lower arm 2

Muscles of the Upper Arm Acting on the Elbow

  • Biceps brachii: Features two heads originating from the scapula and inserts on the radial tuberosity; responsible for elbow flexion and forearm supination.

  • Brachialis: Sits deep to the biceps brachii, originating on the anterior humerus and inserting on the ulnar; serves as the most powerful elbow flexor.

  • Brachioradialis: Originates on the lateral distal humerus and inserts on the distal radius; produces flexion at the elbow.

  • Triceps brachii: Located on the posterior surface with three heads (one from the scapula, two from the humerus); functions to extend the elbow.

Anterior Forearm Muscles (Flexors)

  • Palmaris longus: Identified by its insertion into the fascia of the palm; produces wrist flexion.

  • Flexor carpi radialis: Located on the radial (thumb) side; facilitates wrist flexion and abduction.

  • Flexor carpi ulnaris: Located on the medial (ulnar) side; facilitates wrist flexion and adduction.

  • Flexor digitorum superficialis: Situated deep to the other listed flexors; produces flexion of both the wrist and the digits.

Muscles for Forearm Pronation and Supination

  • Supinator: Originates on the lateral epicondyle of the humerus and inserts on the proximal radius to facilitate supination.

  • Pronator teres: Originates on the medial epicondyle of the humerus and attaches to the lateral radius to facilitate pronation.

  • Pronator quadratus: A rectangular muscle at the distal forearm that produces pronation near the wrist.

Posterior Forearm Muscles (Extensors)

  • Extensor digitorum: Originates on the lateral epicondyle and splits into tendons inserting into each finger; facilitates extension of the digits and wrist.

  • Extensor carpi ulnaris: Located on the ulnar side; produces wrist extension.

  • Extensor carpi radialis longus: Features a long tendon on the radial side; produces wrist extension.

  • Extensor carpi radialis brevis: Features a shorter tendon and sits beneath the longus; produces wrist extension.

Blood Vessels of the Lower Arm

  • Radial artery: A branch of the brachial artery running along the lateral side of the forearm.

  • Ulnar artery: A branch of the brachial artery running along the medial side of the forearm.

  • Radial and Ulnar veins: Deep veins that drain blood from the palm and forearm.

  • Median cubital vein: A superficial vein located in the cubital fossa used for blood draws; connects the cephalic and basilic veins.