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Anatomy of Skeletal Elements

Anatomy of Skeletal Elements. The Musculoskeletal system. 206 bones grouped into the axial and appendicular skeletons 650 muscles approximately 40% of your body weight also divided into an axial and an appendicular division. Classification of Bones.

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Anatomy of Skeletal Elements

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  1. Anatomy of Skeletal Elements

  2. The Musculoskeletal system • 206 bones • grouped into the axial and appendicular skeletons • 650 muscles • approximately 40% of your body weight • also divided into an axial and an appendicular division

  3. Classification of Bones • 6 types - based on anatomical classification • Long bones = greater length than width • Short bones = cube-shaped, spongy bone except at surface • Flat bones = two parallel plates of compact bone sandwiching spongy bone layer

  4. Irregular bones = cannot be grouped • Sesamoid bones = develop in tendons where there is considerable friction, tension and stress • Sutural bones = located within joints between cranial bones

  5. Bone Markings (surface features) • Used to identify specific elevations, depressions, and openings of bones • Bone markings provide distinct and characteristic landmarks for orientation and identification of bones and associated structures.

  6. Bony Processes • Depressions and openings • Fissure – narrow slit • Foramen – hole for nerves, blood vessels • Fossa – cuplike depression • Sulcus – furrow on a bone surface, contains a nerve or blood vessel • Meatus – tubelike opening • Processes – projection or outgrowth on bone for attachment • Condyle – smoothened process at end of bone, forms a joint • Facet – smooth flat surface, forms a joint • Head – rounded condyle on a neck, forms a joint • Crest – prominent ridge or projection, for attachment of connective tissues • Epicondyle – projection above a condyle, for attachment of connective tissues • Line – long, narrow ridge (less prominent than a crest), for attachment of connective tissues • Spinous process – sharp, slender projection, for attachment of connective tissues • Trochanter – process of the femur, for attachment of connective tissues • Tubercle – process of the humerus, for attachment of connective tissues • Tuberosity – roughening on a bone surface, for attachment of connective tissues

  7. Skeletal system includes • Axial division • Skull and associated bones • Auditory ossicles • Hyoid bones • Vertebral column • Thoracic cage • Ribs & sternum • Appendicular division -Pectoral girdle -Pelvic girdle

  8. THE SKELETAL SYSTEM: AXIAL DIVISION Part A

  9. The Axial Skeleton • Axial division • Skull and associated bones • Auditory ossicles • Hyoid bone • Vertebral column • Thoracic cage • Ribs & Sternum

  10. The Skull and Associated Bones

  11. The Adult Skull • skull = 22 bones • cranium = 8 bones: 1 frontal, 1 occipital, 2 temporals, 2 parietals, 1 sphenoid and 1 ethmoid • facial bones = 14 bones: 2 nasals, 2 maxillae, 2 zygomatics ,1 mandible, 2 lacrimals, 2 palatines, 2 inferior nasal conchae, 1 vomer • mandible and auditory ossicles are the only movable skull bones

  12. The Adult Skull • skull is made up of several cavities • 1. cranial cavity • 2. nasal cavity • 3. the orbits • 4. paranasal sinuses • skull contains many holes for the passage of nerves and vessels = foramen/foramina • cranial bones also attach to membranes called meninges • outer surface provides large areas for muscle attachment that move the head or provide facial expressions

  13. Sutures • Immovable joints • form boundaries between skull bones • four main sutures • Coronal • Sagittal • Lambdoid • Squamous • PLUS lots of smaller sutures • e.g. Frontonasal • e.g.Temperozygomatic

  14. Occipital Bone • part of the base of the skull • surrounds the foramen magnum • forms part of the jugular foramen • hypoglossal foramen found under the occipital condyles Mastoid notch

  15. Parietal Bone • Part of the superior and lateral surfaces of the cranium • united by a sagittal suture • connects to frontal bone by coronal suture • connects to occipital bone by lambdoid suture

  16. Temporal Bone Petrous portion Tympanic portion • forms wall of jugular foramen • three portions: squamous, petrous and tympanic • petrous part houses tympanic membrane and middle and inner ears • auditory ossicles of middle ear transmit sound to inner ear

  17. Temporal Bone Temporal surface of greater wing of sphenoid Frontal process of zygomatic bone Squamous portion Lacrimal bone Petrous portion Tympanic portion Maxillary process of zygomatic bone Articular Tubercle

  18. Frontal Bone Internasal suture glabella • Forms the forehead & roof of the orbit Supraorbital ridge or margin Frontal process of maxilla Zygomatic process of maxilla

  19. glabella

  20. Sphenoid Bone • Contributes to floor of cranium • Bridges cranial and facial bones • Optic canal allows passage of optic nerve • Pterygoid processes sites of muscle attachment

  21. Ethmoid Bone • Irregularly shaped bone • forms part of orbit & forms roof of nasal cavity • Cribriform plate with olfactory foramina for olfactory nerves • Perpendicular plate forms part of nasal septum

  22. Facial Bones: Maxilla • Paired bone • Largest of the facial bones • Forms upper jaw

  23. Facial Bones: Mandible • entire lower jaw • articulates with temporal bone at the Temporomandibular joint • moveable part of skull

  24. Facial bones • Nasal bones • Paired bones • Articulate with frontal bone • Extend to superior border of external nares • Vomer • Forms inferior (bottom) portion of nasal septum • Articulates with maxillae and palatine bones Nasal bones

  25. Facial bones • Inferior nasal concha • Located on each side of nasal septum • Increase epithelial surface • Create turbulence in inspired air • Zygomatic bone • Temporal process articulates with zygomatic process of temporal bone • Forms zygomatic arch

  26. Facial bones • Lacrimal bones • Smallest bones in skull • Delivers tears to nasal cavity via nasolacrimal canal • Palatine bones • Small • L-shaped • Form posterior portion of hard palate • Contribute to floor of orbit

  27. The Orbit • Orbital complex • Bony recess that holds the eye • Seven bones • Frontal bone • Lacrimal bone • Palatine bone • Zygomatic bone • Ethmoid • Sphenoid • Maxilla

  28. Skull: Inferior View Basilar Portion Petrous portion Condylar fossa Condylar foramen may be present

  29. Skull: Interior View Figure 6.4 Sectional Anatomy of the Skull, Part I Tuberculum sellae Sella Turcica Cerebral surface of Greater wing of sphenoid Hypophyseal fossa Dorsum sella Lesser wing of sphenoid Foramen Rotundum

  30. Cranial Fossae • Depressions in cranial floor • for the lobes of the brain • Anterior cranial fossa • Frontal bone, ethmoid, lesser wings of sphenoid • Middle cranial fossa • Sphenoid, temporal bones, parietal bones • Posterior cranial fossa • Occipital bone, temporal bones, parietal bones

  31. Skull: Sagittal View

  32. Skull: Sagittal View

  33. The Nasal Complex • Bones and cartilage that enclose the nasal cavity • lined with a nasal mucosa • associated with the 4 paranasal sinuses • hollow airways • lined with mucosa – like nasal mucosa • found in the frontal bones, sphenoid, ethmoid and maxillae

  34. The Paranasal Sinuses

  35. Infant Skull: The Fontanels • the flat bones in the infant skull are separated by fontanels • fibrous connections between skull bones • permit infant skulls to pass through birth canal • permit the skulls of infants and children to continue growing • will be replaced by sutures in the adult skull

  36. The Hyoid Bone • Consists of a body, greater horns and lesser horns • Base for muscles of the tongue and larynx

  37. Adult Vertebral Column • strong, flexible rod • average male = 71 cm (28 inches) • average female – 61 cm (24 inches) • capable of moving • anteriorly • posteriorly • laterally • also rotation • supports the head • encloses and protects the spinal cord • allows for the exit of 31 pairs of spinal nerves – through intervertebral foramina

  38. Adult Vertebral Column • 26 vertebrae • 24 individual vertebrae • Sacrum • Coccyx • Seven cervical vertebrae • Twelve thoracic vertebrae • Five lumbar vertebrae • Sacrum – 5 fused vertebrae • Coccyx – 4 fused vertebrae

  39. Adult Vertebral Column • vertebrae separated by intervertebral discs • discs of fibrocartilage made up of an outer ring and a softer inner region • found between C1 and C2 and all the way down to between L5 and the sacrum • form the joints of the vertebral column

  40. Adult Vertebral Column • absorb shock – flatten, broaden and bulge outward • weakening in the outer ring can allow the herniation of the inner material

  41. Spinal Curvature • Four curvatures: increase the strength of the column • Thoracic (primary) – forms fetally and retain the curve of the fetus • Sacral (primary) – forms fetally and retain the curve of the fetus • Cervical (secondary) – forms when the baby holds its head erect • Lumbar (secondary) – forms upon walking

  42. Vertebrae • Every vertebrae has the following: • 1. body – weight bearing part of the vertebra • separated by the discs • 2. vertebral arch – surrounds the spinal cord • surrounds a hole called a vertebral foramen • 3. processes – seven of them • 1. Spinous (1) – muscle attachment • 2. Transverse (2) – muscle attachment • 3. Superior articular (2) – forms joint with upper vertebra • 4. Inferior articular (2) – forms joint with lower vertebra

  43. Vertebrae • cervical vertebrae = transverse foramina in the transverse processes • bifid spinous process • 1st two cervical vertebrae (atlas and axis) look different but have all aspects of a vertebrae Cervical Vertebra

  44. Thoracic Vertebrae Lumbar Vertebrae

  45. Fused Vertebrae: The sacrum & coccyx • Sacrum - Union of 5 vertebrae (S1 - S5) – completely fused by age 30 • median sacral crest = fused spinous processes • sacral ala = fused transverse processes • sacral canal ends at sacral hiatus • Coccyx = Union of 4 vertebrae (Co1 - Co4) – completely fused by age 30

  46. Rib Cage • 12 pairs of ribs • vertebral end for articulation with the facets of the 12 thoracic vertebrae – both body and the transverse process • sternal end for articulation with the sternum

  47. Rib Cage -three kinds of ribs: 1. True – separate & direct connection to the sternum via costal cartilage 2. False – no direct connection to the sternum – joined via a composite piece of costal cartilage 3. Floating – no connection to the sternum

  48. Sternum • comprised of the: • 1. Manubrium – with two clavicular notches and a jugular notch • 2. Body – connects to manubrium via a sternal angle • 3. Xiphoid process

  49. Sternum & Rib Cage • several muscles and muscle groups either originate from the sternum and/or ribcage (or costal cartilages) or insert onto these structures • sternum: • sternocleidomastoid • sternohyoid & sternothryoid – depresses hyoid bone and larynx • ribcage: • intercostals – external and internal • serratus anterior & posterior • numerous muscles of the vertebral column • pectoralis major & minor • 4 muscles of the abdominal wall

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