Essentials of Human Anatomy & Physiology PDF

Essentials of Human Anatomy & Physiology Thirteenth Edition Global Edition Chapter 5 The Skeletal System Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. The Ske...

Essentials of Human Anatomy & Physiology Thirteenth Edition Global Edition Chapter 5 The Skeletal System Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. The Skeletal System Parts of the skeletal system – Bones (skeleton) – Joints – Cartilages – Ligaments Two subdivisions of the skeleton 1. Axial skeleton 2. Appendicular skeleton Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Functions of the Bones Classification of Bones (1 of 6) Support the body The adult skeleton has 206 bones Protection of soft organs Two basic types of osseous (bone) tissue – Skull and vertebrae protect brain and spinal cord 1. Compact bone – Rib cage protects thoracic cavity organs ▪ Dense, smooth, and homogeneous Allow movement via attached muscles 2. Spongy bone Store minerals and fats – Calcium and phosphorus ▪ Small needlelike pieces of bone – Fat in the internal marrow cavity ▪ Many open spaces Blood cell formation (hematopoiesis) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.1 Flat Bones Consist of a Layer of Spongy Bone Sandwiched Between Two Thin Layers of Compact Bone Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.2 Classification of Bones on Classification of Bones (2 of 6) the Basis of Shape Bones are classified on the basis of shape into four groups – Long – Flat – Short – Irregular Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.2a Classification of Bones on Classification of Bones (3 of 6) the Basis of Shape Long bones – Typically longer than they are wide – Shaft with enlarged ends – Contain mostly compact bone; spongy bone at ends – All of the bones of the limbs (except wrist, ankle, and kneecap bones) are long bones – Examples: ▪ Femur ▪ Humerus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Classification of Bones (4 of 6) Flat bones – Thin, flattened, and usually curved – Two thin layers of compact bone sandwich a layer of spongy bone between them – Examples: ▪ Most bones of the skull ▪ Ribs ▪ Sternum Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.2b Classification of Bones on the Basis of Shape Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Classification of Bones (5 of 6) Short bones – Generally cube-shaped – Contain mostly spongy bone with an outer layer of compact bone – Sesamoid bones are a type of short bone that form within tendons (patella) – Examples: ▪ Carpals (wrist bones) ▪ Tarsals (ankle bones) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.2c Classification of Bones on the Basis of Shape Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.2d Classification of Bones on Classification of Bones (6 of 6) the Basis of Shape Irregular bones – Irregular shape – Do not fit into other bone classification categories – Examples: ▪ Vertebrae ▪ Hip bones Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Concept Link 1 Structure of Bone (1 of 10) As we learn about the structure and organization of Long bone anatomy bones, remember the levels of structural organization – Diaphysis (shaft) (Figure 1.1, p. 25). Bones are organs, so they contain not ▪ Makes up most of bone’s length only osseous tissue but also other connective tissues: fibrous tissue, cartilage, adipose tissue, and blood. ▪ Composed of compact bone – Periosteum ▪ Outside covering of the diaphysis ▪ Fibrous connective tissue membrane ▪ Perforating (Sharpey’s) fibers secure periosteum to underlying bone Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.3a The Structure of a Long Figure 5.3c The Structure of a Long Bone (Humerus of Arm) (1 of 3) Bone (Humerus of Arm) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.3b The Structure of a Long Structure of Bone (2 of 10) Bone (Humerus of Arm) Long bone anatomy – Epiphysis (ends) ▪ Composed mostly of spongy bone enclosed by thin layer of compact bone – Articular cartilage ▪ Covers the external surface of the epiphyses ▪ Made of hyaline cartilage ▪ Decreases friction at joint surfaces Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.3a The Structure of a Long Structure of Bone (3 of 10) Bone (Humerus of Arm) (2 of 3) Long bone anatomy – Epiphyseal line ▪ Remnant of the epiphyseal plate ▪ Seen in adult bones – Epiphyseal plate ▪ Flat plate of hyaline cartilage seen in young, growing bone ▪ Causes lengthwise growth of a long bone Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.3a The Structure of a Long Structure of Bone (4 of 10) Bone (Humerus of Arm) (3 of 3) Long bone anatomy – Endosteum ▪ Lines the inner surface of the shaft ▪ Made of connective tissue – Medullary cavity ▪ Cavity inside the shaft ▪ Contains yellow marrow (mostly fat) in adults ▪ Contains red marrow for blood cell formation until age 6 or 7 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of Bone (5 of 10) Table 5.1 Bone Markings (1 of 3) Bone markings – Sites of attachments for muscles, tendons, and ligaments – Passages for nerves and blood vessels Categories of bone markings – Projections or processes—grow out from the bone surface ▪ All projections begin with “T” – Depressions or cavities—indentations ▪ All depressions begin with “F” (except facet) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 5.1 Bone Markings (2 of 3) Table 5.1 Bone Markings (3 of 3) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.4a Microscopic Structure of Structure of Bone (6 of 10) Bone Microscopic anatomy of spongy bone – Composed of small, needlelike pieces of bone called trabeculae and open spaces – Open spaces are filled by marrow, blood vessels, and nerves Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of Bone (7 of 10) Structure of Bone (8 of 10) Microscopic anatomy of compact bone Microscopic anatomy of compact bone – Osteocytes – Central (Haversian) canal ▪ Mature bone cells situated in bone matrix ▪ Opening in the center of an osteon (Haversian – Lacunae system) ▪ Cavities in bone matrix that house osteocytes ▪ Runs lengthwise through bone – Lamellae ▪ Carries blood vessels and nerves ▪ Concentric circles of lacunae situated around the – Osteon (Haversian system) central (Haversian) canal ▪ A unit of bone containing central canal and matrix rings ▪ Structural and functional unit of compact bone Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.4b Microscopic Structure of Figure 5.4c Microscopic Structure of Bone (1 of 2) Bone Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.4b Microscopic Structure of Structure of Bone (9 of 10) Bone (2 of 2) Microscopic anatomy of compact bone – Canaliculi ▪ Tiny canals ▪ Radiate from the central canal to lacunae ▪ Form a transport system connecting all bone cells to a nutrient supply – Perforating (Volkmann’s) canal ▪ Canal perpendicular to the central canal ▪ Carries blood vessels and nerves Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Bone Formation, Growth, and Structure of Bone (10 of 10) Remodeling (1 of 6) Bone is relatively lightweight and resists tension and Bone formation and growth other forces – Ossification is the process of bone formation Organic parts (collagen fibers) make bone flexible and – Occurs on hyaline cartilage models or fibrous have great tensile strength (stretch without breaking) membranes Calcium salts deposited in the bone make bone hard – Long bone growth involves two major phases (resists compression) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Bone Formation, Growth, and Figure 5.5 Stages of Long-Bone Formation in Remodeling (2 of 6) an Embryo, Fetus, and Young Child Two major phases of ossification in long bones 1. In an embryo, osteoblasts (bone-forming cells) cover the hyaline cartilage model with bone matrix 2. In a fetus, the enclosed cartilage is covered by bone; the cartilage is digested away, opening up a medullary cavity Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Bone Formation, Growth, and Figure 5.6ab Growth and Remodeling of Remodeling (3 of 6) Long Bones By birth, most cartilage is converted to bone except for two regions in a long bone 1. Articular cartilages 2. Epiphyseal plates New cartilage is formed continuously on external face of these two cartilages Old cartilage is broken down and replaced by bony matrix Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.6cd Growth and Remodeling of Bone Formation, Growth, and Long Bones Remodeling (4 of 6) Appositional growth – Bones grow in width – Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis – Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis Bone growth is controlled by hormones, such as growth hormone and sex hormones Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Bone Formation, Growth, and Bone Formation, Growth, and Remodeling (5 of 6) Remodeling (6 of 6) Bones are remodeled throughout life in response to Calcium ion regulation two factors – Parathyroid hormone (PTH) 1. Calcium ion level in the blood determines when ▪ Released when calcium ion levels in blood are low bone matrix is to be broken down or formed ▪ Activates osteoclasts (bone-destroying cells) 2. Pull of gravity and muscles on the skeleton ▪ Osteoclasts break down bone and release calcium determines where bone matrix is to be broken ions into the blood down or formed – Hypercalcemia (high blood calcium levels) prompts calcium storage to bones by osteoblasts Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Bone Fractures (1 of 3) Fracture: break in a bone Types of bone fractures – Closed (simple) fracture is a break that does not penetrate the skin – Open (compound) fracture is a broken bone that penetrates through the skin Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Closed Fracture Open Fracture Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Open Reduction Close Bone Fractures (2 of 3) Bone fractures are treated by reduction and immobilization – Closed reduction: bones are manually coaxed into position by physician’s hands – Open reduction: bones are secured with pins or wires during surgery Healing time is 6–8 weeks Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 5.2 Common Types of Fractures (1 of 3) Table 5.2 Common Types of Fractures (2 of 3) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 5.2 Common Types of Fractures (3 of 3) Bone Fractures (3 of 3) Repair of bone fractures involves four major events – Hematoma (blood-filled swelling, or bruise) is formed – Fibrocartilage callus forms ▪ Cartilage matrix, bony matrix, collagen fibers splint the broken bone – Bony callus replaces the fibrocartilage callus ▪ Osteoblasts and osteoclasts migrate in – Bone remodeling occurs in response to mechanical stresses Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.7 Stages in the Healing of a Bone Fracture Axial Skeleton Forms the longitudinal axis of the body Divided into three parts 1. Skull 2. Vertebral column 3. Bony thorax Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.8a The Human Skeleton (1 of 2) Concept Link 2 Recall the regional body terms you have already learned (look back at Figure 1.4, p. 35). Many of these terms can be associated with a bone name or group of bones. For example, the carpal region is the location of the carpals, or wrist bones. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.8b The Human Skeleton (1 of 2) Skull (1 of 5) Two sets of bones form the skull 1. Cranium bones enclose the brain 2. Facial bones ▪ Hold eyes in anterior position ▪ Allow facial muscles to express feelings Bones are joined by sutures (immovable joints) Only the mandible is attached by a freely movable joint Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Skull (2 of 5) 8 cranial bones protect the brain 1 Frontal bone 2 Occipital bone 3 Ethmoid bone 4 Sphenoid bone 5,6 Parietal bones (pair) 7,8 Temporal bones (pair) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.9 Human Skull, Lateral View Figure 5.10 Human Skull, Superior View (Top of Cranium Removed) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.12 Human Skull, Anterior and Figure 5.11 Human Skull, Inferior View Posterior Views (Mandible Removed) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Skull (3 of 5) 14 facial bones 1, 2 Maxillae (pair) 3, 4 Palatine bones (pair) 5, 6 Lacrimal bones (pair) 7, 8 Zygomatic bones (pair) 9, 10 Nasal bones (pair) 11 Vomer bone 12, 13 Inferior nasal conchae (pair) 14 Mandible Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Skull (4 of 5) Paranasal sinuses – Hollow portions of bones surrounding the nasal cavity – Functions of paranasal sinuses ▪ Lighten the skull ▪ Amplify sounds made as we speak Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.13a Paranasal Sinuses Figure 5.13b Paranasal Sinuses Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Skull (5 of 5) Hyoid bone – Closely related to mandible and temporal bones – The only bone that does not articulate with another bone – Serves as a movable base for the tongue – Aids in swallowing and speech Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.14 Anatomical Location and Structure of the Hyoid Bone Vertebral Column (Spine) (1 of 3) Vertebral column provides axial support – Extends from skull to the pelvis 26 vertebral bones are separated by intervertebral discs – 7 cervical vertebrae are in the neck – 12 thoracic vertebrae are in the chest region – 5 lumbar vertebrae are associated with the lower back – Sacrum (formed by fusion of 5 vertebrae) – Coccyx (formed by fusion of 3–5 vertebrae) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.15 The Vertebral Column Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.16 The C-Shaped Spine Typical of Vertebral Column (Spine) (2 of 3) a Newborn Primary curvatures – Spinal curvatures of the thoracic and sacral regions – Present from birth – Form a C-shaped curvature in newborns Secondary curvatures – Spinal curvatures of the cervical and lumbar regions – Develop after birth – Form an S-shaped curvature in adults Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.17 A Typical Vertebra, Superior Vertebral Column (Spine) (3 of 3) View Common features of vertebrae – Body (centrum) – Vertebral arch ▪ Pedicle ▪ Lamina – Vertebral foramen – Transverse processes – Spinous process – Superior and inferior articular processes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.18a Regional Characteristics Figure 5.18b Regional Characteristics of Vertebrae of Vertebrae Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.18c Regional Characteristics Figure 5.18d Regional Characteristics of Vertebrae of Vertebrae Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.19 Sacrum and Coccyx, Posterior View Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.20a The Bony Thorax (Thoracic Thoracic Cage Cage) Bony thorax, or thoracic cage, protects organs of the thoracic cavity Consists of three parts 1. Sternum 2. Ribs ▪ True ribs (pairs 1–7) ▪ False ribs (pairs 8–12) ▪ Floating ribs (pairs 11–12) 3. Thoracic vertebrae Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.20b The Bony Thorax (Thoracic Cage) Appendicular Skeleton Composed of 126 bones – Limbs (appendages) – Pectoral girdle – Pelvic girdle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.8a The Human Skeleton (2 of 2) Figure 5.8b The Human Skeleton (2 of 2) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.21a Bones of the Shoulder Bones of the Shoulder Girdle Girdle Also called pectoral girdle Composed of two bones that attach the upper limb to the axial skeletal 1. Clavicle 2. Scapula Light, poorly reinforced girdle Allows the upper limb a exceptional flexibility Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.21b Bones of the Shoulder Figure 5.21c Bones of the Shoulder Girdle Girdle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.22a Bones of the Right Arm and Forearm Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.22c Bones of the Right Arm Bones of the Upper Limbs (2 of 3) and Forearm The forearm has two bones 1. Ulna—medial bone in anatomical position ▪ Proximal end articulation – Coronoid process and olecranon articulate with the humerus 2. Radius—lateral bone in anatomical position ▪ Proximal end articulation – Head articulates with the capitulum of the humerus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.23 Bones of the Right Hand, Anterior View Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Bones of the Pelvic Girdle (1 of 3) Bones of the Pelvic Girdle (2 of 3) Formed by two coxal bones The total weight of the upper body rests on the pelvis Composed of three pairs of fused bones Pelvis protects several organs – Reproductive organs 1. Ilium – Urinary bladder 2. Ischium – Part of the large intestine 3. Pubis Pelvic girdle = two coxal bones, sacrum Pelvis = two coxal bones, sacrum, coccyx Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.24a The Bony Pelvis Figure 5.24b The Bony Pelvis Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.24c 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.25b Bones of the Right Thigh and Leg Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Bones of the Lower Limbs (2 of 4) The lower leg has two bones 1. 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 2. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.25c Bones of the Right Thigh and Leg Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.26 Bones of the Right Foot, Superior View Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.27 Arches of the Foot 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Joints (2 of 8) Joints (3 of 8) Functional joint classifications Structural joint classifications – Synarthroses – Fibrous joints ▪ Immovable joints ▪ Generally immovable – Amphiarthroses – Cartilaginous joints ▪ Slightly movable joints ▪ Immovable or slightly movable – Diarthroses – Synovial joints ▪ Freely movable joints ▪ Freely movable Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.28a Types of Joints Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 5.28b Types of Joints Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.28c 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.28d 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 1. Articular cartilage 2. Articular capsule 3. Joint cavity 4. Reinforcing ligaments Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.28f Types of Joints Figure 5.28g Types of Joints Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 5.3 Summary of Joint Classes Joints (8 of 8) Structural class Structural Types Mobility characteristics Types of synovial joints based on shape Fibrous Bone ends/parts Suture (short fibers) Immobile (synarthrosis) Slightly united by collagenic Syndesmosis (longer fibers) mobile (amphiarthrosis) and – Plane joint fibers Gomphosis (periodontal immobile ligament) Immobile – Hinge joint Cartilaginous Bone ends/parts Synchondrosis (hyaline Immobile – Pivot joint united by cartilage cartilage) Symphysis Slightly movable (fibrocartilage) – Condylar joint Synovial Bone ends/parts Plane Freely movable (diarthrosis; covered with Hinge movements depend on design – Saddle joint articular cartilage Pivot of joint) and enclosed within Condylar – Ball-and-socket joint an articular capsule Saddle lined with synovial Ball and Membrane socket Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.29 General Structure of a Figure 5.30a Types of Synovial Joints Synovial Joint Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.30b Types of Synovial Joints Figure 5.30c Types of Synovial Joints Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.30d Types of Synovial Joints Figure 5.30e Types of Synovial Joints Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.31 Ossification Centers in the Skeleton of a 12-Week-Old Fetus Are Indicated by the Darker Developmental Aspects of the Areas 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.32a The Fetal Skull Figure 5.32b The Fetal Skull Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Developmental Aspects of the Developmental Aspects of the Skeleton (3 of 6) Skeleton (4 of 6) Growth of cranium after birth is related to brain growth Size of cranium in relationship to body – Increase in size of the facial skeleton follows tooth – 2 years old—skull is three-fourths the size of adult development and enlargement of the respiratory skull passageways – 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.33a Differences in the Growth Rates for Developmental Aspects of the Some Parts of the Body Compared to Others Skeleton (5 of 6) Determine Body Proportions 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.33b Differences in the Growth Rates for Some Parts of the Body Compared to Others Developmental Aspects of the Determine Body Proportions 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 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 5.34 Osteoporosis Figure 5.35 Vertebral Collapse Due to Osteoporosis Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. THANK YOU Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Essentials of Human Anatomy & Physiology Thirteenth Edition Body Membranes (1 of 2) Global Edition Functions of body membranes – Cover body surfaces – Line body cavities Chapter 4 – Form protective sheets around organs Skin and Body Classified according to tissue types Membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Body Membranes (2 of 2) Epithelial Membranes (1 of 5) Two major categories – Epithelial membranes Epithelial membranes are simple organs ▪ Cutaneous membranes Also called covering and lining membranes ▪ Mucous membranes These membranes contain both: ▪ Serous membranes – Epithelial tissue layer – Connective tissue membranes – Connective tissue layer ▪ Synovial membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Membranes (2 of 5) Cutaneous membrane = skin – Dry membrane – Outermost protective boundary – Consists of two layers ▪ Epidermis is composed of keratinized stratified squamous epithelium ▪ Dermis is mostly dense (fibrous) connective tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1a Classes of Epithelial Membranes Epithelial Membranes (3 of 5) Mucous membranes (mucosae) – Moist membranes – Some mucosae secrete protective, lubricating mucus – Line all body cavities that open to the exterior body surface – Adapted for absorption or secretion – Consists of two layers ▪ Epithelium type depends on site ▪ Loose connective tissue (lamina propria) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1b Classes of Epithelial Membranes Epithelial Membranes (4 of 5) Serous membranes (serosae) – Line compartments in the ventral body cavity that are closed to the exterior of the body – Occur in pairs, separated by serous fluid, with a visceral and parietal layer – Consists of two layers ▪ Simple squamous epithelium ▪ Areolar connective tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1c Classes of Epithelial Figure 4.1d Classes of Epithelial Membranes Membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Membranes (5 of 5) Connective Tissue Membranes Specific serous membranes Synovial membranes – Peritoneum – Loose areolar connective tissue only (no epithelial ▪ Cover organs in the abdominal cavity tissue) – Pleurae – Line fibrous capsules surrounding joints ▪ Surround the lungs ▪ Line bursae – Pericardia ▪ Line tendon sheaths ▪ Surround the heart – Secrete a lubricating fluid to cushion organs moving against each other during muscle activity Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.2 A Typical Synovial Joint Integumentary System Integumentary system consists of the: – Skin (cutaneous membrane) – Skin appendages ▪ Sweat glands ▪ Oil glands ▪ Hair ▪ Nails Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Functions of the Integumentary Functions of the Integumentary System (1 of 2) System (2 of 2) Insulates and cushion deeper body organs Regulates heat loss as controlled by the nervous system Protects the entire body from: – Mechanical damage (bumps and cuts) Acts as a mini-excretory system; sweat aids in the – Chemical damage (acids and bases) loss of – Urea – Thermal damage (heat or cold) – Ultraviolet (UV) radiation (sunlight) – Salts – Water – Microbes (bacteria) – Water loss Synthesizes vitamin D Secretions create a protective acid mantle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 4.1 Functions of the Table 4.1 Functions of the Integumentary System (1 of 2) Integumentary System (2 of 2) Functions How accomplished Functions How accomplished Protects deeper tissues from Physical barrier contains keratin, which toughens Aids in body heat loss or heat retention Heat loss: By activating sweat glands and by cells; fat cells to cushion blows; and both pressure (controlled by the nervous system) allowing blood to flush into skin capillary beds so Mechanical damage (bumps) and pain receptors, which alert the nervous system that heat can radiate from the skin surface. to possible damage. Heat retention: By not allowing blood to flush into skin capillary beds. Chemical damage (acids and bases) Has relatively impermeable keratinized cells; contains pain receptors, which alert the nervous Aids in excretion of urea and uric acid Contained in perspiration produced by sweat system to possible damage. glands. Microbe damage Has an unbroken surface and “acid mantle” (skin Synthesizes vitamin D Modified cholesterol molecules in skin converted secretions are acidic and thus inhibit microbes, such to vitamin D in the presence of sunlight. as bacteria). Phagocytes ingest foreign substances and pathogens, preventing them from penetrating into deeper body tissues. Ultraviolet (UV) radiation (damaging effects Melanin produced by melanocytes offers protection of sunlight or tanning beds) from UV damage. Thermal (heat or cold) damage Contains heat/cold/pain receptors. Desiccation (drying out) Contains a water-resistant glycolipid and keratin. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (1 of 11) Figure 4.3 Skin Structure (1 of 2) Two kinds of tissue compose the skin – Epidermis – Dermis Subcutaneous tissue (hypodermis) – Anchors the skin to underlying organs – Not technically part of the integumentary system – Composed mostly of adipose tissue – Serves as a shock absorber and insulates deeper tissues Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (3 of 11) Structure of the Skin (2 of 11) Summary of strata (layers) of the epidermis from Epidermis—outer layer deepest to most superficial – Composed of stratified squamous epithelium – Stratum basale – Most cells are keratinocytes which produce a fibrous protein called keratin – Stratum spinosum ▪ Keratinization makes the epidermis tough – Stratum granulosum ▪ Desmosomes connect keratinocytes together – Stratum lucidum (thick, hairless skin only) – Avascular – Stratum corneum – Composed of five layers (strata) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Structure of the Skin (4 of 11) Stratum basale (stratum germinativum) – Deepest layer of epidermis – Lies next to dermis – Wavy borderline with the dermis anchors the two together – Cells undergoing mitosis – Daughter cells are pushed upward to become the more superficial layers Stratum spinosum – Cells become increasingly flatter and more keratinized Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.4 The Main Structural Features Structure of the Skin (5 of 11) of the Epidermis Stratum granulosum Stratum lucidum – Formed from dead cells of the deeper strata – Occurs only in thick, hairless skin of the palms of hands and soles of feet Stratum corneum – Outermost layer of epidermis – Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (6 of 11) Structure of the Skin (7 of 11) Melanin Epidermal dendritic cells – Melanin is a pigment produced by melanocytes – Alert and activate immune cells to a threat – Melanocytes are mostly in the stratum basale (bacterial or viral invasion) of the epidermis Merkel cells – Color is yellow to brown to black – Associated with sensory nerve endings – Serve as touch receptors called Merkel discs Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (8 of 11) Dermis – Connective tissue – Underlies the epidermis – Two regions ▪ Papillary ▪ Reticular Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Structure of the Skin (9 of 11) Structure of the Skin (10 of 11) Two regions of the dermis Two regions of the dermis – Papillary layer (upper dermal region) contain – Reticular layer (deepest skin layer) projections called dermal papillae ▪ Dense irregular connective tissue ▪ Areolar connective tissue ▪ Blood vessels ▪ Indent the epidermis above ▪ Sweat and oil glands ▪ Many projections contain capillary loops, and ▪ Deep pressure receptors (lamellar corpuscles) others house pain and touch receptors ▪ On palm and sole surfaces, papillae increase friction and gripping ability ▪ Fingerprints are identifying films of sweat Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.5 Light Micrograph of the Two Layers of the Dermis 100 times Structure of the Skin (11 of 11) Other dermal features – Cutaneous sensory receptors – Phagocytes – Collagen and elastic fibers – Blood vessels – Nerve supply Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Skin Color (1 of 2) Skin Color (2 of 2) Three pigments contribute to skin color Redness (erythema)—due to embarrassment, 1. Melanin inflammation, hypertension, fever, or allergy ▪ Yellow, reddish brown, or black pigments Pallor (blanching)—due to emotional stress (such as 3. Carotene fear), anemia, low blood pressure, impaired blood flow to an area ▪ Orange-yellow pigment (also found in some vegetables) Jaundice (yellow cast)—indicates a liver disorder 4. Hemoglobin Bruises (black and blue marks)—hematomas ▪ Red coloring from blood cells in dermal capillaries ▪ Oxygen content determines the extent of red coloring Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (1 of 10) Cutaneous glands are all exocrine glands – Sebaceous glands – Sweat glands Hair and hair follicles Nails Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.3 Skin Structure (2 of 2) Appendages of the Skin (2 of 10) Sebaceous (oil) glands – Located all over the skin except for palms and soles – Produce sebum (oil) ▪ Makes skin soft and moist ▪ Prevents hair from becoming brittle ▪ Kills bacteria – Most have ducts that empty into hair follicles; others open directly onto skin surface – Glands are activated at puberty with increased androgens Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.6a Cutaneous Glands Appendages of the Skin (3 of 10) Sweat (sudoriferous) glands – Produce sweat – Widely distributed in skin Two types of sudoriferous glands 1. Eccrine glands 2. Apocrine glands Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (4 of 10) Figure 4.6b Cutaneous Glands Eccrine glands – More numerous, located all over the body – Open via duct to sweat pores on the skin’s surface – Produce acidic sweat ▪ Water, salts, vitamin C, traces of metabolic waste – Function in body temperature regulation Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (5 of 10) Appendages of the Skin (6 of 10) Apocrine glands Hair – Ducts empty into hair follicles in the armpit and – Located body-wide except for palms, soles, genitals nipples, lips – Begin to function at puberty – Produced by hair follicle – Release sweat that also contains fatty acids – Root is enclosed in the follicle and proteins (milky or yellowish color) – Shaft projects from the surface of the scalp or – Play a minimal role in body temperature skin regulation – Consists of hard keratinized epithelial cells – Melanocytes provide pigment for hair color – Hair grows in the matrix of the hair bulb in stratum basale Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7a Structure of a Hair Root and Follicle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7b Structure of a Hair Root and Appendages of the Skin (7 of 10) Follicle Hair anatomy – Central medulla – Cortex surrounds medulla – Cuticle on outside of cortex ▪ Most heavily keratinized region of the hair – Melanin provides color Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 4.7c Structure of a Hair Root and Follicle Appendages of the Skin (8 of 10) Associated hair structures – Hair follicle ▪ Composed of an inner epithelial root sheath and an outer fibrous sheath ▪ Dermal region provides a blood supply to the hair bulb (deepest part of the follicle) ▪ Arrector pili muscle connects to the hair follicle to pull hairs upright when we are cold or frightened Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7d Structure of a Hair Root and Follicle Appendages of the Skin (9 of 10) Nails – Heavily keratinized, scalelike modifications of the epidermis – Stratum basale extends beneath the nail bed, which is responsible for growth – Lack of pigment makes nails colorless Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 4.8 Structure of a Nail Appendages of the Skin (10 of 10) Parts of a nail – Free edge – Body is the visible attached portion – Nail folds are skin folds that overlap the edges of the nail; the cuticle is the proximal edge – Root of nail is embedded in skin – Growth of the nail occurs from nail matrix of nail bed Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (1 of 13) Infections and allergies – Athlete’s foot ▪ Caused by fungal infection (Tinea pedis) ▪ Itchy, red peeling skin between the toes – Boils (furuncles) and carbuncles ▪ Caused by inflammation of hair follicles ▪ Carbuncles are clusters of boils caused by bacteria – Cold sores (fever blisters) ▪ Caused by human herpesvirus 1 ▪ Blisters itch and sting Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Homeostatic Imbalances of Skin (2 of 13) Infectio