Test 3

Epiphyseal Growth: Understand the role of specific structures in bone lengthening during childhood.

The epiphyseal plate aka the growth plate is a disc of hyaline cartilage that grows during childhood to lengthen the bone

Functions of the Skeletal System: Review the primary functions of bones, including support, storage, and blood cell production, and identify any functions that may not fit.

1. Support

   1. for body and soft organs

2. protection

   1. of brain, spinal cord, and vital organs

3. Anchorage

   1. as levers for muscle actions

4. Mineral storage

   1. calcium and phosphorus mostly

5. Blood cell formation

   1. hematopoiesis occurs in red bone marrow of certain bones

6. triglyceride (fat) storage

   1. stored in bone cavities; used as energy source

7. Hormone production

   1. osteocalcin - regulates insulin secretion, glucose homeostasis, and energy expenditure

Axial vs. Appendicular Skeleton: Familiarize yourself with the classification of bones, particularly distinguishing between those in the axial and appendicular skeletons.

Axial Skeleton bones:

• facial bones

  • mandible, lacrimal bone, inferior nasal concha, nasal bones, zygomatic bone

• Vertebrae, Sacrum, Coccyx, Rib Cage, Sternum, Hyoid bone

Appendicular Bones

• Shoulder girdle

  • clavicle, scapula

• Upper limb

  • humerus, radius, ulnar, carpal bones, metacarpals, phalanges

• Lower Limb

  • femur, patella, tibia, fibula, tarsal bones, metatarsals, phalanges

• Pelvic Girdle

  • illium, ischium, and pubis

Periosteum Composition: Learn about the protective tissue covering bones and its inner layer, focusing on the types of cells present.

Periosteum - white double layered membrane that covers external surfaces except joints

• fibrous layer - outer layer consisting of dense irregular connective tissue consisting of Sharpeys fiber that secure to bone matrix

• osteogenic layer - inner layer abutting bone; contains primitive osteogenic stem cells that gives rise to most all bone cells

Endosteum

• delicate connective tissue membrane covering internal bone surfaces

• covers trabeculae of spongy bone

• contains osteogenic cells that differentiate into other bone cells.

Attachment of Periosteum: Explore how the periosteum is anchored to the underlying bone structures, ensuring stability and support.

Sharpeys fibers within the fibrous layers that secure to the bone matrix.

Central Canal Function: Investigate the role of central canals in bones, particularly their importance in housing blood vessels and nerve fibers.

Central (Haversian) canal - runs through core of osteon

• contain blood vessels and nerve fibers that serve the needs of osteocytes - passageways for nutrients and neural communication

Perforating canals aka volkmans’s canal - lined with endosteum

• connect blood vessels and nerves of Periosteum, medullary Cavity and central canal.

Bone Resorption: Understand the cellular mechanisms behind bone breakdown and the specific cells involved in this process.

Resorption - function of osteoclasts

1. dig depressions to break down matrix

2. secrete lysosomal enzymes and protons that digest matrix

Osteoclasts phagocytize demineralized matrix and dead osteocytes

• digested products are transcytosed, released into interstitial fluid, and then into blood, goes to apoptosis

• requires PTH parathyroid hormone and Immune T cells

Hormonal Regulation of Bone: Review how hormones influence bone activity, particularly those that promote the release of calcium into the bloodstream.

Growth hormone - stimulate epiphyseal plate in childhood

Thyroid hormone - modulate activity of growth hormone, proportions

Testosterone & Estrogen - promote growth spurt

Parathyroid hormone - stimulates osteoclasts to resorb bone for calcium release into blood in response to low levels

Calcitonin - lowers blood calcium levels temporarily from thyroid gland in response to high levels of blood calcium

Wolff's Law: Learn about the principle that explains how bone structure adapts in response to stress and mechanical forces.

States that bones grow or remodel in responce to demands placed on them

• ex. stress is off center so diaphysis is thickest where bending stress is greatest

Handedness

• left or right will be thick based on your dominant one

• curved are thickest at buckling sites

• trabeculae forms tissues allow stress lines

• bonny projections occur where heavy active muscles are

• fetus and bedridden people are featureless bc of lack of stress.

Effects of Calcitonin: Familiarize yourself with how this hormone impacts calcium levels in the body and its overall effects on bone health.

Released from the ethyroid gland in response to high blood calcium, lowers it briefly at therapeutic levels

Drug therapies have shown that high does prevent bone breakdown.

Matrix Secretion: Understand which cells are responsible for producing the organic matrix of bone tissue.

Osteoblasts are bone forming cells that secrete osteoid, unmineralized bone matrix

they are made up of collagen and calcium binding proteins

COLLAGEN MAKES UP 90% of bone

Spongy Bone Characteristics: Explore the unique features of spongy bone, including its structural components and functions.

Appears organized but is organized along lines of stress to help bone resist stress

• Trabeculae are cables that strengthen the spongy bone to the bone

• filled with red or yellow bone

aka cancellous bone, provides natural support, shock absorption, weight distribution, houses bone marrow for bc production.

Nutritional Needs for Bone Health: Review the essential nutrients needed to prevent conditions like osteoporosis.

Calcium, Vitamin D, (also K, mag, and protein)

Osteocyte Nutrition: Investigate the structures that facilitate nutrient exchange for osteocytes within bone tissue.

Caneculi are hair like canals that connect lancune to each other and to central canal - enables communication and permits nutrients and wastes to be relayed.

Transformation of Osteoblasts: Understand what happens to osteoblasts when they become encased in the matrix they secrete.

They become osteocytes aka bone cells.

Bone Disorders: Familiarize yourself with various bone disorders that involve abnormal bone growth and remodeling.

Osteoporosis - eabsorption exceeds deposit

Paget’s Disease - escessive and haphazard bone deposit and reabsorption, causes fast growth but poor development, highly spongy

Osteomalacia - poor mineralization, results in softness

Rickets in children- vitamin d defienacy or insufficient calcium, causes bowed legs and abnormally enlarged or long bones.

Fracture Locations: Learn about the different parts of a bone and what happens during a fracture, particularly in the shaft.

Parts of bone:

• proximal epiphysis

• metaphysis

• diaphysis

• metaphysis

• distal epiphysis

Fracture types

• comminuted - three or more pieces

• compression - crushed

• spiral - ragged break due to excessive twist

• epiphyseal - sepereates epihysis and diaphysis along the plate

• depressed - bone portion is pressed inward

• greenstick - bone breaks incompletely, one side of the shaft breaks and and the other bends

Diploë Structure: Explore what diploë refers to, particularly in the context of flat bones and their internal composition.

diploe is thin plates of spongy bones tissue located between the inner and outer layers of the skull bones, contains bone marroww

Osteoporosis and Risk Factors: Understand the contributing factors to osteoporosis, especially in populations at higher risk, like postmenopausal women.

affects older women age 60-70 and postmenopausal bc estrogen descreases and the hormone plays a role in bone density

• also insufficient stress to bone

• poor diet

• smoking

• genetics

• hormone conditions

• alcohol and medications

Joint Types: Review the classifications of joints, particularly focusing on cartilaginous joints like synchondroses and symphyses.

Structural joints:

• Fibrous - bones joined by dense fibrous connective tissue

• Cartiliginous - joined by cartilage

• Synovial - separates bone with fluid -

Functional classifications

• syntharthroses - immovable

• amphiarthroses - slightly movable

• diarthrosis - movable

Cartiliginous joints

• sychondroses - unites bones with bar or plate of hyaline cartilage

• symphyses - United bone with fibrocartilage

Skull Anatomy: Familiarize yourself with key bones in the skull and their locations, emphasizing their anatomical significance.

• frontal bone: Forms the forehead and part of the eye sockets. 

• Parietal bones (2): Form the upper and lateral sides of the skull. 

• Temporal bones (2): Form the sides of the skull and part of the base, housing the ears. 

• Occipital bone: Forms the back and base of the skull. 

• Sphenoid bone: A keystone bone at the base of the skull, connecting to other cranial bones. 

• Ethmoid bone: Located between the eyes, forming part of the nasal cavity and eye sockets. 

Facial Skeleton:

• Mandible (lower jaw): The only movable bone in the skull, forming the lower jaw. 

• Maxillae (2): Form the upper jaw and part of the hard palate. 

• Nasal bones (2): Form the bridge of the nose. 

• Lacrimal bones (2): Small bones forming part of the medial wall of the eye socket. 

• Zygomatic bones (2): Form the cheekbones and part of the eye socket. 

• Vomer: A single, unpaired bone forming the lower part of the nasal septum. 

• Palatine bones (2): Form the posterior part of the hard palate and part of the nasal cavity. 

• Inferior nasal conchae (2): Curved bones that project into the nasal cavity.

Sphenoid Bone Structures: Learn about important features of the sphenoid bone, including their functional roles in cranial anatomy.

The sphenoid bone, a butterfly-shaped bone in the skull base, forms part of the cranial and facial skeleton, providing rigidity and housing the pituitary gland within the sella turcica, while also serving as a passage for nerves and blood vessels. 

Upper Limb Bone Structure: Understand the anatomy of the upper limb, focusing on major bones and their functions.

The upper limb bones, from shoulder to hand, include the humerus (arm), radius and ulna (forearm), carpal bones (wrist), metacarpal bones (palm), and phalanges (fingers), enabling grasping, manipulation, and various arm and hand movements. 

Lower Limb Anatomy: Review the critical bones of the lower limb and their respective roles in movement and support.

The lower limb bones, from thigh to foot, include the femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges, supporting body weight, enabling locomotion, and providing stability and mobility. 

Vertebral Column Structure: Familiarize yourself with the sections of the vertebral column and their specific functions in the body.

1. Cervical Spine (Neck):

• Vertebrae: 7 vertebrae (C1-C7). 

• Functions:

  • Supports the weight of the head. 

  • Allows for head movement (nodding, tilting, and turning). 

  • Protects the spinal cord, arteries, and nerves traveling from the brain to the body. 

  • C1 (atlas) supports the skull, and C2 (axis) allows for head rotation. 

2. Thoracic Spine (Mid-Back):

• Vertebrae: 12 vertebrae (T1-T12). 

• Functions:

  • Connects to the rib cage, protecting the heart and lungs. 

  • Supports the upper body and helps maintain posture. 

  • Forms a kyphotic curve (a slight outward curve). 

3. Lumbar Spine (Lower Back):

• Vertebrae: 5 vertebrae (L1-L5). 

• Functions:

  • Supports the weight of the upper body and pelvis. 

  • Allows for flexion, extension, and lateral bending of the spine. 

  • Absorbs stress from lifting and carrying objects. 

  • Forms a lordotic curve (a slight inward curve). 

4. Sacrum:

• Vertebrae: 5 fused vertebrae (S1-S5).

• Functions:

  • Connects the spine to the pelvis.

  • Forms part of the pelvic girdle.

  • Protects the spinal nerves that exit the spine in this area. 

5. Coccyx (Tailbone):

• Vertebrae: 3-5 fused vertebrae.

• Functions:

  • Provides a small attachment point for muscles and ligaments of the pelvic floor.

  • Remains as a vestigial structure in humans. 

Articulations with the Pelvis: Explore the relationship between specific vertebrae and their connection to the pelvis.

Sacrum:

• Vertebrae: 5 fused vertebrae (S1-S5).

• Functions:

  • Connects the spine to the pelvis.

  • Forms part of the pelvic girdle.

  • Protects the spinal nerves that exit the spine in this area

  • The sacrum and the pelvis work together to transfer weight from the spine to the lower limbs, facilitating movement and stability. 

Pituitary Gland Location: Understand the anatomical positioning of the pituitary gland and its relevance within the cranial cavity.

The hypophyseal fossa is the encolsure for the pituitary gland, aka the master gland bc it regulates several bodily functions through hormone realse, including growth, metabolism, reproduction and stress response.

Greater Wing of the Sphenoid: Recognize the greater wing of the sphenoid and its significance in the skull's architecture.

The greater wings of the sphenoid bone are crucial in skull architecture, forming parts of the middle cranial fossa floor, lateral skull walls, and the posterior orbital wall, and housing important foramina for nerves and blood vessels. 

Cranial Nerve Passageways: Learn about important passages in the sphenoid bone that facilitate the movement of cranial nerves.

optic canal, superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum, which allow cranial nerves and blood vessels to pass through and into the cranial cavity. 

• optic canal allows optic nerve, oculomotor nerve, trochlear nerve, maxillary nerve, mandibular nerve.

Weight Distribution in the Vertebral Column: Explore how different sections of the vertebral column bear weight and provide support to the body.

with the lumbar spine bearing the most weight, have largest vertebrae

Transverse Foramina: Investigate the presence of transverse foramina in certain vertebrae and their significance for vascular structures.

• Transverse foramen found in each transverse process for artery passageways

• The presence of transverse foramina in cervical vertebrae is crucial for vascular structure because they provide a protective passage for the vertebral artery and vein, which supply blood to the brain and spinal cord

Vertebrae Characteristics: Familiarize yourself with the distinctive features of various vertebrae, particularly those that lack certain openings.

• Cervical Vertebrae have transverse foramina for the vertebral arteries (except C7, which has a smaller, nonfunctional foramen).

• Thoracic Vertebrae lack transverse foramina but have costal facets for rib attachment.

• Lumbar Vertebrae are robust and lack transverse foramina and costal facets.

• Sacral Vertebrae are fused and lack intervertebral foramina, with spinal nerves exiting through sacral foramina.

• Coccygeal Vertebrae are fused and lack vertebral foramina, as they are part of the tailbone.

Atlas and Axis Functionality: Understand the unique roles of the atlas and axis vertebrae in supporting the skull and facilitating movement.

The atlas (C1) and axis (C2) vertebrae are uniquely specialized for skull support and movement, with the atlas supporting the skull and allowing for nodding, while the axis, featuring the dens, facilitates head rotation

Muscle Attachments: Learn about the attachment points for muscles within the sphenoid bone and their functional importance.

External occipital crest: ridges that are site of attachment for

ligamentum nuchae

Superior and inferior nuchal lines: site of attachment for many neck

and back muscles

• In summary, the sphenoid bone provides attachment points for muscles primarily involved in mastication and eye movements, playing a vital role in the functional movements of the jaw and eyes, as well as contributing to the structural stability of the skul

Optic Nerve Pathways: Review the anatomical pathways for cranial nerves, particularly how they pass through the sphenoid bone.

Optic canals: allow passage of optic nerves, through foramina

Hematopoiesis Process: Understand the process of blood cell formation within bone marrow and its significance for overall health.

1. Blood cell formation, called hematopoiesis, occurs in red bone marrow of certain bones

2. This process is crucial for maintaining overall health, as it ensures a constant supply of blood cells that are vital for various bodily functions, including oxygen transport, immune response, and blood clotting.

Functional Classification of Bones: Explore how bones are categorized based on their functions, such as weight-bearing versus protective roles.

The categorization of bones based on their functional roles helps in understanding their significance in the human body,

Osteon Structure: Familiarize yourself with the structural units of compact bone and their importance in maintaining bone health.

osteon is the fundamental structural unit, crucial for bone strength, nutrient transport and waste removal, optimal stress resistance.

Weight-Bearing and Protective Functions: Reflect on how the structural design of bones supports their roles in both weight bearing and protection.

Bones' structural design, featuring both dense, hard outer layers (compact bone) and porous inner structures (spongy bone), enables them to support weight and protect vital organs by distributing forces and absorbing impacts.