Muscles of the Shoulder and Elbow Joints

Muscles Crossing the Shoulder & Elbow Joints

• Biceps brachii: Located on the anterior side; flexes the elbow and supinates the forearm; weakly flexes the arm at the shoulder.
• Brachialis: Located deep to the biceps brachii; primary forearm flexor, responsible for lifting the ulna as the biceps lifts the radius.
• Brachioradialis: Superficial muscle from the distal humerus to the distal forearm; assists in forearm flexion, especially with a semi-pronated forearm.
• Triceps brachii: The only muscle in the posterior compartment of the arm; powerfully extends the forearm, and may help stabilize the shoulder joint.

Muscles of the Forearm: Movements of the Wrist, Hand & Fingers

• Pronator teres: Located on the anterior side; pronates the forearm and weakly flexes the elbow.
• Flexor carpi radialis: Located diagonally across the forearm; powerful wrist flexor; abducts the hand.
• Flexor carpi ulnaris: Powerful wrist flexor; also adducts the hand in coordination with the extensor carpi ulnaris; stabilizes the wrist during finger extension.
• Flexor digitorum superficialis: A two-headed muscle; flexes the wrist and middle phalanges of fingers 2-5.
• Extensor carpi radialis longus & brevis: Extends and abducts the wrist.
• Extensor digitorum: Prime mover of finger extension; extends the wrist and can abduct fingers.
• Supinator: Located deep and therefore not shown; assists the biceps brachii in supinating the forearm.

Muscles of the Hip, Thigh & Leg

• Iliopsoas: Composite of two muscles; primary mover of hip flexion.
• Sartorius: Strap-like and the longest muscle; flexes and laterally rotates the thigh; weak knee flexor.
• Adductors (magnus, longus, brevis): Located on the medial side of the thigh; adduct, flex, and medially rotate the thigh.
• Pectineus: Adducts, flexes, and medially rotates the thigh.
• Gracilis: Adducts the thigh and medially rotates the leg, important for walking.
• Rectus femoris: Extends the knee and flexes the thigh at the hip.
• Vastus (lateralis, medialis, intermedius): All extend the knee.
• Tibialis anterior: Prime mover of dorsiflexion; inverts the foot.
• Gluteus maximus: The largest and most superficial buttock muscle; major thigh extensor; commonly used for intramuscular injections.
• Gluteus medius: Abducts and medially rotates the thigh; important for walking; also suitable for intramuscular injections.
• Gastrocnemius: Plantar flexes the foot when the knee is extended; flexes the knee if the foot is dorsiflexed.
• Soleus: Located deeper than the gastrocnemius; plantar flexes the ankle; active during walking, running, and dancing.
• Fibularis (peroneus) longus: Plantar flexes and everts the foot; helps keep the foot flat on the ground.
• Calcaneal (Achilles) tendon: The largest tendon in the body, connecting the gastrocnemius and soleus muscles to the calcaneus.

Explore the key muscles that cross the shoulder and elbow joints, including their locations and functions. This quiz also covers the muscles of the forearm that facilitate movements of the wrist, hand, and fingers, providing a comprehensive understanding of upper limb anatomy.