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Anatomy & Physiology: Musculoskeletal Structures and Muscles of Upper and Lower Extremities

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  • Acromioclavicular (AC) joint

    A gliding synovial joint between the acromion of the scapula and the clavicle.

  • Glenohumeral (shoulder) joint

    A ball and socket synovial joint allowing triaxial movement between the humerus and scapula.

  • Elbow joint type

    A uniaxial hinge synovial joint allowing flexion and extension between humerus, radius, and ulna.

  • Radius/ulna joint type

    A uniaxial pivot synovial joint allowing pronation and supination of the forearm.

  • Deltoid muscle actions

    Abduction of the shoulder; anterior head does flexion and medial rotation, posterior head does extension and lateral rotation.

  • Pectoralis major origin and action

    Originates on the medial clavicle and sternum; actions include flexion, adduction, and medial rotation of the humerus.

  • Latissimus dorsi origin and action

    Originates on thoracic and lumbar vertebrae, sacrum, and iliac crest; actions include extension, adduction, and medial rotation of the humerus.

  • Muscles causing lateral rotation of the shoulder

    Infraspinatus and teres minor muscles laterally rotate the humerus at the shoulder joint.

  • Biceps brachii actions

    Flexes the shoulder and elbow; inserts on the radial tuberosity.

  • Triceps brachii long head action

    Extends the shoulder and elbow; inserts on the olecranon process of the ulna.

  • Muscle actions at the elbow joint

    Brachialis and brachioradialis flex the elbow; pronator teres pronates the forearm.

  • Flexor carpi radialis and ulnaris actions

    Flexor carpi radialis causes flexion and abduction of the wrist; flexor carpi ulnaris causes flexion and adduction.

  • Extensor carpi radialis longus and brevis actions

    Both muscles cause extension and abduction of the wrist.

  • Pelvic bone components

    Includes ilium, ischium, and pubis bones forming the coxal bone with features like iliac crest, ischial tuberosity, and pubic symphysis.

  • Hip joint type

    A ball and socket synovial joint between the femur head and acetabulum of the pelvis.

  • Muscles causing hip abduction

    Gluteus medius and gluteus minimus abduct the hip.

  • Quadriceps femoris actions

    Extends the knee; rectus femoris also flexes the hip.

  • Hamstrings actions

    Extend the hip and flex the knee; includes biceps femoris, semimembranosus, and semitendinosus.

  • Tibialis anterior action

    Causes dorsiflexion of the ankle.

  • Gastrocnemius actions

    Flexes the knee and causes plantar flexion of the ankle; inserts via Achilles tendon on the calcaneus.

  • Knee joint ligaments

    Includes medial collateral ligament (MCL), lateral collateral ligament (LCL), anterior cruciate ligament (ACL), and posterior cruciate ligament (PCL).

  • Muscle stabilizing the knee via IT band

    Tensor fascia latae (TFL) originates on the iliac crest and inserts on the IT band to stabilize the knee.