Muscle Descriptions

 

By Rick Morris

 

I know what you're thinking. Why should I care about muscle descriptions? I just want to run. I understand that, but I also believe that understanding what each muscle does will help you in designing safe and effective distance running plans. So here it goes.

 

BICEPS BRACHII

 

This muscle is more commonly know as simply biceps. The biceps is actually composed of two heads, one long and one short. This is the large and easily seen muscle on the front of the upper arm.

 

ACTION

 

The biceps muscle is used primarily to flex the elbow or bend the forearm towards your body. The biceps muscle is most effective when the hands are in a palm up or “supinated” position. When the palms are facing down, the effectiveness of this muscle is lessened.

 

STRENGTHENING EXERCISES

 

Standing biceps curl

Seated biceps curl

Concentration biceps curl

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BICEPS FEMORIS

 

The biceps femoris is one of a group of three muscles that, together, are known as the “hamstrings”. The other two muscles are the semimembranosus and semitendinosus. These muscles are used mainly to extend the hip or push you leg behind your body and flex the leg at the knee. This is when you bend your leg so that your foot is behind your body. The hamstring muscles are the large muscles on the back of your upper leg.

 

ACTION

 

The biceps femoris is used to extend the hip and flex the knee. This muscle along with the other hamstring muscles is used extensively in powerful running and jumping activities. In the sport of track and field; sprinters, long jumpers and triple jumpers will have very well developed hamstring muscles. The hamstrings are most effective as hip extenders when the legs are straight or nearly so. When the legs are bent, the gluteus maximus (butt muscle) takes over the duty of hip extension.

 

STRENGTHENING EXERCISES

 

Leg curl

Seated leg curl

Standing hip extension

Squats

Lunges

Leg Press

 

BRACHIORADIALIS

 

The brachioradialis muscle is located on the front of the lower arm on the same side as the thumb.

 

ACTION

 

The brachioradialis muscle flexes or bends the lower arm forward at the elbow. This muscle is most effective when the hands are in a neutral position. When you are holding a burning candle in an upright position, your hand is in a neutral position. This muscle also rotates the lower arm in both directions.

 

STRENGTHENING EXERCISES

 

Reverse curl

Neutral position curl

 

DELTOID

 

This is the muscle that is easily visible wrapping around from the front of the upper shoulder to the back of the shoulder.

 

ACTION

 

The deltoid muscle moves the upper arm from side to side and front to back. It also assists the rotator cuff muscles in rotating the arm both towards and away from the body.

 

STRENGTHENING EXERCISES

 

Bench press

Incline bench press

Decline bench press

Chest fly

Resisted punch

Shoulder pullover

Shoulder press

Front shoulder raise

Rear deltoid rows

Lateral shoulder raise

Reverse fly

Wide grip pulldowns

Narrow grip pulldowns

Seated lat rows

Bent over rows

Stiff arm pulldowns

 

GASTROCNEMIUS

 

The gastrocnemius is one of two muscles that are responsible for plantar flexion of the ankle, which is the motion that results in standing on your toes. The other muscle involved is the soleus muscle. The gastrocnemius is the largest muscle on the back of your lower leg. This muscle also assists in flexing your knee.

 

ACTION

 

The gastrocnemius is used to plantar flex your ankle or push the front of your foot down. The gastrocnemius is most effective when your knees are straight. When the knees are bent this muscle becomes less effective. Running, jumping and hopping motions all bring this muscle into play.

 

STRENGTHENING EXERCISES

 

Standing calf raise

Seated straight leg calf raise

 

GLUTEUS MAXIMUS

 

The gluteus maximus is probably the most well known muscle on the human body. Everyone knows where his or her gluteus is. This is the large muscle located on the rear of the pelvis.

 

ACTION

 

The gluteus maximus extends and externally rotates the hip. External rotation is when your knee is pointing towards the middle of your body. This muscle is used extensively in running and jumping activities. The gluteus maximus is most effective after the hip has been extended beyond 15 degrees or when the leg is pushed just behind your body from a standing position. Because of this, the gluteus is not used extensively in a normal walking stride. In running and race walking, the leg is extended well behind the body, which does use this muscle strongly.

 

STRENGTHENING EXERCISES

 

Leg press

Standing hip extension

Leg kickback

 

LATISSIMUS DORSI

 

This muscle is more commonly know as your “lats”. This is the large muscle on each side of your upper and middle back.

 

ACTION

 

The latissimus dorsi muscle is the most important muscle used to extend your arms or pull them down from over your head down towards your body. Climbing a rope or pulling down on a pulley are examples of motions controlled by this muscle.

 

STRENGTHENING EXERCISES

 

Shoulder pullover

Shoulder extension

Wide grip pulldowns

Narrow grip pulldowns

Seated rows

Lat fly

Reverse grip pulldowns

Bent over rows

Stiff arm pulldown

 

PECTORALIS MAJOR

 

This muscle is more commonly referred to as your “pecs”. This is the large muscle on each side of the front of your chest.

 

ACTION

 

The pectoralis major muscle is used primarily in pushing and throwing motions. Push-ups, throwing a baseball and serving a tennis ball are all common examples of the actions of this muscle.

 

STRENGTHENING EXERCISES

 

Bench press

Incline bench press

Decline bench press

Chest fly

Resisted punch

Shoulder pullover

One arm fly

Push Ups

 

RECTUS ABDOMINIS

 

The rectus abdominis muscle is the large muscle located at the front of the trunk. Many times this is referred to as your “abs”. The rippled effect or “six pack” appearance that most of us want to achieve is the result of a highly developed rectus abdominis and low body fat.

 

ACTION

 

The rectus abdominis muscle flexes or bends the lower spine forward. The oblique muscles which are on each side of the rectus abdominis, bend the spine diagonally to each side. The rectus abdominis is always used to stabilize the spine when performing other exercises.

 

STRENGTHENING EXERCISES

 

Abdominal crunch

Resisted abdominal crunch

Reverse crunch

Oblique abdominal crunch

Trunk rotation

Core Stabilization

 

ROTATOR CUFF

 

The rotator cuff is composed of four muscles. The supraspinatus, infraspinatus, teres minor and subscapularis muscles. These muscles work together to allow full rotation of the shoulder.

 

ACTION

 

The rotator cuff muscles perform rotation at the shoulder joint. These muscles are very active in all throwing and serving motions.

 

STRENGTHENING EXERCISES

 

Rotator cuff internal rotation

Rotator cuff external rotation

Lateral shoulder raise

Empty can shoulder raise

Wide grip lat pulldowns

Narrow grip lat pulldowns

Shoulder pullovers

 

SARTORIUS

 

The sartorius is a long muscle that acts as both a hip flexor, which is when you bring your knees up towards your body, and as a knee flexor, when you bring your heel up toward your rear end. This muscle is effective when performing one of these motions, but is weak at performing both at the same time.

 

ACTION

 

The sartorius is two joint muscle. This means that it passes over and affects two joints. In this case, the hip joint and the knee joint. This muscle is most effective as a hip extender when the knees are extended (legs straight).

 

STRENGTHENING EXERCISES

 

Standing hip flexion

Leg raises

 

SEMIMEMBRANOSUS

 

The semimembranosus is one of a group of three muscles that, together, are known as the “hamstrings”. The other two muscles are the biceps femoris and semitendinosus. These muscles are used mainly to extend the hip or push you leg behind your body and flex the leg at the knee. This is when you bend your leg so that your foot is behind your body. The hamstring muscles are the large muscles on the back of your upper leg.

 

ACTION

 

The semimembranosus is used to extend the hip and flex the knee. This muscle along with the other hamstring muscles is used extensively in powerful running and jumping activities. In the sport of track and field; sprinters, long jumpers and triple jumpers will have very well developed hamstring muscles. The hamstrings are most effective as hip extenders when the legs are straight or nearly so. When the legs are bent, the gluteus maximus (butt muscle) takes over the duty of hip extension.

 

STRENGTHENING EXERCISES

 

Leg curl

Seated leg curl

Standing hip extension

 

SEMIMEMBRANOSUS

 

The semimembranosus is one of a group of three muscles that, together, are known as the “hamstrings”. The other two muscles are the biceps femoris and semitendinosus. These muscles are used mainly to extend the hip or push you leg behind your body and flex the leg at the knee. This is when you bend your leg so that your foot is behind your body. The hamstring muscles are the large muscles on the back of your upper leg.

 

ACTION

 

The semimembranosus is used to extend the hip and flex the knee. This muscle along with the other hamstring muscles is used extensively in powerful running and jumping activities. In the sport of track and field; sprinters, long jumpers and triple jumpers will have very well developed hamstring muscles. The hamstrings are most effective as hip extenders when the legs are straight or nearly so. When the legs are bent, the gluteus maximus (butt muscle) takes over the duty of hip extension.

 

STRENGTHENING EXERCISES

 

Leg curl

Seated leg curl

Standing hip extension

 

SOLEUS

 

The soleus is one of two muscles that are responsible for plantar flexion of the ankle, which is the motion that results in standing on your toes. The other muscle involved is the gastrocnemius muscle. The soleus is located under the gastrocnemius on the back of your lower leg.

 

ACTION

 

The soleus is used to plantar flex your ankle or push the front of your foot down. The soleus is most effective when your knees are bent as in a sitting position. When your knees are straight this muscle is still involved in plantar flexion, but becomes less effective. Running, jumping and hopping motions all bring this muscle into play.

 

STRENGTHENING EXERCISES

 

Seated bent leg calf raise

Standing calf raise

Seated straight leg calf raise

 

TRAPEZIUS

 

The trapezius muscle is sometimes referred to with the slang “traps”. This muscle originates from the base of the skull down the spine to the lowest rib. It attaches to the top of the shoulder blade (scapula) and the collarbone (clavicle).

 

ACTION

 

The primary purpose of the trapezius is to stabilize the shoulder and keep the shoulder from being pulled down or out when lifting an object with the arms. It is also used when you shrug your shoulders.

 

STRENGTHENING EXERCISES

 

Shoulder press

Lateral shoulder raise

Shoulder extension

Shoulder shrug

Scapular retraction

Stiff arm pulldown

 

TRICEPS BRACHII

 

This muscle is or commonly known as simply “triceps”. The triceps is a three-head muscle. It is the large muscle on the back of your upper arm.

 

ACTION

 

The triceps muscle extends or straightens the arm at the elbow and moves the upper arm towards the back of the body. This muscle becomes involved in any pushing movement involving the upper body.

 

STRENGTHENING EXERCISES

 

Triceps pushdown

Triceps extension

French press

Shoulder press

Bench press

Resisted punch

Triceps kickback

 

VASTUS INTERMEDIUS

 

The vastus intermedius is one of a group of four muscles that, together, are known as the quadriceps muscles. The other three muscles in the group are the rectus femoris, vastus lateralis and vastus medialis. The vastus intermedius is located on the front of the thigh under the rectus femoris muscle. Its location under the rectus femoris muscle hides it from view and touch.

 

ACTION

 

The vastus intermedius is used to extend or straighten the knee. This muscle is used extensively in running, walking and jumping motions. This muscle along with the other quadriceps muscles is especially effective when the hips are flexed as in a sitting position.

 

STRENGTHENING EXERCISES

 

Leg extension

Leg press

Squats

Bench Step Ups

Bench Step Downs

Lunges

 

VASTUS LATERALIS

 

The vastus lateralis is one of a group of four muscles that, together, are known as the quadriceps muscles. The other three muscles in the group are the rectus femoris, vastus intermedius and vastus medialis. The vastus lateralis is the large muscle located on the outside portion of the front of the thigh.

 

ACTION

 

The vastus lateralis is used to extend or straighten the knee. This muscle is used extensively in running, walking and jumping motions. This muscle along with the other quadriceps muscles is especially effective when the hips are flexed as in a sitting position. Because the muscle attaches to the outside of the kneecap, tightness in this muscle, especially when combined with underdevelopment of the vastus medialis muscle, which attaches to the inside of the kneecap, can cause the kneecap to be pulled out of proper alignment. This is an especially common problem for females because the angle of the thighs caused by wider hips will aggravate this condition.

 

STRENGTHENING EXERCISES

 

Leg extension

Leg press

Squats

Bench Step Ups

Bench Step Downs

Lunges

 

VASTUS MEDIALIS

 

The vastus medialis is one of a group of four muscles that, together, are known as the quadriceps muscles. The other three muscles in the group are the rectus femoris, vastus intermedius and vastus lateralis. The vastus medialis is the large muscle located on the inside portion of the front of the thigh.

 

ACTION

 

The vastus medialis is used to extend or straighten the knee. This muscle is used extensively in running, walking and jumping motions. This muscle along with the other quadriceps muscles is especially effective when the hips are flexed as in a sitting position. It is especially important to keep this muscle well developed in order to keep you kneecap tracking properly. Because this muscle attaches to the inside of the kneecap, it compensates for the pull placed on the outside of the kneecap by the vastus lateralis muscle.

 

STRENGTHENING EXERCISES

 

Leg extension

Leg press

Lunge

Bench Step Ups

Bench Step Downs

Squats

 

 

 

 

 

 

 

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