Secondary Muscles

Secondary Muscles
Anatomical Drawing

Trunk:
1. External Oblique: (Obliquus externus abdominis). Fibers run obliquley toward pubis.
Origin: lower 8 ribs with digitations, Upper 4 interweave with the Serratus anterior and the lower 4 with the Latissimus dorsi.
Insertion: illiac crest, linea alba and inguinal ligament. The linea alba is a tough, fibrous strap that runs through the midline of the trunk. The external oblique muscles cover the abdominis rectus with a broad aponeurosis, (expanded tendon for muscle attachment).
Function: bends trunk forward and rotates it to the opposite side.

Back:
2. Rhomboideus major and minor: rhomboid shape, beneath the trapezius.
Origin: spinous processes of lower cervical and upper thoracic vertebrae.
Insertion: medial border of the scapula.
Function: rotates the scapula medially and upward and steadies scapula during movement of the arm.

Shoulder:
3. Infraspinatus:
Origin: infraspinous fossa.
Insertion: major tuberosity of humerus.
Function: outward and backward rotation of the arm.

Pelvis:
4. Gluteus medius:
Origin: outer surface of the illiac.
Insertion: lateral aspect of the great trochanter.
Function: abduction and medial rotation of the thigh.

Arm:
5. Extensor carpi radialis longus: runs along with the brachioradialis.
Origin: lateral edge of humerus.
Insertion: radial side of metacarpal.
Function: extend and abduct hand.

6. Extensor digitorum:
Origin: lateral epicondyle of humerus.
Insertion: one tendon into distal phlanges, two tendons into mid phlanges.
Function: extends the fingers except for the thumb.

7. Extensor carpi ulnaris:
Origin: lateral epicondyle of humerus and posterior aspect of the ulna.
Insertion: ulnar side of metacarpal.
Function: extends the wrist and adducts hand.


8. Brachialis: greater part is covered by the biceps brachii muscle.
Origin: humerus bone below the deltoid.
Insertion: coranoid process of the ulna bone.
Function: forearm flexion.

Leg:
9. Biceps femoris: lateral flexor. 2 heads.
Origin: long head at the sciatic tuber of the ishium and the short head on the linea aspera of femor.
Insertion: head of fibula.
Function: flexion and medial rotation of the leg.

10. Semitendinosis: medial flexor.
Origin: ishium tuberosity.
Insertion: medial surface of the tibia.
Function: flexion and medial rotation of the leg.

11. Sartorius: (tailors muscle), is the longest muscle in the body.
Origin: anterior superior illiac spine.
Insertion: inner side of tibia.
Function: abducts and flexes thigh, lateral rotation of thigh and flexion of the leg on the thigh.

12. Tibialis anterior:
Origin: lateral condyle of the tibia.
Insertion: medial side metatarsals.
Function: extends the foot.