University of Duhok

College of Engineering
Biomedical Department – 3rd stage
Biomechanics

Biomechanics of Head and Neck

Prepared by Supervisor
Man Sabah Yaseen Dr. Rayan Basheer

(2023 – 2024)
 Table of Contents
Introduction 3
Anatomy of Head and Neck 4
Biomechanical Considerations 5
Head to Neck Lever 8
The Effects of Head Weight on The Body and Neck 10
How to Reduce Effects on The Neck and Body? 12
Conclusion 13
References 14

Introduction

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 The biomechanics of the head and neck is the study of how the various
structures and tissues in this region function under mechanical forces. It
involves understanding the anatomy and motion of the head and neck, as well
as how external forces and internal muscle actions affect these areas. This
field has applications in injury analysis, clinical medicine, the design of
prosthetic devices, ergonomics, and sports performance. By studying the
biomechanics of the head and neck, we can improve our understanding of how
these structures work and develop strategies to enhance safety, healthcare, and
overall well-being.

Biomechanics of the head and neck involves various sub-disciplines, such as

kinematics (study of motion), kinetics (study of forces), and computational
modeling. Research in this field is crucial for advancing our understanding of
the human body, developing medical technologies, and improving the overall
health and well-being of individuals. Moreover, as the field continues to
evolve, it holds the potential to offer innovative solutions for a wide range of
clinical and non-clinical challenges related to the head and neck region.

As we embark on this exploration, we will unravel the complexities of the

head and neck's biomechanics, shedding light on its role in our daily lives,
clinical applications, and the ever-evolving frontiers of research. By the end of
this report, you will gain a deeper appreciation for the pivotal role that
biomechanics plays in shaping our understanding of this crucial anatomical
region and its broader impact on healthcare, technology, and human well-
being.

Anatomy of Head and Neck

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 The anatomy of the head and neck is a complex and diverse region of the
human body that includes various structures, each with specific functions. I'll
provide an overview of the major components of the head and neck anatomy:

1) Skull: The skull is the bony structure that encases the brain and supports
the face. It consists of two main parts.
2) Brain: The brain is the central organ of the nervous system and is located
within the cranial cavity.
3) Scalp: The scalp is the soft tissue covering the top of the head and is
composed of skin, connective tissue, and muscles.
4) Face: The face contains various structures, including: Eyes, Nose, Mouth
and Ears
5) Neck: The neck connects the head to the rest of the body and contains
several important structures: Throat, Blood Vessels and Muscles

Biomechanical Considerations

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 Biomechanical principles in the head and neck consider factors such as:
1) Movement
2) Muscle force.
3) Joint stability
4) Load distribution

1) Movement: All movements of the neck are combinations or varying

percentages of these essential movements. They are:

 Flexion: is the movement that allows you to bend your head toward your
chest. In normal flexion, you can touch your chin to your chest.

 Extension: Is the movement you make when tilting your head back. In
normal extension, a person can tilt their head back to look at the ceiling.

 Left and Right Lateral Rotation: Lateral rotation is the motion you
make when you turn your head to either side. Your chin stays parallel to
the floor. In normal rotation, your chin will hover over your shoulders.

 Left and Right Lateral Flexion: Lateral Flexion is best described by

bending your neck so that your ear leans toward your shoulders. In normal
lateral flexion, you should be able to bend your neck about 45 degrees.

Biomechanical Considerations

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 2) Muscle Force: Muscle force is the mechanical power generated by muscles
when they contract. It's responsible for all forms of movement in the body,
from simple actions like bending an arm to complex activities like running.
Muscles contract, develop tension, and produce force, enabling us to perform
everyday activities and maintain posture. Understanding muscle force is vital
in fields like biomechanics, sports, rehabilitation, and prosthetics, contributing
to improved health, performance, and technology.

3) Joint Stability: Joint stability refers to the ability of a joint to stay in its
proper position and function effectively during movement. It depends on the
interplay of ligaments, muscles, and proprioception (body awareness). Joint
stability is crucial for preventing injuries, rehabilitation after injuries, athletic
performance, and maintaining good posture. Adequate joint stability ensures
the joint is less susceptible to damage, dislocation, or sprains. It's a key factor
in both injury prevention and recovery.

Biomechanical Considerations
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4) Load Distribution: Load distribution in the neck is a crucial aspect of
biomechanics that helps us understand how various forces are distributed d
and facilitates a wide range of movements. The neck experiences various
dynamic and static loads due to its crucial role in supporting the head and
facilitating a wide range of movements. This is how dynamic and static loads
affect the neck:

 Dynamic Loads:
 Muscle Activation: Dynamic loads are primarily associated with muscle
activity. When we move our head or neck, muscles contract to generate
the required force. For example, when turning the head to look in a
different direction, neck muscles must exert dynamic forces to produce
this movement.
 External Forces: External factors, such as carrying heavy objects or
participating in sports activities, subject the neck to dynamic loads. These
loads vary in intensity and direction based on the specific activity or
movement being performed.
 Impact and Accidents: Traumatic events, like car accidents or falls, can
expose the neck to sudden and often extreme dynamic loads. This can
result in forces that lead to injuries, such as whiplash, which affects the
neck's soft tissues and joints.

 Static Loads:
 Gravity: The weight of the head exerts a constant static load on the neck.
The neck's muscles, ligaments, and vertebrae must continually work to
counteract the gravitational force, which can vary from person to person
depending on the size and weight of the head.
 Sustained Postures: Maintaining prolonged static positions, such as
sitting at a desk with poor posture or cradling a phone between the
shoulder and ear, creates static loads on the neck. Over time, these loads
can lead to muscle fatigue and discomfort.
 Sleeping Position: Sleeping positions can also contribute to static loads
on the neck. Poor pillow support or sleeping in awkward positions may
lead to neck pain and stiffness.

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Head to Neck Lever

A lever system in the context of the head and neck refers to the mechanical
principles that govern head movements and stability, taking into account
the arrangement of bones, joints, and muscles. Specifically, the head can
be considered a load, the neck acts as a lever arm, and various muscles and
joints are involved in generating and controlling movements.
The connection between the head and the cervical spine is a class one lever
system. The class one lever is stable, but not very flexible. The additional
flexibility needed for the head is provided by the cervical spine.

Head to head lever consists of:

 Load (Head): The head is considered the load in this lever system. It
has weight and is positioned at the end of the lever (the neck) that is
moved.
 Lever Arm (Neck): The neck serves as the lever arm in this system.
The cervical spine, which consists of seven cervical vertebrae, is the
rigid structure that connects the head to the rest of the body. These
vertebrae are interconnected by joints and surrounded by muscles and
ligaments.

 Fulcrum (Pivot Point): The fulcrum, or pivot point, in this head-to-

neck lever system is primarily formed by the joints in the cervical
spine.

 Applied Force (Muscles): The muscles of the neck, including the

sternocleidomastoid, trapezius, and others, provide the force necessary
to move and stabilize the head. These muscles contract and relax to
control head movements and maintain stability.

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Head to Neck Lever

In this lever system, the muscles apply force to the lever arm (the neck) to
move the load (the head) around the fulcrum (the joints in the cervical
spine). The balance between these forces and the lever arm's structure
allows for a wide range of head movements, including nodding, turning,
tilting, and maintaining an upright posture.
The head-to-neck lever system is essential for everyday activities such as
looking around, maintaining eye contact, and holding the head in an
upright position. It underscores the biomechanical principles that govern
the complex interactions within the neck and head region.

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The Effects of Head Weight on The Body and Neck

The weight of the head can have significant effects on both the neck and the
rest of the bod. The head, on average, weighs about 10-12 pounds (4.5-5.4
kilograms), making it one of the heaviest parts of the body. Especially when
considering factors like posture, Such as:

1) Neck Effects:

Muscle Strain: The head, on average, weighs about 10-12 pounds (4.5-5.4
kilograms). Proper posture ensures the weight is evenly distributed at the top
of the spine. The neck muscles, particularly those in the cervical region, are
responsible for supporting this weight. When the head is not properly
aligned with the spine (as in poor posture), it can lead to increased muscle
strain as the neck muscles work harder to hold the head up. Over time, this
can cause discomfort and tension in the neck.

Cervical Spine Alignment: The weight of the head influences the

alignment of the cervical spine. Proper alignment is crucial to maintain the
spine's natural curvature, which allows it to function optimally in supporting
the head and facilitating movements. Incorrect alignment, due to the head's
weight or poor posture, can lead to issues like forward head posture
(commonly referred to as "text neck") and increased stress on the cervical
spine.

Risk of Neck Pain and Injury: Prolonged periods of poor posture or

excessive strain on the neck muscles can result in chronic neck pain and
discomfort. In more severe cases, it can lead to conditions like cervical
spondylosis or herniated discs, affecting the cervical spine's overall health.

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The Effects of Head Weight on The Body and Neck

2) Body Effects:

Postural Changes: The weight of the head plays a significant role in overall
body posture. When the head is properly aligned with the spine, the rest of the
body tends to follow suit with good posture. However, if the head is held
forward or in an imbalanced position, it can lead to postural issues in the
shoulders, upper back, and even the lower back, affecting overall body
posture.

Muscle Imbalances: The body will naturally adjust to accommodate the

head's weight in different postures. For example, poor posture can lead to
muscle imbalances in the shoulders and upper back as these muscles work
harder to compensate for the forward head position. This can result in pain,
tension, and decreased mobility.

Breathing and Circulation: The head's position can impact the ability of the
ribcage to expand fully during breathing. Forward head posture can restrict
lung capacity, potentially affecting respiratory function and oxygen intake.
Circulation, including blood flow to the brain, can also be influenced by
posture and head position.

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How to Reduce Effects on The Neck and Body?

Reducing the effects of the head's weight on the neck and body is crucial for
preventing discomfort, strain, and potential long-term health issues. Here are
several wats o help alleviate the stress caused by the weight of the head:

1) Improve Posture: Maintaining proper posture is essential for minimizing

the strain on the neck and spine. When you have good posture, the head
is balanced directly over the spine, reducing the forces that can lead to
neck pain and discomfort.

2) Ergonomic Workspace: Ensure your workspace is ergonomically

designed. This includes setting up your computer, chair, and desk to
support an upright, comfortable posture. Adjust your monitor to eye
level, use an ergonomic chair, and position your keyboard and mouse
properly.

3) Regular Exercise: Engage in regular physical activity to strengthen the

muscles in your neck and shoulders. Exercise can improve overall
posture and reduce the strain on your neck.

4) Frequent Breaks: Take regular breaks from activities that require you to
keep your head in one position for an extended period. For example, if
you work at a computer, take short breaks to stretch and change your
head and neck position.

5) Proper Pillow and Mattress: Choose a supportive pillow and mattress

that maintain the natural alignment of your spine, especially when
sleeping. This can reduce strain on the neck and back.

6) Manage Heavy Loads: When lifting heavy objects, use proper lifting
techniques. Bend your knees, keep the load close to your body, and use
your leg muscles to lift, reducing strain on your neck and back.

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Conclusion

In conclusion, the biomechanics of the head and neck play a fundamental role
in understanding the complex interplay of forces and structures in this vital
anatomical region. The head and neck house the brain, support sensory
organs, and facilitate crucial functions like communication and swallowing. A
thorough understanding of their biomechanics is essential for a range of
applications, including injury prevention, diagnostics, medical treatment, and
the design of protective equipment.
The head and neck are characterized by a delicate balance between structural
stability and a wide range of motion. Joints, muscles, and ligaments work in
harmony to support and facilitate movements such as nodding, turning, and
tilting. Various forces, including gravity, muscle contractions, and external
impacts, exert pressure on the neck and head. Understanding how these forces
are distributed is critical for predicting injury risks and developing protective
measures.
Biomechanics helps explain how injuries occur in this region, from whiplash
in car accidents to sports-related head and neck trauma. This knowledge is
essential for injury prevention and treatment strategies.
Biomechanics of the head and neck have broad applications in fields such as
sports medicine, automotive safety, and medical diagnostics. It informs the
development of safety equipment, customized treatment plans, and prosthetic
devices. The field of head and neck biomechanics continues to evolve, with
ongoing research in computational modeling, injury prevention, and
personalized medicine, offering promising directions for improving the
understanding and management of this intricate region.

In summary, the biomechanics of the head and neck are not only crucial for
safeguarding this vital part of the body but also hold the potential to enhance
our overall well-being through advancements in safety, medical treatments,
and injury prevention strategies. Understanding the biomechanical intricacies
of the head and neck is a cornerstone in the pursuit of health and safety.

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 .

References

 https://www.semanticscholar.org/paper/Differences-in-neck-surface-
electromyography%2C-and-A-Lascurain-Aguirrebe%C3%B1a-Newham/
6e6f91e095ebceed59d77f99b7bc5f9e8602c4c1

 https://thespineexperts.brain-spine.com/2019/08/05/six-movements-of-the-
neck/

 https://waergo.com/JES/BodyBasics.htm

 http://resource.download.wjec.co.uk.s3.amazonaws.com/vtc/2015-16/15-
16_21/eng/section3.html .

 https://www.beechborophysiotherapy.com.au/what-the-heck-is-text-neck/

 https://pettibonsystem.com/blog/deep-dive-into-forward-head-posture/

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