Lecture 7 & 8 Skeletal System 2 & 3

Introduction To Human Anatomy 7101101 Lecture 7 (± 1hr): Skeletal system 2: Bone Vasculature and Innervation of bones Trauma to Bone and Bone Changes  Vasculature and Innervation of bones Refer for the textbook for further details Nutrient arteries enters through nutrient...

Introduction To Human Anatomy 7101101 Lecture 7 (± 1hr): Skeletal system 2: Bone Vasculature and Innervation of bones Trauma to Bone and Bone Changes  Vasculature and Innervation of bones Refer for the textbook for further details Nutrient arteries enters through nutrient foramina. divides into longitudinal branches Periosteal arteries Havarsian systems or osteons (microscopic canal systems) compact bone small blood vessels Metaphysial and epiphysial arteries arise mainly from the arteries that supply the joints.  Vasculature and Innervation of bones In the limbs, metaphysial and epiphysial arteries are typically part of a periarticular arterial plexus, which surrounds the joint, ensuring blood flow distal to the joint regardless of the position assumed by the joint.  Vasculature and Innervation of bones Veins accompany arteries through the nutrient foramina. Many large veins also leave through foramina near the articular ends of the bones. Bones containing red bone marrow have numerous large veins. Lymphatic vessels are also abundant in the periosteum.  Vasculature and Innervation of bones Nerves accompany blood vessels supplying bones. The periosteum is richly supplied with sensory nerves— periosteal nerves—that carry pain fibers. The periosteum is especially sensitive to tearing or tension, which explains the acute pain from bone fractures. Bone itself is relatively sparsely supplied with sensory endings. Within bones, vasomotor nerves cause constriction or dilation of blood vessels, regulating blood flow through the bone marrow Trauma to Bone and Bone Changes Bones are living organs that cause pain when injured, bleed when fractured, remodel in relationship to stresses placed on them, and change with age. Like other organs, bones have blood vessels, lymphatic vessels, and nerves, and they may become diseased. Bone atrophy: decrease in size of unused bones, such as in a paralyzed limb or in space. Bone may be absorbed, which occurs in the mandible when teeth are extracted. Bones hypertrophy: bone enlargement when they support increased weight for a long period  Fractures A fracture is a break in the bone. Signs and Symptoms of a bone fracture can vary wildly depending on the affected region and severity. However, they often include some of the following: pain swelling bruising and redness deformity Inability to move the affected area open fractures may be bleed  Fracture healing For proper healing broken ends must be brought together, approximating their normal position. (Fracture Reduction). During bone healing, the surrounding fibroblasts (connective tissue cells) proliferate and secrete collagen, which forms a collar of callus to hold the bones together Bone remodeling occurs in the fracture area, and the callus calcifies. Eventually, the callus is resorbed and replaced by bone. After several months, little evidence of the fracture remains, especially in young people.  Osteoporosis Osteoporosis is a reduction in the quantity of bone (or atrophy of skeletal tissue) in which the organic and inorganic components of bone both decrease. The bones become brittle, lose their elasticity, and fracture easily. Bone scanning is an imaging method used to assess normal and diminished bone mass Causes of Osteoporosis: Aging and lack of some hormones Some medications (corticosteroids) Thyroid problems, Lack of muscle use  Sternal puncture Insertion of a wide-bore (large diameter) needle through the thin cortical bone into the spongy bone of the manubrium of the sternum to aspirate a sample of red bone marrow. Laboratory examination of bone marrow provides valuable information for evaluating hematological (blood) diseases. Why is it common to use the sternum site for harvesting bone marrow? Because it lies just beneath the skin (i.e., is subcutaneous) and is easily accessible,  Displacement and Separation of Epiphyses knowledge of bone growth and the appearance of bones and the location of epiphyses in radiographic and other diagnostic images at various ages is required in order not to Mistake a displaced epiphysial plate for a fracture, Interpret a separation of an epiphysis as a displaced piece of a fractured bone. Differences and notes to keep in mind: The edges of the diaphysis and epiphysis are smoothly curved in the region of the epiphysial plate. Bone fractures always leave a sharp, often uneven edge of bone. An injury that causes a fracture in an adult usually causes the displacement of an epiphysis in a child.  Avascular Necrosis Death of bone tissue due to loss of arterial blood supply (G. nekrosis, deadness). It may affect an epiphysis or other parts of a bone After every fracture, small areas of adjacent bone undergo necrosis. In some fractures, avascular necrosis of a large fragment of bone may occur. A number of clinical disorders of epiphyses in children result from avascular necrosis of unknown etiology (cause). These disorders are referred to as osteochondroses. Introduction To Human Anatomy 7101101 Lecture 8 (2hrs): ‫ﺗدرس ﻣن اﻟﺳﻼﯾدات‬ Skeletal system 3: Axial skeleton Appendicular skeleton Bone markings Axial and Appendicular Skeleton The skeletal system is divided into two functional parts: The axial skeleton consists of the bones of the head (cranium or skull), neck (hyoid bone and cervical vertebrae), and trunk (ribs, sternum, vertebrae, and sacrum). The appendicular skeleton consists of the bones of the limbs, including those forming the pectoral (shoulder) and pelvic girdles  The skull Bones The skull “cranium” is the skeleton of the head. A series of bones form the skull two parts, 1. The neurocranium: the braincase 2. The viscerocranium: the facial skeleton  The neurocranium Formed by the superior aspect of the skull. It encloses and protects the brain Composed of eight Immovable bones (Their borders meet to form immovable joints “sutures"), two of them are paired  The neurocranium The neurocranium can be subdivided into: Calvarium: The dome-like roof (skullcap) comprised of regions of the frontal, occipital and two parietal bones. Basicranium: the floor or the cranial base comprised of regions of six bones: the frontal, sphenoid, ethmoid, occipital, parietal and temporal bones. Note: regions of the frontal, occipital and parietal bones are found in both subdivisions  The viscerocranium (facial skeleton) Total of 14 bones, all are paired except the mandibular and the vomer bones Two bones provide distinctive shape to face – Maxillae (upper jaw bones) – Mandible (lower jaw bone) All facial bones connected by immovable joints (sutures) – One exception (mandible)  The Vertebral Column Protects the spinal cord and supports the head and body 26 bones: 24 vertebrae, the sacrum, and the coccyx Cervical vertebrae (‫)اﻟﻌﻨﻘﯿﺔ‬ – Vertebrae of the neck (cervic/o = neck) – Identified as C1 – C7 Thoracic vertebrae (‫)اﻟﺼﺪرﯾﺔ‬ – Vertebrae of the chest (thorac/o = chest) – Identified as T1 – T12 Lumbar vertebrae (‫)اﻟﻘﻄﻨﯿﺔ‬ – Vertebrae of lower back (lumb/o = lower back, loins) – Identified as L1-L5  The Vertebral Column Sacrum (‫)اﻟﻌﺠﺰ‬ – 5 fused sacral bones Coccyx (‫)اﻟﻌﺼﻌﺺ‬: Also called “tailbone” – 4 fused coccygeal bones  Bones of the Thorax (The Thoracic Cage ; ‫)اﻟﻘﻔص اﻟﺻدري‬ Consists of: Thoracic vertebrae Ribs Sternum  The Pelvic Girdle (‫)اﻟزﻧﺎر او اﻟﺣزام اﻟﺣوﺿﻲ‬ Consists of: The two hip bones (also known as coxal, innominate or pelvic bones) which consist of three parts: ilium, ischium, and pubis The sacrum and the coccyx.  The Pectoral Girdle (‫)اﻟزﻧﺎر او اﻟﺣزام اﻟﺻدري‬ The pectoral girdle (also called: the shoulder girdle) consists of the two clavicles and the two scapulae; Segments and Bones of the Upper Limb Note: Three phalanges, a proximal, a middle and a distal phalanx (singular of phalanges) are present in each finger and toe, with the exception of the thumb and large toe, which possess only two, a proximal and a distal phalanx Segments and Bones of the Lower Limb Note: Three phalanges, a proximal, a middle and a distal phalanx (singular of phalanges) are present in each finger and toe, with the exception of the thumb and large toe, which possess only two, a ‫ﻋظﺎم اﻟرﺻﻎ‬ proximal and a distal phalanx Bone Markings & Formations Bone markings appear: wherever tendons, ligaments, and fascias are attached where arteries lie adjacent to or enter bones. Other formations occur in relation to the passage of a tendon (often to direct the tendon or improve its leverage), or to control the type of movement occurring at a joint. Bone Markings & Formations Some of the various markings and features of bones are: 1. Capitulum: small, round, articular head (e.g., the capitulum of the humerus). 2. Trochlea: spool-like articular process or process that acts as a pulley (e.g., the trochlea of the humerus). Bone Markings & Formations 3. Condyle: rounded, knuckle-like articular area, often occurring in pairs (e.g., the lateral and medial femoral condyles). 4. Crest: ridge of bone (e.g., the iliac crest). 5. Tuberosity: large rounded elevation (e.g., the ischial tuberosity). 6. Notch: indentation at the edge of a bone (e.g., the greater sciatic notch). Bone Markings & Formations 7. Epicondyle: eminence superior to a condyle (e.g., the lateral epicondyle of the humerus). 8. Fossa: hollow or depressed area (e.g., the infraspinous fossa of the scapula, radial and coronoid fossa) 9. Spine: thorn-like process (e.g., the spine of the scapula). Bone Markings & Formations 10. Facet: smooth flat area, usually covered with cartilage, where a bone articulates with another bone (e.g., the superior costal facet on the body of a vertebra for articulation with a rib). Superior Superior Costal Articular 11. Spinous process: facet facet projecting spine- Articular facet for like part (e.g., the tubercle of 6th rib spinous process Crest of head of a vertebra). Vertebral body Spinous process of T6 vertebra Right 7th rib posterolateral view Bone Markings & Formations 12. Head (L. caput): large, round articular end (e.g., the head of the humerus). 13. Groove: elongated depression or furrow (e.g., the radial groove of the humerus). 14. Tubercle: small raised eminence (e.g., the greater tubercle of the humerus). Bone Markings & Formations 15. Line: linear elevation (e.g., the soleal line of the tibia). 16. Malleolus: rounded process (e.g., the lateral malleolus of the fibula). 17. Protuberance: projection of bone (e.g., the external occipital protuberance). Bone Markings & Formations 18. Trochanter: large blunt elevation (e.g., the greater trochanter of the femur). 19. Foramen: passage through a bone (e.g., the obturator foramen, the vertebral foramen). Accessory (supernumerary) bones Many bones develop from several centers of ossification, eventually the separate parts normally merge. Sometimes, one of these centers fails to fuse with the main bone thus giving the appearance of an extra bone. Examples: Wormian bones (sutural bones): small, irregular, wormlike bones sometimes seen in the cranium Foot accessory bones: common and important to know to avoid mistaking them for bone fragments in radiographs and other medical images. Heterotopic Bones In medicine, heterotopia is the presence of a particular tissue type at a non-physiological site, but usually co-existing with original tissue in its correct anatomical location Bones that sometimes form in soft tissues where they are not normally present (e.g., in scars, areas of recurrent muscle injury). Examples: Rider's bones: Horse riders often develop heterotopic bones in their thighs (rider's bones), probably because of chronic muscle strain resulting in small hemorrhagic areas that undergo calcification and eventual ossification. Shooter's bones: Heterotopic ossification located in the deltoid muscle region probably due to recurrent muscle injury. This is seen in soldiers undergoing military training programmes