BPK 325 Lecture Notes - Costal Cartilage, Rib Cage, Thoracic Vertebrae

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KIN 325-Unit 2-The Skeletal System
1. Discuss the functions of the skeletal system.
-the skeletal system is fundamental to the maintenance of an erect position
-provides protection for the soft tissues of the body, such as the brain within the
-provides support; ex: suspension of the upper limb by the shoulder girdle
-important in movement; provides muscle attachments, articular surfaces, and a well-
developed lever system; since bones are not solid, they can provide all of the above
functions with a minimal load on the muscles
-inner core of a bone is filled with marrow; red marrow is responsible for formation of
blood cells
-the inorganic component of bone provides a changeable or labile storage area for
calcium and phosphate
-an imbalance of calcium and/or phosphate metabolism in the body is manifest as an
increased deposition of inorganic salts on existing bone or as an increased reabsorption
of bone
2. Describe the general structure of a typical long bone and list the functions of
each of its parts.
-covers most of the surface of each bone; covers all surfaces of the bone except
where it takes part in a joint or articulation
-2 layers thick: a dense outer fibrous layer and an inner, looser network adjacent
to the bone itself
-periosteum fibers connect with fibers of tendons, ligaments, and muscles, as
well as underlying bone
-osteogenic or osteoblastic cells in the periosteum produce new bone
-blood vessels and nerves travel within the periosteum
-hyaline cartilage:
-provides a smooth lubricating surface on parts of the bone that participates in a
joint; acts as a shock absorber; prevents wear and tear of the bone
-compact bone:
-immediately deep of the periosteum; extremely dense and resembles teeth
-thickest in the shaft (diaphysis) of the bone
-thinnest in the ends (epiphyses) of the bone
-arranged in a very well-structured histological pattern consisting of osteons or
Haversian systems, based on repeating units of longitudinally directed blood vells
contained in Haversian canals
-diaphysis and epiphyses:
-diaphysis: tubular shaft; forms the long axis of a long bone
-epiphyses: bone ends covered
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-epiphyseal plate:
-thin plate of cartilage located between the epiphysis and diaphysis
-allows growth in length of bone; fuses to form bone once bone growth is
-spongy bone:
-composed of a network of flat plates called trabeculae, which are arranged in
coliums along stress-lines for maximum strength plus lightness
-best seen in the epiphyses of long bones, which consist primarily of spongy
bone covered by a relatively thin layer of compact bone
-not located in the shaft
-thin layer of connective tissue membrane is found on the inner surface of the
compact bone in the shaft
-consists of osteoblasts that are responsible for the deposition of new bone
tissue on the inner surfaces of the bone
-located between the bony trabeculae of cancellous bone and fills much of the
central space (medullary cavity)
-fetus and infants have red marrow
-vascularity and formation of blood cells cause the red color, and as the child
grows there is a tendency for the red marrow to recede to the epiphyses of the
long bones
-the medullary cavity then becomes filled with yellow marrow because much of it
is composed of adipose tissue
-adults have red marrow and blood cell formation in the vertebrae, skull bones,
ribs, sternum, and iliac crests
3. Describe the structural features and functions of fontanelles.
-soft spots on a young baby’s head, areas that have not yet become ossified,
meaning that it is only the fibrous membrane protecting the brain
-4 fontanelles in the fetal skull: anterior, posterior, mastoid, and sphenoidal
-anterior: large diamond-shaped area between the front and parietal bones
-posterior: triangular depression between the parietal and occipital bones; usually
fused within 2 months of birth
4. Distinguish between axial and appendicular skeleton and locate and identify
the structural features of the major bones that comprise the axial and
appendicular skeleton.
-axial skeleton: made up of the vertebral column, thorax, cranium, and facial bones;
protection for many of the vital organs of the body, such as the brain and spinal
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-appendicular skeleton: composed of two upper limbs and two lower limbs and their
respective bony girdles that support the limbs and attach them to the axial skeleton
-upper limb: pectoral/shoulder girdle comprised of the clavicle and scapula, arm
and forearms comprised of the humerus, radius, ulna, carpal bones,
metacarpals, and phalanges
-lower limb: pelvic girdle,
-cranium: consists of several cranial or skull bones; protects the brain
-series of flat plate-like bones that join together to form an almost
complete box enveloping the brain
-each side of the cranium consists of 4 major bones: frontal, parietal,
temporal, and occipital bones
-14 facial bones that articulate with each other to form the skull
-vertebral column: bony housing for the spinal cord; coordinates functioning in
the nervous system; contains cell bodies as well as long tracts of fibers that
connect the brain with all other parts of the body
-thorax: composed of the sternum, ribs, and costal cartilages that form a bony
cage that is narrow at the top, broad inferiorly, and kidney-bean shaped in cross-
section, containing the lungs, esophagus, heart, and other great vessels
-diaphragm: sheet of muscle that separates the thoracic contents from
the structures within the abdominal cavity
-thoracic cage is comprised of the sternum and 12 pairs of ribs; protects
and supports the vital organs within it and also provides bone and muscle
attachments for the suspension and movement of the upper limbs;
structure is well adapted to respiration
-7 true ribs on each side of the ribcage that connect with the
sternum by means of costal cartilages, 5 false ribs connect
indirectly or do not connect to the sternum (first 3 connect with each
other and connect indirectly to the sternum, last 2 are floating)
-typical rib structure: head with a smooth area that articulates with the
vertebral body of the corresponding number plus the vertebral boy above
it; adjacent to the head is a short neck that provides attachments for
ligaments; distal end of the neck has a prominence called the tubercule of
the rib, which articulates with the transverse process of the corresponding
vertebra; lateral to the tubercule, the shaft turns ventrally to form the angle
of the rib and then extends anteriorly to connect to the costal cartilages
and provides attachment for muscles; costal groove is a depression in the
inferior margin of each rib and contains intercostal nerve and blood
-sternum: long flat bone composed of 3 regions
-manubrium: most superior portion, articulates with the clavicle, first
rib, and one-half of the second rib
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