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BIOL 4260 Human Evolu3onary Anatomy Lecture 6: Trunk and Respiratory Anatomy Lecture 2: Fossil Record Appositional Bone Growth - increases diameter of bone Q: As you grow, how much wider do your bones get? Bone Remodeling Bone is dynamic living tissue • 500 mg of calcium may enter or leave the adult skeleton each day. • Cancellous bone of the skeleton is replaced every 3 – 4 years • Compact bone is replaced every 10 years • Other real life examples: • Realignment of teeth by orthodon3st • Shrinking of bone following disuse • Hardening of bone with exercise Bone Remodeling • Bone deposit and removal • Occurs at periosteal and endosteal surfaces • Bone remodeling • Bone deposi.on – accomplished by osteoblasts (blast=Greek germinate) • Bone reabsorp.on – accomplished by osteoclasts (clast=Greek to break). • Summary: Bone remodeling is coordinated by a fine mix of osteoblast, osteocyte ac.vity • Control: • Indirectly via Calcium regula.on • Directly arising from stresses Vertebral Column Dual pillar system for weight bearing: anterior/ventral pillar (bodies) & posterior/dorsal pillar (arch) Monotonic increase in size of body The Axial Skeleton 80 named bones Consists of: skull-‐22 bones associated bones Hyoid+6 auditory bones vertebral column bony thorax Support for head, neck, trunk Protection The Vertebral Column • Formed from 26 bones in the adult • Supports and transmits weight of head, neck and trunk to the appendicular skeleton of lower limbs • Surrounds and protects the spinal cord • Serves as attachment sites for the ribs and muscles of the neck and back ¨ Held in place by ligaments ¤ Anterior and posterior longitudinal ligaments ¤ Ligamentum flavum ¤ Others The Vertebral Column regions and Normal curvatures Vertebral column is divided into five major regions Four dis.nct curvatures give vertebral column an S-‐shape Normal Curvatures • Four distinct curvatures give vertebral column an S-shape • Primary: Thoracic and sacral curvatures • Are convex posteriorly • Secondary: Cervical and lumbar curvature • Are concave posteriorly • Curvatures increase the resilience of the spine • Note: In fetus, only the primary curves present. Column therefore C shaped Abnormal curvatures • Abnormal spinal curvatures • Scoliosis – an abnormal lateral curvature • Kyphosis – an exaggerated thoracic curvature • Lordosis – an accentuated lumbar curvature – “swayback” • Stenosis of the lumbar spine • A narrowing of the vertebral canal General features of vertebrae • • • • • • • • • A. Centrum-aka body: weight bearing • Separated by IV discs B. Pedicle paired: Encloses posteriolateral C. Lamina paired D. Spinous process E. Transverse process paired F. Neural arch b+c. Some people say “A” contributes to arch. Not entirely accurate G. Intervertebral disc H. Articular facets Ligaments and Intervertebral Discs Herniated Disc • May be caused by trauma to the spine • Aging is also a contributing factor • Nucleus pulposes loses cushioning proper3es • Anulus fibrosis weakens Herniated Disc Rib Formation Derived from costal processes of thoracic vertebrae Rib Anatomy • Head (with articular facets) Neck • Tubercle (with articular facet) Posterior angle • Body/shaft Costal groove Sternum Manubrium, body, xiphoid process Articulates with clavicle and typically 7 ribs (via costal cartilage) Only bony contact between shoulder girdle and axial skeleton Respiratory System 1 8 Functions of the Respiratory System • Air inhalation • Provides site for exchange of oxygen and CO2 • Provides protection against invading pathogens • By moving air, produces sound • Olfaction • Assists in the regulation of blood volume, blood pressure, and body fluid pH Division of respiratory system Functional Conduction pathway (non collapsible) tubes Exchange surfaces (lungs) Anatomical division Upper respiratory system Lower respiratory Anatomic Division of respiratory system • • • • • • • • • Nose Nasal cavity Sinuses Pharynx Larynx Trachea Bronchi Bronchioles Alveoli Upper respiratory system Lower respiratory system Figure 24.1 Structures of the Respiratory System Frontal sinus Nasal cavity Nasal conchae Nose Sphenoidal sinus UPPER RESPIRATORY SYSTEM LOWER RESPIRATORY SYSTEM Clavicle Internal nares Tongue Nasopharynx Hyoid bone Larynx Esophagus Trachea Bronchus Bronchioles RIGHT LUNG Ribs LEFT LUNG Diaphragm Air pathway • Air enters the external nares • Passes by the nasal vestibule • Area surrounded by the two pairs of alar cartilage Air pathway Air enters the nasal vestibule and flows in and around the nasal conchae Q: Func3on? Sinuses of nasal cavity • Spaces in frontal, maxillary, ethmoid and sphenoid bones • Continuous with nasal cavity • Thin respiratory epithelium with cilia • Fewer goblet cells The Lower Respiratory System The Larynx • A cylinder whose cartilaginous walls are stabilized by ligaments or skeletal muscles or both • Level of vertebrae C4 or C5 to C7 Anatomy of the Larynx Anatomy of the Larynx The Vocal Cords Fig. 24-‐5 30 The Lower Respiratory System • Air passing between the vocal cords creates sound • Pitch - diameter, length, and tension in the vocal cords • Children have slender, short vocal folds • At puberty, male vocal cords of males thicker • Amplification of sound - sinus cavities • Sound articulation - lips, tongue, and cheeks Breathing vs. Swallowing Figure 24.8 Movements of the Larynx during Swallowing Tongue forces compacted bolus into oropharynx. Hard palate Soft palate Tongue Bolus Epiglottis Larynx Trachea Laryngeal movement folds epiglottis; pharyngeal muscles push bolus into esophagus. Soft palate Bolus Epiglottis Bolus moves along esophagus; larynx returns to normal position. Epiglottis Bolus Trachea The Trachea • About 2.5 cm in diameter • Contains tracheal car3lage • Each car3lage ring is actually C-‐shaped, not a complete ring • annular ligaments connect adjacent rings • Respiratory epithelia Hyoid bone Larynx Annular ligaments Trachea Tracheal cartilages Location of carina (internal ridge) Root of right lung Root of left lung Superior lobar bronchus Lung tissue Primary bronchi Superior lobar bronchus Secondary bronchi Middle lobar bronchus Inferior lobar bronchi RIGHT LUNG LEFT LUNG Anterior view showing the plane of section for part (b) ANTERIOR AND POSTERIOR VIEWS OF TRACHEA IN SITU anterior 3 6 Esophagus Trachealis muscle Lumen of trachea Thyroid gland Respiratory epithelium Tracheal cartilage The trachea Histological cross-sectional view of the trachea showing its relationship to surrounding structures LM × 3 The Primary Bronchi • The left and right primary bronchi branch off the trachea at the area of the carina The Primary Bronchi • The right primary bronchus is steeper and larger in diameter than the left **Children can aspirate foreign objects more commonly onto the right lung** 4 0 Structure of the Pulmonary Bronchi • Outside the lungs – extrapulmonary; inside the lungs they are called intrapulmonary bronchi • Each primary bronchus divides to form: • Secondary bronchi and tertiary bronchi • Bronchopulmonary segment Bronchial Tree and Lung Divisions Detailed Branching of the Primary Bronchi • Right lung • 10 tertiary bronchi and therefore 10 bronchopulmonary segments • Left lung • 8 or 9 segments • Trachea and primary bronchi - rings of cartilage • Secondary and tertiary - cartilage plates • Bronchioles - no cartilage The Bronchioles • Ø = 0.3–0.5 mm • Self-supporting • Smooth muscle for bronchodilation (sympathetic stimulation) and bronchoconstriction (parasympathetic stimulation) • Bronchioles: clusters of alveolar sacs Figure 24.13a Bronchi and Bronchioles Trachea Respiratory epithelium Bronchiole Bronchial artery (red), vein (blue), and nerve (yellow) Left primary bronchus Visceral pleura Branch of pulmonary artery Smooth muscle around terminal bronchiole Terminal bronchiole Secondary bronchus Tertiary bronchi Respiratory bronchiole Elastic fibers Smaller bronchi Bronchioles Branch of pulmonary vein Capillary beds Terminal bronchiole Respiratory bronchiole Arteriole Lymphatic vessel Alveolar duct Alveoli Alveoli in a pulmonary lobule Bronchopulmonary segment Alveolar sac Interlobular septum Visceral pleura Pleural cavity Parietal pleura The structure of one portion of a single pulmonary lobule Alveolar Ducts and Alveoli • 150 million alveoli per lung • Extensive network of capillaries surround each alveolus • Gas exchange • Elastic tissue surrounds each alveolus The Pleural Cavities and Pleural Membranes Each lung is lined by a serous membrane • Visceral pleura • Parietal pleura • Pleural cavity Respiratory Muscles and Pulmonary Ventilation The muscles involved in pulmonary ventilation (breathing) are: • Diaphragm • Contracts (lowers) to cause inhalation • Relaxes (raises) to cause exhalation • External intercostals • Elevate the ribs to aid in inhalation • Internal intercostals • Depress the ribs to aid in exhalation Ribs and sternum elevate Diaphragm contracts As the ribs are elevated or the diaphragm is depressed, the volume of the thoracic cavity increases and air moves into the lungs. The outward movement of the ribs as they are elevated resembles the outward swing of a raised bucket handle. Accessory Muscles of Inspiration External intercostal muscles Sternocleidomastoid muscle Scalene muscles Accessory Muscles of Exhalation Internal intercostal muscles Pectoralis minor muscle Transversus thoracis muscle Serratus anterior muscle External oblique muscle Diaphragm Rectus abdominus Internal oblique muscle The primary and accessory muscles of respiration Pneumothorax 5 1 5 2