ANATOMY UNIT B WEEK 7: APPENDICULAR MUSCLE

Pectoralis major

• Action: Flexes arm (prime mover), adducts, medially rotates arm.

• Origin: Clavicle, sternum.

• Insertion: Humerus.

• Nerve: Pectoral nerves.

Deltoid

• Action: Abducts arm (prime mover), flexion, extension.

• Origin: Clavicle, scapula.

• Insertion: Humerus.

• Nerve: Axillary nerve.

Latissimus dorsi

• Action: Extends arm (prime mover), adducts, medially rotates arm.

• Origin: Vertebrae, ilium, ribs.

• Insertion: Humerus.

• Nerve: Thoracodorsal nerve.

Teres major

• Action: Extends, adducts, medially rotates arm (synergist of latissimus dorsi).

Supraspinatus

• Action: Initiates arm abduction; stabilizes shoulder.

Infraspinatus

Action: Laterally rotates arm; stabilizes shoulder.

Teres minor

Action: Laterally rotates arm; stabilizes shoulder.

Biceps brachii (both heads)

• Action: Supinates and flexes forearm.

• Origin: Scapula.

• Insertion: Radius.

• Nerve: Musculocutaneous nerve.

Brachialis

• Action: Flexes forearm (prime mover).

• Origin: Humerus.

• Insertion: Ulna.

• Nerve: Musculocutaneous nerve.

Coracobrachialis

• Action: Flexes and adducts arm.

• Nerve: Musculocutaneous nerve.

Triceps brachii (all heads)

• Action: Extends elbow (prime mover).

• Origin: Scapula (long), humerus (lateral/medial).

• Insertion: Ulna.

• Nerve: Radial nerve.

Pronator teres

• Action: Pronates forearm.

• Nerve: Median nerve.

Flexor carpi radialis

• Action: Flexes and abducts hand.

• Origin: Humerus.

• Insertion: Metacarpals II–III.

• Nerve: Median nerve.

Palmaris longus

• Action: Weakly flexes wrist; tenses palmar aponeurosis.

• Nerve: Median nerve.

Flexor carpi ulnaris

• Action: Flexes and adducts hand.

• Origin: Humerus.

• Insertion: Carpals.

• Nerve: Ulnar nerve.

Flexor digitorum superficialis

• Action: Flexes fingers II–V and hand.

• Origin: Humerus.

• Insertion: Middle phalanges II–V.

• Nerve: Median nerve.

Flexor digitorum profundus

• Action: Flexes fingers II–V.

• Origin: Ulna.

• Insertion: phalanges II–V.

• Nerve: Median nerve.

Flexor pollicis longus

• Action: Flexes thumb.

• Origin: Radius.

• Insertion: Distal phalanx of thumb.

• Nerve: Median nerve.

Brachioradialis

• Action: Flexes forearm (synergist).

• Origin: Humerus.

• Insertion: Radius.

• Nerve: Radial nerve.

Extensor carpi radialis longus/brevis

• Action: Extends and abducts hand.

• Origin: Humerus.

• Insertion: Metacarpals.

• Nerve: Radial nerve.

Extensor digitorum

• Action: Extends fingers II–V (prime mover).

• Nerve: Radial nerve.

Extensor digiti minimi

• Action: Extends little finger.

• Nerve: Radial nerve.

Extensor carpi ulnaris

• Action: Extends and adducts hand.

• Origin: Humerus, ulna.

• Insertion: Metacarpal V.

• Nerve: Radial nerve.

Supinator

• Action: Supinates forearm (synergist of biceps brachii).

• Nerve: Radial nerve.

Abductor pollicis longus

• Action: Abducts and extends thumb.

• Nerve: Radial nerve.

Extensor pollicis longus/brevis

• Action: Extends thumb.

• Origin: Ulna, radius.

• Insertion: Distal phalanx of thumb.

• Nerve: Radial nerve.

Iliacus (iliopsoas)

• Action: Flexes thigh (prime mover).

• Origin: Ilium.

• Insertion: Femur.

• Nerve: Femoral nerve.

Psoas major (iliopsoas)

• Action: Flexes thigh (prime mover); flexes trunk.

• Origin: Lumbar and lower thoracic vertebrae.

• Insertion: Femur.

• Nerve: Femoral nerve.

Sartorius

• Action: Laterally rotates thigh.

• Nerve: Femoral nerve.

Rectus femoris

• Action: Extends knee (quadriceps prime mover); flexes thigh.

• Origin: Ilium.

• Insertion: Tibia via patella and patellar ligament.

• Nerve: Femoral nerve.

Vastus lateralis, intermedialis, medialis

• Action: Extends knee (quadriceps prime mover).

• Origin: Femur.

• Insertion: Tibia via patella and patellar ligament.

• Nerve: Femoral nerve.

Gracilis

• Action: Adducts thigh.

• Nerve: Obturator nerve.

Pectineus

• Action: Adducts thigh.

• Nerve: Obturator nerve.

Adductor longus, brevis, magnus

• Action: Adducts thigh.

• Origin: Pubis.

• Insertion: Femur.

• Nerve: Obturator nerve.

Gluteus maximus

• Action: Extends thigh (prime mover).

• Origin: Ilium, sacrum, coccyx.

• Insertion: Femur.

• Nerve: Gluteal nerves.

Gluteus medius

• Action: Abducts thigh (prime mover); stabilizes pelvis; medially rotates thigh.

• Nerve: Gluteal nerves.

Gluteus minimus

• deep muscle

• Action: Abducts and medially rotates thigh; stabilizes pelvis.

• Nerve: Gluteal nerve.

Piriformis

• Action: Laterally rotates extended thigh; abducts flexed thigh.

• Nerve: Sacral spinal nerves.

Biceps femoris (both heads)

• hamstrings

• Action: Flexes leg (prime mover), thigh extension.

• Origin: Ischium (long), femur (short).

• Insertion: Fibula, tibia.

• Nerve: Sciatic nerve.

Semitendinosus

• Action: Flexes leg (prime mover), thigh extension.

• Origin: Ischium.

• Insertion: Tibia.

• Nerve: Sciatic nerve.

Semimembranosus

• deep muscle

• Action: Flexes leg (prime mover), thigh extension.

• Origin: Ischium.

• Insertion: Tibia.

• Nerve: Sciatic nerve.

Tensor fasciae latae

• Action: Stabilizes trunk on thigh, makes IT band taught.

Tibialis anterior

• Action: Dorsiflexes (prime mover).

• Origin: Tibia.

• Insertion: Medial cuneiform, metatarsal I.

• Nerve: Deep fibular nerve.

Extensor digitorum longus (EDL)

• Action: Extends toes II–V.

• Origin: Tibia, fibula.

• Insertion: Middle and distal phalanges II–V.

• Nerve: Deep fibular nerve.

Extensor hallucis longus (EHL)

• Action: Extends great toe.

• Origin: Fibula.

• Insertion: Distal phalanx of great toe.

• Nerve: Deep fibular nerve.

Fibularis longus/brevis

• Action: Everts and plantar flexes foot.

• Nerve: Superficial fibular nerve.

Gastrocnemius

• Action: Plantar flexes foot.

• Origin: Femur.

• Insertion: Calcaneus via calcaneal tendon.

• Nerve: Tibial nerve.

Soleus

• Action: Plantar flexes foot (prime mover with gastrocnemius).

• Nerve: Tibial nerve.

Flexor digitorum longus (FDL)

• Action: Flexes toes II–V; plantar flexes and inverts foot.

• Origin: Tibia.

• Insertion: Phalanges II–V.

• Nerve: Tibial nerve.

Tibialis posterior

• Action: Inverts (prime mover) and plantar flexes foot.

• Origin: Tibia, fibula.

• Insertion: Tarsals, metatarsals II–IV.

• Nerve: Tibial nerve.

Flexor hallucis longus (FHL)

• Action: Flexes great toe; assists plantar flexion and inversion.

• Origin: Fibula.

• Insertion: Phalanx of great toe.

• Nerve: Tibial nerve.

Quadriceps tendon

Structure: Connects quadriceps muscles to patella. Function: Transmits force for knee extension.

Patellar ligament

• Structure: Connects patella to tibia.

• Function: Transmits force for knee extension.

Iliotibial band

• Structure: Thickened fascia along lateral thigh attaching to tibia.

• Function: Stabilizes hip and knee.

Calcaneal tendon

• Structure: Connects gastrocnemius and soleus to calcaneus.

• Function: Transmits force for plantarflexion.