Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
SKELETAL SYSTEM The skeletal system is formed of bones and cartilages The bones are connected together by joints to form the skeleton Functions of bones • They form the skeleton which gives the body shape and form • They provide attachment for muscles & ligaments • They allow movements of the body • They provide protection for vital organs • They provide storage places for calcium salts • Production of blood cells in the red bone marrow Structure of Bone • The bone is a type of connective tissue • It is hard because of its high content of calcium salts • There are 2 types of bone tissue: Compact bone: which is dense & hard. It forms the shaft of long bones and outer shell of other bones. It consists of cylindrical units of closely packed lamellae (Haversian system) Cancellous (spongy) bone: a delicate bony meshwork that fills the inside of bones. Compact Haversian system Types of Bones (according to shape) • Long bones: these are longer than wide, and are found in limbs, e.g. humerus. • Short bones: they are cuboidal in shape, and found in the hand and foot (carpal & tarsal bones) • Flat bones: thin and flattened, e.g. scapula & skull bones • Irregular bones: they are irregular in shape, e.g. vertebrae • Pneumatic bones: they contain air-filled cavities, e.g. ethmoid bone • Sesamoid bones: embedded within certain tendons, e.g. patella • Sutural bones: found between the skull sutures Remember!! Metatarsal & metacarpal bones and phalanges are considered long bones Short bones Long bones Long bone Flat bone Pneumatic bone Sutural bones Irregular bone Patella Sesamoid bone Features of Long Bones: Long bones consist of a “shaft” and 2 “ends” Shaft (Diaphysis): • This is the tubular part of the long bone. It is formed of compact bone and contains a central cavity called “medullary” or “bone marrow cavity”. • The shaft is lined by a membrane called “endosteum” and covered by a vascular membrane called “periosteum” • The periosteum contains osteoblasts and causes the increase in width of the bones, it is also needed for repair of bone fractures. Ends (Epiphysis): • These are the expanded ends of the long bone. • They are formed of cancellous bone covered by a thin layer of compact bone. Note!! the diaphysis is separated from the epiphysis by the “epiphyseal cartilage” The Metaphysis: is the part of the diaphysis adjacent to the epiphyseal line Ossification of bone • This is the process of bone formation from specialized mesenchymal tissue • It starts by the appearance of certain points (1ry ossification centers) which are responsible for ossification of the central parts of the bone. • After birth, 2ry ossification centers appear in the peripheral parts of the bone and complete the process of ossification. Types of Ossification Cartilaginous ossification: The bone is formed by replacement of the cartilaginous model by bone tissue (like in long bones) Membranous ossification: The bone is formed directly from connective tissue membrane (like in flat bones) Blood supply of bone Bones receive blood from: •Nutrient arteries, which enter the diaphysis through a nutrient foramen •Periosteal arteries •Metaphyseal and epiphyseal arteries Epiphyseal & metaphyseal arteries Nutrient artery Surface Features of Bones Elevations & projections • Process: elongated projection • Spine: pointed (or sharp) projection • Tubercle: a small rounded elevation • Tuberosity: large tubercle • Trochanter: large tuberosity • Line: faint linear elevation • Ridge: raised line • Crest: thick ridge Temporal lines process spine Perforations • Foramen: a hole connecting two surfaces • Fissure: a cleft between two bones • Canal: a passage between two openings • Hiatus: a narrow passage with one opening seen fissure foramen Carotid canal Depressions: •Fossa: depression below the surface •Sulcus: elongated depression •Notch: deficient part of bone •Meatus: a tube-like passage head Articular surfaces • Head: a rounded end • Condyle: round or oval projection • Trochlea: pulley-shaped projection • Capitulum: like a small head • Facet: small smooth flat (or slightly concave) surface trochlea capitulum facet condyle SKELETON Axial skeleton: • Skull • Sternum • Ribs • Vertebrae Appendicular skeleton: • Bones of upper limb & Shoulder girdle • Bones of lower limb & Pelvic girdle Shoulder girdle SKULL The skull is formed of two parts: •Brain box: the upper & posterior part of the skull •Facial skeleton: the anterior part of the skull The skull is made up of 22 bones • 1 movable bone, the mandible • 21 immovable bones articulating by fibrous joints (sutures) Single bones of the skull Paired bones of the skull •Frontal bone •Occipital bone •Ethmoid bone •Sphenoid bone •Vomer •Mandible •Parietal bone •Temporal bone •Maxilla •Zygomatic bone •Nasal bone •Lacrimal bone •Palatine bone •Inferior nasal concha Features of the Skull Norma Frontalis, shows: • Frontal bone • Nasal bones • Maxillae • Zygomatic bones • Mandible Orbit opening • Orbital openings • Anterior nasal aperture • Mental foramen Anterior nasal aperture Mental foramen Norma verticalis, shows: • Frontal bone • Parietal bones • Occipital bone • Coronal, sagittal and lambdoid sutures • Parietal foramen Frontal bone Coronal suture Sagittal suture Lambdoid suture Parietal foramen Occipital bone Norma lateralis, shows: • Frontal, Parietal, Temporal, Occipital and Zygomatic bones • Zygomatic arch • Temporal lines & temporal fossa • External auditory meatus Temporal lines Zygomatic bone Zygomatic arch External auditory meatus Norma occipitalis, shows: • Occipital bone • Parietal bones • External occipital protuberence & crest • Nuchal lines Parietal External occipital protuberence Superior & inferior Nuchal lines bones Occipital bone Norma basalis externa, shows: • Alveolar arch • Hard palate • Posterior nasal apertures • Foramina and canals which give passage to structures which enter or leave the skull • foramen ovale • foramen magnum • carotid canal Posterior nasal aperture • jugular foramen Hard palate Alveolar arch Foramen ovale Carotid canal Foramen magnum Jugular foramen Norma basalis interna, shows • Anterior, middle & posterior cranial fossae • Frontal, ethmoid, sphenoid, temporal & occipital bones • Foramina: • Foramen rotundum • Foramen ovale • Foramen lacerum Frontal bone • Jugular foramen • Foramen magnum Ethmoid bone Foramen rotundum Sphenoid bone Foramen ovale Foramen lacerum Temporal bone Jugular foramen Occipital bone Foramen magnum Vertebral Column (Spine) •The vertebral column (spine) consists of: •7 cervical vertebrae •12 thoracic vertebrae •5 lumbar vertebrae •5 sacral vertebrae (fused together to form the sacrum) •4 coccygeal vertebrae (fused together to form the coccyx) •The vertebral column provides support for the head and trunk •It provides protection for the spinal cord Basic Structure a Vertebra • Body: disc shaped and anterior in position • Vertebral arch: a bony ring behind the body. It is formed of 2 pedicles and 2 laminae • Vertebral foramen: the ring bound by the vertebral arch. The vertebral canal is formed by the succession of vertebral foramina • 7 Processes: They project from the vertebral arch • A Spinous process, projects posteriorly • 2 Transverse processes, one projecting on each side • 2 Superior articular processes projecting up to articulate with the inferior articular processes of the vertebra above. • 2 Inferior articular processes projecting down to articulate with the superior articular processes of the vertebra blow. Characteristics of Vertebrae Cervical Thoracic Lumbar Body Small & oval Heart-shaped with articular demifacets Large & kidney-shaped Spinous process Short & bifid Long & directed down Short & thick Transverse processes Show a foramen transversarium Have articular facets Long & slender Vertebral foramen Large & triangular Small & circular Large & circular Foramen transversarium Cervical Vertebra Bifid spine Thoracic Vertebra Lumbar Vertebra 1st & 2nd Cervical Vertebrae Sacrum: It is formed of 5 vertebrae that are fused together Intervertebral foramina • These are notches in the upper and lower borders of each pedicle of the vertebral arch • Adjacent notches from an intervertebral foramen for the passage of spinal nerves Curves of the vertebral column • The vertebral column presents 4 curves that are termed cervical, thoracic, lumbar and pelvic. • At birth, the vertebral column forms one C-shaped curve (1ry curve) which is convex backward • Later in life, 2 curves (2ry curves) appear in the cervical and lumbar regions and are convex forward. • Thus, the cervical & lumbar curves are convex forward, while the thoracic & pelvic curves are convex backward Cervical curve Thoracic curve Lumbar curve C-shaped curve of fetal spine Pelvic curve Abnormal curves of the vertebral column Lordosis: increased forward curvature of the lumbar region Kyphosis: increased backward curvature of the thoracic region Scoliosis: lateral curvature usually in the thoracic region. Kyphosis Lordosis Scoliosis Sternum & Ribs The sternum is composed of 3 fused pieces •manubrium sterni •body •ziphoid process Sternal angle: is the junction between the manubrium and the body Ribs • There are 12 pairs of ribs • All the ribs are attached at their posterior ends to the vertebrae. • Anteriorly: • The upper 7 pairs (true ribs) are attached directly to the sternum by their costal cartilages • The 8th, 9th, and 10th ribs (false ribs) are attached to the 7th costal cartilage. • The 11th and 12th ribs (floating ribs) have no anterior attachment. Basic features of ribs • Head: articulates with the thoracic vertebrae • Neck: the constriction just beyond the head • Tubercle: articulates with the transverse process of its corresponding vertebra • Angle: the sharp turn in the rib • Shaft: thin and flattened, its lower border is sharp and shows a groove for intercostal nerves & vessels. APPENDICULAR SKELETON Skeleton of the Upper Limb consists of: Shoulder girdle: 2 bones • Clavicle, anteriorly • Scapula, posteriorly Upper arm, one bone • Humerus Forearm, 2 bones • Radius, laterally • Ulna, medially Hand, formed of: • Carpus (8 bones) • Metacarpus (5 bones) • Phalanges (3 in each finger, except the thumb which contains 2 phalanges) APPENDICULAR SKELETON Skeleton of the Lower Limb consists of: Hip bone Pelvic girdle: 1 bone • Hip bone Thigh, 1 bone • Femur Leg, 2 bones • Fibula, laterally • Tibia, medially Foot, formed of: • Tarsus (7 bones) • Metatarsus (5 bones) • Phalanges (3 in each toe, except the big toe which contains 2 phalanges)