The pectoralis major is the main muscle that covers the front of the
chest. It is a thick, fan shaped muscle which gives the chest its contour. It
makes up most of the males chest shape and lies under the breasts on
females. The latissimus dorsi covers the back of the chest and sides of the
abdomen. It adducts, extends and medially rotates the shoulder joint.
The serratus anterior runs around the side wall of the chest.

Muscles of the Chest & Upper Arm

Name    Location        Action

Pectoralis major

Across upper chest

Used in throwing and climbing; adducts arms

Pectoralis minor

Underneath pectoralis major

Draws shoulders downwards and forwards

Deltoids

Surrounds shoulders

Lifts arms sideways, forwards and backwards

Biceps

Front of upper arm

Flexes elbow; supinates the forearm and hand

Triceps

Back of upper arm

Extends the elbow

Brachialis

Under the biceps

Flexes the elbow

 

Muscles of the Hand & Forearm

Name    Location   Action

Brachio radialis
On the thumb-side of the forearm
Flexes the elbow

Flexors Middle of the forearm
Flexes and bends the wrist drawing it towards the forearm

Extensors
Little finger side of the forearm
Extends and straightens the wrist and hand

Thenar muscle
Palm of the hand below the thumb
Flexes the thumb and moves it outwards and inwards

Hypothenar muscle
Palm of hand below little finger
Flexes little finger and moves it outwards and inwards

Muscles of the Abdomen

Name   Location   Action

Rectus abdominis
Front of abdomen from the pelvis to the sternum
Flexes the spine; compresses the abdomen; tilts the pelvis

Oblique’s
Internal – either side of the rectus abdominis
External – lies on top of the internal oblique’s
Both compress the abdomen and twist the trunk

 

Muscles of the Back
Name    Location   Action

Trapezius
The back of the neck and collar-bones
Moves scapula up, down and back; raises the clavicle

Latissimus dorsi Across the back
Used in rowing and climbing; adducts the shoulder downwards and pulls it backwards

Erector spinae
Three groups of muscles which lie either side of the spine from the neck to the pelvis
Extends the spine; keeps body in an upright position

Rhomboids Between the shoulders
Braces the shoulders; rotates the scapula

Muscles of the Buttocks and Legs

Name   Location   Action

Gluteals   In the buttocks
Abducts and rotates the
femur; used in walking and running

Hamstrings   Back of the thigh
Flexes the knee; extends the knee

Gastrocnemius   Calf of the leg
Flexes the knee; plantar-flexes the foot

Soleus
Calf of leg, below the Gastrocnemius
Plantar-flexes the foot

Quadriceps extensor
Front of the thigh: group of four muscles
Extends the knee; used in kicking

Sartorius
Crosses the front of the thigh
Flexes the knee and hip; abducts and rotates the femur

Adductors   Inner thigh
Adducts the hip; flexes and rotates the femur

Tibialis anterior   Front of the lower leg
Inverts the foot; dorsi-flexes the foot; rotates the foot outwards