Gluteus Maximus Definition

The gluteus maximus is one of the three gluteal muscles that make up the buttocks. This is the most prominent arrangement where the buttocks and hips get shape and function. since it is the biggest and most superficial of the three. The gluteus maximus aids in hip lateral rotation and extension. Specific activities include keeping the body erect, elevating the body from seating and bending positions, and maintaining equilibrium while going to stand on one leg.

When all three gluteal muscles emerge from the pelvic ilium, the gluteus maximus arises from the lateral side of the iliac crest. It gathers to the side and attaches to the greater trochanter of the femur by a tendon that inserts toward the posterior of the body. The gluteus maximus is supplied by the inferior gluteal nerve (L5-S2) and vascularized by the superior and inferior gluteal arteries.

Background of Muscles

Muscle Tissues and Cells

The human body has three kinds of muscle tissue: cardiac muscle, smooth muscle, and skeletal muscle. The heart is made up of cardiac muscle, which circulates blood everywhere in the whole body. Smooth muscle is present in many involuntary biological processes, including the digestive tract, respiratory system, urinary system, and reproductive organs, as well as the walls of blood vessels. Skeletal muscle is present all across the body and serves a variety of purposes. Skeletal muscle is mostly used to move bodily components voluntarily. It may also be present at the digestive, urinary, and respiratory systems’ openings and closings.

Skeletal muscle tissue makes up the gluteus maximus.

Individual cells known as myocytes make up all three kinds of muscles, despite the fact that the cells for every tissue type differ considerably. The cardiac muscle cells are small, branched, ridged, and connected by intercalated discs. There is normally just one nucleus in these cells. Similar in length to striated muscle cells, smooth muscle cells are non-striated and spindle-shaped. Each cell has a single nucleus. Skeletal muscle cells have a cylindrical form and are long and striated. Multiple nuclei are seen in these cells. Muscle fibres are also known as cardiac and skeletal muscles.

Skeletal Muscle Parts and Properties

Muscles are known for a variety of characteristics, including strong elasticity. The tissue may stretch, lengthen, and return to its original form and size. Muscle cells contain many mitochondria that produce ATP because they need a great deal of power in the form of adenosine triphosphate (ATP). When activated by action potentials, muscle cells become “excitable,” comparable to nerve cells. This characteristic is necessary for muscular contraction.

Muscle cells share traits, structures, and organelles in common with other cell types, but they also have their own nomenclature and distinguishing characteristics. The sarcolemma is the cell membrane that surrounds all muscle fibres. Sarcoplasm, the intracellular analogue of cytoplasm, is also seen in muscle cells.

Nonetheless, these cells include crosswise tubes that transmit contraction impulses all through the fibre to facilitate muscle activation. When muscles contract, myofibrils are accountable for the extension of the cell. These myofibrils include several sarcomere structures with dense (myosin) and slender (actin) filaments, which enhance strain during muscular contractions and shrink the muscle. The sarcoplasmic reticulum (similar to the endoplasmic reticulum) surrounds the myofibrils and is responsible for the storage of calcium ions (Ca2+). The terminal cisternae are branches near the terminal of the sarcoplasmic reticulum that are responsible for calcium ion absorption after muscular contractions.

Neuromuscular Junction

While neurons around the neuromuscular junction excite muscle fibres, muscle contractions occur (also referred to as the myoneural junction). A motor neuron is a nerve cell that exists for each skeletal muscle fibre. A chemical messenger called acetylcholine is released by the motor neuron, which activates the muscle fibre. The gap between the muscle fibre and the motor neuron is known as the neuromuscular junction.

The three fundamental components of neurons are the cell body (or soma) that carries the nucleus, many small and branched dendrites, and then a lengthy axon that generates action potentials. An action potential is the electrical change that occurs while cell membranes depolarize (or undergo an abrupt rise in membrane charge owing to ion fluxing). The synaptic terminal is located at the axon’s end. Synaptic vesicles, which contain acetylcholine, are found at the synaptic terminal. The synaptic vesicles discharge the accumulated acetylcholine into the synaptic cleft, which is the minuscule space between both the terminal and the sarcolemma of the muscle fibre.

(It is important to note that an enzyme called acetylcholinesterase is usually discharged into the synaptic cleft to avoid overstimulation of the muscle fibre.)

Once the released acetylcholine reaches the muscle fibre, it connects to receptors on the sarcolemma. This connection results in an action potential, which “excites” the muscle fibre and propagates contraction impulses all through the cell. Calcium ions are liberated by the sarcoplasmic reticulum into the sarcoplasm upon stimulation, where they interact with troponin (a protein seen on the muscle fiber).

The pre-attached tropomyosin is withdrawn, revealing activated spots on G-actins for the attachment of myosin heads. Myosin heads associated with the action “walk” along it, leading to thin filaments to slide and the sarcomere to contract. As this occurs in several sarcomeres, myofibril length reduces and the entire muscle contracts. After muscle contraction, calcium ions are aggressively carried out of the sarcoplasm into the terminal cisternae.

The gluteus maximus is innervated by the motor neurons of the inferior gluteal nerve.

Muscle Movements

There are a variety of terminologies that are used to describe the activities of muscles. The following are some examples of generic body terminology and their actions:

Abduction: refers to the migration of a body part away from the body’s centre.

Adduction: is the migration of a body part toward the body’s centre.

Elevation: is the process of raising a bodily component.

Depression: Moving a bodily part down in depression

Flexion: is the process of reducing the angle of a bodily component (example: having to bend an elbow or leaning the head to the chest).

Extension: Increasing the angle of a bodily portion is called extension (example: extending your legs to rise up from a chair).

Rotation: External spin is the movement of a body part outward from the axis of the body (example: twisting your hip and leg such that your foot points outward while your torso remains facing forward).

Internal: Moving a bodily portion closer to the axis of the body (example: twisting your hip and leg such that your foot points forward while your torso continues to look forward).

Additionally, the head may be spun at any angle around the body’s axis.

The gluteus maximus is responsible for both hip extension and rotation.

Gluteus Maximus

The gluteus maximus, together with the gluteus medius and gluteus minimus, is one of the three gluteal muscles that comprise the buttocks. The gluteus maximus is the largest and most prominent of the three gluteal muscles and is responsible for the majority of the contour of the buttocks and hips. The hip and thigh are mostly extended and externally rotated.

Additionally, the gluteus maximus is important for maintaining body posture. While these activities are combined, this muscle is heavily employed when performing a variety of basic tasks, such as rising from a chair, elevating the upper body after bending down, and going up stairs. Furthermore, the gluteus maximus stabilises the femur and supports the pelvis when the body is balanced on one leg because of its deep connections.

The gluteus maximus is a big muscle that originates from multiple locations in the pelvis. The iliac crest of the pelvis, the inner upper ilium, the lower section of the sacrum, and the coccyx are all places where it starts. Moreover, it inserts itself into two points: the greater trochanter’s superficial fibres and the thigh’s fascia lata. It also links to deep fibres that go between the adductor magus and the vastus lateralis and enter into the gluteal tuberosity (both seen on the thigh).

The gluteus maximus is divided into superior and inferior sections and runs inferior and laterally. The superior component goes into the iliotibial tract of the fascia lata, whereas the inferior section goes into the gluteal tuberosity of the femur.

The superior and inferior gluteal arteries also provide blood to the gluteus maximus.

Gluteus Maximus Exercises

The key muscle responsible for hip extension is the gluteus maximus. This is particularly noticeable in activities like squats and leg presses that require simultaneous hip and knee movement.

Scientists and medical practitioners employ electromyography (EMG) to monitor the electrical potential fields created during the sarcolemma depolarization. As a consequence, when particular activities are observed under controlled settings, the EMG is capable of summing the action potentials from motor neurons to indicate the levels of muscular activity. As a result, exercise physiologists can pinpoint the best motions for strengthening certain muscles, such as the gluteus maximus.

Exercises using step-ups, including variations like lateral, diagonal, and cross-over step-ups, were shown to provide the greatest gluteus maximus activation levels. Gluteus maximus activation may also be increased by bilateral movements including hip thrusts, squats, lunges, and deadlifts. Individual variances in exercise methods, on the other hand, might result in varied amounts of activation. Outlier elements, including workout kinetics, movement velocity, motion range, fatigue levels, and mechanical complexity, may also influence the outcome.

Gluteus Maximus Associated Pain and Weakness

Biologically, the neuromuscular system is designed to allow movement despite muscle failure. Internal muscle coordination may vary in the gluteus maximus. Notwithstanding the absence of physical signs, biochemical excess may result in damage. Especially once a muscle remains to function when another is damaged, potentially resulting in numerous injuries. Knee discomfort, lower back pain, hamstring tension, ankle sprains, and other pre-existing problems may all lead to gluteus maximus weakening. As a result of these injuries, gluteus maximus activity is assumed to be reduced, which benefits short-term muscle health and prevents injuries after major movements.

Given the gluteus maximus’ evolutionary role in maintaining upright postures and appropriate motions, some lifestyle choices might weaken this muscle, resulting in discomfort. Sitting for lengthy periods of time might cause gluteus maximus frailty as well as cell atrophy. Because the human body employs more efficient motor pathways when seated, the secondary hip extensor muscles, particularly the hamstrings, are more intensively engaged. As a result, the energy needs of the less utilised muscles are reduced, resulting in increased gluteal region discomfort. Additionally, with time, the hip flexor muscles might contract, causing the cells of the gluteus maximus to expand.

Treatments for gluteus maximus weakness and discomfort vary depending on the individual, but may include the following: Physical therapy, inhibitory injections (such as botulinum toxin type A), enhancing gluteus maximus workouts, enhancing seated and standing body positions, and minimising sitting durations are all options for addressing the primary injury that caused gluteal paralysis.

Self-massage methods using a foam roller may improve general mobility and performance for discomfort caused by muscular stiffness. Furthermore, all exercises should be performed correctly to ensure that the relevant muscles are addressed. These workouts should instead match the muscles that were previously inappropriately addressed (due to bad athletic habits or sitting postures) with the desired goals.

Conclusions

The gluteus maximus is the largest and most superficial gluteal muscle in the buttocks and thighs. The inferior gluteal nerve innervates the gluteal maximus, which stretches and laterally spins the hip, helping the body to maintain an upright posture and recuperate from sitting and bending positions. Step-up and bilateral exercises may help strengthen the gluteus maximus muscle, which can be weakened by poor sitting position and other ailments in the nearby regions.

References

• Buckthorpe, M., Stride, M., & Villa, F. D. (2019). “Assessing and Treating Gluteus Maximus Weakness – A Clinical Commentary.” International journal of sports physical therapy. 14(4), 655–669.
• Elzanie, A and Borger, J. (2020) “Anatomy, Bony Pelvis and Lower Limb, Gluteus Maximus Muscle.” [Updated 2020 Apr 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.
• Freeman, S., Quillin, K., Allison, L. A., Black, M., Podgorski, G., Taylor, E., & Carmichael, J. (2017). “Biological science (Sixth edition.).” Boston: Pearson Learning.
• Marieb, Elaine Nicpon, & Katja. Hoehn. (2016) “Human Anatomy & Physiology. Tenth edition.” Boston: Pearson. Print.