Human Muscular Anatomy Explained

Written by Chris Bradley

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To fully understand how our human body works, it helps to know about our different muscles.

Whether you’re preparing for a marathon or in the stages of recovering from a muscle injury, understanding how your muscles function will aid you when training and help mitigate recurring injuries.

How do our bodies move? What are the skeletal muscles? Here are the answers to these questions and more.

Why is it Essential to Understand Muscles?

Below are just a few reasons it’s beneficial to have a good understanding of your muscles.

Physical Health and Functionality

Understanding how muscles function is instrumental in maintaining optimal physical health. 

By customising fitness routines based on this understanding, individuals can prevent injuries and sustain a healthy lifestyle over the long term.

Injury Prevention 

A profound comprehension of muscle function serves as a proactive measure against injuries. 

Individuals can significantly reduce the risk of injuries during physical activities by identifying potential areas of strain or weakness.  

Optimising Physical Performance

Athletes and fitness enthusiasts can elevate their performance by delving into the intricacies of muscle function. 

This knowledge allows them to fine-tune their training regimens, targeting specific muscles involved in different movements. 

Individuals can enhance their overall athletic abilities by optimising muscle engagement to achieve peak performance levels.

Posture and Ergonomics

Awareness of muscle function plays a pivotal role in maintaining proper posture and ergonomics. 

When individuals comprehend how muscles contribute to efficient body mechanics, they can minimise the risk of musculoskeletal issues and promote long-term spinal and joint health. 

Proper muscle engagement ensures that individuals can carry out their daily activities precisely, reducing the strain on their bodies.

Rehabilitation and Physical Therapy

Healthcare professionals, such as the physical therapists at our clinic in London, leverage an in-depth understanding of muscle function to design personalised rehabilitation programs. 

These programs are tailored to target specific muscles and address functional limitations, aiding individuals in their recovery from injuries, surgeries, or medical conditions. 

What are Muscles?

Muscles

Made up of thousands of tiny fibres, muscles are structured to provide strength and flexibility. These fibres are organised into strands, each contributing to the overall function of the muscle. 

The connective tissue surrounding these fibres helps facilitate movement.

At the microscopic level, the basic functional unit of a muscle is the sarcomere. This minute structure comprises overlapping filaments of proteins, primarily actin and myosin. The interplay between these proteins allows for the contraction and relaxation of muscles. During contraction, these filaments slide past each other, enabling the muscle to generate force and produce a wide range of movements.

The contractile property of muscles is a key feature that empowers them to carry out various movements. Whether executing simple gestures or engaging in complex athletic activities, muscles leverage the coordinated effort of sarcomeres to contract and relax, producing the force necessary for dynamic motion.

Muscles in the human body can be broadly categorised as voluntary and involuntary depending on the type of muscle and their function 

Voluntary muscles are under conscious control from a part of the brain called the Motor Cortex. These muscles allow us to move intentionally, such as those involved in walking or lifting objects. 

On the other hand, involuntary muscles function without conscious effort and are controlled by other areas of the brain such as the hypothalamus, overseeing vital processes like digestion and circulation.

Muscle Types

Skeletal Muscles

Skeletal Muscles

Skeletal muscles are the voluntary muscles that aid in everyday tasks. 

There are over 650 named skeletal muscles in the human body, representing diverse functions. 

These muscles are attached to bones by tendons and are responsible for the voluntary movements we consciously control, such as walking, reaching, and lifting. 

Skeletal muscles work in coordinated pairs, where one muscle contracts (agonist) to produce a specific movement while its opposing muscle relaxes (antagonist). 

Beyond movement, skeletal muscles provide stability by supporting posture and preventing excessive joint movement, ensuring efficient body mechanics.

Smooth Muscles

Smooth muscles are involuntary muscles found in the walls of organs, blood vessels, and other internal structures. 

Unlike skeletal muscles, smooth muscles operate involuntarily.

These muscles play a crucial role in various bodily functions, including food movement through the digestive system, regulation of blood flow, and other visceral activities.

Their smooth, non-striated appearance distinguishes them from the striated appearance of skeletal muscles.

Cardiac Muscles

Cardiac muscles are specialised muscles found in the heart, contributing to its vital function of pumping blood throughout the body.

Like smooth muscles, cardiac muscles are involuntary, and their rhythmic contractions create the heartbeat.

The unique nature of cardiac muscles enables them to contract rhythmically and continuously without fatigue, ensuring the constant circulation of blood.

Muscles and Their Roles

Now, focusing on skeletal muscles, we will detail specific muscles and muscle groups that aid in movement necessary for everyday life. These areas are often prone to injury due to work, sports, accidents, or simply carrying out everyday repetitive tasks.

Face, Head, and Neck Muscles

Face, head and neck muscles

Muscles of the facial expression

These muscles are responsible for facial expressions, conveying emotions, and enabling non-verbal communication.

Muscles of mastication

Orchestrating the mechanical breakdown of food within the mouth, this specialised group of muscles emphasises how some are designed to execute tasks tailored to the body’s diverse needs.

Muscles of the orbit

The role of these muscles is to control the delicate art of eye movement. These muscles choreograph our gaze, allowing us to track objects and maintain visual focus.

Muscles of the tongue 

These muscles facilitate speech, aid in manipulating food during chewing, and contribute significantly to taste perception.  

Muscles of the pharynx 

These integrate into the complex symphony of swallowing, reminding us that skeletal muscles are not confined to external movements alone. 

Muscles of the larynx

These muscles enable multiple necessary capabilities, from the voluntary articulation of words to the involuntary production of sounds.

Muscles of the neck

From head rotation and tilting to contributing to overall posture, these muscles underscore the indispensable role of skeletal muscles in providing both support and function to the upper body. Neck pain is common, emphasising the need to understand muscles in this region.

Zygomaticus 

This muscle allows us to pull off a myriad of facial expressions, including the act of smiling. 

Depressor anguli oris

This muscle pulls the corners of the mouth downward and is involved in expressions of sadness or frowning.

Masseter

What are the strongest muscles in the human body? Well, based on its mass, the Masseter is a great contender. Nestled in the jaw, this muscle performs the critical role of enabling the teeth to close with impressive force and chew food.

Sternocleidomastoid (SCM) 

The SCM enables the rotation, tilting, and forward movement of the head, portraying the versatility of skeletal muscles.

Frontalis

This muscle in the forehead raises eyebrows and creates horizontal forehead wrinkles.

Orbicularis oculi

Surrounding the eye, this muscle is responsible for blinking, squinting, and closing the eyes.

Torso and Abdomen Muscles

Torso and Abdomen Muscles

Erector spinae

This group of muscles, situated along the back and running parallel to the spine, is the support system for the backbone. Comprising three distinct columns – the iliocostalis, longissimus, and spinalis – the erector spinae enables the spine to bend, arch, and twist gracefully and flexibly.

Oblique muscles

Comprising both external and internal components, the external obliques, positioned diagonally on the abdomen’s sides, facilitate flexion and rotation.

Beneath them, the internal obliques work synergistically to support posture and contribute significantly to lateral movements, highlighting their crucial role in core stability and trunk rotation.

Intercostal muscles 

Surrounding the ribs, the external intercostals elevate the ribs during inhalation. The internal and innermost intercostals contribute to forced exhalation by depressing the ribs. Together, they help with breathing, orchestrating the expansion and contraction of the chest cavity during respiratory movements.

Diaphragm

The diaphragm, a dome-shaped muscular partition, is essential for breathing. As it contracts, it flattens, expanding the thoracic cavity and creating a negative pressure that draws air into the lungs. It resumes its dome shape in relaxation, reducing thoracic cavity volume and initiating exhalation.

Levator Ani

Delving into the intricacies of pelvic support, the levator ani helps to maintain pelvic organ integrity and supports bowel movements. Comprising the pubococcygeus and iliococcygeus, this pelvic floor muscle not only aids in preventing pelvic floor disorders and incontinence but also helps support sexual function.

Hands, Wrists, Arms, and Shoulder Muscles

Shoulder and Arm Muscles

What are our shoulder muscles called? Well, the primary muscle group is the rotator cuff muscles, composed of four individual muscles situated at both the front and back of the shoulder, providing maximum support of the shoulder joint but many other muscles are just as essential to allow arm and shoulder movement.

These are some of the skeletal muscles responsible for moving our hands, wrists, arms, and shoulders.

Abductor Pollicis Brevis

This muscle, found in the base of the thumb, expertly aids in the elegant and precise movement of the thumb away from the palm, a motion essential for tasks requiring fine motor control.

Flexor Pollicis Brevis

The Flexor Pollicis Brevis assists in the nuanced flexion of the thumb, contributing to our ability to grasp, hold, and manipulate objects with finesse.

Dorsal Interossei

Positioned between the metacarpal bones, the Dorsal Interossei allows for the spread of expansive and controlled digits.

Palmar Interossei

Occupying the palm side, these muscles act as harmonisers, bringing the fingers together toward the middle finger with precision and control.

Four Lumbrical Muscles

These lumbrical muscles assist in flexing metacarpophalangeal joints while extending the interphalangeal joints, demonstrating the hand’s control over grip strength and finger positioning.

Trapezius

Positioned along the upper back and neck, the Trapezius muscle executes actions such as tilting the head back, elevating shoulders, and retracting shoulder blades, maintaining optimal upper body movement and posture. 

Trapezius strain is common and can affect everyday tasks, necessitating appropriate treatment.

Pectoralis Major

Commanding the upper chest region, the Pectoralis Major muscle facilitates essential arm movements, including rotation, vertical lifting, and lateral motions. Therefore, this muscle plays a pivotal role in a diverse array of activities involving the arms and shoulders.

Deltoid

Encircling the shoulder, the Deltoid muscle is essential for upper body movement, such as lifting and rotating the arm. Its contribution to shoulder mobility also imparts a distinctive, rounded appearance to the shoulder itself.

Biceps Brachii

Situated in the upper arm, the Biceps Brachii muscle enables the flexion of the forearm. This essential function allows for the bending of elbows, a fundamental movement in various activities involving lifting or pulling with the arms.

Triceps Brachii

Positioned at the back of the upper arm, the Triceps Brachii muscles help extend the forearm and straighten the elbow. Their significance is underscored in activities requiring forceful pushing or extending arm motions.

Legs and Feet Muscles

Injuries to the legs are relatively common, as the legs are involved in various activities such as walking, running, jumping, and supporting the body’s weight. The types and frequency of leg injuries can vary depending on age, activity level, and overall health.

For example, sudden, involuntary contractions of muscles can occur due to dehydration, overuse, or electrolyte imbalances. Cramps are often temporary but can be painful.

Shin splints are another common injury, often seen in athletes, that involves pain along the shinbone (tibia). Shin splints can be caused by excessive running, jumping, or other repetitive stress on the legs.

Other areas around our muscles can be affected due to overuse, such as our tendons.

Inflammation of tendons, which are the tissues that connect muscles to bones, can occur from overuse or repetitive movements.

Are you experiencing any of the above? If so, learning more about your leg and foot muscles is a good idea.

Learning about leg and foot muscles enables you to identify muscle imbalances. Strengthening both agonist and antagonist muscles around joints creates better stability and reduces the risk of injury.

For instance, if the muscles on one side of the thigh (quadriceps) are more robust than those on the other (hamstrings), it can lead to instability and increase the likelihood of injuries, such as strains or tears. A balanced strengthening program can help ensure that opposing muscle groups adequately support joints during various activities.

These are some of the skeletal muscles responsible for moving our legs and feet.

Gluteus Maximus

Positioned in the buttocks, the gluteus maximus is a powerful skeletal muscle crucial for hip and thigh movement. It is the largest of the muscle group and actively supports posture, aids in standing up from a seated position, and contributes to ascending stairs.

Quadriceps

Situated at the front of the thigh, the quadriceps is a muscle group responsible for straightening the leg at the knee. These muscles work synergistically to facilitate activities like walking, running, and jumping.

Hamstrings

Located at the back of the legs, the hamstrings are a group of skeletal muscles that extend the thighs and bend the knees. They play a vital role in walking, running, and bending forward.

Tibialis Anterior

The tibialis anterior, a lower leg muscle, is engaged when lifting the feet off the ground. It contributes to dorsiflexion, allowing for controlled movements during activities like walking and running.

Soleus

Situated in the calf region, the soleus muscle is essential for lowering the feet to the ground. It aids in maintaining good posture during walking and is actively engaged in activities that involve ankle movement and support.

You should now have a deeper understanding of your body and how muscles help you to function and move, contributing to daily living.

As mentioned, a detailed knowledge of skeletal muscles allows you to pinpoint specific weaknesses or imbalances in your musculoskeletal system.

If you’re aware of the muscles involved in a particular movement or activity, you can identify areas of weakness or imbalance that may have contributed to your injury.

Addressing these weaknesses through targeted exercises can help mitigate further injuries by promoting better joint stability and function.

One of our physios at bodytonic clinic can assist with any injuries and work with you on a treatment plan, including a tailored exercise programme, to aid in your recovery.  

Even if you don’t have an injury, consider booking a deep tissue massage to reduce tension and improve flexibility, promoting healthy muscles.