HUBS1108_ 7. Pectoral girdle _ shoulder Part 1_default_e4333244

Chapter 1: Introduction

• Overview of Lecture Structure

  • Lecture on bones of the pectoral girdle and shoulder divided into two parts.

  • Part One:

    • Bones of the pectoral girdle: clavicle, scapula, and humerus.

    • Major landmarks and classification of joints, including glenohumeral joint and its ligaments.

  • Part Two:

    • Muscles associated with the scapula and humerus.

    • Definition of the axilla (armpit region).

• Terminology

  • Clavicle: Collarbone.

  • Scapula: Shoulder blade, intricate bone with flat surfaces, processes, angles, and borders.

  • Axilla: Armpit region, contains axillary arteries and veins.

  • Pectoral: From Latin 'pectus' meaning chest, pertains to the pectoral region.

  • Brachium: Means arm, usually refers to the area between shoulder and elbow in anatomical discussions.

  • Upper Limb: Comprises the entire structure from the pectoral girdle, humerus, forearm, wrist, to the hand.

• Pectoral Girdle Structure

  • Composition: Two clavicles and two scapulae.

  • Function: Connects upper limb to axial skeleton via the sternum.

  • Helps in movement but lacks stability when adapting for function due to bipedalism.

• Clavicle:

  • Serves as a pivot point attached to the axial skeleton.

  • Only bony connection between the upper limb and axial skeleton.

  • Features of the clavicle:

    • Medial End: Larger, articulates with the sternum.

    • Lateral End: Acromial end articulates with acromion of scapula.

    • Specific markings for muscle and ligament attachments.

Chapter 2: The Sternoclavicular Joint

• Identifying the Clavicle

  • Left or right identification based on the orientation of medial and lateral ends and specific features.

• Clavicle Movement

  • The clavicle pivots at the sternoclavicular joint, aiding reachability and movement in the shoulder region.

• Scapula Structure

  • A flat triangular bone that overlies ribs 2-7, joined to the clavicle.

  • Features of the scapula:

    • Surfaces: Anterior (subscapular fossa for muscle attachment) and posterior (includes acromion and spine).

    • Processes: Acromion and coracoid processes for muscle attachment.

    • Glenoid Cavity: Articulates with humerus to form the glenohumeral joint.

Chapter 3: Scapula and Humerus

• Glenohumeral Joint Formation

  • The scapula's glenoid cavity articulates with the humeral head.

  • Stability Concerns: Minimal congruency leading to reduced stability, making it a highly mobile but unstable joint.

• Humerus Features

  • Key areas include the head (spherical for socket fitting), surgical neck (common fracture site), and tubercles (muscle attachment points).

  • Posterior Aspect:

    • Radial groove for vessels/nerves, deltoid tuberosity for muscle attachment, intertubercular groove (bicipital groove) for biceps tendon.

Chapter 4: A Synovial Joint

• Joint Types in Pectoral Girdle

  • Sternoclavicular Joint: Formed by sternum and clavicle, classified as a synovial saddle joint with mobility and strong capsule.

    • Supported by ligaments: sternoclavicular, interclavicular, and costoclavicular ligaments.

  • Acromioclavicular Joint: Between acromion of scapula and lateral end of clavicle.

    • It allows for slight movement, supported by acromioclavicular and coracoclavicular ligaments.

• Glenohumeral Joint Details

  • Classified as a ball-and-socket joint, possessing extensive mobility and stability influenced by ligaments and surrounding structures.

  • Essential features include the labrum for socket depth, fibrous capsule, and additional ligaments for support.

Chapter 5: Whole Joint Capsule

• Glenohumeral Joint Stability

  • Predisposed to dislocation due to its anatomical design.

  • Includes synovial membrane, bursae for friction reduction, and redundant capsules aiding movement.

• Injury Types

  • Common injuries include dislocations, ligament tears, and fractures from falls or blunt trauma.

Chapter 6: Conclusion

• Summary of Joint and Bone Features

  • Bones: clavicle, scapula, and humerus, including important landmarks for muscle attachments.

  • Joints covered: sternoclavicular, acromioclavicular, and glenohumeral, with associated ligaments and structures affecting stability and mobility.

• Next Steps

  • Part Two: Discussion on muscles of the shoulder region and the axilla.