Exercise 8: Skeletal Overview

Functions and Structure of the Skeleton

• Functions of the Skeleton: The skeleton provides support, protection for internal organs, facilitates movement, stores minerals (such as calcium and phosphorus), and houses bone marrow for blood cell production.

• Major Types of Skeletal Cartilages: There are three main types:

  • Hyaline cartilage: Most abundant; found in articular surfaces, costal cartilages, respiratory tract, and embryonic skeleton.

  • Elastic cartilage: Contains more elastic fibers; found in the ear and epiglottis.

  • Fibrocartilage: Highly compressible; found in intervertebral discs, pubic symphysis, and menisci.

• Characteristics of Each Cartilage Type: Hyaline is glassy and smooth, elastic is flexible, fibrocartilage is tough and dense.

• Bones Classification: Bones are classified by shape:

  • Long bones (e.g., femur)

  • Short bones (e.g., carpals)

  • Flat bones (e.g., sternum)

  • Irregular bones (e.g., vertebrae)

• Structure of a Long Bone: Includes diaphysis (shaft), epiphyses (ends), metaphysis, medullary cavity, periosteum, and endosteum. Figure 8.3 illustrates these parts.

• Microscopic Structure of Compact Bone: Osteon (Haversian system) is the structural unit. Figure 8.4 shows concentric lamellae, central canal, lacunae, and canaliculi.

• Inorganic and Organic Components of Bone Matrix:

  • Inorganic: Hydroxyapatite (calcium phosphate crystals) provides hardness.

  • Organic: Collagen fibers and ground substance provide flexibility and tensile strength.

• Bone Markings: Table 8.1 lists terms such as foramen, process, tubercle, etc., which describe features on bones for attachment or passage of structures.

• Epiphyseal Plate Zones: The epiphyseal plate (growth plate) has zones: resting, proliferative, hypertrophic, calcification, and ossification. These zones are involved in longitudinal bone growth.

Exercise 9: Axial Skeleton

Overview and Identification

• Axial Skeleton: Consists of the skull, vertebral column, and thoracic cage (ribs and sternum).

• Skull: Focus on names and locations of bones (e.g., frontal, parietal, temporal, occipital, sphenoid, ethmoid), and major features such as foramina, sutures, and processes. Figures 9.1, 9.2, 9.3, 9.5, 9.7, 9.8 are referenced for study.

• Sphenoid and Ethmoid Bones: Know their locations and unique features (e.g., sella turcica of sphenoid, cribriform plate of ethmoid).

• Paranasal Sinuses: Air-filled spaces in skull bones (frontal, ethmoid, sphenoid, maxillary) that lighten the skull and enhance voice resonance.

• Vertebral Column: Composed of 33 vertebrae in five regions: cervical (7), thoracic (12), lumbar (5), sacral (5, fused), coccygeal (4, fused). Know how to identify vertebrae by region and specific features of C1 (atlas) and C2 (axis).

• Sacrum and Coccyx: Sacrum is a triangular bone at the base of the spine; coccyx is the tailbone.

• Thoracic Cage: Includes ribs (true, false, floating), sternum (manubrium, body, xiphoid process), and costal cartilages. Be able to identify individual ribs and their features.

• Bone Marrow Harvesting: The iliac crest of the pelvis is a common site for bone marrow aspiration.

• Fetal vs. Adult Skull: Fetal skull has fontanelles (soft spots) and different proportions compared to the adult skull.

Exercise 10: Appendicular Skeleton

Identification and Functional Aspects

• Appendicular Skeleton: Includes pectoral girdle (clavicle, scapula), upper limbs, pelvic girdle (hip bones), and lower limbs.

• Bone Sides: Be able to identify left vs. right bones (e.g., scapula, humerus, femur) based on anatomical landmarks.

• Pelvis: Know differences between male and female pelvis (female pelvis is wider and shallower for childbirth).

• Carpals, Tarsals, and Metapodials: Know the names and arrangement of carpal (wrist) and tarsal (ankle) bones. You are not required to identify individual metacarpals, metatarsals, or phalanges.

• Patella and Ulnar: Know the location and function of the patella (kneecap) and ulna (forearm bone).

Exercise 11: Articulations and Body Movements

Classification and Function of Joints

• Functional Categories of Joints: Joints are classified by function as:

  • Synarthroses: Immovable joints (e.g., sutures of the skull).

  • Amphiarthroses: Slightly movable joints (e.g., intervertebral discs).

  • Diarthroses: Freely movable joints (e.g., shoulder, knee).

• Structural Categories of Joints: Joints are also classified by structure:

  • Fibrous: Bones joined by dense connective tissue (e.g., sutures).

  • Cartilaginous: Bones joined by cartilage (e.g., symphysis, synchondrosis).

  • Synovial: Bones separated by a fluid-filled joint cavity (e.g., most limb joints).

• Synovial Joints: Know the types (plane, hinge, pivot, condyloid, saddle, ball-and-socket) and examples of each. Figure 11.1 and Figure 11.2 illustrate these types.

• Movements of Joints: Terminology includes flexion, extension, abduction, adduction, rotation, circumduction, etc. Table 11.3 lists major joints and their movements.

• Major Joints: Focus on the shoulder, elbow, hip, and knee. Know the bones, muscles, cartilage, ligaments, and tendons involved.

• Ligaments and Tendons: Ligaments connect bone to bone; tendons connect muscle to bone.

Table: Functional and Structural Classification of Joints

Additional info:

• Practice quizzes and lab review sheets are recommended for further study.

• Refer to the myA&P website for interactive practice tools.