The Skeletal Plan

e A . . 7 exercise eleven The Skeletal Plan In this exercise we will study the structure of the skeleton as a whole and the anatomy of a typical long bone. Detailed examination of individual parts will follow in subsequent exercises. Materials: fresh beef bones, sawed longitudinally articulated human skeleton Long Bone Structure We see in figure 11.1 a diagram of the femur cut open, longitudinally, to reveal its internal structure. Note that it has a long shaft called the diaphysis and two enlarged ends, the epiphyses. Where the epi- physes meet the diaphysis are growth zones called metaphyses. During the growing years a plate of hyaline car- tilage, the epiphyseal disk, exists in each of these growth areas. As new cartilage forms on the epi- physeal side, it is destroyed and replaced by bone on the diaphyseal side. While the metaphysis during the growing years consists of the epiphyseal disk and calcified cartilage, at maturity the area becomes completely ossified, and linear growth ceases. Note that the central portion of the diaphysis is a hollow chamber, the medullary cavity. Lining this cavity is a thin membrane called the endos- team. This membrane is continuous with the linings of the central canals of the osteons. The entire medullary cavity and much of the cancellous tissue of the bone extremities contain yellow marrow, a fatty-like substance. The cancel- lous bone of the epiphyses of the femur (and humerus) contains red marrow in the adult. Other long bones of the skeleton contain only yellow mar- row. Most of the red marrow in adults is contained in the ribs, sternum, and vertebree. A tough covering, the periosteum, envelops the surfaces of the entire bone except for the areas of articulation. This covering consists of fibrous con- nective tissue that is quite vascular. The surfaces of each epiphysis that contact adjacent bones are cov- ered with smooth articular cartilage that is of the hyaline type. Assignment: Identify the labels in figure 11.1. 11 ___ Articular Cartilage — Medullary Cavity _ Compact Bone Tissue ___ Metaphysis __ Diaphysis __ Periosteum _ Endosteum — Red Marrow ___ Epiphysis — Yellow Marrow Figure 11.1 Long bone structure. Beef Bone Study Examine a freshly cut section of bone. Identify all structures shown in figure 11.1. Probe into the periosteum near a torn ligament or tendon; note the continuity of fibers between the 47

Exercise 11 ¢ The Skeletal Plan periosteum and these structures. Probe into the marrow and note its texture. Bone Processes, Depressions and Openings In addition to the structures seen in figure 11.1, the following terms pertaining to processes, depres- sions, openings, and canals will be encountered as this skeletal study progresses. Foramen: An opening in a bone that provides a passageway for nerves and blood vessels. Fossa: A shallow depression in a bone. In some instances the fossa is a socket into which another bone fits. Sulcus: A groove or furrow. Meatus: A canal or long tube-like passageway. Fissure: A narrow slit. Sinus (antrum): A cavity in a bone. Condyle: A rounded knuckle-like eminence on a bone that articulates with another bone. Tuberosity: A large roughened process on a bone that serves as a point of anchorage for a muscle. Tubercle: A small rounded process. Trochanter: A very large process on a bone. Head: A portion of a bone supported by a con- stricted part, or neck. Crest: A narrow ridge of bone. Spine: A sharp slender process. Parts of the Skeleton The adult skeleton is made up of 206 named bones and many smaller ones. They vary in configuration, some being long, others short, flat, irregular, or round (sesamoid) in shape. The bones of the skeleton fall into two main groups: those that make up the axial skeleton and those forming the appendicular skeleton. Identify the following in figure 11.2. The Axial Skeleton The parts of the axial skeleton are the skull, hyoid bone, vertebral column (spine), and rib cage. The hyoid bone is a horseshoe-shaped bone that is situated in the neck under the lower jaw. The rib cage consists of twelve pairs of ribs and a sternum (breastbone). The Appendicular Skeleton This portion of the skeleton includes the upper and lower extremities. Each upper extremity consists of a pectoral gir- dle, arm, and hand. The pectoral girdle consists of a scapula (shoulder blade) and clavicle (collar bone). Each arm consists of an upper portion, the humerus, and two forearm bones, the radius and ulna. The radius is lateral to the ulna. The hand includes the bones of the fingers and wrist. 48 The lower extremities consist of the pelvic gir- dle and legs. The pelvic girdle is formed by two bones, the os coxae, which are attached posteriorly, to the sacrum of the vertebral column and anterior- 1y, to each other. The anterior joint where the os coxae are united on the median line is the symph- ysis pubis. ___ Clavicle ___ Patella — Skull ___ Femur __ Pectoral Girdle _ Sternum ___Fibula — Radius __ Symphysis pubis —_Humerus __ Rib —_ Tibia __ Hyoid — Rib Cage —_Ulna ___Oscoxa — Scapula —_ Vertebral Column Figure 11.2 The human skeleton. “A-“-“““--“-‘.‘“'\““'\h'\".‘.‘-‘

yy iy ll 'I sl L L L L L L Ll e || | e | At el L L | | LABORATORY REPORT 11 A Hiustrations Record the labels for figures 11.1, 11.2, and 11.3 in the answer columns. Long Bone Structure Identify the terms described by the following statements. . Shaft portion of bone. . Hollow chamber in bone shaft. Type of marrow in medullary canal. Enlarged end of a bone. Type of bone in diaphysis. Fibrous covering of bone shaft. Linear growth area of long bone. Smooth gristle covering bone end. Type of bone marrow in bone ends. 10. Lining of medullary canal. 11. Type of bone tissue in bone ends. 12. Lines the central canals. R R N S Student: Desk No.: Section: The Skeletal Plan Answers Structure Bones 1 1. 2 2. 3 3. 4, 4. 5. 5. articular cartilage— 1 6. 6. cancellous bone—2 7 7. compact bone—3 s s diaphysis—4 ’ endosteum—35 9 9. epiphyseal disk—6 10. 10. epiphysis—7 1. ” medullary canal—§ periosteum—9 12. 12 red marrow—10 13. yellow marrow-—11 Fig. 11.2 14. 15. Bone Identification Select the structures on the right that match the statements on the left. Shoulder blade Collarbone Breastbone Shinbone Kneecap Upper arm bone Bones of spine Thighbone Lateral bone of forearm Joint between ossa coxae . Horseshoe-shaped bone . Bones of shoulder girdle One half of pelvic girdle . Medial bone of forearm . Thin bone paralleling tibia (calf bone) —_ POrPNaULAhLD = —_ —_ —— clavicle—1 femur—2 fibula—3 humerus—4 hyoid—5 0s coxa—6 patella—7 radius—38 scapula—9 sternum—10 symphysis pubis—11 tibia—12 ulna—13 vertebrae—14 Fig. 11.1

The Skeletal Plan D. Medical Select the condition that is described by the following statements. Since not all conditions are described in this manual it will be necessary for you to consult your lecture text or medical dictionary for some of the terminology. closed reduction—I1 fissured fracture—6 osteoporosis—11 Colles’ fracture—2 greenstick fracture—7 pathological fracture—12 comminuted fracture—3 open reduction—8 Pott’s fracture—13 compacted fracture—4 osteomalacia—9 rickets—14 compound fracture—5 osteomyelitis—10 simple fracture—15 1. Fracture due to weak bone structure, not trauma. 2. Fracture in which the skin is not broken. 3. Fracture characterized by bone ends penetrating the skin. 4. Procedure used to set broken bones without using surgery. 5. Fracture caused by severe vertical forces. 6. Skeletal softness in adults. 7. Bone is split longitudinally. 8. Fracture characterized by two or more fragments. 16. 17. Term applied to bone setting with the aid of surgery. Skeletal softness in children due to vitamin D deficiency. . Infection of bone marrow. Bone fracture extends only partially through a bone; incomplete fracture. . Skeletal deformation due to vitamin D deficiency. Bone condition in which increased porosity occurs due to widening of central canals. Outward displacement of foot due to fracture of lower part of fibula and malleolus. Incomplete bone fracture in which fracture is apparent only on convex surface. Displacement of hand backward and outward due to fracture of lower end of radius. E. Terminology The following statements decribe various processes, depressions, openings, and cavities that are seen on various bones of the skeleton. Identify the term at the right that best matches each of the following descriptive statements. 404 A long tubelike passageway. condyle—1 A rounded knucklelike process that fissure—2 articulates with another bone. foramen—3 A hole through which nerves pass. fossa—4 A narrow slit. meatus—35 A hollow cavity within a bone. sinus—6 A small rounded process. spine—7 A sharp or long slender process. trochanter—8 A depression in a bone. tubercle—9 A very large process on a bone. tuberosity—10 A large roughened process on a bone to which a muscle is attached. Answers Medical © o N e s 0N 10. Fig. 11.3 © ® N ;s LN i o nnnrnprnrrrrrrrrrrrrrrrrrrrrrrrrrri