Muscles of the Upper Body

TRAPEZIUS

Pronounced: Trap-eez-iuss

Origin: 7th cervical vertebra and all thoracic vertebrae

Insertion: Clavicle and scapula

Joints crossed: Shoulder girdle

Direction of fibres: Three different directions

Action: Upper fibres elevate the shoulders and extend the neck. Middle fibres retract the scapula. Lower fibres depress the scapula.

Exercise examples: Shoulder shrugs

The trapezius starts where it attaches to the thoracic and cervical spine, and finishes where it attaches on the scapula and clavicle.

RHOMBOIDS

Pronounced: Rom-boyds

Origin: 7th cervical vertebra and all thoracic 1-5

Insertion: Scapula

Joints crossed: Shoulder girdle

Direction of fibres: Diagonal

Action: Retracts the shoulder girdle and rotates the scapula (internally)

Exercise examples: Pulling shoulder blades together for posture

The rhomboids start where they attach to the thoracic and cervical spine, and finish where they attach on the scapula.

PECTORALIS

Pronounced: Pec-tor-alis

Origin: Clavicle and sternum

Insertion: Humerus

Joints crossed: Shoulder

Direction of fibres: Horizontal

Action: Horizontal flexion, adduction and inward rotation of the arm.

Exercise examples: Press ups and Pec dec

Pectoralis major starts where it attaches to the clavicle and sternum, and finishes where it attaches near the top of the humerus.

DELTOID

Pronounced: Del-toyd

Origin: Clavicle and scapula

Insertion: Humerus

Joints crossed: Shoulder

Direction of fibres: Three sets of fibres running vertically

Action: Abducts the arm and assists in shoulder rotation and flexion.

Exercise examples: Dumbell lateral raise

The deltoid starts where it attaches to the scapula and clavicle, and finishes where it attaches on the side of the humerus.

LATISSIMUS DORSI

Pronounced: La-tiss-i-mus dpr-sy

Origin: Lumbar and sacral vertebrae, thoracic vertebrae 7-12

Insertion: Humerus

Joints crossed: Shoulder

Direction of fibres: Diagonal

Action: Adducts, extends and inwardly rotates the shoulder.

Exercise examples: Lat pull downs

The latissimus dorsi starts where they attach to the lumbar and sacral spine, and finish where they attach near the top of the humerus.

BICEPS

Pronounced: Bi-seps

Origin: Scapula

Insertion: Radius

Joints crossed: Elbow and shoulder

Direction of fibres: Vertical

Action: Flexes the elbow and supinates forearm.

Exercise examples: Bicep curls

The biceps start where they attach to the scapula and finish where they attach just below the elbow onto the radius.

TRICEPS

Pronounced: Tri-seps

Origin: Scapula and humerus

Insertion: Ulna

Joints crossed: Elbow and shoulder

Direction of fibres: Vertical

Action: Extends the elbow.

Exercise examples: Tricep dips

The triceps start where they attach to the scapula and humerus, and finish where they attach just below the elbow onto the ulna.

 

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