Human Skeleton Anatomy PDF

Composed of 126 bones Limbs (appendages) Pectoral girdle Pelvic girdle Figure 5.8a The Human Skeleton (2 of 2) Figure 5.8b The Human Skeleton (2 of 2) Bones of the Shoulder Girdle Also called pectoral girdle Composed of two bones that attach the upper limb to the axial skeletal Clavicle S...

Composed of 126 bones Limbs (appendages) Pectoral girdle Pelvic girdle Figure 5.8a The Human Skeleton (2 of 2) Figure 5.8b The Human Skeleton (2 of 2) Bones of the Shoulder Girdle Also called pectoral girdle Composed of two bones that attach the upper limb to the axial skeletal Clavicle Scapula Light, poorly reinforced girdle Allows the upper limb a exceptional flexibility Figure 5.21a Bones of the Shoulder Girdle Figure 5.21b Bones of the Shoulder Girdle Figure 5.21c Bones of the Shoulder Girdle Figure 5.21d Bones of the Shoulder Girdle Bones of the Upper Limbs (1 of 3) Humerus Forms the arm Single bone Proximal end articulation Head articulates with the glenoid cavity of the scapula Distal end articulation Trochlea and capitulum articulate with the bones of the forearm Figure 5.22a Bones of the Right Arm and Forearm Figure 5.22b Bones of the Right Arm and Forearm Bones of the Upper Limbs (2 of 3) The forearm has two bones Ulna---medial bone in anatomical position Proximal end articulation Coronoid process and olecranon articulate with the humerus Radius---lateral bone in anatomical position Proximal end articulation Head articulates with the capitulum of the humerus Figure 5.22c Bones of the Right Arm and Forearm Bones of the Upper Limbs (3 of 3) Hand Carpals---wrist bones 8 bones arranged in two rows of 4 bones in each hand Metacarpals---palm bones 5 per hand Phalanges---fingers and thumb 14 phalanges in each hand In each finger, there are 3 bones In the thumb, there are only 2 bones Figure 5.23 Bones of the Right Hand, Anterior View Bones of the Pelvic Girdle (1 of 3) Formed by two coxal bones Composed of three pairs of fused bones Ilium Ischium Pubis Pelvic girdle = two coxal bones, sacrum Pelvis = two coxal bones, sacrum, coccyx Bones of the Pelvic Girdle (2 of 3) The total weight of the upper body rests on the pelvis Pelvis protects several organs Reproductive organs Urinary bladder Part of the large intestine Figure 5.24a The Bony Pelvis Figure 5.24b The Bony Pelvis Bones of the Pelvic Girdle (3 of 3) The female's pelvis Inlet is larger and more circular Shallower, on the whole, and the bones are lighter and thinner Ilia flare more laterally Sacrum is shorter and less curved Ischial spines are shorter and farther apart; thus, the outlet is larger Pubic arch is more rounded because the angle of the pubic arch is greater Figure 5.24c The Bony Pelvis Bones of the Lower Limbs (1 of 4) Femur---thigh bone The heaviest, strongest bone in the body Proximal end articulation Head articulates with the acetabulum of the coxal (hip) bone Distal end articulation Lateral and medial condyles articulate with the tibia in the lower leg Figure 5.25a Bones of the Right Thigh and Leg Figure 5.25b Bones of the Right Thigh and Leg Bones of the Lower Limbs (2 of 4) The lower leg has two bones Tibia---shinbone; larger and medially oriented Proximal end articulation Medial and lateral condyles articulate with the femur to form the knee joint Distal end articulation Medial malleolus forms the inner part of the ankle Fibula---thin and sticklike; lateral to the tibia Has no role in forming the knee joint Distal end articulation Lateral malleolus forms the outer part of the ankle Figure 5.25c Bones of the Right Thigh and Leg Bones of the Lower Limbs (3 of 4) Foot Tarsals---7 bones Two largest tarsals are the: Calcaneus (heel bone) Talus Metatarsals---5 bones form the sole of the foot Phalanges---14 bones form the toes Figure 5.26 Bones of the Right Foot, Superior View Bones of the Lower Limbs (4 of 4) Arches of the feet Bones of the foot are arranged to form three strong arches Two longitudinal One transverse Figure 5.27 Arches of the Foot Joints (1 of 8) Joints are articulations Occur where two or more bones meet Functions of joints Hold bones together securely Allow for mobility Two ways joints are classified Functionally Structurally Joints (2 of 8) Functional joint classifications Synarthroses Immovable joints Amphiarthroses Slightly movable joints Diarthroses Freely movable joints Joints (3 of 8) Structural joint classifications Fibrous joints Generally immovable Cartilaginous joints Immovable or slightly movable Synovial joints Freely movable Concept Link 3 To understand the structural classes of joints more clearly, recall the properties of tissues that form the joints. Fibrous connective tissue contains many collagen fibers for strength. The three types of cartilage (hyaline, fibrocartilage, elastic) provide structure with some degree of flexibility, and fibrocartilage also has the ability to absorb compressive shock (Chapter 3, pp. 92--93). Synovial membranes contain areolar connective tissue and line the joint cavities of synovial joints (Chapter 4, pp. 107, 109). Joints (4 of 8) Fibrous joints Bones are united by fibrous tissue Types Sutures Immobile Syndesmoses Allow more movement than sutures but still immobile Found on the distal ends of tibia and fibula Gomphoses Immobile Found where the teeth meet the facial bones Figure 5.28a Types of Joints Figure 5.28b Types of Joints Joints (5 of 8) Cartilaginous joints Bones are connected by fibrocartilage Types Synchrondrosis Immobile Found in epiphyseal plates of growing long bones Symphysis Slightly movable Found in the pubic symphysis, intervertebral joints Figure 5.28c Types of Joints Figure 5.28d Types of Joints Figure 5.28e Types of Joints Joints (6 of 8) Synovial joints Articulating bones are separated by a joint cavity Synovial fluid is found in the joint cavity Four distinguishing features of synovial joints Articular cartilage Articular capsule Joint cavity Reinforcing ligaments Figure 5.28f Types of Joints Figure 5.28g Types of Joints Figure 5.28h Types of Joints Joints (7 of 8) Synovial joints Bursae---flattened fibrous sacs Lined with synovial membranes Filled with synovial fluid Not actually part of the joint Tendon sheath Elongated bursa that wraps around a tendon Table 5.3 Summary of Joint Classes Structural class Structural characteristics Types Mobility Fibrous Bone ends/parts united by collagenic fibers Suture (short fibers) Syndesmosis (longer fibers) Gomphosis (periodontal ligament) Immobile (synarthrosis) Slightly mobile (amphiarthrosis) and immobile Immobile Cartilaginous Bone ends/parts united by cartilage Synchondrosis (hyaline cartilage) Symphysis (fibrocartilage) Immobile Slightly movable Synovial Bone ends/parts covered with articular cartilage and enclosed within an articular capsule lined with synovial Membrane Plane Hinge Pivot Condylar Saddle Ball and socket Freely movable (diarthrosis; movements depend on design of joint) Joints (8 of 8) Types of synovial joints based on shape Plane joint Hinge joint Pivot joint Condylar joint Saddle joint Ball-and-socket joint Figure 5.29 General Structure of a Synovial Joint Figure 5.30a Types of Synovial Joints Figure 5.30b Types of Synovial Joints Figure 5.30c Types of Synovial Joints Figure 5.30d Types of Synovial Joints Figure 5.30e Types of Synovial Joints Figure 5.30f Types of Synovial Joints Developmental Aspects of the Skeleton (1 of 6) Birth to adulthood First "long bones" of a fetus are hyaline cartilage Earliest "flat bones" of the fetal skull are fibrous membranes As fetus grows, all bone models are converted to bone Figure 5.31 Ossification Centers in the Skeleton of a 12-Week-Old Fetus Are Indicated by the Darker Areas Developmental Aspects of the Skeleton (2 of 6) Fetal skull Fontanels are fibrous membranes connecting the cranial bones Known as "soft spots" Allow skull compression during birth Allow the brain to grow during later pregnancy and infancy Usually ossify by 2 years of age Figure 5.32a The Fetal Skull Figure 5.32b The Fetal Skull Developmental Aspects of the Skeleton (3 of 6) Growth of cranium after birth is related to brain growth Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways Developmental Aspects of the Skeleton (4 of 6) Size of cranium in relationship to body 2 years old---skull is three-fourths the size of adult skull 8 or 9 years old---skull is near adult in size and proportion Between ages 6 and 11, the face grows out from the skull Developmental Aspects of the Skeleton (5 of 6) Skeletal changes At birth, the head and trunk are proportionately much longer than the lower limbs During puberty: Female pelvis broadens Entire male skeleton becomes more robust By the end of adolescence: Epiphyseal plates become fully ossified Figure 5.33a Differences in the Growth Rates for Some Parts of the Body Compared to Others Determine Body Proportions Figure 5.33b Differences in the Growth Rates for Some Parts of the Body Compared to Others Determine Body Proportions Developmental Aspects of the Skeleton (6 of 6) Older adults Osteoporosis Bone-thinning disease afflicting: 50 percent of women over age 65 20 percent of men over age 70 Disease makes bones fragile, and bones can easily fracture Vertebral collapse results in kyphosis (also known as "dowager's hump") Estrogen aids in health and normal density of a female skeleton