Upper Limb Anatomy - Chapter A1

Upper Limb Anatomy - Chapter A1

• Pectoral Region Muscles:
  • Pectoralis Major: Originates from the sternum, upper 6 costal cartilages, and medial 1.5 clavicle. Inserts into the anterior axillary fold (lateral humerus). Actions include arm adduction, flexion, and medial rotation. Innervated by the medial and lateral pectoral nerves.
  • Pectoralis Minor: Originates from ribs 3-5 and inserts into the coracoid process of the scapula. Actions include depressing the shoulder tip and stabilizing the scapula. Innervated by the medial and lateral pectoral nerves.
  • Trapezius: Originates from the occipital protuberance, cervical and thoracic vertebrae, and the spine of the scapula and lateral one-third of the clavicle. Inserts into the lateral third of the clavicle and the spine of the scapula. Actions include elevation, retraction, and rotation of the scapula; and bracing the shoulder backwards. Innervated by the spinal accessory nerve.
  • Latissimus Dorsi: Originates from T6-L5 spines, iliac crest, and thoracolumbar fascia. Inserts into the intertubercular groove of the humerus. Actions include arm adduction, medial rotation, and raising the body towards the arms. Innervated by the thoracodorsal nerve.
  • Serratus Anterior: Originates from the lateral surfaces of ribs 1-8. Inserts into the medial border of the scapula. Actions include scapular rotation (for abduction), protraction, and holding the scapula against the thoracic wall. Innervated by the long thoracic nerve.
  • Subscapularis: Originates from the subscapular fossa and inserts into the lesser tubercle of the humerus. Actions include medial rotation and adduction of the arm. Innervated by the subscapular nerves.
  • Teres Major: Originates from the lower angle of the scapula and inserts into the intertubercular sulcus of the humerus. Actions include adduction and medial rotation of the arm. Innervated by the lower subscapular nerve.

Pectoral Region Joints

• Sterno-clavicular Joint: A joint characterized by fibrocartilage with articular discs and stability due to ligaments. Allows for pectoral movements. Similar to acromio-clavicular joints, stability is from ligaments preventing dislocation.

Axilla

• Acromio-clavicular Joint: Structure also involves fibrocartilage and stability from ligaments, allowing for pectoral movements. Forcep-like ligaments and the coraco-clavicular joint prevent dislocation during falls.

Brachial Plexus (diagram reference)

• Nerve supply information is provided in a diagram, this is omitted from notes as the question was vague and the diagram is not clearly understandable.

This quiz covers the anatomy of the upper limb, focusing on major muscles in the pectoral region, including their origins, insertions, and actions. Test your knowledge of the pectoralis major, pectoralis minor, trapezius, and latissimus dorsi. Perfect for students studying anatomy and physiology!