Tertiary Muscles

Tertiary Muscles
Anatomical Drawing

Shoulder: adductors.
1. Teres major:
Origin: Posterior aspect of the lower corner of the scapula.
Insertion: along with the Latissimus dorsi below the lesser tuberosity of the humerus.
Function: Adducts and rotates arm inward, lowers the arm when raised vertically.

2. Teres minor:
Origin: lateral margin of the Infraspinous fossa.
Insertion: major tuberosity of the humerus, just below the Infraspinatus.
Function: Adducts and rotates arm outward.

Arm: flexors.
3. Flexor carpi ulnaris:
Origin: medial Epicondyle of the humerus, oleocranon and posterior aspect of the ulna.
Insertion: ulnar side carpal bone, (pisiform).
Function: flexion and adduction of the wrist.

4. Flexor carpi radialis:
Origin: medial Epicondyle of the humerus.
Insertion: second metacarpal bone, 1st finger.
Function: flexes and pronates the hand.

Thumb: extenders and abductors.
5. Abductor pollicis Longus: runs obliquely from the ulna to the thumb.
Origin: posterior surface of the ulna and radius; interosseous membrane.
Insertion: base of the first metacarpal.
Function: extension and abduction of the thumb.

6. Extensor pollicis brevis: tendons of the brevis & longus form the (tabatiere).
Origin: posterior surface of the ulna; interosseous membrane.
Insertion: distal phalanx of the thumb.
Function: extension of the distal phalanx of the thumb.

Hand:
7. Dorsal Interosseous: abducts the index finger.

Features of the hand: palmar side.
Thenar eminence, (thumb side), palmar excavation and hypothenar eminence.
Palmar side of the wrist exhibits 3-4 major wrinkles resulting from flexion of the thumb and 4 fingers.
Above the wrist: tendons of the Palmaris longus, (middle and most prominent) and the Flexor carpi radialis, (lateral tendon).

Features of the hand: Dorsal side.
Arc of the knuckles followed by the arc of the fingers.
Middle finger is longest. Thumb reaches to the 1st phalanx of the index finger.

Trunk:
8. Serratus anterior:
Origin: digitations from uppermost 8 or nine ribs.
Insertion: the whole medial border of the scapula.
Function: draws scapula forward and laterally.

Leg:
9. Tensor fasciae latae: ilio-tibial band.
Origin: anterior superior iliac spine.
Insertion: Lateral condyle of the tibia.
Function: elevation and abduction of the thigh.

10. Peroneus longus:
Origin: upper half of lateral surface of fibula.
Insertion: behind the outer knob of the ankle.
Function: flexion and eversion of foot, steadies the leg when standing on one foot.

11. Extensor Hallucis Longus:
Origin: Interosseous membrane, surface of fibula.
Insertion: base of the distal phalanx of the great toe.
Function: extention of the great toe.

Foot:
12. Extensor digitorum brevis:
Origin: upper surface of the calcaneum (heel bone).
Insertion: One tendon (the extensor hallucis brevis) inserts into the base of the proximal phalanx of the big toe. The other tendons unite with the corresponding tendons of the extensor digitorum.
Function: extends the toes.

Features of the foot:
The tendon of the tibialis anterior is prominent upon inversion and flexion of the foot.

The medial maleolus of the tibia is superior to the lateral maleolus of the fibula.

Three fat pads on the plantar side of the foot.

Toes tend to step downward to the distal phalanx.

The arc of the fingers is similar to that of the foot.