Trunk Muscles

Fig.1 Gluteus maximus.

Gluteus maximus

Origin: Iliac crest to the sacrum/coccyx
Insertion: Femur
Action: Retraction of the leg and lateral rotation of the leg

Fig.2 Gluteus medius and Gluteus minimus.

Gluteus medius

Origin: Iliac crest
Insertion: Femur (Great Troochanter)
Action: Lateral and medial rotation and abduction

Gluteus minimus

Origin: Iliac crest
Insertion: Femur (Great Troochanter)
Action: Lateral and medial rotation and abduction

Fig.3 Erector spinae.

Erector spinae

Origin: Transverse processes on the vertebral column
Insertion: Transverse and spinous process on the vertebral column
Action: Antagonists to the abdominal muscles. Hyperextension and extension of the spine

Fig.4 Trapezius and Lattissimus dorsi.

Trapezius

Origin: Skull to the vertebral column
Insertion: Scapula
Action: Rotation of the scapula, retraction of the skull

Lattissimus dorsi

Origin: Vertebral column to the sacrum and ilium
Insertion: Humerus
Action: Adduction and some retraction

Fig.5 Rhomboids, Teres major and Levator scapulae.

Rhomboids

Origin: Vertebral column
Insertion: Scapula
Action: Rotation of the scapula

Teres major

Origin: Scapula
Insertion: Humerus
Action: Adduction of the arm

Levator scapulae

Origin: Cervical vertebral column
Insertion: top of the scapula
Action: Raises the scapula

Fig.6 Supraspinatis, Infraspinatis and Teres minor.

Supraspinatis

Origin: Scapula
Insertion: Humerus
Action: Adduction of the arm, rotation

Infraspinatis

Origin: Scapula
Insertion: Humerus
Action: Adduction of the arm, rotation

Teres minor

Origin: Scapula
Insertion: Humerus
Action: Adduction of the arm, rotation

Fig.7 Pectoralis major and Deltoideus.

Pectoralis major

Origin: Sternum to the clavicle
Insertion: Humerus
Action: Adduuction

Deltoideus

Origin: Scapula and clavicle
Insertion: Humerus
Action: Moves the arm; abduction, rotation and retraction

Fig.8 Serratus anterior.

Serratus anterior

Origin: Ribs
Insertion: Scapula
Action: Stabilises the scapula

Fig.9 Splenius capitus.

Splenius capitus

Origin: Top of the vertebral column
Insertion: Base of the skull
Action: Hyper extend the vertebrae and lateral flexing

Fig.10 Psoas and Illiacus.

Psoas

Origin: Base of the vertebral column
Insertion: Top and medial of the femur
Action: Hip flexor

Iliacus

Origin: Iliac crest
Insertion: Top and medial of the femur
Action: Hip flexor

Fig.11 Subscapularis.

Subscapularis

Origin: Scapula
Insertion: Humerus
Action: Medial rotation and stabilises the shoulder

Fig.12 Sternocleido mastoid.

Sternocleido mastoid

Origin: Clavicle and sternum
Insertion: Occipital and temporal bone
Action: Rotate and flex the head. In deep breathing, raises the rib cage

Fig.13 Abdominus rectus.

Abdominus rectus

Origin: Sternum
Insertion: Pubis
Action: Flexing lumbar vertebrae

Fig.14 Abdominus transversalis.

Abdominus transversalis

Origin: -
Insertion: -
Action: Supporting trunk muscles

Fig.15 Internal oblique.

Internal oblique

Origin: Pelvic girdle
Insertion: Linea alba
Action: Twisting the trunk

Fig.16 External oblique.

External oblique

Origin: Ribs
Insertion: Pelvic girdle (opposite side)
Action: Twisting the trunk