Ch 07 The Skeletal System
We're Going to Save the Planet
Everyone should contribute to aid the environment.
Importance of collaboration among all living beings (humans, animals, etc.).
Mention of skeletal system in relation to life.
Basic Skeleton Structure
Need to Know
Axial Skeleton Bones: Main framework of the body.
Appendicular Skeleton Bones: Attached to axial skeleton; includes limbs.
Vertebral Sections: Structure of the spine.
Pelvic Girdle: Connects trunk to lower limbs
Bones of the Skull: Protects the brain and forms the face.
Organization of the Skeleton
Axial and Appendicular Skeletons
Axial Skeleton
Comprised of 80 bones.
Includes skull, hyoid, vertebral column, thoracic cage (ribs and sternum).
Appendicular Skeleton
Contains 126 bones, including limbs and girdles.
Further includes clavicle, scapula, and hip bone.
Structure of bones in arms and legs, with the corresponding bones such as femur, tibia, fibula, etc.
Axial Skeleton Breakdown
Components
80 bones: Head, neck, trunk involved
Key bones: skull, hyoid bone, vertebral column, thoracic cage (12 pairs of ribs), and sternum.
Specific Bones
Hyoid Bone
A unique bone located in the throat; supports the larynx and serves as an attachment for muscles.
Cranial and Facial Bones
Cranial Bones: Parietal, Occipital, Maxilla, Frontal, Mandible, Zygomatic.
Vertebral Column
Composed of:
Cervical (7),
Thoracic (12),
Lumbar (5),
Sacrum (1, fused),
Coccyx (1, fused).
Ribs Structure
Total of 12 pairs of ribs:
True ribs: 7 pairs, directly attached to the sternum.
Function of ribs: Protect vital organs like the heart and lungs.
Sternum Overview
Central chest bone connecting ribs, crucial for respiratory protection.
Pelvis Overview
Structure
Comprised of sacrum, coccyx, ilium, pubis, ischium.
Pelvic Girdle Components:
Pubic symphysis, provides structural stability.
Appendicular Skeleton Overview
Consists of 126 bones: Free appendages and attachments to the skeleton.
Limb Components:
Bones connecting to the Pectoral Girdle (scapula, clavicle, arms) and Pelvic Girdle (coxal bones, legs).
Bone Classification by Shape
Types of Bones
Long Bones: Arms and legs (e.g., Femur, Humerus)
Short Bones: Small bones in wrists and ankles (e.g., Carpals, Tarsals)
Flat Bones: Skull and ribcage (e.g., Ribs, Frontal bone)
Irregular Bones: Vertebrae, pelvic bones.
Bone Growth and Development
Ossification Types
Intramembranous Ossification: Bones develop from fibrous membranes (e.g., skull).
Endochondral Ossification: Bones develop from cartilage models; includes the primary fragility during growth phase.
Bone Structure
Epiphysis: Ends of long bones.
Diaphysis: Shaft of the bone.
Periosteum: Membrane covering the bone.
Medullary Cavity: Contains yellow and red bone marrow.
Cellular Components of Bone
Osteoclasts: Break down old bone.
Osteoblasts: Build new bone.
Osteocytes: Mature bone cells that maintain bone matrix.
Bone Disorders
Osteoporosis
Condition where bones become porous and fragile mainly due to increased activity of osteoclasts.
Abnormalities of the Spine
Kyphosis: Hunchback curve.
Lordosis: Swayback in the lower region.
Scoliosis: Lateral curvature of the spine.
Impact of spine abnormalities on overall health.
Regulation of Blood Calcium
Hypocalcemia & Hypercalcemia: Balancing calcium levels in the body via hormonal release.
Calcitonin: Released when calcium levels are high.
Parathyroid Hormone: Released when calcium levels are low, stimulating bones to release calcium.
Fun Facts About Bones
Babies are born with 300 bones; adults have about 206.
Giraffes and humans have the same number of neck bones: seven.
Bones break in different ways; osteophytes (bone spurs) can limit mobility.
We're Going to Save the Planet
Overview
Collective Responsibility: It's essential for everyone, including humans, animals, and other living beings, to contribute to environmental conservation efforts. Recognizing the interconnectedness of all life is crucial for sustainable living.
Skeletal System Relation: The skeletal system plays a vital role in supporting life, serving as the framework for movement, protection of internal organs, and the production of blood cells.
Basic Skeleton Structure
Need to Know
Axial Skeleton Bones: This forms the main framework of the body, crucial for supporting the head, neck, and trunk.
Appendicular Skeleton Bones: These are attached to the axial skeleton and include the limbs, enhancing mobility and facilitating existence.
Vertebral Sections
Understanding the sections of the vertebral column is critical for comprehending body movement and overall posture.
Pelvic Girdle: This structure connects the trunk to the lower limbs, providing stability and support during movement.
Bones of the Skull: It protects the brain and forms the structure of the face, indicating the relationship between skeletal framework and overall health.
Organization of the Skeleton
Axial and Appendicular Skeletons
Axial Skeleton
Comprised of 80 bones, encompassing vital components such as the skull, hyoid bone, vertebral column, and thoracic cage (ribs and sternum).
Appendicular Skeleton
Contains 126 bones, including limbs and girdles, which are essential for movement. Key components include the clavicle, scapula, and hip bone.
The structure of bones in arms (humerus, radius, ulna) and legs (femur, tibia, fibula) elaborates on functional anatomy.
Axial Skeleton Breakdown
Components
Total of 80 bones that include the head, neck, and trunk, supporting vital organs and enabling movement.
Key Bones
Hyoid Bone: Unique in the throat, it supports the larynx and provides attachment points for muscles critical for swallowing and speech.
Cranial and Facial Bones: Cranial bones consist of parietal, occipital, maxilla, frontal, mandible, and zygomatic bones which contribute to protection of the brain and sensory functions.
Vertebral Column
The vertebral column is divided into:
Cervical (7): Supports the head, allowing nodding and rotation.
Thoracic (12): Articulates with ribs, providing stability.
Lumbar (5): Provides strength for lifting and carrying weight.
Sacrum (1, fused) and Coccyx (1, fused): Provide stability and support for the pelvis.
Ribs Structure
Comprising a total of 12 pairs of ribs:
True ribs (7 pairs) directly attach to the sternum.
Protect vital organs such as the heart and lungs, acting as a shield against trauma.
Sternum Overview
The central chest bone connecting ribs plays a vital role in respiratory protection and is a common site for medical examination.
Pelvis Overview
Structure
Composed of the sacrum, coccyx, and the three main bones: ilium, pubis, and ischium that form the pelvic girdle.
The pubic symphysis provides structural stability and support for the body.
Appendicular Skeleton Overview
Consists of 126 bones for free appendages and skull attachments; essential for daily functions.
Limb Components: Include bones connecting to the Pectoral Girdle (scapula, clavicle, arms) and Pelvic Girdle (coxal bones, legs) facilitating a wide range of motion.
Bone Classification by Shape
Types of Bones
Long Bones: Found in arms and legs (e.g., Femur, Humerus) crucial for mobility.
Short Bones: Small wrist and ankle bones (e.g., Carpals, Tarsals) aid in stability.
Flat Bones: Include the skull and ribcage (e.g., Ribs, Frontal bone), protecting internal organs.
Irregular Bones: Such as the vertebrae and pelvic bones, serve varied functions related to support and flexibility.
Bone Growth and Development
Ossification Types
Intramembranous Ossification: Aks for development of flat bones from fibrous membranes, enabling mature bone formation.
Endochondral Ossification: Bones develop from cartilage models, significant during growth phases where bones are fragile.
Bone Structure
Epiphysis: Ends of long bones crucial for joint articulation.
Diaphysis: The shaft provides structural support to the bone.
Periosteum: A membrane covering that aids in repair and nutrition.
Medullary Cavity: Contains yellow (fat storage) and red (blood cell production) bone marrow.
Cellular Components of Bone
Osteoclasts: Cells that break down old bone tissue, playing a role in bone remodeling.
Osteoblasts: Build new bone tissue, contributing to growth and repair.
Osteocytes: Mature bone cells that maintain the bone matrix, essential for strength.
Bone Disorders
Osteoporosis
A condition where bones become porous and fragile, mainly due to increased osteoclast activity, leading to higher fracture risk.
Abnormalities of the Spine
Kyphosis: A hunchback curve affecting posture.
Lordosis: A swayback curve in the lower region, placing strain on back muscles.
Scoliosis: A lateral curvature affecting alignment, impacting lung capacity and overall health.
Regulation of Blood Calcium
Hypocalcemia & Hypercalcemia: Balance calcium levels in the body through hormonal release.
Calcitonin: Released when calcium levels are high to inhibit bone resorption.
Parathyroid Hormone: Released when calcium levels are low, stimulating bones to release calcium.
Fun Facts About Bones
Babies are born with approximately 300 bones, which fuse to about 206 in adulthood.
Both giraffes and humans have the same number of neck bones (seven), indicating a fascinating aspect of evolutionary biology.
Bones can break in various ways; osteophytes (bone spurs) can develop as a result of stress and age, potentially limiting mobility.