hyaline cartilage Spongy bone formation Bone collar Primary ossification center 1 Bone collar Epiphyseal plate cartilage Medullary cavity Blood vessel of periosteal bud 2 Cartilage in the 3 The periosteal forms around center of the hyaline cartilage diaphysis calcifies model. and then develops cavities. bud inavades the internal cavities and spongy bone begins to form. Copyright © 2010 Pearson Education, Inc. Spongy bone 4 The diaphysis elongates and a medullary cavity forms as ossification continues. Secondary ossification centers appear in the epiphyses in preparation for stage 5. 5 The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Control of Remodeling • What controls continual remodeling of bone? • Hormonal mechanisms that maintain calcium homeostasis in the blood • Mechanical and gravitational forces Copyright © 2010 Pearson Education, Inc. Hormonal Control of Blood Ca2+ • Primarily controlled by parathyroid hormone (PTH) Blood Ca2+ levels Parathyroid glands release PTH PTH stimulates osteoclasts to degrade bone matrix and release Ca2+ Blood Ca2+ levels Copyright © 2010 Pearson Education, Inc. Calcium homeostasis of blood: 9–11 mg/100 ml BALANCE BALANCE Stimulus Falling blood Ca2+ levels Thyroid gland Osteoclasts degrade bone matrix and release Ca2+ into blood. Copyright © 2010 Pearson Education, Inc. Parathyroid glands PTH Parathyroid glands release parathyroid hormone (PTH). Response to Mechanical Stress • Curved bones are thickest where they are most likely to buckle • Trabeculae form along lines of stress • Large, bony projections occur where heavy, active muscles attach Copyright © 2010 Pearson Education, Inc. Load here (body weight) Head of femur Tension here Compression here Point of no stress Copyright © 2010 Pearson Education, Inc. Figure 6.13 Homeostatic Imbalances • Read about Osteoporosis and focus on its risk factors, symptoms and characteristics Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Figure 6.16 THE SKELETON Copyright © 2010 Pearson Education, Inc. The Skeleton • Two Major Divisions of the Skeletal System: Axial and Appendicular • The Axial Skeleton Includes Three Regions: • Skull and associated bones (aud. ossicles and hyoid) • Vertebral column • Thoracic cage Copyright © 2010 Pearson Education, Inc. Skull Thoracic cage (ribs and sternum) Vertebral column Sacrum Cranium Facial bones Clavicle Scapula Sternum Rib Humerus Vertebra Radius Ulna Carpals Phalanges Metacarpals Femur Patella Tibia Fibula (a) Anterior view Copyright © 2010 Pearson Education, Inc. Tarsals Metatarsals Phalanges Figure 7.1a The Skull •Two sets of bones 1. Cranial bones (8) • Enclose the brain in the cranial cavity • Calvaria: • Cranial base: anterior, middle, and posterior cranial fossae Copyright © 2010 Pearson Education, Inc. The Skull 2. Facial bones • Cavities for: special sense organs for sight, taste, and smell • Provide sites of attachment for: teeth and muscles of facial expression • All skull bones are joined by: sutures except temperomandibular joint(TMJ) Copyright © 2010 Pearson Education, Inc. Bones of cranium (cranial vault) Coronal suture Squamous suture Lambdoid suture Copyright © 2010 Pearson Education, Inc. Facial bones Anterior cranial fossa Middle cranial fossa Posterior cranial fossa (b) Superior view of the cranial fossae Copyright © 2010 Pearson Education, Inc. Frontal Bone • Forms most of forehead • Superior wall of orbits Copyright © 2010 Pearson Education, Inc. Frontal bone Parietal bone Squamous part of frontal bone Frontonasal suture Supraorbital foramen (notch) Supraorbital margin (a) Anterior view Copyright © 2010 Pearson Education, Inc. Figure 7.4a Parietal Bones and Major Associated Sutures • Superior and lateral aspects of craniaum • Four sutures mark the articulations of parietal bones with frontal, occipital, and temporal bones: 1. Coronal suture—between parietal bones and frontal bone 2. Sagittal suture—between right and left parietal bones 3. Lambdoid suture—between parietal bones and occipital bone 4. Squamous (squamosal) sutures—between parietal and temporal bones on each side of skull Copyright © 2010 Pearson Education, Inc. Coronal suture Parietal bone Frontal bone Sphenoid bone (greater wing) Temporal bone Lambdoid suture Squamous suture Occipital bone (a) External anatomy of the right side of the skull Copyright © 2010 Pearson Education, Inc. Figure 7.5a Occipital Bone • Most of skull’s posterior wall and posterior cranial fossa • Articulates with 1st vertebra at occipital condyles • Contains the foramen magnum Copyright © 2010 Pearson Education, Inc. Sagittal suture Parietal bone Lambdoid suture Occipital bone Superior nuchal line External occipital protuberance (b) Posterior view Copyright © 2010 Pearson Education, Inc. Occipital condyle Figure 7.4b Occipital Condyles (a) Inferior view of the skull (mandible removed) Copyright © 2010 Pearson Education, Inc. Foramen Magnum Figure 7.6a Temporal Bones • Inferior to parietal bones • External acoustic canal leads to eardrum • Zygomatic process joins with cheek bone • Mandibular fossa for mandible Copyright © 2010 Pearson Education, Inc. External acoustic meatus Zygomatic process Mastoid process Mandibular fossa Styloid process Copyright © 2010 Pearson Education, Inc. Figure 7.8 Sphenoid Bone • Complex, bat-shaped bone • Processes : greater & lesser wings • Contains the: sella turcica (for pituitary) Copyright © 2010 Pearson Education, Inc. Frontal bone Olfactory foramina Sphenoid Lesser wing Greater wing Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Temporal bone (petrous part) Foramen magnum View Parietal bone Occipital bone (a) Superior view of the skull, calvaria removed Copyright © 2010 Pearson Education, Inc. Figure 7.7a Body of sphenoid Greater wing Lesser wing Superior orbital fissure Pterygoid process (b) Posterior view Copyright © 2010 Pearson Education, Inc. Ethmoid Bone • Helps form the nasal septum • Contains crista galli and cribriform plate for olfactory fibers to pass Copyright © 2010 Pearson Education, Inc. Frontal bone Parietal bone Nasal bone Sphenoid bone Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Middle nasal concha Ethmoid Perpendicular bone plate Inferior nasal concha Vomer (a) Anterior view Copyright © 2010 Pearson Education, Inc. Figure 7.4a Ethmoid bone Cribriform plate Crista galli Frontal bone Olfactory foramina Anterior cranial fossa Optic canal Sphenoid Lesser wing Greater wing Hypophyseal fossa of sella turcica Middle cranial fossa Temporal bone (petrous part) Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Internal acoustic meatus Jugular foramen Hypoglossal canal Posterior cranial fossa Parietal bone Occipital bone (a) Superior view of the skull, calvaria removed Copyright © 2010 Pearson Education, Inc. Foramen magnum View Mandible • Lower jaw • Temporomandibular joint: only freely movable joint in skull Copyright © 2010 Pearson Education, Inc. Temporomandibular joint Mandibular fossa of temporal bone Mandibular condyle Copyright © 2010 Pearson Education, Inc. Figure 7.11a Maxillary Bones • Medially fused to form upper jaw • Carry teeth in the alveolar margin Copyright © 2010 Pearson Education, Inc. Articulates with frontal bone Alveolar margin (b) Maxilla, right lateral view Copyright © 2010 Pearson Education, Inc. Figure 7.11b Frontal bone Parietal bone Nasal bone Sphenoid bone Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Maxilla Ethmoid bone Inferior nasal concha Vomer (a) Anterior view Copyright © 2010 Pearson Education, Inc. Figure 7.4a Zygomatic Bones • Cheekbones • Inferolateral margins of orbits Copyright © 2010 Pearson Education, Inc. (a) Anterior view Copyright © 2010 Pearson Education, Inc. Figure 7.4a Nasal Bones and Lacrimal Bones • Nasal bones • Form: bridge of nose • Lacrimal bones • In medial walls of orbits • Lacrimal fossa houses lacrimal sac Copyright © 2010 Pearson Education, Inc. Lacrimal bone Lacrimal fossa (a) External anatomy of the right side of the skull Copyright © 2010 Pearson Education, Inc. Figure 7.5a Palatine Bones and Vomer • Palatine bones • Posterior one-third of hard palate Copyright © 2010 Pearson Education, Inc. • Vomer • Lower part of nasal septum Maxilla (palatine process) Hard Palatine bone palate (horizontal plate) Vomer (a) Inferior view of the skull (mandible removed) Copyright © 2010 Pearson Education, Inc. Figure 7.6a Superior nasal concha Ethmoid Middle bone nasal concha Inferior nasal concha Nasal bone Sphenoid bone Palatine bone • Inferior Nasal ConchaeForm part of lateral walls of nasal cavity Copyright © 2010 Pearson Education, Inc. Orbits • Encase: eyes and lacrimal glands • Sites of attachment for: eye muscles • Formed by: parts of seven bones Copyright © 2010 Pearson Education, Inc. Superior orbital fissure Optic canal sphenoid bone • Ethmoid bone •Frontal bone • Lacrimal bone Zygomatic bone • Maxillary bone (b) Contribution of each of the seven bones forming the right orbit Copyright © 2010 Pearson Education, Inc. Hyoid Bone • Not a bone of the skull • Does not articulate directly with another bone • Site of attachment for muscles of swallowing and speech Copyright © 2010 Pearson Education, Inc. Greater horn Lesser horn Body Copyright © 2010 Pearson Education, Inc. Figure 7.12 THE SKELETAL SYSTEM: THE AXIAL SKELETON (CONT.) Copyright © 2010 Pearson Education, Inc. Vertebral Column • Flexible curved structure containing 26 irregular bones (vertebrae) • Cervical vertebrae (7)—vertebrae of the neck • Thoracic vertebrae (12)—vertebrae of the thoracic cage • Lumbar vertebrae (5)—vertebra of the lower back • Sacrum—bone inferior to the lumbar vertebrae • Coccyx—terminus of vertebral column Copyright © 2010 Pearson Education, Inc. Vertebral Column: Curvatures • Increase the resilience and flexibility of the spine • Primary curvatures • Thoracic and sacral • Present at birth • Secondary curvatures • Cervical and lumbar • Form after birth (holding head upright, walking upright) Copyright © 2010 Pearson Education, Inc. C1 Cervical curvature (concave) Thoracic curvature (convex) Lumbar curvature (concave) Sacral curvature (convex) Coccyx Anterior view Copyright © 2010 Pearson Education, Inc. Right lateral view Figure 7.16 Copyright © 2010 Pearson Education, Inc. Figure 7.37 General Structure of Vertebrae • Body • Anterior, weight-bearing region • Vertebral foramen • Together make up vertebral canal for spinal cord Copyright © 2010 Pearson Education, Inc. General Structure of Vertebrae • Seven processes per vertebra: • Spinous process—projects posteriorly • Transverse processes (2)—project laterally • Superior articular processes (2)—protrude superiorly • Inferior articular processes (2)—protrude inferiorly Copyright © 2010 Pearson Education, Inc. Lamina Transverse process Posterior Spinous process Vertebral foramen Body Pedicle Anterior Copyright © 2010 Pearson Education, Inc. Vertebral arch Cervical Vertebrae • smallest, lightest vertebrae • C3 to C7 share the following features • Transverse foramen in: each transverse process Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Dens of axis Transverse ligament of atlas C1 (atlas) C2 (axis) C3 Inferior articular process Bifid spinous process Transverse processes C7 (vertebra prominens) (a) Cervical vertebrae Copyright © 2010 Pearson Education, Inc. Cervical Vertebrae • C1 (atlas) and C2 (axis) have unique features • Atlas (C1) • No body or spinous process • Superior articular facets articulate with the skull Copyright © 2010 Pearson Education, Inc. C1 Posterior Posterior Posterior arch Transverse process Inferior articular facet Transverse foramen Anterior arch Posterior arch Transverse foramen Anterior arch (a) Superior view of atlas (C1) Copyright © 2010 Pearson Education, Inc. Superior articular facet (b) Inferior view of atlas (C1) Cervical Vertebrae • Axis (C2) • Dens projects superiorly into the anterior arch of the atlas Copyright © 2010 Pearson Education, Inc. Posterior C2 Inferior articular process Spinous process Lamina Pedicle Transverse process Superior articular facet Dens Body (c) Superior view of axis (C2) Copyright © 2010 Pearson Education, Inc. Thoracic Vertebrae • T1 to T12 • All have costal facets for ribs Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Transverse process Superior articular process Transverse costal facet (for tubercle of rib) Body Spinous process Inferior demifacet (for head of rib) Inferior articular process (b) Thoracic vertebrae Copyright © 2010 Pearson Education, Inc. Lumbar Vertebrae • L1 to L5 • Short, thick pedicles and laminae Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Table 7.2 Superior articular process Transverse process Body Intervertebral disc Inferior articular process Spinous process (c) Lumbar vertebrae Copyright © 2010 Pearson Education, Inc. Figure 7.20c Sacrum and Coccyx • Sacrum • 5 fused vertebrae (S1– S5) • Forms: posterior wall of pelvis • Sacral Canal • Articulates with L5 superiorly, and with coxal bones laterally Copyright © 2010 Pearson Education, Inc. • Coccyx • Tailbone • 3–5 fused vertebrae • Articulates superiorly with: sacrum Body of first sacral vertebra Coccyx (a) Anterior view Copyright © 2010 Pearson Education, Inc. Figure 7.21a Sacral canal Coccyx (b) Posterior view Copyright © 2010 Pearson Education, Inc. Facet of superior articular process Thoracic (Rib) Cage • Composed of • Thoracic vertebrae • Sternum • Ribs and their costal cartilages Copyright © 2010 Pearson Education, Inc. Sternum • Three fused bones • Manubrium (superior) • Body (middle) • Xiphoid process (inferior) Copyright © 2010 Pearson Education, Inc. Ribs and Their Attachments • 12 pairs • All attach posteriorly to thoracic vertebrae • Pairs 1 through 7 • True ribs • Attach directly to the sternum by individual costal cartilages Copyright © 2010 Pearson Education, Inc. Ribs and Their Attachments • Pairs 8 through10 • False ribs • Attach indirectly to sternum by joining costal cartilage of rib above • Pairs 11–12 • Floating ribs • No attachment to sternum Copyright © 2010 Pearson Education, Inc. Manubrium Sternal angle Body Xiphisternal joint Xiphoid process True ribs (1–7) False ribs (8–10) Costal cartilage L1 Vertebra Copyright © 2010 Pearson Education, Inc. Sternum Floating ribs (11, 12) Articular facet on tubercle of rib Neck of rib Head of rib Superior costal facet (for head of rib) Copyright © 2010 Pearson Education, Inc. Spinous process Transverse costal facet (for tubercle of rib) Body of thoracic vertebra Figure 7.23b THE SKELETAL SYSTEM: THE APPENDICULAR SKELETON Copyright © 2010 Pearson Education, Inc. Pectoral Girdle (Shoulder Girdle) • Clavicles and the scapulae • Attach the upper limbs to the axial skeleton Copyright © 2010 Pearson Education, Inc. Acromioclavicular joint Clavicle Scapula (a) Articulated pectoral girdle Copyright © 2010 Pearson Education, Inc. Figure 7.24a Clavicles • Acromial end (lateral end) articulates with the scapula • Sternal end (medial) articulates with the sternum Copyright © 2010 Pearson Education, Inc. Sternal (medial) end Posterior Anterior Acromial (lateral) end (b) Right clavicle, superior view Copyright © 2010 Pearson Education, Inc. Figure 7.24b Scapulae (Shoulder Blades) • On dorsal surface of rib cage • Glenoid cavity houses the head of humerus • Spine is on posterior aspect • Three fossa are the site of origin for the rotator cuff muscles: supraspinous, infraspinous and subscapular fossa Copyright © 2010 Pearson Education, Inc. Superior border Glenoid cavity Lateral border Subscapular fossa Medial border (a) Right scapula, anterior aspect Copyright © 2010 Pearson Education, Inc. Figure 7.25a Suprascapular notch Coracoid process Superior angle Supraspinous fossa Spine Infraspinous fossa Acromion Glenoid cavity at lateral angle Medial border Lateral border (b) Right scapula, posterior aspect Copyright © 2010 Pearson Education, Inc. Figure 7.25b Acromion Supraspinous fossa Supraglenoid tubercle Coracoid process Supraspinous fossa Infraspinous fossa Posterior Spine Glenoid cavity Infraspinous fossa Infraglenoid tubercle Subscapular fossa Anterior (c) Right scapula, lateral aspect Copyright © 2010 Pearson Education, Inc. Subscapular fossa Inferior angle Figure 7.25c The Upper Limb • Arm • Humerus • Forearm • Radius and ulna • Hand • 8 carpal bones in the wrist • 5 metacarpal bones in the palm • 14 phalanges in the fingers Copyright © 2010 Pearson Education, Inc. Humerus • Largest, longest bone of upper limb • Head of Humerus articulates with: glenoid cavity of scapula • Contains: Greater and Lesser Tubercles • Articulates inferiorly with radius and ulna via the capitulum and trochlea respectively Copyright © 2010 Pearson Education, Inc. Greater tubercle Lesser tubercle Capitulum Copyright © 2010 Pearson Education, Inc. Head of humerus Trochlea Bones of the Forearm • Ulna • Medial bone in forearm • Contains olecranon process and trochlear notch • Radius • Lateral bone in forearm • Contains radial head and ulnar notch Copyright © 2010 Pearson Education, Inc. Radial notch of the ulna Head Olecranon process Trochlear notch Coronoid process Head of radius Interosseous membrane Ulna Radius Radius (a) Anterior view Copyright © 2010 Pearson Education, Inc. (b) Posterior view Humerus Capitulum Head of radius Trochlea Coronoid process of ulna (c) Anterior view at the elbow region Humerus Olecranon fossa Olecranon process (d) Posterior view of extended elbow Copyright © 2010 Pearson Education, Inc. Hand: Carpus • Eight bones in two rows • Only scaphoid and lunate articulate with radius to form wrist joint Copyright © 2010 Pearson Education, Inc. Hand: Metacarpus and Phalanges • Metacarpus • Five metacarpal bones (#1 to #5) form the palm • Phalanges • Each finger (digit), except the thumb, has three phalanges—distal, middle, and proximal • The thumb (pollex) has no middle phalanx Copyright © 2010 Pearson Education, Inc. Phalanges • Distal • Middle • Proximal Metacarpals Carpals • Trapezium • Trapezoid • Scaphoid Radius (a) Anterior view of left hand Copyright © 2010 Pearson Education, Inc. Carpals • Hamate • Capitate • Pisiform • Triquetrum • Lunate Ulna Carpals • Trapezium • Trapezoid • Scaphoid Radius (b) Posterior view of left hand Figure 7.28a-b 17. 18. 14. 15. Copyright © 2010 Pearson Education, Inc. 16. Pelvic (Hip) Girdle • Consists of Two coxal bones • Attaches lower limbs to the axial skeleton with strong ligaments • Transmits weight of upper body to lower limbs • Each coxal bone consists of three fused bones: • Ilium• Ischium• Pubis- Copyright © 2010 Pearson Education, Inc. Ala Ilium Acetabulum Ischium Pubis Obturator foramen (a) Lateral view, right hip bone Copyright © 2010 Pearson Education, Inc. Iliac fossa Coxal bone Sacroiliac joint Anterior superior iliac spine llium Pubic bone Sacrum Coccyx Pelvic brim Acetabulum Ischium Pubic symphysis Pubic arch Copyright © 2010 Pearson Education, Inc. Figure 7.29 Comparison of Male and Female Pelves • Female pelvis • Adapted for childbearing • True pelvis: (inferior to pelvic brim) defines birth canal • Cavity of the true pelvis is broad, shallow, and has greater capacity Copyright © 2010 Pearson Education, Inc. Comparison of Male and Female Pelves • Male pelvis • Adapted for support of male’s heavier build and stronger muscles • Cavity of true pelvis is narrow and deep Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. The Lower Limb • Three segments of the lower limb • Thigh: femur • Leg: tibia and fibula • Foot: 7 tarsal bones in the ankle, 5 metatarsal bones in the metatarsus, and 14 phalanges in the toes Copyright © 2010 Pearson Education, Inc. Femur • Largest and strongest bone in the body • Femoral head articulates proximally with the acetabulum of the hip and distally with the tibia and patella • Contains greater and lesser trochanters, medial and lateral condyles and patellar surface Copyright © 2010 Pearson Education, Inc. Greater trochanter Head Lesser trochanter Apex Anterior Lateral condyle Intercondylar fossa Medial condyle Posterior (a) Patella (kneecap) Patellar surface Anterior view Posterior view (b) Femur (thigh bone) Copyright © 2010 Pearson Education, Inc. Bones of the Distal Leg • Tibia • Medial leg bone • Articulates with femur , fibula and talus • Contains medial and lateral condyles, medial malleolus and anterior crest • Fibula • Lateral leg bone (Not weight bearing; no articulation with femur) • Articulates with tibia at proximal and distal ends and with talus • Contains fibular head and lateral malleolus Copyright © 2010 Pearson Education, Inc. Lateral condyle Proximal tibiofibular joint Medial condyle Interosseous membrane Fibula Tibia Distal tibiofibular joint (a) Anterior view Copyright © 2010 Pearson Education, Inc. Foot: Tarsals • Seven tarsal bones form the posterior half of the foot • Talus transfers most of the weight from the tibia to the calcaneus Copyright © 2010 Pearson Education, Inc. Foot: Metatarsals and Phalanges • Metatarsals: • Five metatarsal bones (#1 to #5) • Phalanges (The 14 bones of the toes) • Each digit (except the hallux) has three phalangesproximal, middle, distal • The great toe (Hallux) has no middle phalanx Copyright © 2010 Pearson Education, Inc. Distal Middle Proximal 1 Medial cuneiform Intermediate cuneiform Navicular Talus Trochlea of talus (a) Superior view Copyright © 2010 Pearson Education, Inc. 2 3 4 5 Phalanges Metatarsals Lateral cuneiform Cuboid Tarsals Calcaneus Figure 7.33a Intermediate cuneiform First metatarsal Talus Facet for medial Navicular malleolus Sustentaculum tali (talar shelf) Calcaneus Medial cuneiform (b) Medial view PLAY Calcaneal tuberosity Animation: Rotatable bones of the foot Copyright © 2010 Pearson Education, Inc. Figure 7.33b Joints (Articulations) • Articulation—site where two or more bones meet • Functions of joints: • Give skeleton mobility • Hold skeleton together Copyright © 2010 Pearson Education, Inc. Synovial Joints Four Distinguishing features: 1. Articular cartilage: hyaline cartilage 2. Articular (joint) capsule: 3. Joint (synovial) cavity: small potential space -encloses synovial fluid 4. Reinforcing ligaments Copyright © 2010 Pearson Education, Inc. Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Articular Synovial capsule membrane Periosteum Copyright © 2010 Pearson Education, Inc.