14.10: Typical Communication Flows
- Differentiate between downward, upward, horizontal, diagonal, and external communication flows.
Organizational Communication Flows
Information can flow in four directions in an organization: downward, upward, horizontally, and diagonally. The size, nature, and structure of the organization dictate which direction most of the information flows. In more established and traditional organizations, much of the communication flows in a vertical—downward and upward—direction. In informal firms, such as tech start-ups, information tends to flow horizontally and diagonally. This, of course, is a function of the almost flat organizational hierarchy and the need for collaboration. Unofficial communications, such as those carried in the company grapevine, appear in both types of organizations.
Downward Communication Flows
Downward communication is when company leaders and managers share information with lower-level employees. Unless requested as part of the message, the senders don’t usually expect (or particularly want) to get a response. An example may be an announcement of a new CEO or notice of a merger with a former competitor. Other forms of high-level downward communications include speeches, blogs, podcasts, and videos. The most common types of downward communication are everyday directives of department managers or line managers to employees. These can even be in the form of instruction manuals or company handbooks.
Downward communication delivers information that helps to update the workforce about key organizational changes, new goals, or strategies; provide performance feedback at the organizational level; coordinate initiatives; present an official policy (public relations); or improve worker morale or consumer relations.
Upward Communication Flows
Information moving from lower-level employees to high-level employees is upward communication (also sometimes called vertical communication). For example, upward communication occurs when workers report to a supervisor or when team leaders report to a department manager. Items typically communicated upward include progress reports, proposals for projects, budget estimates, grievances and complaints, suggestions for improvements, and schedule concerns. Sometimes a downward communication prompts an upward response, such as when a manager asks for a recommendation for a replacement part or an estimate of when a project will be completed.
An important goal of many managers today is to encourage spontaneous or voluntary upward communication from employees without the need to ask first. Some companies go so far as to organize contests and provide prizes for the most innovative and creative solutions and suggestions. Before employees feel comfortable making these kinds of suggestions, however, they must trust that management will recognize their contributions and not unintentionally undermine or ignore their efforts. Some organizations have even installed “whistleblower” hotlines that will let employees report dangerous, unethical, or illegal activities anonymously to avoid possible retaliation by higher-ups in the company.
Horizontal and Diagonal Communication Flows
Horizontal communication involves the exchange of information across departments at the same level in an organization (i.e., peer-to-peer communication). The purpose of most horizontal communication is to request support or coordinate activities. People at the same level in the organization can work together to work on problems or issues in an informal and as-needed basis. The manager of the production department can work with the purchasing manager to accelerate or delay the shipment of materials. The finance manager and inventory managers can be looped in so that the organization can achieve the maximum benefit from the coordination. Communications between two employees who report to the same manager is also an example of horizontal communication. Some problems with horizontal communication can arise if one manager is unwilling or unmotivated to share information, or sees efforts to work communally as threatening his position (territorial behavior). In a case like that, the manager at the next level up will need to communicate downward to reinforce the company’s values of cooperation.
Diagonal communication is cross-functional communication between employees at different levels of the organization. For example, if the vice president of sales sends an e-mail to the vice president of manufacturing asking when a product will be available for shipping, this is an example of horizontal communication. But if a sales representative e-mails the vice president of marketing, then diagonal communication has occurred. Whenever communication goes from one department to another department, the sender’s manager should be made part of the loop. A manager may be put in an embarrassing position and appear incompetent if he isn’t aware of everything happening in his department. Trust may be lost and careers damaged by not paying attention to key communication protocols.
Diagonal communication is becoming more common in organizations with a flattened, matrix, or product-based structure. Advantages include:
- Building relationships between senior-level and lower-level employees from different parts of the organization.
- Encouraging an informal flow of information in the organization.
- Reducing the chance of a message being distorted by going through additional filters.
- Reducing the workloads of senior-level managers.
External Communication Flows
Communications do not start and stop within the organization. External communication focuses on audiences outside of the organization. Senior management—with the help of specialized departments such as public relations or legal—almost always controls communications that relate to the public image or may affect its financial situation. First-level and middle-level management generally handle operational business communications such as purchasing, hiring, and marketing. When communicating outside the organization (regardless of the level), it is important for employees to behave professionally and not to make commitments outside of their scope of authority.
Contributors and Attributions
- Typical Communication Flows. Authored by : John/Lynn Bruton and Lumen Learning. License : CC BY: Attribution
- Miles O'Brien RNASA. Authored by : NASA. Located at : https://commons.wikimedia.org/wiki/File:MilesO%27BrienRNASAjsc2013e026538.jpg . License : Public Domain: No Known Copyright


15.2: Naming Aromatic Compounds
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Objectives
After completing this section, you should be able to
- draw the structure of each of the common aromatic compounds in Figure 16 (Common benzene derived compounds with various substituents), given their IUPAC-accepted trivial names.
- write the IUPAC-accepted trivial name for each of the compounds in Figure 16, given the appropriate Kekulé, condensed or shorthand structure.
- identify the ortho, meta and para positions in a monosubstituted benzene ring.
- use the ortho/meta/para system to name simple disubstituted aromatic compounds.
- draw the structure of a simple disubstituted aromatic compound, given its name according to the ortho/meta/para system.
- provide the IUPAC name of a given aromatic compound containing any number of the following substituents: alkyl, alkenyl or alkynyl groups; halogens; nitro groups; carboxyl groups; amino groups; hydroxyl groups.
- draw the structure of an aromatic compound containing any number of the substituents listed in Objective 6, above, given the IUPAC name.
- provide the IUPAC name of a given aromatic compound in which the phenyl group is regarded as a substituent.
- draw the Kekulé, condensed or shorthand structure of an aromatic compound in which the phenyl group is regarded as a substituent, given its IUPAC name.
Key Terms
Make certain that you can define, and use in context, the key terms below.
- arene
- benzyl group
- phenyl group
Study Notes
You should already know the names and structures of several of the hydrocarbons shown in Figure 15.1. A compound containing a benzene ring which has one or more alkyl substituents is called an arene.
A phenyl group consists of a benzene ring with one of its hydrogens removed.
You should memorize the structures and formulas shown in Figure 16. You will meet these compounds frequently throughout the remainder of this course.
Note that the ortho/meta/para system cannot be used when more than two substituents are present in the benzene ring. The “numbering system” can be used instead of the ortho/meta/para system in most cases when only two substituents are present.
Sources of Aromatic Compounds
Initially aromatic compounds were isolated from coal tar. Coal tar, which is a distillate obtained when heating coal at 1000 o C in the absence of air, is a source of an amazing number of aromatic compounds. Many simple aromatic compounds, some of which includes nitrogen, oxygen, and sulfur, as well as hydrocarbons are obtained.
Some of the Aromatic Compounds Obtained from Coal Tar
Prior to World War II, coal tar was the only important source of aromatic hydrocarbons, but during the war the demand for benzene and toluene, a precursor to the explosive TNT, rose so sharply that other sources had to be found. Today, most of the benzene and almost all of the toluene produced in the United States are derived from petroleum. Although petroleum does contain some aromatic compound, it primarily made up of alkanes of various chain lengths. Aromatic compounds are synthesized from petroleum the by a process referred to in the petroleum industry as catalytic re-forming or hydroforming. This involves heating a C6-C10 alkane fraction of petroleum with hydrogen in the presence of a catalyst to modify the molecular structure of its components. Some amazing transformations take place, and the C6-C7 alkanes can be converted to cycloalkanes, which, in turn, are converted to arenes. Benzene, and methylbenzene (toluene) are produced primarily in this way.
Nomenclature of Mono-Substituted Benzenes
Unlike aliphatic organics, nomenclature of benzene-derived compounds can be confusing because a single aromatic compound can have multiple possible names (such as common and systematic names) be associated with its structure. Common names are often used in the nomenclature of aromatic compounds. IUPAC still allows for some of the more widely used common name to be used. A partial list of these common name is shown in Figure \(\PageIndex{2}\) and there are numerous others. These common names take the place of the benzene base name. Methylbenzene is commonly known with the base name toluene, hydroxyphenol is known as phenol etc. It is very important to be able to identify these structures as they will be utilized in the nomenclature of more complex compounds.
Mono-substituted benzene rings, with a substituent not on the list above, are named with benzene being the parent name. These compounds are named as such: Name of the substituent + Benzene.
The use of Phenyl and Benzyl in Nomenclature
If the alkyl group attached to the benzene contains seven or more carbons the compounds is named as a phenyl substituted alkane. The name phenyl (C 6 H 5 -)is often abbreviated (Ph) and comes from the Greek word pheno which means "I bear light". This name commemorates the fact that benzene was first isolated by Michael Faraday in 1825 from the residue left in London street lamps which burned coal gas. If the alkyl substituent is smaller than the benzene ring (six or fewer carbons), the compound is named as an alkyl-substituted benzene following the rules listed above.
The benzyl group (abbv. Bn), similar to the phenyl group and can be written as C 6 H 5 CH 2 -R, PhCH 2 -R, or Bn-R. Nomenclature of benzyl group based compounds are very similar to the phenyl group compounds. For example, a chlorine attached to a benzyl group would simply be called benzyl chloride, whereas an OH group attached to a benzyl group would simply be called benzyl alcohol.
Nomenclature of Disubstituted Benzenes
With disubstituted benzenes there are three distinct positional isomers which can occur and must be identified in the compounds name. Although numbering can be used to indicate the position of the two subsituents it is much more common for the compounds to be named using prefixes. These prefixes are italicized and are often abbreviated with a single letter. They are defined as the following:
- ortho- (o-): 1,2- (next to each other in a benzene ring)
- meta- (m): 1,3- (separated by one carbon in a benzene ring)
- para- (p): 1,4- (across from each other in a benzene ring)
Nomenclature of Benzenes with Three or more Substituents
When three or more substituents are present the ortho, meta, para positional prefixes become inadequate and a numbering system for the ring must be applied. Here again it is important to check if any of the substituents are listed in Figure \(\PageIndex{2}\) . If a substituent from Figure \(\PageIndex{2}\) is present it is given the parent name in the nomenclature. Also, this substituent is given position one in the numbering system. The other substituents are numbered such that they get the lowest possible sum. In the compound's name the subsituents are given their position number and listed alphabetically. Remember that di-, tri, tetra- prefixes are still used to indicate multiple of the same substituent being present but are ignored for alphabetical listing.
References
- Nicolaou, K. C., & Montagnon, T. (2008). Molecules That Changed the World. KGaA, Weinheim: Wiley-VCH. p. 54
- Pitman, V. (2004). Aromatherapy. Great Britain, UK: Nelson Thornes. p.135-136
- Burton, G. (2000). Chemical Ideas. Bicester, Oxon: Heinemann. p.290-292
- Vollhardt, K. P.C. & Shore, N. (2007). Organic Chemistry (5 th Ed.). New York: W. H. Freeman. p. 667-669
- Schnaubelt, K. (1999). Medical Aromatherapy. Berkeley, CA: Frog Books. p. 211-213
- Patrick, G. L. (2004). Organic Chemistry. New York, NY: Taylor & Francis. p. 135-136
- Talbott, S. M. (2002). A Guide to Understanding Dietary Supplements. Binghamton, NY: Haworth Press. p. 616-619
- Lifton, R. J. (2000). The Nazi doctors. New York, NY: Basic Books. p. 255-261
- Myers, R. L., & Myers, R. L. (2007). The 100 most important chemical compounds. Westport, CT: Greenwood Publishing Group. p. 281-282
Exercises
Exercise \(\PageIndex{1}\)
(True/False) The compound above contains a benzene ring and thus is aromatic.
- Answer
-
False, this compound does not contain a benzene ring in its structure.
Exercise \(\PageIndex{2}\)
Benzene unusual stability is caused by how many conjugated pi bonds in its cyclic ring? ____
- Answer
-
3
Exercise \(\PageIndex{3}\)
Menthol, a topical analgesic used in many ointments for the relief of pain, releases a peppermint aroma upon exposure to the air. Based on this conclusion, can you imply that a benzene ring is present in its chemical structure? Why or why not?
- Answer
-
No, a substance that is fragrant does not imply a benzene ring is in its structure. See camphor example (figure 1)
Exercise \(\PageIndex{4}\)
- Answer
-
No reaction, benzene requires a special catalyst to be hydrogenated due to its unusual stability given by its three conjugated pi bonds.
Exercise \(\PageIndex{5}\)
At normal conditions, benzene has ___ resonance structures.
- Answer
-
2
Exercise \(\PageIndex{6}\)
Which of the following name(s) is/are correct for the following compound?
- nitrohydride benzene
- phenylamine
- phenylamide
- aniline
- nitrogenhydrogen benzene
- All of the above is correct
- Answer
- b, d
Exercise \(\PageIndex{7}\)
Convert 1,4-dimethylbenzene into its common name.
- Answer
-
p-Xylene
Exercise \(\PageIndex{8}\)
TNT's common name is: ______________________________
- Answer
-
2,4,6-trinitrotoluene
Exercise \(\PageIndex{9}\)
Name the following compound using OMP nomenclature:
- Answer
-
p-chloronitrobenzene
Exercise \(\PageIndex{10}\)
Draw the structure of 2,4-dinitrotoluene.
- Answer
-
Exercise \(\PageIndex{11}\)
Name the following compound:
- Answer
-
4-phenylheptane
Example \(\PageIndex{12}\)
Which of the following is the correct name for the following compound?
- 3,4-difluorobenzyl bromide
- 1,2-difluorobenzyl bromide
- 4,5-difluorobenzyl bromide
- 1,2-difluoroethyl bromide
- 5,6-difluoroethyl bromide
- 4,5-difluoroethyl bromide
Solution
a
Exercise \(\PageIndex{13}\)
(True/False) Benzyl chloride can be abbreviated Bz-Cl.
- Answer
-
False, the correct abbreviation for the benzyl group is Bn, not Bz. The correct abbreviation for Benzyl chloride is Bn-Cl.
Exercise \(\PageIndex{14}\)
Benzoic Acid has what R group attached to its phenyl functional group?
- Answer
-
COOH
Exercise \(\PageIndex{15}\)
(True/False) A single aromatic compound can have multiple names indicating its structure.
- Answer
-
True. TNT, for example, has the common name 2,4,6-trinitrotoluene and its systematic name is 2-methyl-1,3,5-trinitrobenzene.
Exercise \(\PageIndex{16}\)
List the corresponding positions for the OMP system (o-, m-, p-).
- Answer
-
Ortho - 1,2 ; Meta - 1,3 ; Para - 1,4
Exercise \(\PageIndex{17}\)
A scientist has conducted an experiment on an unknown compound. He was able to determine that the unknown compound contains a cyclic ring in its structure as well as an alcohol (-OH) group attached to the ring. What is the unknown compound?
- Cyclohexanol
- Cyclicheptanol
- Phenol
- Methanol
- Bleach
- Cannot determine from the above information
- Answer
-
The correct answer is f). We cannot determine what structure this is since the question does not tell us what kind of cyclic ring the -OH group is attached on. Just as cyclohexane can be cyclic, benzene and cycloheptane can also be cyclic.
Exercise \(\PageIndex{18}\)
Which of the following statements is false for the compound, phenol?
- Phenol is a benzene derived compound.
- Phenol can be made by attaching an -OH group to a phenyl group.
- Phenol is highly toxic to the body even in small doses.
- Phenol can be used as a catalyst in the hydrogenation of benzene into cyclohexane.
- Phenol is used as an antiseptic in minute doses.
- Phenol is amongst one of the three common names retained in the IUPAC nomenclature.
- Answer
-
d
Exercise \(\PageIndex{19}\)
State wither the following is para, meta, or ortho substituted.
- Answer
-
A – meta; B – para; C – ortho
Exercise \(\PageIndex{20}\)
Name the following compounds.
- Answer
-
a. 1,3-Dibromobenzene
b. 1-phenyl-4-methylhexane
c. 1,4-Dichloro-2,5-dimethylbenzene
d. 2-methyl-1,3,5-trinitrobenzene. (Also known as trinitrotoluene, or TNT)
Exercise \(\PageIndex{21}\)
Draw the following structures
- p-chloroiodobenzene
- m-bromotoluene
- p-chloroaniline
- 1,3,5-trimethylbenzene
- Answer
-


4.2: Basic Concepts
Organizational Culture
The formal leaders of an organization provide a sense of direction and overall guidance for their employees by establishing organizational vision, mission, and values statements. An organization’s vision statement defines why the organization exists, describes how the organization is unique from similar organizations, and specifies what the organization is striving to be. The mission statement describes how the organization will fulfill its vision and establishes a common course of action for future endeavors. See Figure 4.1 [1] for an illustration of a mission statement. A values statement establishes the values of an organization that assist with the achievement of its vision and mission. A value statement also provides strategic guidelines for decision-making, both internally and externally, by members of the organization. The vision, mission, and value statements are expressed in a concise and clear manner that is easily understood by members of the organization and the public. [2]
Organizational culture refers to the implicit values and beliefs that reflect the norms and traditions of an organization. An organization’s vision, mission, and value statements are the foundation of organizational culture. Because individual organizations have their own vision, mission, and value statements, each organization has a different culture. [3]
As health care continues to evolve and new models of care are introduced, nursing managers must develop innovative approaches that address change while aligning with that organization’s vision, mission, and values. Leaders embrace the organization’s mission, identify how individuals’ work contributes to it, and ensure that outcomes advance the organization’s mission and purpose. Leaders use vision, mission, and values statements for guidance when determining appropriate responses to critical events and unforeseen challenges that are common in a complex health care system. Successful organizations require employees to be committed to following these strategic guidelines during the course of their work activities. Employees who understand the relationship between their own work and the mission and purpose of the organization will contribute to a stronger health care system that excels in providing first-class patient care. The vision, mission, and values provide a common organization-wide frame of reference for decision-making for both leaders and staff. [4]
Learning Activity
Investigate the mission, vision, and values of a potential employer, as you would do prior to an interview for a job position.
Reflective Questions
- How well do the organization’s vision and values align with your personal values regarding health care?
- How well does the organization’s mission align with your professional objective in your resume?
Followership
Followership is described as the upward influence of individuals on their leaders and their teams. The actions of followers have an important influence on staff performance and patient outcomes. Being an effective follower requires individuals to contribute to the team not only by doing as they are told, but also by being aware and raising relevant concerns. Effective followers realize that they can initiate change and disagree or challenge their leaders if they feel their organization or unit is failing to promote wellness and deliver safe, value-driven, and compassionate care. Leaders who gain the trust and dedication of followers are more effective in their leadership role. Everybody has a voice and a responsibility to take ownership of the workplace culture, and good followership contributes to the establishment of high-functioning and safety-conscious teams. [5]
Team members impact patient safety by following teamwork guidelines for good followership. For example, strategies such as closed-loop communication are important tools to promote patient safety.
Read more about communication and teamwork strategies in the “ Collaboration Within the Interprofessional Team ” chapter.
Leadership and Management Characteristics
Leadership and management are terms often used interchangeably, but they are two different concepts with many overlapping characteristics. Leadership is the art of establishing direction and influencing and motivating others to achieve their maximum potential to accomplish tasks, objectives, or projects. [6] , [7] See Figure 4.2 [8] for an illustration of team leadership. There is no universally accepted definition or theory of nursing leadership, but there is increasing clarity about how it differs from management. [9] Management refers to roles that focus on tasks such as planning, organizing, prioritizing, budgeting, staffing, coordinating, and reporting. [10] The overriding function of management has been described as providing order and consistency to organizations, whereas the primary function of leadership is to produce change and movement. [11] View a comparison of the characteristics of management and leadership in Table 4.2a.
| MANAGEMENT | LEADERSHIP |
|---|---|
Planning, Organizing, and Prioritizing
|
Establishing Direction
|
Budgeting and Staffing
|
Influencing Others
|
Coordinating and Problem-Solving
|
Motivating
|
Not all nurses are managers, but all nurses are leaders because they encourage individuals to achieve their goals. The American Nurses Association (ANA) established Leadership as a Standard of Professional Performance for all registered nurses. Standards of Professional Performance are “authoritative statements of action and behaviors that all registered nurses, regardless of role, population, specialty, and setting, are expected to perform competently.” [13] See the competencies of the ANA Leadership standard in the following box and additional content in other chapters of this book.
Competencies of ANA’s Leadership Standard of Professional Performance
- Promotes effective relationships to achieve quality outcomes and a culture of safety
- Leads decision-making groups
- Engages in creating an interprofessional environment that promotes respect, trust, and integrity
- Embraces practice innovations and role performance to achieve lifelong personal and professional goals
- Communicates to lead change, influence others, and resolve conflict
- Implements evidence-based practices for safe, quality health care and health care consumer satisfaction
- Demonstrates authority, ownership, accountability, and responsibility for appropriate delegation of nursing care
- Mentors colleagues and others to embrace their knowledge, skills, and abilities
- Participates in professional activities and organizations for professional growth and influence
- Advocates for all aspects of human and environmental health in practice and policy
Read additional content related to leadership and management activities in corresponding chapters of this book:
- Read about the culture of safety in the “ Legal Implications ” chapter.
- Read about effective interprofessional teamwork and resolving conflict in the “ Collaboration Within the Interprofessional Team ” chapter.
- Read about quality improvement and implementing evidence-based practices in the “ Quality and Evidence-Based Practice ” chapter.
- Read more about delegation, supervision, and accountability in the “ Delegation and Supervision ” chapter.
- Read about professional organizations and advocating for patients, communities, and their environments in the “ Advocacy ” chapter.
- Read about budgets and staffing in the “ Health Care Economics ” chapter.
- Read about prioritization in the “ Prioritization ” chapter.
Leadership Theories and Styles
In the 1930s Kurt Lewin, the father of social psychology, originally identified three leadership styles: authoritarian, democratic, and laissez-faire. [14] , [15]
Authoritarian leadership means the leader has full power. Authoritarian leaders tell team members what to do and expect team members to execute their plans. When fast decisions must be made in emergency situations, such as when a patient “codes,” the authoritarian leader makes quick decisions and provides the group with direct instructions. However, there are disadvantages to authoritarian leadership. Authoritarian leaders are more likely to disregard creative ideas of other team members, causing resentment and stress. [16]
Democratic leadership balances decision-making responsibility between team members and the leader. Democratic leaders actively participate in discussions, but also make sure to listen to the views of others. For example, a nurse supervisor may hold a meeting regarding an increased incidence of patient falls on the unit and ask team members to share their observations regarding causes and potential solutions. The democratic leadership style often leads to positive, inclusive, and collaborative work environments that encourage team members’ creativity. Under this style, the leader still retains responsibility for the final decision. [17]
Laissez-faire is a French word that translates to English as, “leave alone.” Laissez-faire leadership gives team members total freedom to perform as they please. Laissez-faire leaders do not participate in decision-making processes and rarely offer opinions. The laissez-faire leadership style can work well if team members are highly skilled and highly motivated to perform quality work. However, without the leader’s input, conflict and a culture of blame may occur as team members disagree on roles, responsibilities, and policies. By not contributing to the decision-making process, the leader forfeits control of team performance. [18]
Over the decades, Lewin’s original leadership styles have evolved into many styles of leadership in health care, such as passive-avoidant, transactional, transformational, servant, resonant, and authentic. [19] , [20] Many of these leadership styles have overlapping characteristics. See Figure 4.3 [21] for a comparison of various leadership styles in terms of engagement.
Passive-avoidant leadership is similar to laissez-faire leadership and is characterized by a leader who avoids taking responsibility and confronting others. Employees perceive the lack of control over the environment resulting from the absence of clear directives. Organizations with this type of leader have high staff turnover and low retention of employees. These types of leaders tend to react and take corrective action only after problems have become serious and often avoid making any decisions at all. [22]
Transactional leadership involves both the leader and the follower receiving something for their efforts; the leader gets the job done and the follower receives pay, recognition, rewards, or punishment based on how well they perform the tasks assigned to them. [23] Staff generally work independently with no focus on cooperation among employees or commitment to the organization. [24]
Transformational leadership involves leaders motivating followers to perform beyond expectations by creating a sense of ownership in reaching a shared vision. [25] It is characterized by a leader’s charismatic influence over team members and includes effective communication, valued relationships, and consideration of team member input. Transformational leaders know how to convey a sense of loyalty through shared goals, resulting in increased productivity, improved morale, and increased employees’ job satisfaction. [26] They often motivate others to do more than originally intended by inspiring them to look past individual self-interest and perform to promote team and organizational interests. [27]
Servant leadership focuses on the professional growth of employees while simultaneously promoting improved quality care through a combination of interprofessional teamwork and shared decision-making. Servant leaders assist team members to achieve their personal goals by listening with empathy and committing to individual growth and community-building. They share power, put the needs of others first, and help individuals optimize performance while forsaking their own personal advancement and rewards. [28]
Visit the Greenleaf Center site to learn more about What is Servant Leadership ?
Resonant leaders are in tune with the emotions of those around them, use empathy, and manage their own emotions effectively.  They create an environment where employees are highly engaged, making them willing and able to contribute with their full potential. [29]
Authentic leaders have an honest and direct approach with employees, demonstrating self-awareness, internalized moral perspective, and relationship transparency. They strive for trusting, symmetrical, and close leader–follower relationships; promote the open sharing of information; and consider others’ viewpoints. [30]
| Authoritarian | Democratic | Laissez-Faire or Passive-Avoidant |
|---|---|---|
|
|
|
| Transactional | Transformational | Servant |
|---|---|---|
|
|
|
| Resonant Leaders | Authentic Leaders |
|---|---|
|
|
Outcomes of Various Leadership Styles
Leadership styles affect team members, patient outcomes, and the organization. A systematic review of the literature published in 2021 showed significant correlations between leadership styles and nurses’ job satisfaction. Transformational leadership style had the greatest positive correlation with nurses’ job satisfaction, followed by authentic, resonant, and servant leadership styles. Passive-avoidant and laissez-faire leadership styles showed a negative correlation with nurses’ job satisfaction. [31] In this challenging health care environment, managers and nurse leaders must promote technical and professional competencies of their staff, but they must also act to improve staff satisfaction and morale by using appropriate leadership styles with their team. [32]
Systems Theory
Systems theory is based on the concept that systems do not function in isolation but rather there is an interdependence that exists between their parts. Systems theory assumes that most individuals strive to do good work, but are affected by diverse influences within the system. Efficient and functional systems account for these diverse influences and improve outcomes by studying patterns and behaviors across the system. [33]
Many health care agencies have adopted a culture of safety based on systems theory. A culture of safety is an organizational culture that embraces error reporting by employees with the goal of identifying systemic causes of problems that can be addressed to improve patient safety. According to The Joint Commission, a culture of safety includes the following components [34] :
- Just Culture: A culture where people feel safe raising questions and concerns and report safety events in an environment that emphasizes a nonpunitive response to errors and near misses. Clear lines are drawn by managers between human error, at-risk, and reckless employee behaviors. See Figure 4.4 [35] for an illustration of Just Culture.
- Reporting Culture: People realize errors are inevitable and are encouraged to speak up for patient safety by reporting errors and near misses. For example, nurses complete an “incident report” according to agency policy when a medication error occurs or a client falls. Error reporting helps the agency manage risk and reduce potential liability.
- Learning Culture: People regularly collect information and learn from errors and successes while openly sharing data and information and applying best evidence to improve work processes and patient outcomes.
The Just Culture model categorizes human behavior into three categories of errors. Consequences of errors are based on whether the error is a simple human error or caused by at-risk or reckless behavior [36] :
- Simple human error: A simple human error occurs when an individual inadvertently does something other than what should have been done. Most medical errors are the result of human error due to poor processes, programs, education, environmental issues, or situations. These errors are managed by correcting the cause, looking at the process, and fixing the deviation. For example, a nurse appropriately checks the rights of medication administration three times, but due to the similar appearance and names of two different medications stored next to each other in the medication dispensing system, administers the incorrect medication to a patient. In this example, a root cause analysis reveals a system issue that must be modified to prevent future patient errors (e.g., change the labelling and storage of look alike-sound alike medications). [37]
- At-risk behavior: An error due to at-risk behavior occurs when a behavioral choice is made that increases risk where the risk is not recognized or is mistakenly believed to be justified. For example, a nurse scans a patient’s medication with a barcode scanner prior to administration, but an error message appears on the scanner. The nurse mistakenly interprets the error to be a technology problem and proceeds to administer the medication instead of stopping the process and further investigating the error message, resulting in the wrong dosage of a medication being administered to the patient. In this case, ignoring the error message on the scanner can be considered “at-risk behavior” because the behavioral choice was considered justified by the nurse at the time. [38]
- Reckless behavior: Reckless behavior is an error that occurs when an action is taken with conscious disregard for a substantial and unjustifiable risk. For example, a nurse arrives at work intoxicated and administers the wrong medication to the wrong patient. This error is considered due to reckless behavior because the decision to arrive intoxicated was made with conscious disregard for substantial risk. [39]
These categories of errors result in different consequences to the employee based on the Just Culture model:
- If an individual commits a simple human error, managers console the individual and consider changes in training, procedures, and processes. [40] In the “simple human error” example above, system-wide changes would be made to change the label and location of the medications to prevent future errors from occurring with the same medications.
- Individuals committing at-risk behavior are held accountable for their behavioral choices and often require coaching with incentives for less risky behaviors and situational awareness. [41] In the “at-risk behavior” example above, when the nurse chose to ignore an error message on the barcode scanner, mandatory training on using barcode scanners and responding to errors would likely be implemented, and the manager would track the employee’s correct usage of the barcode scanner for several months following training.
- If an individual demonstrates reckless behavior, remedial action and/or punitive action is taken. [42] In the “reckless behavior” example above, the manager would report the nurse’s behavior to the State Board of Nursing for disciplinary action. The SBON would likely mandate substance abuse counseling for the nurse to maintain their nursing license. However, employment may be terminated and/or the nursing license revoked if continued patterns of reckless behavior occur.
See Table 4.2c describing classifications of errors using the Just Culture model.
| Human Error | At-Risk Behavior | Reckless Behavior |
|---|---|---|
| The caregiver made an error while working appropriately and focusing on the patient’s best interests. | The caregiver made a potentially unsafe choice resulting from faulty or self-serving decision-making. | The caregiver knowingly violated a rule and/or made a dangerous or unsafe choice. |
| Investigation reveals system factors contributing to similar errors by others with similar knowledge and skills. | Investigation reveals the system supports risky action and the caregiver requires coaching. | Investigation reveals the caregiver is accountable and needs retraining. |
| Manage by fixing system errors in processes, procedures, training, design, or environment. |
Manage by coaching the caregiver and fixing any system issues:
|
Manage by disciplining the caregiver. If the system supports reckless behavior, it requires fixing. |
| CONSOLE | COACH | PUNISH |
Systems leadership refers to a set of skills used to catalyze, enable, and support the process of systems-level change that is encouraged by the Just Culture Model. Systems leadership is comprised of three interconnected elements: [43]
- The Individual: The skills of collaborative leadership to enable learning, trust-building, and empowered action among stakeholders who share a common goal
- The Community: The tactics of coalition building and advocacy to develop
- The System: An understanding of the complex systems shaping the challenge to be addressed
- “ Mission_statement.jpg ” by RadioFan ( talk ) is licensed under CC BY-SA 3.0 ↵
- This work is a derivative of Leadership and Influencing Change in Nursing by Joan Wagner and is licensed under CC BY 4.0 ↵
- This work is a derivative of Leadership and Influencing Change in Nursing by Joan Wagner and is licensed under CC BY 4.0 ↵
- This work is a derivative of Leadership and Influencing Change in Nursing by Joan Wagner and is licensed under CC BY 4.0 ↵
- This work is a derivative of Leadership and Influencing Change in Nursing by Joan Wagner and is licensed under CC BY 4.0 ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- “ 3D_Team_Leadership_Arrow_Concept.jpg ” by lumaxart is licensed under CC BY-SA 2.0 ↵
- Scully, N. J. (2015). Leadership in nursing: The importance of recognising inherent values and attributes to secure a positive future for the profession. Collegian, 22 (4), 439-444. https://doi.org/10.1016/j.colegn.2014.09.004 ↵
- Hannaway, J. (1989). Managers managing: The workings of an administrative system. Oxford University Press, p. 39. ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- American Nurses Association. (2021). Nursing: Scope and standards of practice (4th ed.). American Nurses Association. ↵
- Carlin, D. (2019, October 18). Democratic, authoritarian, laissez-faire: What type of leader are you? Forbes. https://www.forbes.com/sites/davidcarlin/2019/10/18/democratic-authoritarian-laissez-faire-what-type-of-leader-are-you/?sh=618359422a6b ↵
- Lewin, K., Lippitt, R., & White, R. K. (1939). Patterns of aggressive behavior in experimentally created “social climates.” Journal of Social Psychology, 10 (2), 271-301. https://doi.org/10.1080/00224545.1939.9713366 ↵
- Carlin, D. (2019, October 18). Democratic, authoritarian, laissez-faire: What type of leader are you? Forbes. https://www.forbes.com/sites/davidcarlin/2019/10/18/democratic-authoritarian-laissez-faire-what-type-of-leader-are-you/?sh=618359422a6b ↵
- Carlin, D. (2019, October 18). Democratic, authoritarian, laissez-faire: What type of leader are you? Forbes. https://www.forbes.com/sites/davidcarlin/2019/10/18/democratic-authoritarian-laissez-faire-what-type-of-leader-are-you/?sh=618359422a6b ↵
- Carlin, D. (2019, October 18). Democratic, authoritarian, laissez-faire: What type of leader are you? Forbes. https://www.forbes.com/sites/davidcarlin/2019/10/18/democratic-authoritarian-laissez-faire-what-type-of-leader-are-you/?sh=618359422a6b ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- “ Full_Range_Leadership_model.jpg ” by John Pons is licensed under Public Domain, CC0 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Northhouse, P. (2004). Leadership: Theory and practice (9th ed.). Sage Publications. ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Specchia, M. L., Cozzolino, M. R., Carini, E., Di Pilla, A., Galletti, C., Ricciardi, W., & Damiani, G. (2021). Leadership styles and nurses' job satisfaction. Results of a systematic review. International Journal of Environmental Research and Public Health, 18 (4), 1552. https://doi.org/10.3390/ijerph18041552 ↵
- Anderson, B. R. (2016). Improving health care by embracing systems theory. The Journal of Thoracic and Cardiovascular Surgery, 152 (2), 593-594. https://www.jtcvs.org/article/S0022-5223(16)30001-0/pdf ↵
- The Joint Commission. (2017, March 1). The essential role of leadership in developing a safety culture. Sentinel Event Alert , Issue 57. https://www.jointcommission.org/-/media/tjc/documents/resources/patient-safety-topics/sentinel-event/sea_57_safety_culture_leadership_0317pdf.pdf ↵
- "Just Culture Infographic.png" by Valeria Palarski 2020. Used with permission. ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- American Nursing Association. (2010). Position statement: Just culture. https://www.nursingworld.org/~4afe07/globalassets/practiceandpolicy/health-and-safety/just_culture.pdf ↵
- Dreier, L., Nabarro, D., & Nelson, J. (2019). Systems leadership for sustainable development: Strategies for achieving system change. CR Initiative at Harvard Kennedy School. https://www.hks.harvard.edu/sites/default/files/centers/mrcbg/files/Systems%20Leadership.pdf ↵


8.5: Bones of the Lower Limb
By the end of this section, you will be able to:
- Identify the divisions of the lower limb and describe the bones of each region
- Describe the bones and bony landmarks that articulate at each joint of the lower limb
Like the upper limb, the lower limb is divided into three regions. The thigh is that portion of the lower limb located between the hip joint and knee joint. The leg is specifically the region between the knee joint and the ankle joint. Distal to the ankle is the foot . The lower limb contains 30 bones. These are the femur, patella, tibia, fibula, tarsal bones, metatarsal bones, and phalanges (see Figure 8.2). The femur is the single bone of the thigh. The patella is the kneecap and articulates with the distal femur. The tibia is the larger, weight-bearing bone located on the medial side of the leg, and the fibula is the thin bone of the lateral leg. The bones of the foot are divided into three groups. The posterior portion of the foot is formed by a group of seven bones, each of which is known as a tarsal bone , whereas the mid-foot contains five elongated bones, each of which is a metatarsal bone . The toes contain 14 small bones, each of which is a phalanx bone of the foot .
Femur
The femur, or thigh bone, is the single bone of the thigh region (Figure \(\PageIndex{1}\) ). It is the longest and strongest bone of the body, and accounts for approximately one-quarter of a person’s total height. The rounded, proximal end is the head of the femur , which articulates with the acetabulum of the hip bone to form the hip joint . The fovea capitis is a minor indentation on the medial side of the femoral head that serves as the site of attachment for the ligament of the head of the femur . This ligament spans the femur and acetabulum, but is weak and provides little support for the hip joint. It does, however, carry an important artery that supplies the head of the femur.
The narrowed region below the head is the neck of the femur . This is a common area for fractures of the femur. The greater trochanter is the large, upward, bony projection located above the base of the neck. Multiple muscles that act across the hip joint attach to the greater trochanter, which, because of its projection from the femur, gives additional leverage to these muscles. The greater trochanter can be felt just under the skin on the lateral side of your upper thigh. The lesser trochanter is a small, bony prominence that lies on the medial aspect of the femur, just below the neck. A single, powerful muscle attaches to the lesser trochanter. Running between the greater and lesser trochanters on the anterior side of the femur is the roughened intertrochanteric line . The trochanters are also connected on the posterior side of the femur by the larger intertrochanteric crest .
The elongated shaft of the femur has a slight anterior bowing or curvature. At its proximal end, the posterior shaft has the gluteal tuberosity , a roughened area extending inferiorly from the greater trochanter. More inferiorly, the gluteal tuberosity becomes continuous with the linea aspera (“rough line”). This is the roughened ridge that passes distally along the posterior side of the mid-femur. Multiple muscles of the hip and thigh regions make long, thin attachments to the femur along the linea aspera.
The distal end of the femur has medial and lateral bony expansions. On the lateral side, the smooth portion that covers the distal and posterior aspects of the lateral expansion is the lateral condyle of the femur . The roughened area on the outer, lateral side of the condyle is the lateral epicondyle of the femur . Similarly, the smooth region of the distal and posterior medial femur is the medial condyle of the femur , and the irregular outer, medial side of this is the medial epicondyle of the femur . The lateral and medial condyles articulate with the tibia to form the knee joint. The epicondyles provide attachment for muscles and supporting ligaments of the knee. The adductor tubercle is a small bump located at the superior margin of the medial epicondyle. Posteriorly, the medial and lateral condyles are separated by a deep depression called the intercondylar fossa . Anteriorly, the smooth surfaces of the condyles join together to form a wide groove called the patellar surface , which provides for articulation with the patella bone. The combination of the medial and lateral condyles with the patellar surface gives the distal end of the femur a horseshoe (U) shape.
Interactive Link
Watch this video to view how a fracture of the mid-femur is surgically repaired. How are the two portions of the broken femur stabilized during surgical repair of a fractured femur?
Patella
The patella (kneecap) is largest sesamoid bone of the body (see Figure 8.16). A sesamoid bone is a bone that is incorporated into the tendon of a muscle where that tendon crosses a joint. The sesamoid bone articulates with the underlying bones to prevent damage to the muscle tendon due to rubbing against the bones during movements of the joint. The patella is found in the tendon of the quadriceps femoris muscle, the large muscle of the anterior thigh that passes across the anterior knee to attach to the tibia. The patella articulates with the patellar surface of the femur and thus prevents rubbing of the muscle tendon against the distal femur. The patella also lifts the tendon away from the knee joint, which increases the leverage power of the quadriceps femoris muscle as it acts across the knee. The patella does not articulate with the tibia.
Interactive Link
Visit this site to watch a virtual knee replacement surgery. The prosthetic knee components must be properly aligned to function properly. How is this alignment ensured?
Homeostatic Imbalances
Runner’s Knee
Runner’s knee, also known as patellofemoral syndrome, is the most common overuse injury among runners. It is most frequent in adolescents and young adults, and is more common in females. It often results from excessive running, particularly downhill, but may also occur in athletes who do a lot of knee bending, such as jumpers, skiers, cyclists, weight lifters, and soccer players. It is felt as a dull, aching pain around the front of the knee and deep to the patella. The pain may be felt when walking or running, going up or down stairs, kneeling or squatting, or after sitting with the knee bent for an extended period.
Patellofemoral syndrome may be initiated by a variety of causes, including individual variations in the shape and movement of the patella, a direct blow to the patella, or flat feet or improper shoes that cause excessive turning in or out of the feet or leg. These factors may cause in an imbalance in the muscle pull that acts on the patella, resulting in an abnormal tracking of the patella that allows it to deviate too far toward the lateral side of the patellar surface on the distal femur.
Because the hips are wider than the knee region, the femur has a diagonal orientation within the thigh, in contrast to the vertically oriented tibia of the leg (Figure \(\PageIndex{2}\)). The Q-angle is a measure of how far the femur is angled laterally away from vertical. The Q-angle is normally 10–15 degrees, with females typically having a larger Q-angle due to their wider pelvis. During extension of the knee, the quadriceps femoris muscle pulls the patella both superiorly and laterally, with the lateral pull greater in females due to their large Q-angle. This makes females more vulnerable to developing patellofemoral syndrome than males. Normally, the large lip on the lateral side of the patellar surface of the femur compensates for the lateral pull on the patella, and thus helps to maintain its proper tracking.
However, if the pull produced by the medial and lateral sides of the quadriceps femoris muscle is not properly balanced, abnormal tracking of the patella toward the lateral side may occur. With continued use, this produces pain and could result in damage to the articulating surfaces of the patella and femur, and the possible future development of arthritis. Treatment generally involves stopping the activity that produces knee pain for a period of time, followed by a gradual resumption of activity. Proper strengthening of the quadriceps femoris muscle to correct for imbalances is also important to help prevent reoccurrence.
Tibia
The tibia (shin bone) is the medial bone of the leg and is larger than the fibula, with which it is paired (Figure \(\PageIndex{3}\) ). The tibia is the main weight-bearing bone of the lower leg and the second longest bone of the body, after the femur. The medial side of the tibia is located immediately under the skin, allowing it to be easily palpated down the entire length of the medial leg.
The proximal end of the tibia is greatly expanded. The two sides of this expansion form the medial condyle of the tibia and the lateral condyle of the tibia . The tibia does not have epicondyles. The top surface of each condyle is smooth and flattened. These areas articulate with the medial and lateral condyles of the femur to form the knee joint . Between the articulating surfaces of the tibial condyles is the intercondylar eminence , an irregular, elevated area that serves as the inferior attachment point for two supporting ligaments of the knee.
The tibial tuberosity is an elevated area on the anterior side of the tibia, near its proximal end. It is the final site of attachment for the muscle tendon associated with the patella. More inferiorly, the shaft of the tibia becomes triangular in shape.
The anterior apex of this triangle forms the anterior border of the tibia , which begins at the tibial tuberosity and runs inferiorly along the length of the tibia. Both the anterior border and the medial side of the triangular shaft are located immediately under the skin and can be easily palpated along the entire length of the tibia. A small ridge running down the lateral side of the tibial shaft is the interosseous border of the tibia . This is for the attachment of the interosseous membrane of the leg , the sheet of dense connective tissue that unites the tibia and fibula bones. Located on the posterior side of the tibia is the soleal line , a diagonally running, roughened ridge that begins below the base of the lateral condyle, and runs down and medially across the proximal third of the posterior tibia. Muscles of the posterior leg attach to this line.
The large expansion found on the medial side of the distal tibia is the medial malleolus (“little hammer”). This forms the large bony bump found on the medial side of the ankle region. Both the smooth surface on the inside of the medial malleolus and the smooth area at the distal end of the tibia articulate with the talus bone of the foot as part of the ankle joint. On the lateral side of the distal tibia is a wide groove called the fibular notch . This area articulates with the distal end of the fibula, forming the distal tibiofibular joint .
Fibula
The fibula is the slender bone located on the lateral side of the leg (see Figure \(\PageIndex{3}\) ). The fibula does not bear weight. It serves primarily for muscle attachments and thus is largely surrounded by muscles. Only the proximal and distal ends of the fibula can be palpated.
The head of the fibula is the small, knob-like, proximal end of the fibula. It articulates with the inferior aspect of the lateral tibial condyle, forming the proximal tibiofibular joint . The thin shaft of the fibula has the interosseous border of the fibula , a narrow ridge running down its medial side for the attachment of the interosseous membrane that spans the fibula and tibia. The distal end of the fibula forms the lateral malleolus , which forms the easily palpated bony bump on the lateral side of the ankle. The deep (medial) side of the lateral malleolus articulates with the talus bone of the foot as part of the ankle joint. The distal fibula also articulates with the fibular notch of the tibia.
Tarsal Bones
The posterior half of the foot is formed by seven tarsal bones (Figure \(\PageIndex{4}\) ). The most superior bone is the talus . This has a relatively square-shaped, upper surface that articulates with the tibia and fibula to form the ankle joint . Three areas of articulation form the ankle joint: The superomedial surface of the talus bone articulates with the medial malleolus of the tibia, the top of the talus articulates with the distal end of the tibia, and the lateral side of the talus articulates with the lateral malleolus of the fibula. Inferiorly, the talus articulates with the calcaneus (heel bone), the largest bone of the foot, which forms the heel. Body weight is transferred from the tibia to the talus to the calcaneus, which rests on the ground. The medial calcaneus has a prominent bony extension called the sustentaculum tali (“support for the talus”) that supports the medial side of the talus bone.
The cuboid bone articulates with the anterior end of the calcaneus bone. The cuboid has a deep groove running across its inferior surface, which provides passage for a muscle tendon. The talus bone articulates anteriorly with the navicular bone, which in turn articulates anteriorly with the three cuneiform (“wedge-shaped”) bones. These bones are the medial cuneiform , the intermediate cuneiform , and the lateral cuneiform . Each of these bones has a broad superior surface and a narrow inferior surface, which together produce the transverse (medial-lateral) curvature of the foot. The navicular and lateral cuneiform bones also articulate with the medial side of the cuboid bone.
Interactive Link
Use this tutorial to review the bones of the foot. Which tarsal bones are in the proximal, intermediate, and distal groups?
Metatarsal Bones
The anterior half of the foot is formed by the five metatarsal bones, which are located between the tarsal bones of the posterior foot and the phalanges of the toes (see Figure 8.19). These elongated bones are numbered 1–5, starting with the medial side of the foot. The first metatarsal bone is shorter and thicker than the others. The second metatarsal is the longest. The base of the metatarsal bone is the proximal end of each metatarsal bone. These articulate with the cuboid or cuneiform bones. The base of the fifth metatarsal has a large, lateral expansion that provides for muscle attachments. This expanded base of the fifth metatarsal can be felt as a bony bump at the midpoint along the lateral border of the foot. The expanded distal end of each metatarsal is the head of the metatarsal bone . Each metatarsal bone articulates with the proximal phalanx of a toe to form a metatarsophalangeal joint . The heads of the metatarsal bones also rest on the ground and form the ball (anterior end) of the foot.
Phalanges
The toes contain a total of 14 phalanx bones (phalanges), arranged in a similar manner as the phalanges of the fingers (see Figure 8.19). The toes are numbered 1–5, starting with the big toe ( hallux ). The big toe has two phalanx bones, the proximal and distal phalanges. The remaining toes all have proximal, middle, and distal phalanges. A joint between adjacent phalanx bones is called an interphalangeal joint.
Interactive Link
View this link to learn about a bunion, a localized swelling on the medial side of the foot, next to the first metatarsophalangeal joint, at the base of the big toe. What is a bunion and what type of shoe is most likely to cause this to develop?
Arches of the Foot
When the foot comes into contact with the ground during walking, running, or jumping activities, the impact of the body weight puts a tremendous amount of pressure and force on the foot. During running, the force applied to each foot as it contacts the ground can be up to 2.5 times your body weight. The bones, joints, ligaments, and muscles of the foot absorb this force, thus greatly reducing the amount of shock that is passed superiorly into the lower limb and body. The arches of the foot play an important role in this shock-absorbing ability. When weight is applied to the foot, these arches will flatten somewhat, thus absorbing energy. When the weight is removed, the arch rebounds, giving “spring” to the step. The arches also serve to distribute body weight side to side and to either end of the foot.
The foot has a transverse arch, a medial longitudinal arch, and a lateral longitudinal arch (see Figure 8.19). The transverse arch forms the medial-lateral curvature of the mid-foot. It is formed by the wedge shapes of the cuneiform bones and bases (proximal ends) of the first to fourth metatarsal bones. This arch helps to distribute body weight from side to side within the foot, thus allowing the foot to accommodate uneven terrain.
The longitudinal arches run down the length of the foot. The lateral longitudinal arch is relatively flat, whereas the medial longitudinal arch is larger (taller). The longitudinal arches are formed by the tarsal bones posteriorly and the metatarsal bones anteriorly. These arches are supported at either end, where they contact the ground. Posteriorly, this support is provided by the calcaneus bone and anteriorly by the heads (distal ends) of the metatarsal bones. The talus bone, which receives the weight of the body, is located at the top of the longitudinal arches. Body weight is then conveyed from the talus to the ground by the anterior and posterior ends of these arches. Strong ligaments unite the adjacent foot bones to prevent disruption of the arches during weight bearing. On the bottom of the foot, additional ligaments tie together the anterior and posterior ends of the arches. These ligaments have elasticity, which allows them to stretch somewhat during weight bearing, thus allowing the longitudinal arches to spread. The stretching of these ligaments stores energy within the foot, rather than passing these forces into the leg. Contraction of the foot muscles also plays an important role in this energy absorption. When the weight is removed, the elastic ligaments recoil and pull the ends of the arches closer together. This recovery of the arches releases the stored energy and improves the energy efficiency of walking.
Stretching of the ligaments that support the longitudinal arches can lead to pain. This can occur in overweight individuals, with people who have jobs that involve standing for long periods of time (such as a waitress), or walking or running long distances. If stretching of the ligaments is prolonged, excessive, or repeated, it can result in a gradual lengthening of the supporting ligaments, with subsequent depression or collapse of the longitudinal arches, particularly on the medial side of the foot. This condition is called pes planus (“flat foot” or “fallen arches”).


1.46: Experiences of a Caribbean immigrant- going beyond clinical care
At the end of this case, students will be able to:
- Discuss the roots of racism in the US and how systemic racism presents
- Distinguish between a health disparity and a difference in health status
- Discuss how systemic racism contributes to health disparities
Introduction
Racism is a multidimensional construct that infiltrates every aspect of life in the United States. 1 Its basic principles involve the subordination and discrimination of one racial group by another, with race used to determine superiority. The origins, history and evolution of the United States is rooted in racism, which presents as the favored group (white persons) acquiring and having access to more resources and power.
The United States is founded on a harsh and violent history, including the stealing of Native American land, followed by centuries of oppression of Africans through their labor on this stolen land. 2 These are only a few of the events which are the source of the debates surrounding the phrase “all men are created equal,” found within the US Declaration of Independence. Since its adoption in 1776, there has been much debate about the meaning of ‘all men.’ The simplest of arguments infer that this equality excludes women, African Americans, indigenous people, and other persons of color.  This oppression is still present today throughout all institutions and is considered the most complex form of racism, systemic racism. 1,2 This level of racism is evidenced by systems which favor the majority and dominant white culture. Persons belonging to the majority hold the power, and thus can create the regulations, policies and procedures governing all of society’s institutions, which are reflective of their beliefs and biases. Freedom and equality are not enjoyed by all, and despite hundreds of years of US evolution, this inequality for certain groups has remained.
One major example of systemic racism is depicted by the practice of redlining by mortgage lenders. Pursuant to the Great Depression, several federal policies were put in place in the 1930s in an attempt to ‘right’ the housing market by preventing foreclosures and assisting with housing for those who lost their homes. 3 The Home Owners Loan Corporation was created for this, controlling mortgage risk by implementing a system of property appraisals. Neighborhoods were graded on attributes such as area quality and population composition. As a result, neighborhoods with all forms of minority populations were graded lower than others, and these grades were used by financial institutions to determine loan eligibility. This led to the systematic denial of loans to persons of color. Despite the illegality of redlining today, it has majorly contributed to the long-term disenfranchisement of historically poorly graded neighborhoods.
Education is another sector of society where outcomes are significantly impacted by systemic racism. Persons of color experience many barriers that impede their success in their pursuit of education. From as early as kindergarten, Black students have a higher likelihood of suspension in comparison to white students. 4,5 This is thought to be because of the trend of suspicion of guilt (e.g., darker skin tone is associated with perceptions of evil) which Black persons face throughout all aspects of their lives. 6 On a more pervasive level, schools enrolled with mainly students of color are typically underfunded and have less resources. 7 Access to less resources also leads to students in these groups having to take on more debt when pursuing higher levels of education. All these barriers and more work together to result in lower graduation rates for students of color at all levels in comparison to white students.
The effects of systemic racism are also experienced in healthcare. One of these effects is the presentation of health disparities, which are more than differences in health status when comparing one group to another. A disparity is a direct result of a social disadvantage, with resulting differences in health status that could have been prevented, and therefore, are unjust. 8 For instance, lack of appropriate training of healthcare professionals fails to prepare them to adequately assess and manage occurrences of pain reported by Black patients. This leads to Black patients with similar conditions as white patients being less likely to receive pain medications. 9,10 Furthermore, common stereotypes still persist, such as Black patients having thicker skin and nerve endings, giving them higher pain thresholds. 11 Cultural competency training to promote life-long cultural humility is not mandatory for most healthcare professions programs. As a result, providers are not equipped or able to interact with patients belonging to under-represented groups in a culturally sensitive manner. This in turn leads to patients not trusting their healthcare professionals, which then leads to non-adherence to their respective therapy. 12,13
As one of the most trusted professions, pharmacists have a duty to include strategies while caring for patients which may help lessen the impact of systemic racism and the resulting health disparities. They should be part of the solution as opposed to contributing to the problem. Consider that lack of cultural competence, as well as implicit and explicit biases in providers, help perpetuate systemic racism. It is up to pharmacists to work together with other healthcare professionals to make experiences within the healthcare system for patients of color, in the very least, survivable.
Case
You are a clinical pharmacist working on an interdisciplinary healthcare team in an infectious disease clinic.
CC: “I’m here for a follow-up with my caseworker and to sort out my medication.”
Patient: JS is a 70-year-old female immigrant (65 in, 68 kg) from the Caribbean.
HPI: She contracted HIV from her (now deceased) husband of 45 years. According to JS, she was first diagnosed with HIV in her home country in her early thirties but only started antiretroviral therapy when she became a US resident. JS initially sought therapy for her condition when her husband became gravely ill one year prior to his death.
PMH: HIV; osteoarthritis; hypercholesterolemia
FH:
- Husband: (deceased, AIDS); T2DM, dyslipidemia
- Mother: (deceased, breast cancer); T1DM
- Father: alive; T2DM, arthritis, hypercholesterolemia
- Son: alive
- Daughter: alive; asthma
SH: No alcohol, tobacco, or illicit drug use
ROS: JS reports no major change since her last visit six months ago. The only complaint she has is that her joints are “extra stiff” now with the colder weather. She reports that she remembers to take her HIV medication as scheduled because she knows how important it is.
V itals:
- BP 110/70 mmHg
- HR 70 bpm
- RR 18/min
- Temp 97.9°F
Medications:
- Atorvastatin 10 mg once daily
- Dovato 1 tablet once daily
- Acetaminophen 650 mg every 4-6 hours PRN pain
Additional context: While catching up with JS, you learn that she is transferring herself out of the health system where you manage her. She mentions that she has finally found an HIV specialist who is from the same island that she is from. The new HIV specialist is farther from where she lives, but she is willing to commute the additional 45 minutes. JS states that she is only presenting to your clinic today to see the Caribbean case worker, and because she would like you to transfer her cholesterol medications to her new pharmacy.
You decide to have a deeper conversation with JS since this may be the last time you have the opportunity. At your clinic, patients with HIV usually have their follow-up visits scheduled for every two to three months. However, JS has been classified as a patient who is non-compliant with regards to clinic visits. This non-compliance has led to JS having challenges adhering to her antiretroviral therapy. Through your conversation with JS, you learn that she has always been uncomfortable accessing healthcare in your health system. Her mother, who died of breast cancer 10 years ago, visited one of the oncologists here. In her opinion, her mother’s pain and discomfort were never managed appropriately. According to JS, the oncologist rebuked her mother for seeking alternative means of pain management. She also watched as her mother agonized and begged for more pain relief in her final days. These pleas were largely ignored.
JS also shares that both of her daughters had pregnancies that were “touch and go.” She continues to tell you that for her eldest daughter’s first child, the OB-GYN was not very knowledgeable of and sensitive towards their cultural background. Their breakdown in communication led to many delivery complications, which almost resulted in her daughter’s death. As a result, her daughter sought out an OB-GYN from the Caribbean for her second pregnancy, which had a more favorable delivery. To end your conversation, JS remarks, “Besides most people here don’t look and sound like me.”
Case Questions
- What specific experiences did JS and her family have that contributed to them seeking only providers who shared their cultural background?
- JS’ daughter experienced complications during her first pregnancy that were near fatal. Which groups of women in the United States have the highest rates of maternal morbidity and mortality?
- How does systemic racism frame the experiences of this patient and her family?
- How has systemic racism contributed to the health disparities experienced by JS?
- How can pharmacists provide care to patients with a background like JS?
- Within the normal scope of transitioning care, what are some highlights worth mentioning to JS’ new HIV healthcare team?
- How can pharmacists help decrease the occurrence of systemic racism in our healthcare system?
Author Commentary
One of the most important takeaways about systemic racism is that it is pervasive throughout all institutions. For this type of racism to still be having an impact on certain groups of patients over so many centuries, means that it is actively being maintained and supported, most often by the complicity of those who benefit from it. For professionals within healthcare, we can simplify the definition of systemic racism by looking at its impact on our patients. It is important to acknowledge that there is a basic mechanism of action at play here, where one group has access to all levels of power, using their status as leverage and to disadvantage other groups with little to no power. Over time, the face of systemic racism may change but its goal of maintaining power and advantage over one group never does.
The presentation of health disparities, which affect specific patient groups, is only one of the adverse effects of systemic racism in healthcare. Pharmacists, along with other healthcare professionals, must act together to champion systemic change. Therefore, it is essential to recognize that systemic racism is a public health issue, acknowledge that healthcare disparities exist, and understand the role that implicit and explicit bias and cultural competence plays when being an advocate for patients.
Patient Approaches and Opportunities
Individuals who do not identify as a person of a color must become allies (someone who belongs to the majority but is willing to use their privilege and power to fight alongside persons belonging to the disadvantaged groups, and support actions of change). To achieve this, one of the first things that must occur is listening and realizing the truth in what you are being told. Even if one does not engage in individual racist acts, there are advantages and privileges throughout society and different institutions that they receive as a member of the majority.
Allyship has a place in patient interactions as well. Pharmacists can enact change by becoming an advocate. Trust is important for patients of color and a basic essential of any successful relationship (professional or personal). Accordingly, pharmacists should strive to become a long-term partner of their patients by gaining their trust and getting to know them on a holistic level. For instance, when considering the SDH/SDOH alone, one must acknowledge that there are many layers of factors at play when a patient pursues healthcare that may in turn affect their health outcomes. Understanding and being empathetic towards the different barriers a patient may be experiencing in their healthcare pursuit is likely one of the simplest actions that can be taken as a pharmacist to start effecting change in our healthcare system.
Related chapters of interest:
- Communicating health information: hidden barriers and practical approaches.
- Saying what you mean doesn’t always mean what you say: cross-cultural communication
- Plant now, harvest later: services for rural underserved patients
- More than just diet and exercise: social determinants of health and well-being
- You say medication, I say meditation: effectively caring for diverse populations
- Equity for all: providing accessible healthcare for patients living with disabilities
- Expanding the pharmacists’ role: assessing mental health and suicide
- The great undoing: a multigenerational journey from systemic racism to social determinants of health
External resources:
-
Websites:
- Harvard University. Project Implicit. h ttps://implicit.harvard.edu/implicit/takeatest.html
- Transcultural C.A.R.E. Associates. Transcultural care. http://transculturalcare.net/
- African American Wellness Project. https://aawellnessproject.org/
- Coates T. The Atlantic. The case for reparations. https://www.theatlantic.com/magazine/archive/2014/06/the-case-for-reparations/361631/
- Agency for Healthcare Research and Quality. Resources for addressing disparities and improving quality. https://nhqrnet.ahrq.gov/inhqrdr/resources/info
-
Videos:
- Race Forward. What is systemic racism? https://www.raceforward.org/videos/systemic-racism
- Vox. Glad you asked, season 2. Series of five videos. https://www.youtube.com/playlist?list=PLJ8cMiYb3G5cOFj1VQf8ykNOI0ptuHybc
- Jones LA. Get comfortable with being uncomfortable. https://www.youtube.com/watch?v=QijH4UAqGD8&t=184s
- PBS. Health disparities. https://www.pbs.org/video/stay-tuned-health-disparities/
References
- Tourse RW, Hamilton-Mason J, Wewiorski NJ. Systemic racism in the United States. Cham, Switzerland: Springer International, 2018.
- Feagin J. Systemic racism: a theory of oppression. Routledge, 2013.
- An B, Orlando AW, Rodnyansky S. The physical legacy of racism: How redlining cemented the modern built environment. 2019. https://ssrn.com/abstract=3500612 or http://dx.doi.org/10.2139/ssrn.3500612 .
- Sullivan, A. L., Klingbeil, D. A., & Van Norman, E. R. (2013). Beyond behavior: Multilevel analysis of the influence of sociodemographics and school characteristics on students’ risk of suspension. School Psychology Review , 42(1), 99-114.
- Racial, Ethnic, and Gender Differences in School Discipline among U.S. High School Students: 1991-2005
- Alter AL, Stern C, Granot Y, Balcetis E. The “bad is black” effect: Why people believe evildoers have darker skin than do-gooders. Pers Soc Psychol Bull 2016;42(12):1653-65.
- Darling-Hammond L. The color line in American education: race, resources, and student achievement. Du Bois Review 2004;1(2):213.
- Adler NE, Rehkopf DH. US disparities in health: descriptions, causes, and mechanisms. Annu Rev Public Health 2008;29:23552.
- Sabin JA, Greenwald AG. The influence of implicit bias on treatment recommendations for 4 common pediatric conditions: pain, urinary tract infection, attention deficit hyperactivity disorder, and asthma. Am J Public Health 2012;102(5):988-95.
- Green AR, Carney DR, Pallin DJ, Ngo LH, Raymond KL, Iezzoni LI, Banaji MR. Implicit bias among physicians and its prediction of thrombolysis decisions for black and white patients. J Gen Intern Med 2007;22(9):1231-1238.
- Aronowitz SV, McDonald CC, Stevens RC, Richmond TS. Mixed studies review of factors influencing receipt of pain treatment by injured black patients. J Adv Nurs 2020;76(1):34-46.
- Hall MB, Carter-Francique AR, Lloyd SM, Eden TM, Zuniga AV, Guidry JJ, Jones LA. Bias within: Examining the role of cultural competence perceptions in mammography adherence. Sage Open 2015;5(1):2158244015576547.
- Gaston GB. African-Americans’ perceptions of health care provider cultural competence that promote HIV medical self-care and antiretroviral medication adherence. AIDS Care 2013;25(9):1159-65.


2: Developing the Theory
Continental drift was hotly debated off and on for decades following Wegener's death before it was largely dismissed as being eccentric, preposterous, and improbable. However, beginning in the 1950s, a wealth of new evidence emerged to revive the debate about Wegener's provocative ideas and their implications. In particular, four major scientific developments spurred the formulation of the plate-tectonics theory: (1) demonstration of the ruggedness and youth of the ocean floor; (2) confirmation of repeated reversals of the Earth magnetic field in the geologic past; (3) emergence of the seafloor-spreading hypothesis and associated recycling of oceanic crust; and (4) precise documentation that the world's earthquake and volcanic activity is concentrated along oceanic trenches and submarine mountain ranges.
Ocean floor mapping
About two thirds of the Earth's surface lies beneath the oceans. Before the 19th century, the depths of the open ocean were largely a matter of speculation, and most people thought that the ocean floor was relatively flat and featureless. However, as early as the 16th century, a few intrepid navigators, by taking soundings with hand lines, found that the open ocean can differ considerably in depth, showing that the ocean floor was not as flat as generally believed. Oceanic exploration during the next centuries dramatically improved our knowledge of the ocean floor. We now know that most of the geologic processes occurring on land are linked, directly or indirectly, to the dynamics of the ocean floor.
"Modern" measurements of ocean depths greatly increased in the 19th century, when deep-sea line soundings (
bathymetric
surveys) were routinely made in the Atlantic and Caribbean. In 1855, a bathymetric chart published by U.S. Navy Lieutenant Matthew Maury revealed the first evidence of underwater mountains in the central Atlantic (which he called "Middle Ground"). This was later confirmed by survey ships laying the trans-Atlantic telegraph cable. Our picture of the ocean floor greatly sharpened after World War I (1914-18), when echo-sounding devices -- primitive sonar systems -- began to measure ocean depth by recording the time it took for a sound signal (commonly an electrically generated "ping") from the ship to bounce off the ocean floor and return. Time graphs of the returned signals revealed that the ocean floor was much more rugged than previously thought. Such echo-sounding measurements clearly demonstrated the continuity and roughness of the submarine mountain chain in the central Atlantic (later called the
Mid-Atlantic Ridge
) suggested by the earlier bathymetric measurements.
The mid-ocean ridge (shown in red) winds its way between the continents much like the seam on a baseball.
In 1947, seismologists on the U.S. research ship Atlantis found that the sediment layer on the floor of the Atlantic was much thinner than originally thought. Scientists had previously believed that the oceans have existed for at least 4 billion years, so therefore the sediment layer should have been very thick. Why then was there so little accumulation of sedimentary rock and debris on the ocean floor? The answer to this question, which came after further exploration, would prove to be vital to advancing the concept of plate tectonics.
Computer-generated detailed topographic map of a segment of the Mid-Oceanic Ridge. "Warm" colors (yellow to red) indicate the ridge rising above the seafloor, and the "cool" colors (green to blue) represent lower elevations. This image (at latitude 9° north) is of a small part of the East Pacific Rise. (Imagery courtesy of Stacey Tighe, University of Rhode Island.)
In the 1950s, oceanic exploration greatly expanded. Data gathered by oceanographic surveys conducted by many nations led to the discovery that a great mountain range on the ocean floor virtually encircled the Earth. Called the global mid-ocean ridge, this immense submarine mountain chain -- more than 50,000 kilometers (km) long and, in places, more than 800 km across -- zig-zags between the continents, winding its way around the globe like the seam on a baseball. Rising an average of about 4,500 meters(m) above the sea floor, the mid-ocean ridge overshadows all the mountains in the United States except for Mount McKinley (Denali) in Alaska (6,194 m). Though hidden beneath the ocean surface, the global mid-ocean ridge system is the most prominent topographic feature on the surface of our planet.
Magnetic striping and polar reversals
Beginning in the 1950s, scientists, using magnetic instruments (magnetometers) adapted from airborne devices developed during World War II to detect submarines, began recognizing odd magnetic variations across the ocean floor. This finding, though unexpected, was not entirely surprising because it was known that basalt - - the iron-rich, volcanic rock making up the ocean floor-- contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. This distortion was recognized by Icelandic mariners as early as the late 18th century. More important, because the presence of magnetite gives the basalt measurable magnetic properties, these newly discovered magnetic variations provided another means to study the deep ocean floor.
A theoretical model of the formation of magnetic striping. New oceanic crust forming continuously at the crest of the mid-ocean ridge cools and becomes increasingly older as it moves away from the ridge crest with seafloor spreading (see text): a. the spreading ridge about 5 million years ago; b. about 2 to 3 million years ago; and c. present-day.
Early in the 20th century,
paleomagnetists
(those who study the Earth's ancient magnetic field) -- such as Bernard Brunhes in France (in 1906) and Motonari Matuyama in Japan (in the 1920s) -- recognized that rocks generally belong to two groups according to their magnetic properties. One group has so-called
normal polarity,
characterized by the magnetic minerals in the rock having the same polarity as that of the Earth's present magnetic field. This would result in the north end of the rock's "compass needle" pointing toward magnetic north. The other group, however, has
reversed polarity,
indicated by a polarity alignment opposite to that of the Earth's present magnetic field. In this case, the north end of the rock's compass needle would point south. How could this be? This answer lies in the magnetite in volcanic rock. Grains of magnetite -- behaving like little magnets -- can align themselves with the orientation of the Earth's magnetic field. When
magma
(molten rock containing minerals and gases) cools to form solid volcanic rock, the alignment of the magnetite grains is "locked in," recording the Earth's magnetic orientation or polarity (normal or reversed) at the time of cooling.
The center part of the figure -- representing the deep ocean floor with the sea magically removed -- shows the magnetic striping (see text) mapped by oceanographic surveys offshore of the Pacific Northwest. Thin black lines show transform faults (discussed later) that offset the striping.
As more and more of the seafloor was mapped during the 1950s, the magnetic variations turned out not to be random or isolated occurrences, but instead revealed recognizable patterns. When these magnetic patterns were mapped over a wide region, the ocean floor showed a zebra-like pattern. Alternating stripes of magnetically different rock were laid out in rows on either side of the mid-ocean ridge: one stripe with normal polarity and the adjoining stripe with reversed polarity. The overall pattern, defined by these alternating bands of normally and reversely polarized rock, became known as magnetic striping.
Seafloor spreading and recycling of oceanic crust
The discovery of magnetic striping naturally prompted more questions: How does the magnetic striping pattern form? And why are the stripes symmetrical around the crests of the mid-ocean ridges? These questions could not be answered without also knowing the significance of these ridges. In 1961, scientists began to theorize that mid-ocean ridges mark structurally weak zones where the ocean floor was being ripped in two lengthwise along the ridge crest. New magma from deep within the Earth rises easily through these weak zones and eventually erupts along the crest of the ridges to create new oceanic crust. This process, later called
seafloor spreading,
operating over many millions of years has built the 50,000 km-long system of mid-ocean ridges. This hypothesis was supported by several lines of evidence: (1) at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; (2) the youngest rocks at the ridge crest always have present-day (normal) polarity; and (3) stripes of rock parallel to the ridge crest alternated in magnetic polarity (normal-reversed-normal, etc.), suggesting that the Earth's magnetic field has flip-flopped many times. By explaining both the zebralike magnetic striping and the construction of the mid-ocean ridge system, the seafloor spreading hypothesis quickly gained converts and represented another major advance in the development of the plate-tectonics theory. Furthermore, the oceanic crust now came to be appreciated as a natural "tape recording" of the history of the reversals in the Earth's magnetic field.
Additional evidence of seafloor spreading came from an unexpected source: petroleum exploration. In the years following World War II, continental oil reserves were being depleted rapidly and the search for offshore oil was on. To conduct offshore exploration, oil companies built ships equipped with a special drilling rig and the capacity to carry many kilometers of drill pipe. This basic idea later was adapted in constructing a research vessel, named the
Glomar Challenger,
designed specifically for marine geology studies, including the collection of drill-core samples from the deep ocean floor. In 1968, the vessel embarked on a year-long scientific expedition, criss-crossing the Mid-Atlantic Ridge between South America and Africa and drilling core samples at specific locations. When the ages of the samples were determined by paleontologic and isotopic dating studies, they provided the clinching evidence that proved the seafloor spreading hypothesis.
Above:
The
Glomar Challenger
was the first research vessel specifically designed in the late 1960s for the purpose of drilling into and taking core samples from the deep ocean floor.
Below:
The
JOIDES Resolution
is the deep-sea drilling ship of the 1990s (
JOIDES
= Joint Oceanographic Institutions for Deep Earth Sampling). This ship, which carries more than 9,000 m of drill pipe, is capable of more precise positioning and deeper drilling than the
Glomar Challenger.
(Photographs courtesy of Ocean Drilling Program, Texas A & M University.)
A profound consequence of seafloor spreading is that new crust was, and is now, being continually created along the oceanic ridges. This idea found great favor with some scientists who claimed that the shifting of the continents can be simply explained by a large increase in size of the Earth since its formation. However, this so-called "expanding Earth" hypothesis was unsatisfactory because its supporters could offer no convincing geologic mechanism to produce such a huge, sudden expansion. Most geologists believe that the Earth has changed little, if at all, in size since its formation 4.6 billion years ago, raising a key question: how can new crust be continuously added along the oceanic ridges without increasing the size of the Earth?
This question particularly intrigued Harry H. Hess, a Princeton University geologist and a Naval Reserve Rear Admiral, and Robert S. Dietz, a scientist with the U.S. Coast and Geodetic Survey who first coined the term
seafloor spreading.
Dietz and Hess were among the small handful who really understood the broad implications of sea floor spreading. If the Earth's crust was expanding along the oceanic ridges, Hess reasoned, it must be shrinking elsewhere. He suggested that new oceanic crust continuously spread away from the ridges in a conveyor belt-like motion. Many millions of years later, the oceanic crust eventually descends into the oceanic
trenches
-- very deep, narrow canyons along the rim of the Pacific Ocean basin. According to Hess, the Atlantic Ocean was expanding while the Pacific Ocean was shrinking. As old oceanic crust was consumed in the trenches, new magma rose and erupted along the spreading ridges to form new crust. In effect, the ocean basins were perpetually being "recycled," with the creation of new crust and the destruction of old oceanic lithosphere occurring simultaneously. Thus, Hess' ideas neatly explained why the Earth does not get bigger with sea floor spreading, why there is so little sediment accumulation on the ocean floor, and why oceanic rocks are much younger than continental rocks.
Concentration of earthquakes
During the 20th century, improvements in seismic instrumentation and greater use of earthquake-recording instruments (seismographs) worldwide enabled scientists to learn that earthquakes tend to be concentrated in certain areas, most notably along the oceanic trenches and spreading ridges. By the late 1920s, seismologists were beginning to identify several prominent earthquake zones parallel to the trenches that typically were inclined 40-60° from the horizontal and extended several hundred kilometers into the Earth. These zones later became known as Wadati-Benioff zones, or simply Benioff zones, in honor of the seismologists who first recognized them, Kiyoo Wadati of Japan and Hugo Benioff of the United States. The study of global seismicity greatly advanced in the 1960s with the establishment of the Worldwide Standardized Seismograph Network (WWSSN) to monitor the compliance of the 1963 treaty banning above-ground testing of nuclear weapons. The much-improved data from the WWSSN instruments allowed seismologists to map precisely the zones of earthquake concentration worldwide.
As early as the 1920s, scientists noted that earthquakes are concentrated in very specific narrow zones (see text). In 1954, French seismologist J.P. Rothé published this map showing the concentration of earthquakes along the zones indicated by dots and cross-hatched areas. (Original illustration reproduced with permission of the Royal Society of London.)
But what was the significance of the connection between earthquakes and oceanic trenches and ridges? The recognition of such a connection helped confirm the seafloor-spreading hypothesis by pin-pointing the zones where Hess had predicted oceanic crust is being generated (along the ridges) and the zones where oceanic lithosphere sinks back into the mantle (beneath the trenches).
Contributors and Attributions
W. Jacquelyne Kious and Robert Tilling (" The Dynamic Earth " via the U.S. Geological Survey )