Skeletal Muscle Series Part 5

LOWER LIMB MUSCLES

The lower limb muscles are best described and divided based on their function. They consist of:

1. Muscles in the gluteal region that move the thigh.
2. Muscles in the thigh that move the thigh and leg.
3. Muscles that move the feet and toes.

The paragraphs and tables below provide a generalised description and comprehensive* lists of muscles of the lower limbs. Most of the actions and functions of each muscle presented in the tables here are simplified for easier comprehension. Human anatomy books will first divide the lower limbs into anatomical compartments and then place the muscles into their respective compartments. Each compartment has a specific action or function. Such descriptions of lower limb muscles may become confusing and present too much information so, for this article, we’ll divide the lower limb muscles into functional groups directly. Please note: the word muscle is removed from the actual muscle names to shorten reading.

*Comprehensive but may not include all the skeletal muscles found in the pelvic girdle and lower limbs.

The Pelvic Girdle

The pelvic girdle is the foundation of your lower limbs. It’s actually made up of the hip bone (also called the pelvis) consisting of three fused smaller bones: pubis, ilium, and ischium. The pelvic girdle serves the same purpose as the shoulder or pectoral girdle. Comparatively, there’s less movement in the pelvic girdle compared to the shoulder girdle. The reason behind this is because it’s connected to the base of your spine and its primary purpose is to stabilise and support your body. The body’s centre of gravity is located in the pelvis and remains fixed, establishing a base which allows you to stand up without difficulty. The pelvic girdle is mentioned here because it serves as an anchor or a point of origin for muscles that move the thigh and knee. These same muscles also provide stability to the pelvic girdle.

1. Muscles in the Gluteal Region that Move the Thigh

Most of the muscles in the gluteal region that move and attach to the thigh bone (called femur) originate from the pelvic girdle.
Note: The obturator internus and piriformis were previously mentioned and included with the pelvic area muscles (Part 3). In addition to moving the thigh, they also help support the pelvic diaphragm.

2. Muscles in the Thigh that Move the Thigh (femur) and Leg

MUSCLES IN THE THIGH THAT MOVE THE THIGH AND LEG
Muscle	Action/Function
Gracilis Sartorius Biceps femoris (also called hamstrings) Semitendinosus Semimembranosus	Leg flexion (bending), used when kneeling. The sartorius muscle also helps to mount a bike.
Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius *Collectively, these muscles are called quadriceps femoris. Bodybuilders shorten it to “quads”.	Leg extension, used when kicking a ball.
Copyright © Return2Health Limited. All Rights Reserved.

3. Muscles that Move the Feet and Toes

*The intrinsic muscles of the foot originate and insert within the foot. This is similar to the intrinsic muscles of the hand.

CLINICAL SIGNIFICANCE OF SOME SELECTED MUSCLES OF THE LOWER LIMBS

The powerful and assorted muscles that make up the lower limbs and support the pelvic girdle also experience problems of their own whenever they get injured or sick. Below are some examples.

1. Achilles tendinitis. The Achilles tendon connects the gastrocnemius (calf muscle) to the heel bone. It’s found at the back of your lower leg near the heel. It’s a part of the gastrocnemius muscle and is considered the largest tendon of the human body.
   It’s capable of immense strength, but it can still get injured from time to time. Achilles tendinitis happens when strenuous, high impact exercises produce small tears in the tendon itself (jumping, running). The essential part of treatment is adequate rest to allow the tendon and muscle to heal. If left untreated, the tendon can rupture. Surgery is considered as a last resort for a severe case like a ruptured tendon.
2. Muscular dystrophy is a small group of genetic diseases that lead to progressive weakness and subsequent loss of muscle mass. This is because abnormal genes (with mutations) disrupt the production of normal proteins required to produce healthy and functioning muscle.
   
   The most common form of muscular dystrophy is Duchenne muscular dystrophy. Unlike other dystrophies, which begin with the weakness of muscles in the face and/or shoulders, Duchenne muscular dystrophy usually starts with the muscles of the lower limbs (thighs). The disease often begins during early childhood and primarily affects boys and rarely girls. There’s no specific cure for muscular dystrophy, but some medications can delay the disease progression.
3. Biceps femoris tendon rupturehappens during high-intensity sports (sprinting, water skiing, and playing soccer) when you don’t warm up properly or are already exhausted, and you push the muscle beyond fatigue. The most common symptom is sharp pain at the back of the knee, followed by difficulty in walking the affected limb. Depending on the severity of the injury, the damage to your hamstrings may be treated conservatively or surgically.

Note: If symptoms persist in any of the conditions or injuries above, consult your doctor.

MAINTENANCE AND RECOVERY OF LOWER LIMB MUSCLES

1. Taking care of an injured thigh, leg, or foot muscle follows the same treatment outlined for the upper limb muscles – RICE (rest, ice, compression, and elevation). Click here to know more about RICE.
2. Nordic hamstring exercises (NHE) have been shown to decrease hamstring (biceps femoris) injury by as much as 51% based on a study and systematic review involving more than 8,000 athletes. This exercise, also known as the Nordic hamstring curl, increases strength and changes the architecture of the muscle to withstand forces during high-intensity sports better. Click here to see how to execute this exercise properly.
3. ESWT. There are two types of Achilles tendonitis injury, insertional and noninsertional. Insertional Achilles tendinitis means the lower portion of the tendon that attaches to the heel bone is included in the injury. An article published in the Journal of Orthopaedic Surgery and Research in 2021 provided convincing evidence that ESWT or a combination of ESWT and eccentric exercises are useful in treating insertional Achilles tendinitis.

ESWT stands for extracorporeal shockwave therapy. ESWT uses shockwave impulses to jumpstart the healing process of the damaged tissues in the tendon and muscle. Eccentric exercises should initially be performed under the direct supervision of a physical therapist. Other forms of nonoperative treatment like dextrose injections, sclerosing therapy, and soft tissue treatments lack sufficient evidence that they adequately treat insertional Achilles tendinitis.

The muscles of the lower limbs are less mobile and provide fewer movements than the muscles of the upper limbs. Furthermore, the muscles of the lower limbs have the additional function of providing a stable base and centre of gravity (pelvic girdle, pelvis) for your entire body. These muscles also experience specific muscle diseases and injuries. However, their maintenance and recovery still follow the basic principles used in the upper limbs.

Check out these articles for the other skeletal muscles in your body: Please attach the link to the articles when posted.

Skeletal Muscles in the Head – Part 1
Skeletal Muscles in the Neck – Part 2
Skeletal Muscles in the Trunk – Part 3
Skeletal Muscles in the Shoulders and Upper Limbs – Part 4