Muscles of the Upper Body

Muscles of the Upper Body

Sternocleidomastoid

• Function: Flexes and laterally rotates the head.
• Origin: Manubrium and medial part of the clavicle.
• Insertion: Mastoid process of the temporal bone.

External Intercostals

• Function: Elevates ribs to assist with inhalation.
• Origin: Inferior border of the ribs.
• Insertion: Superior border of the ribs below.

Internal Intercostals

• Function: Depresses ribs to assist with exhalation.
• Origin: Superior border of the ribs.
• Insertion: Inferior border of the ribs above.

Serratus Anterior

• Function: Rotates scapula upward and draws scapula forward.
• Origin: Anterior surface of ribs 1-9.
• Insertion: Medial border of the scapula.

Pectoralis Minor

• Function: Draws scapula downward and rotates it downward.
• Origin: Anterior surface of ribs 3-5.
• Insertion: Coracoid process of the scapula.

Rhomboideus Minor

• Function: Rotates scapula downward.
• Origin: Spinous processes of C7-T1.
• Insertion: Medial border of scapula.

Rhomboideus Major

• Function: Rotates scapula downward.
• Origin: Spinous processes of T2-T5.
• Insertion: Medial border of scapula.

Levator Scapulae

• Function: Elevates scapula and assists in its downward rotation.
• Origin: Transverse processes of C1-C4.
• Insertion: Superior angle of scapula.

Quadratus Lumborum

• Function: Flexes the vertebral column laterally.
• Origin: Iliac crest and iliolumbar ligament.
• Insertion: Transverse processes of lumbar vertebrae and lower ribs.

Latissimus Dorsi

• Function: Extends, adducts, and medially rotates the shoulder.
• Origin: Spinous processes of T7-L5, iliac crest, and lower ribs.
• Insertion: Intertubercular groove of the humerus.

Pectoralis Major

• Function: Medial rotation and adduction of the shoulder.
• Origin: Sternum, costal cartilages of ribs 1-6, and medial half of clavicle.
• Insertion: Greater tubercle of the humerus.

Trapezius

• Function: Elevates, retracts, and rotates the scapula.
• Origin: Occipital bone and spinous processes of C7-T12.
• Insertion: Lateral third of the clavicle and acromion of the scapula.

Teres Minor

• Function: Laterally rotates the shoulder.
• Origin: Lateral border of the scapula.
• Insertion: Greater tubercle of the humerus.

Infraspinatus

• Function: Laterally rotates the shoulder.
• Origin: Infraspinous fossa of the scapula.
• Insertion: Greater tubercle of the humerus.

Supraspinatus

• Function: Abducts the humerus.
• Origin: Supraspinous fossa of the scapula.
• Insertion: Greater tubercle of the humerus.

Teres Major

• Function: Extends, adducts, and medially rotates the shoulder.
• Origin: Dorsal surface of the inferior angle of the scapula.
• Insertion: Intertubercular groove of the humerus.

Transversus Abdominis

• Function: Compresses the abdomen.
• Origin: Lateral one-third of the inguinal ligament, iliac crest, and thoracolumbar fascia.
• Insertion: Linea alba.

Rectus Abdominis

• Function: Flexes the vertebral column and compresses the abdomen.
• Origin: Pubic crest and pubic symphysis.
• Insertion: Xiphoid process and costal cartilages of ribs 5-7.

Internal Oblique

• Function: Compresses the abdomen and flexes the vertebral column.
• Origin: Iliac crest and thoracolumbar fascia.
• Insertion: Inferior borders of ribs 10-12 and linea alba.

External Oblique

• Function: Compresses the abdomen and assists in trunk rotation.
• Origin: External surfaces of ribs 5-12.
• Insertion: Linea alba and pubic tubercle.

Brachioradialis

• Function: Flexes elbow and stabilizes elbow during forearm rotations.
• Origin: Lateral supracondylar ridge of the humerus.
• Insertion: Styloid process of the radius.