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Chap08 Skeletal System
- 1. 8-1 Chapter 8 Skeletal System Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 2. 8-2 The Skeletal System • Overview of the skeleton • The skull • The vertebral column and thoracic cage • The pectoral girdle and upper limb • The pelvic girdle and lower limb
- 3. 8-3 Overview of the Skeleton • Regions of the skeleton – axial skeleton = central axis • skull, vertebral column, ribs, sternum and sacrum – appendicular skeleton = limbs and girdles • Number of bones – 206 in typical adult skeleton • varies with development of sesamoid bones (patella) – start at 270 at birth, decreases with fusion • Surface markings defined in Table 8.2
- 4. 8-4
- 5. 8-5 Surface Features of Bones
- 6. 8-6 The Skull • 22 bones joined together by sutures • Cranial bones surround cranial cavity – 8 bones in contact with meninges • frontal, parietal, – calvaria (skullcap) forms roof and walls • Facial bones support teeth and form nasal cavity and orbit – 14 bones with no direct contact with brain or meninges – attachment of facial and jaw muscles
- 7. 8-7 Frontal Bone • Forms forehead and part of the roof of the cranium • Forms roof of the orbit • Contains frontal sinus
- 8. 8-8 Parietal Bone • Cranial roof and part of its lateral walls • Bordered by 4 sutures – coronal, sagittal, lambdoid and squamous • Temporal lines of temporalis muscle Temporal lines
- 9. 8-9 Temporal Bone • Lateral wall and part of floor of cranial cavity – squamous part • zygomatic process • mandibular fossa and TMJ – tympanic part • external auditory meatus • styloid process – mastoid part • mastoid process – mastoiditis from ear infection • mastoid notch – digastric muscle
- 10. 8- Petrous Portion of Temporal Bone • Part of cranial floor – separates middle from posterior cranial fossa • Houses middle and inner ear cavities – receptors for hearing and sense of balance – internal auditory meatus = opening for CN VII (vestibulocochlear nerve)
- 12. 8- Openings in Temporal Bone • Carotid canal – passage for internal carotid artery supplying the brain • Jugular foramen – irregular opening between temporal and occipital bones – passageway for drainage of blood from brain to internal jugular vein
- 13. 8- Occipital Bone • Rear and base of skull • Foramen magnum holds spinal cord • Skull rests on atlas at occipital condyles • Hypoglossal canal transmits hypoglossal nerve (CN XII) supplying tongue muscles • External occipital protuberance for nuchal ligament • Nuchal lines mark neck muscles
- 14. 8- Sphenoid Bone • Lesser wing • Greater wing • Body of sphenoid • Medial and lateral pterygoid processes
- 15. 8- Sphenoid Bone • Body of the sphenoid – sella turcica contains hypophyseal fossa – houses pituitary gland • Lesser wing – optic foramen • Greater wing – foramen rotundum and ovale for brs. trigeminal nerve – foramen spinosum for meningeal artery
- 17. 8- Ethmoid Bone • Between the orbital cavities • Lateral walls and roof nasal cavity • Cribriform plate and crista galli • Ethmoid air cells form ethmoid sinus • Perpendicular plate forms part of nasal septum • Concha (turbinates) on lateral wall
- 18. 8- Maxillary Bones • Forms upper jaw – alveolar processes are bony points between teeth – alveolar sockets hold teeth • Forms inferomedial wall of orbit – infraorbital foramen • Forms anterior 2/3’s of hard palate – incisive foramen – cleft palate
- 19. 8- Locations of Paranasal Sinuses • Maxillary sinus fills maxillae bone • Other bones containing sinuses are frontal, ethmoid and sphenoid.
- 20. 8- Zygomatic Bones • Forms angles of the cheekbones and part of lateral orbital wall • Zygomatic arch is formed from temporal process of zygomatic bone and zygomatic process of temporal bone
- 21. 8- Lacrimal Bones • Form part of medial wall of each orbit • Lacrimal fossa houses lacrimal sac in life – tears collect in lacrimal sac and drain into nasal cavity
- 22. 8- Nasal Bones • Forms bridge of nose and supports cartilages of nose • Often fractured by blow to the nose
- 23. 8- Vomer • Inferior half of the nasal septum • Supports cartilage of nasal septum
- 24. 8- • Only movable bone – jaw joint between mandibular fossa and condyloid process • Holds the lower teeth • Attachment of muscles of mastication – temporalis muscle onto coronoid process – masseter muscle onto angle of mandible • Mandibular foramen • Mental foramen Mandible
- 25. 8- The Vertebral Column • 33 vertebrae and intervertebral discs of fibrocartilage • Five vertebral groups – 7 cervical in the neck – 12 thoracic in the chest – 5 lumbar in lower back – 5 fused sacral – 4 fused coccygeal • Variations in number of lumbar and sacral vertebrae
- 26. 8- Newborn Spinal Curvature • Spine exhibits one continuous C- shaped curve • Known as primary curvature
- 27. 8- Adult Spinal Curvatures • S-shaped vertebral column with 4 curvatures • Secondary curvatures develop after birth – lifting head as it begins to crawl develops cervical curvature – walking upright develops lumbar curvature
- 28. 8- General Structure of Vertebra • Body • Vertebral foramen form vertebral canal • Neural arch – 2 lamina – 2 pedicles • Processes – spinous, transverse and articular
- 29. 8- Intervertebral Foramen and Discs • Intervertebral foramen – Notches between adjacent vertebrae – passageway for nerves • Intervertebral discs – bind vertebrae together – absorb shock – gelatinous nucleus pulposus surrounded by anulus fibrosus (ring of fibrocartilage) – herniated disc pressures spinal nerve or cord
- 30. 8- Typical Cervical Vertebrae • Small body and larger vertebral foramen • Transverse process short with transverse foramen for protection of vertebral arteries • Bifid or forked spinous process in C2 to C6 • C7 vertebra prominens
- 31. 8- The Unique Atlas and Axis • Atlas (C1) supports the skull – concave superior articular facet • nod your head in “yes” movement – ring surrounding large vertebral foramen • anterior and posterior arch • no vertebral body • Axis (C2) – dens or odontoid process is held in place inside the vertebral foramen of the atlas by ligaments – allows rotation of head -- “no”
- 32. 8- Atlas and Axis Articulation
- 33. 8- Typical Thoracic Vertebrae • Larger body than cervical but smaller than lumbar • Spinous processes pointed and angled downward • Superior articular facets face posteriorly permitting some rotation between adjacent vertebrae • Rib attachment – costal facets on vertebral body and at ends of transverse processes for articulation of ribs
- 34. 8- Lumbar Vertebrae • Thick, stout body and blunt, squarish spinous process • Superior articular processes face medially – lumbar region resistant to twisting movements
- 35. 8- Sacrum (Anterior View) • 5 sacral vertebrae fuse by age 26 • Anterior surface – smooth and concave – sacral foramina were intervertebral foramen • nerves and blood vessels – 4 transverse lines indicate line of fusion of vertebrae
- 36. 8- Sacrum (Posterior View) • Median sacral crest • Lateral sacral crest • Posterior sacral foramina • Sacral canal ends as sacral hiatus • Auricular surface is part of sacroiliac joint
- 37. 8- Coccyx • Single, small bone – 4 vertebrae fused by 30 – Co1 to Co4 • Attachment site for muscles of pelvic floor • Cornua – hornlike projections on Co1 for ligaments attach coccyx to sacrum • Fractured by fall or during childbirth
- 38. 8- Thoracic Cage • Consists of thoracic vertebrae, sternum and ribs • Attachment site for pectoral girdle and many limb muscles • Protects many organs • Rhythmically expanded by respiratory muscles to draw air into the lungs
- 39. 8- Rib Structure • Flat blade called a shaft – inferior margin has costal groove for nerves and vessels • Proximal head and tubercle are connected by neck • Articulation – head with body of vertebrae – tubercle with transverse process Tubercle Head
- 41. 8- True and False Ribs • True ribs (1 to 7) attach to sternum with hyaline cartilage • False ribs (8-12) – 11-12 are floating and not attached to sternum • 12 pairs of ribs in both sexes
- 42. 8- Pectoral Girdle • Attaches upper extremity to the body • Scapula and clavicle • Clavicle attaches medially to the sternum and laterally to the scapula – sternoclavicular joint – acromioclavicular joint • Scapula articulates with the humerus – humeroscapular or shoulder joint – easily dislocated due to loose attachment
- 43. 8- Clavicle • S-shaped bone, flattened dorsoventrally • Inferior - marked by muscle and ligament • Sternal end rounded -- acromial end flattened
- 44. 8- Scapula • Triangular plate overlies ribs 2 to 7 • Spine ends as acromion process • Coracoid process = muscle attachment • Subscapular, infraspinous and supraspinous fossa • Glenoid fossa = socket for head of humerus
- 46. 8- Upper Limb • 30 bones per limb • Brachium (arm) = humerus • Antebrachium (forearm) = radius and ulna (radius on thumb side) • Carpus (wrist) = 8 small bones(2 rows) • Manus (hand) = 19 bones(2 groups) – 5 metacarpals in palm – 14 phalanges in fingers
- 47. 8- Humerus • Hemispherical head • Anatomical neck • Greater and lesser tubercles and deltoid tuberosity • Intertubercular groove holds biceps tendon • Rounded capitulum articulates with radius • Trochlea articulates with ulna • Olecranon fossa holds olecranon process of ulna • Forearm muscles attach to medial and lateral epicondyles
- 48. 8- Ulna and Radius • Radius – head = disc rotates during pronation and supination • articulates with capitulum – radial tuberosity for biceps muscle • Ulna – olecranon and trochlear notch – radial notch holds ulna • Interosseous membrane – ligament attaches radius to ulna along interosseous margin of each bone
- 49. 8- Carpal Bones • Form wrist – flexion, extension, abduction and adduction • 2 rows (4 bones each) – proximal row = scaphoid, lunate, triquetrum and pisiform – distal row = trapezium, trapezoid, capitate and hamate
- 50. 8- Metacarpals and Phalanges • Phalanges are bones of the fingers – thumb or pollex has proximal and distal phalanx – fingers have proximal, middle and distal phalanx • Metacarpals are bones of the palm – base, shaft and head
- 51. 8- Sesamoid Bone
- 52. 8- Pelvic Girdle • Girdle = 2 hip bones • Pelvis = girdle and sacrum • Supports trunk on the legs and protects viscera • Each os coxae is joined to the vertebral column at the sacroiliac joint • Anteriorly, pubic bones are joined by pad of fibrocartilage to form pubic symphysis
- 53. 8- Pelvic Inlet and Outlet • False and true pelvis separated at pelvic brim • Infant’s head passes through pelvic inlet and outlet
- 54. 8- Os Coxae (Hip Bone) • Acetabulum is hip joint socket • Ilium – iliac crest and iliac fossa – greater sciatic notch contains sciatic nerve • Pubis – body, superior and inferior ramus • Ischium – ischial tuberosity bears body weight – ischial spine – lesser sciatic notch between ischial spine and tuberosity – ischial ramus joins inferior pubic ramus
- 55. 8- Comparison of Male and Female • Female lighter, shallower pubic arch( >100 degrees), and pubic inlet round or oval • Male heavier, upper pelvis nearly vertical, coccyx more vertical, and pelvic inlet heart-shaped
- 56. 8- Femur and Patella (Kneecap) • Nearly spherical head and constricted neck – ligament to fovea capitis • Greater and lesser trochanters for muscle attachment • Posterior ridge called linea aspera • Medial and lateral condyles and epicondyles found distally • Patella = triangular sesamoid
- 57. 8- Tibia • Tibia is thick, weight- bearing bone (medial) • Broad superior head with 2 flat articular surfaces • medial and lateral condyles – roughened anterior surface palpated below patella (tibial tuberosity) – distal expansion = medial malleolus
- 58. 8- Fibula • Slender lateral strut stabilizes ankle • Does not bear any body weight – spare bone tissue • Head = proximal end • Lateral malleolus = distal expansion • Joined to tibia by interosseous membrane
- 59. 8- The Ankle and Foot • Tarsal bones are shaped and arranged differently from carpal bones due to load-bearing role of the ankle • Talus is most superior tarsal bone – forms ankle joint with tibia and fibula – sits upon calcaneus and articulates with navicular • Calcaneus forms heel (achilles tendon) • Distal row of tarsal bones – cuboid, medial, intermediate and lateral cuneiforms
- 60. 8- The Foot • Remaining bones of foot are similar in name and arrangement to the hand • Metatarsal I is proximal to the great toe (hallux) – base, shaft and head • Phalanges – 2 in great toe • proximal and distal – 3 in all other toes • proximal, middle and distal
- 61. 8- Embryonic Limb Rotation • Rotation of upper and lower limbs in opposite directions – largest digit medial in foot and lateral in hand – Elbow flexes posteriorly and knee flexes anteriorly
- 62. 8- Foot Arches • Sole of foot not flat on ground • 3 springy arches absorb stress – medial longitudinal arch from heel to hallux – lateral longitudinal arch from heel to little toe – transverse arch across middle of foot • Arches held together by short, strong ligaments – pes planis (flat feet)
- 65. 8- Bipedalism and Head Position