Neck Muscles of The Human Body
This article takes a detailed look at the various muscles that make up the human neck. Although often overlooked, these muscles play a critical role in supporting the head, facilitating movement, and carrying out various physiological functions.
We will examine each neck muscle, including its origin and insertion points, to understand their structural placement and potential leverage points. Furthermore, we will explore how each muscle works individually to contribute to neck movements and stability, as well as how they work together to perform complex movements and maintain posture. Additionally, we will discuss the neural networks that control and coordinate these muscles. This article aims to provide valuable insights for medical professionals, fitness enthusiasts, and anyone interested in understanding the dynamic and nuanced workings of the neck muscles, highlighting their importance in the context of overall bodily function and health.
Defining Terms
Origin – The fixed attachment point of a muscle. This is typically the end of the muscle that attaches to the more stationary bone in a pair of bones being moved by that muscle. The origin is generally proximal, meaning closer to the center of the body, or on the more stable part of the skeletal structure.
Insertion – The insertion point of a muscle is where it attaches to the bone and is the part that moves during muscle contraction. This part of the muscle is usually located far from the center of the body, and moves towards the muscle’s origin when it contracts. Understanding the insertion point is important in determining a muscle’s function in movement and leverage, as it influences the direction and force of the movement produced by the muscle contraction.
Isolated Function – The term “isolated function” refers to the specific action a muscle performs when it contracts independently, without the influence of other muscles. Understanding this concept is crucial for comprehending the primary role of each muscle in movement, as it highlights the muscle’s unique ability to produce a particular movement at a joint. The study of isolated functions is often used to understand muscle imbalances, rehabilitation needs, and design targeted exercises for strengthening or stretching a specific muscle.
Integrated Function – The coordinated action of muscles is crucial during complex movements and requires them to work in concert with other muscles and body systems. Isolated function, which focuses on a muscle acting alone, is not enough to fully understand bodily movements. Integrated function, on the other hand, emphasizes how muscles function together in groups, providing a more holistic view of bodily movements. This concept is essential to comprehend how muscles contribute to overall body mechanics, stability, and efficiency during everyday activities and sports.
Innervation – the supply of nerves to a muscle, which enables the muscle to receive and respond to neural signals. This connection is crucial for muscle activation and control, as it allows the nervous system to regulate muscle contractions, both voluntary and involuntary. Innervation is a key aspect in understanding how muscles function, their responsiveness to stimuli, and their role in movement and sensation.
Concentric – refers to a type of muscle contraction in which the muscle fibers shorten as they contract. This occurs when a muscle generates enough force to overcome resistance, resulting in the movement of body parts towards each other. A common example of a concentric contraction is the upward movement during a bicep curl, where the bicep muscle shortens to lift the weight. Concentric contractions are integral to many types of physical activities and exercises, playing a key role in building muscle strength and movement.
Eccentric – refers to a type of muscle contraction where the muscle lengthens while under tension. This occurs when a muscle gradually controls or resists the movement caused by an external force, like gravity. Eccentric contractions are often associated with controlled lowering or decelerating actions, such as lowering a weight during a bicep curl or descending stairs. They play a crucial role in activities requiring controlled movements and are significant in muscle strengthening and injury prevention.
Isometric – refers to a type of muscle contraction where the muscle generates force without changing its length. During isometric exercises, the muscle neither shortens (as in concentric contractions) nor lengthens (as in eccentric contractions), but tension is still produced. Common examples include holding a plank position or maintaining a squat. Isometric contractions are essential for stabilizing joints and maintaining posture, and they are often used in rehabilitation and strength training programs.
Levator Scapulae
Origin
Transverse processes of C1-C4
Insertion
Superior vertebral border of the scapula
Isolated Function
Concentric action – Cervical extension, lateral flexion and ipsilateral rotation when the scapula is anchored and assists in elevation and downward rotation of the scapula
Integrated Function
Eccentric action – Cervical flexion, contralateral cervical rotation, lateral flexion, scapular depression and upward rotation when the neck is stabilized
Isometric action – Stabilizes the cervical spine and scapula
Innervation
Ventral rami C3-C4 and dorsal scapular nerve
Sternocleidomastoid
Origin
Sternal head – Top of manubrium of the sternum
Clavicular head – Medial one-third of the clavicle
Insertion
Mastoid process and lateral superior nuchal line of the occiput of the skull
Isolated Function
Concentric action – Cervical flexion, rotation, and lateral flexion
Integrated Function
Eccentric action – Cervical extension, rotation and lateral flexion
Isometric action – Stabilizes the cervical spine and acromioclavicular joint
Innervation
Cranial nerve Xl
Scalenes
Origin
Transverse processes of C3-C7
Insertion
First and second ribs
Isolated Function
Concentric action – Cervical flexion, rotation and lateral flexion and assists rib elevation during inhalation
Integrated Function
Eccentric action – Cervical extension, rotation and lateral flexion
Isometric action – Stabilizes the cervical spine
Innervation
Ventral rami (C3-C7)
Longus Colli
Origin
Anterior portion of T1-T3
Insertion
Anterior and lateral C1
Isolated Function
Concentric action – Cervical flexion, lateral flexion and ipsilateral rotation
Integrated Function
Eccentric action – Cervical extension, lateral flexion and contralateral rotation
Isometric action – Stabilizes the cervical spine
Innervation
Ventral rami (C2-C8)
Longus Capitis
Origin
Transverse processes of (C3-C6)
Insertion
Inferior occipital bone
Isolated Function
Concentric action – Cervical flexion and lateral flexion
Integrated Function
Eccentric action – Cervical extension
Isometric action – Stabilizes the cervical spine
Innervation
Ventral rami (C1-C3)
Conclusion
In concluding our exploration of the neck muscles, we have unraveled the complexities and vital functions of this often-underappreciated region of the human body. Through our thorough investigation of each muscle, including their origins, insertions, and both isolated and integrated functions, we have gained a deeper understanding of how these structures contribute to head support, movement, and posture. The study of their innervation has provided insight into the sophisticated neural mechanisms that govern and fine-tune the neck’s movements and stability.
This comprehensive analysis is invaluable for anyone seeking to understand the intricate anatomy of the neck, from medical and fitness professionals to individuals aiming to improve their neck health and function. As we conclude, it becomes clear that the neck muscles, with their complex interplay and essential roles, are integral to our daily lives, enabling a wide range of motions and playing a key role in our overall well-being and physical capabilities.
References
National Academy of Sports Medicine. NASM Essentials of Personal Training. Jones and Bartlett Publishers; 7th edition (Jan. 4, 2021)
National Academy of Sports Medicine. NASM Essentials of Corrective Exercise Training. Jones and Bartlett Publishers; 2nd edition (Jan. 13, 2021)