Skeletal System 2 PDF

Principles of Human Structure Skeletal System 2 Dr Siobhain O’ Mahony Axial Skeleton  The bones of the skull: General arrangement Squamous suture...

Principles of Human Structure Skeletal System 2 Dr Siobhain O’ Mahony Axial Skeleton  The bones of the skull: General arrangement Squamous suture Coronal suture Frontal bone Lambdoid Parietal bone suture Lacrimal Temporal bone Sphenoid bone Occipital Nasal Zygomatic bone bone Maxilla bone Palatine Conchae Ethmoid Vomer bone bone Only 1 Mandible Only 1 Clinical Relevance  Skull fractures -Four major types Neurocranium (8) 1) Linear  linear fracture Viscerocranium (14) 2) Depressed fracture  comminuted, depressed inwards 3) Diastatic  separation of the cranial sutures Compound fracture  laceration of all layers 9/27/2019 4) Basiliar  base of skull involvement 3 www.getbodysmart.com  Fibrous joint – Sutures Cranial Sutures: Thin layer of dense fibrous connective tissue between the bones Adult: Seams between the skull bones Newborns: linear attachments of fibrous tissue and fontanelles (6) (44 separate bony elements) Sutural ligament: 2 layers of periosteum + dense fibrous connective tissue Margins of bones = continuous bone growth Synostosis = ossified suture Functionally = Synarthrosis Clinical relevance: Plagiocephaly Cranial Sutures 9/27/2019 4  Anterior-posterior full Vertebral Column length view of V.C. Aggregate structure composed of: 33 vertebrae & components that unite them into single structural, functional entity-”axis” of axial skeleton! C1-C7 ;T1-T12; L1-L5; Sacrum-5 vertebrae fused in adults ; Coccyx/tail-3- 5 vertebrae fused at 30 yrs Vertebrae are larger as descend towards sacrum & progressively smaller towards end of coccyx Max size (just above sacrum-transferral of weight to pelvic girdle) Functions: Bears weight; Supports the head; Allows movement of the body; Point of attachment of the ribs; Protection (elements in close proximity: spinal cord; descending aorta; venae cavae; thoracic duct; oesophagus); 5 Helps maintain posture 9/27/2019  Clinical Significance Fractures-may lead to injury of spinal cord/nerves Cervical region-above C4 may lead to sudden death due to paralysis of diaphragm; below C4-quadraplegia Thoracic region-may result paraplegia Lumbar region-may lead to variable sensory/motor loss in lower extremities Ankylosing spondylitis-inflammation of VC joints-making VC rigid Whiplash-sudden forceful movement of head in posterior direction 9/27/2019 6  Characteristics of a typical vertebrae Vertebral body-function-support body weight Situated anteriorly Size depends on site Vertebral arch-function-protect spinal cord Encloses the large vertebral foramen (all form vertebral canal-contain spinal cord, roots, meninges, fat, vessels) Lateral walls-pedicles Posterior walls-laminae Seven processes Transverse Transverse process (2)-function-muscle attachment & movement process Spinous process-can be felt through the skin (1)- function muscle attachment & movement Articular processes (4)-function-restrict movement Superior articular processes 9/27/2019 Inferior articular processes 7 Cervical Vertebrae Form skeleton of neck; smallest; greatest range & variety of movement Vertebral body- Short & square shaped, concave superior and Superior convex inferior surface articular Vertebral process Vertebral arch -Vertebral foramen is triangular in shape body Inferior articular Spinous process-short and bifid (except for C7) process C1 and C2-specialised to accommodate the skull Transversepr Pedicle ocess Spinous process Ant. Ant. Rami tubercle emerge Post. tubercle 8 9/27/2019 Atlas (C1) * * Groove for vertebral artery Ant. Atlantooccipital joint arch Post. tubercle Atlas-atypical vertebra Post. – No body or spinous process – Transverse processes-more laterally placed arch – Ring of bone on which skull rests-paired lateral masses *occipital condyles – Widest vertebrae-increased leverage for attached muscles – Condyloid joints-permit nodding of head 9/27/2019 9  Axis (C2) Lateral atlantoaxial joint Axis-strongest of cervical vertebrae Forms pivot upon which C1-side to side movement of the head-superior articular facets Dens Strong odontoid process (dens)- rises perpendicularly from the upper surface of the body-serves as a pivot Held in place by transverse ligament Superior articular process Open mouth view 9/27/2019 10 Thoracic Vertebrae Upper back-provide attachment for ribs Greatest degree of rotation-due to location of articular facets T1-T12 Larger than cervical-more body weight to support Descending size increases Body-heart-shaped, foramen-circular Spines overlap Bodies (partial facets-superior and inferior) and transverse processes have facets for articulation with ribs 11 9/27/2019 Costovertebral Joint Connects ribs with the bodies of thoracic vertebrae Plane, synovial joints Tubercle Radiate Joining occurs at 2 places, the head and the Head Neck ligament Rib tubercle of the rib-a few exceptions Two convex facets for the head to attach to two adjacent vertebrae (strengthened by the radiate ligament)-also internal ligament dividing joint in 2- intra-articular ligament Sup. Articulation of the tubercle is to the transverse costotransverse process of the adjacent vertebrae (reinforced Intra-articular ligament by the lateral and superior costotransverse ligament of ligaments) head of rib 12 9/27/2019 Lumbar Vertebrae Costovertebral Lower back; Largest of the vertebrae-concave kidney-shaped body joint Short, sturdy spinous process for muscle attachment-do not overlap Some individuals have four lumbar vertebrae, while others have six Pedicle Inf. articular process Sup. articular process Lumbosacral joint 13 9/27/2019 Sacrum 5 vertebrae fused-forms a wedge-shaped bone with concave anterior surface Articulates with L5; Each side articulates with ilium (sacroiliac joint) ; Inferiorly articulates with coccyx; Promontory protrudes into pelvic cavity ; Foramina-passage of nerves 14 9/27/2019 Coccyx oCoccyx/tailbone o4 terminal bones fused oAllows for attachment of muscles and ligaments oStabilises the sitting person Sacrococcygeal joint Clinical significance -coccydynia-pain in coccygeal region-fall onto buttocks may result in bruising/fracture of coccyx/fracture dislocation of sacrococcygeal joint. Childbirth may result in injuries to mothers coccyx 9/27/2019 15 Intervertebral Disc Separate adjacent vertebrae-contribute 25% of length; Thinnest in cervical region-progressively thicker towards lumbar Shock absorbing function & adds to flexibility of VC Nucleus pulposus-soft, pulpy, yellowish elastic material Anulus fibrosus-concentric ring of fibrous tissue and fibrocartilage Clinical Significance Misleadingly called a "slipped disc“- a tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc allows the nucleus pulposus to bulge out May put pressure on spinal nerve-causing pain 16 Disc dehydration counts for as much as 1.8cm in loss of height in man; thin with age- accounts for some of the loss in height in elderly 9/27/2019  Curvature In the adult, the vertebral column presents 4 curves – 2 primary curvatures (thoracic, sacral) – 2 secondary curvatures (cervical, lumbar) 9/27/2019 17  Abnormal Curves 9/27/2019 18  Thoracic Cage 9/27/2019 19  Appendicular skeleton 9/27/2019 20  Upper Limb and Pectoral Girdle 9/27/2019 21  Lower Limb and Pelvic Girdle 9/27/2019 22  Fracture repair Blood leaks from Few days after ~1.5 week after Continues for broken blood fracture fracture several months vessels in the New blood vessels Trabeculae form in after fracture periosteum and form across the the callus Excess material is the bone hematoma Becomes solid ~2 removed Formation of a Periosteum and months after Compact bone is blood clot endosteum cells fracture formed (hematoma) proliferate and Remodelling along Stimulation of pain start producing lines of stress and stretch fibrocartilage Fig. 6.15 Marieb receptors 9/27/2019 23  Common problems - Fractures 9/27/2019 24 9/27/2019 25  Common problems – Fractures 9/27/2019 26 9/27/2019 27  Common problems - Fractures 9/27/2019 28 9/27/2019 29  Common problems Osteomalacia - Rickets – Disorders in which mineralization is poor – Low diet vitamin D or Calcium phosphate Bony spur – Abnormal projection on a bone due to overgrowth Osteoporosis – Chemical composition of the matrix is normal – Resorption is faster than deposition, high number of osteoclasts – Thinner compact bone, fewer trabeculae – 30% women 60-70 years, 70% women by 80 years – 30% women will suffer fracture due to osteoporosis Osteogenesis imperfecta – Mutation in the collagen gene – Brittle bone Paget’s disease – 9/27/2019 Excessive rates of deposition and resorption lead to malformation of bone tissue 30  Other problems 9/27/2019 31