Vishram singh-1

Chapter Overview

  • Contents

    • Chapter 20: Pericardium and Heart (Page 256)

    • Chapter 21: Superior Vena Cava, Aorta, Pulmonary Trunk, and Thymus (Page 283)

    • Chapter 22: Trachea and Esophagus (Page 292)

    • Chapter 23: Thoracic Duct, Azygos and Hemiazygos Veins, and Thoracic Sympathetic Trunks (Page 302)

    • Multiple Choice Questions (Page 311)

    • Index (Page 325)

Introduction to the Upper Limb

  • Function: The upper limb is crucial for manual activities; the hand is adapted for grasping and manipulation.

  • Comparative Anatomy: Four limbs present in terrestrial vertebrates; forelimbs adapted for specific functions.

  • Evolutionary Adaptation:

    • Quadrupeds (e.g. dogs) evolved limbs for weight transmission and locomotion.

    • In humans, hind limbs are responsible for locomotion, while upper limbs are adapted for manipulation (pre-hensile capabilities).

  • Types of Grips:

    • Power grip: Primitive, seen in higher primates.

    • Hook grip: Also primitive.

    • Precision grip: Characteristic of humans, allowing skilled movements (e.g., holding a pen).

  • Significance of Upper Limb: Sound understanding of the structure is essential for clinical significance and restoring functions after injury.

Structure of the Pectoral Girdle

  • Definition: Connects upper limbs to the axial skeleton.

  • Composition:

    • Scapula and clavicle are the main bones.

    • Scapula connects to the clavicle via the acromioclavicular joint.

    • Clavicle connects to the axial skeleton at the sternoclavicular joint.

  • Characteristics:

    • Incomplete girdle: Only anteriorly attached.

    • Functions: Attachment point for numerous muscles, aiding in arm and forearm movement.

    • Delicate compared to pelvic girdle, which is complete and weight-bearing.

Parts of the Upper Limb

  • Divisions:

    1. Shoulder

    2. Arm (Brachium)

    3. Forearm (Antebrachium)

    4. Hand

Shoulder Region

  • Components:

    • Axilla (armpit)

    • Scapular area

    • Pectoral area (front of chest)

  • Bones:

    • Clavicle (collar bone) and scapula (shoulder blade) form the shoulder girdle.

    • Articulates at the acromioclavicular joint.

    • Articulates with the rest of the skeleton via the sternoclavicular joint.

Arm

  • Definition: Segment between shoulder and elbow.

  • Bone: Humerus.

    • Articulates with the scapula at the shoulder and the radius and ulna at the elbow joint.

Forearm

  • Definition: Area between elbow and wrist.

  • Bones: Radius and ulna.

    • Articulations with the humerus and each other at radio-ulnar joints for movement.

Hand

  • Components:

    • Wrist (carpus)

    • Hand proper (metacarpus)

    • Digits (thumb and fingers)

  • Wrist Bones: Eight carpal bones arranged in two rows.

    • Articulate with each other (intercarpal joints), radius (radio-carpal wrist joint), and metacarpals (carpometacarpal joints).

Evolutionary Adaptations

  • Modifications: Adaptations in the upper limb during evolution respond to prehensile needs.

    • Development of joints facilitating rotatory movements (supination and pronation).

    • Addition of clavicle for structural support.

    • Thumb rotation for opposition, enabling grasping.

    • Enhanced mobility of fingers for diverse functions.