MUSCLES IN THE HUMAN BODY

Anterior

means front

Posterior

means back

Occipitofrontalis

large muscle that covers the scalp and connects the forehead and back of the head; aka – epicranius muscle

Skeletal muscles

are tissues that are attached to bones and enable movement; aka voluntary muscles because they are under conscious control

30-40%

t comprise ——-% of your total body mass

Hamstrings

Extend the hip and flex the knee. They also help stabilize the knee and hip joints during walking.

hamstring muscles

are a group of three muscles that run down the back of the thigh from the hip to the lower leg. They are responsible for extending the leg and bending the knee

Biceps femoris, Semimembranosus, Semitendinosus

hamstring muscles

Biceps femoris

Flexes the knee, extends the thigh, and rotates the lower leg

Semimembranosus

Flexes the knee, extends the thigh, and rotates the hip and lower leg

Semitendinosus

Functions similarly to the semimembranosus

Hamstring injuries

-        Hamstring injuries can range from mild to severe

-        Stretching or overloading the hamstrings can cause injury

-        Hamstring injuries can occur suddenly

Hamstring treatments

-        Mild strains can be treated with rest and over-the-counter pain medication

-        For more severe injuries, see a doctor for a diagnosis and treatment

-        Physical therapy can help with tight hamstrings

-        Massage therapy can help loosen the hamstrings

-        Hot or cold packs can reduce inflammation and pain

-        Anti-inflammatory medications can help

Quadriceps

Extend the leg at the knee and flex the thigh at the hip. They also help stabilize the knee.

four muscles

The quadriceps are a group of ——- in the front of the thigh that extend the leg. They are some of the body's largest and strongest muscle.

quadriceps femoris

is a hip flexor and a knee extensor. It consists of four individual muscles;      three vastus muscles and the rectus femoris.

Flexor

a muscle serving to bend a body part (as a limb)

Extensor

a muscle serving to extend a body part (as a leg or arm)

Rectus femoris, Vastus lateralis,      Vastus intermedius, Vastus medialis

quadriceps muscles

Rectus femoris

One of the four quadriceps muscles, it crosses both the hip and knee joints. 

Vastus lateralis

Located on the lateral side of the thigh, it helps extend the knee. 

Vastus intermedius

Located deep and intermediately to the other two vastus muscles, it helps extend the knee. 

Vastus medialis

Also known as the vastus medialis oblique (VMO), it helps extend the knee and stabilize the kneecap

Quadriceps function

The quadriceps help with movements such as walking, running, squatting, and jumping. They connect to the patella via the quadriceps tendon.

Lunges

are an exercise that primarily target the quadriceps

Gastrocnemius

Involved in walking and posture. They affect the lower limb, hip, and lumbar area.

gaster, kneme

Derived from the Greek words “—-”, meaning stomach or belly, and “—-”, meaning leg

gastrocnemius muscle

is a complex muscle that is fundamentally involved in walking and posture. It affects the entire lower limb and the movement of the hip and the lumbar area. It is a muscular district called to work during daily and sports activities and maintain orthostatism.

Orthostatism

is the medical term for an upright standing position. Orthostatic hypotension is a condition that causes a sudden drop in blood pressure when standing up.

Dizziness, Light-headedness, Fainting, Confusion, and Blurred vision.

Symptoms include:

gastrocnemius location

• Located in the back of the lower leg, just under the skin

• Has two heads that start on the inside and outside of the thighbone

• Attaches to the Achilles tendon

gastrocnemius function

• Involved in walking, posture, running, and jumping

• Pulls the heel up and extends the foot downward

• Provides the propelling force in running and jumping

gastrocnemius Injury

• Common because it connects to two joints (the knee joint and the ankle joint) 

• Vulnerable to injury because it crosses three joints 

Deltoids

Help move the arms in different directions and stabilize the shoulder joint.

deltoid muscles

Your ——- cover the top of your shoulder. They help you lift your arm to front, side and back. Deltoid muscle pain can affect swimmers, pitchers or anyone who performs repetitive overhead arm movements.

Deltoid Muscle Functions

• Arm abduction (raising arm to the side).

• Compensates for lost arm strength (e.g., rotator cuff tear).

• Flexion (arm forward) & extension (arm backward).

• Stabilizes shoulder joint, preventing dislocations.

Rotator Cuff

• Group of muscles/tendons securing the humerus in the shoulder socket.

• Common injury in athletes, causing pain/weakness.

Shoulder Dislocations

• Caused by falls, sports injuries, or accidents.

• Do not force back into place—seek medical help.

Gluteal muscles

Help extend and abduct the thigh. They also help adduct, internally rotate, and externally rotate the thigh.

buttocks

The gluteal muscles are the muscles in the ——— that make up the gluteal region. They include the gluteus maximus, gluteus medius, and gluteus minimus. 

Gluteus maximus 

• The largest and most superficial of the three gluteal muscles

• Helps maintain posture and extend the hip

• A key muscle for daily activities, athletic performance, and joint stability

Gluteus medius 

• The middle layer of the gluteal muscles

• Helps abduct the hip

• Works with the gluteus minimus to stabilize the pelvis

Gluteus minimus 

• The smallest of the gluteal muscles

• Helps abduct and internally rotate the hip