AnatomyLesson 3 of 4 in the course The Muscular System

Muscles of the Shoulder, Forearm, Wrist, and Hand

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces the muscles that stabilize and position the pectoral girdle and those that move the arm at the shoulder. The girdle provides a mobile base for the upper limb, while coordinated muscle action allows a wide range of arm movements.

The pectoral girdle, also called the shoulder girdle, is formed by the clavicles and scapulae. It links the upper limbs to the axial skeleton and provides a base for movement at the shoulder joint, where the head of the humerus meets the glenoid fossa of the scapula.

All flashcards

What is the main role of the pectoral girdle?
It connects the upper limbs to the axial skeleton and provides a mobile base for arm movement.
What is the main action of the rhomboid muscles on the scapula?
They retract the scapula toward the vertebral column and help stabilize it.
Which four muscles form the rotator cuff?
Subscapularis, supraspinatus, infraspinatus, and teres minor; their tendons help stabilize the shoulder joint.
How do extrinsic and intrinsic hand muscles differ?
Extrinsic muscles originate in the forearm and send tendons into the hand; intrinsic muscles originate and insert within the hand.
What actions do the lumbricals perform at the finger joints?
They flex the metacarpophalangeal joints and extend the interphalangeal joints.

Quiz questions

  1. Which muscle is the principal extensor of the forearm at the elbow?Answer: Triceps brachii.
  2. In anatomical position, what does pronation do to the forearm?Answer: Turns the palm to face posteriorly.
  3. What does opposition of the thumb involve?Answer: Bringing the thumb across the palm toward the fingers.
  4. How are intrinsic hand muscles distinguished from extrinsic hand muscles?Answer: They originate and insert within the hand.
  5. Compression of which nerve in the carpal tunnel can contribute to carpal tunnel syndrome?Answer: Median nerve.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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