Bones of Upper Extremity

Bones of Upper Extremity

Basic Identification of Bones & X-Rays

  • Introductory Concept: Understanding the major bones that make up the upper extremity and how they can be identified in X-rays.

Outline of Bones of Upper Extremity

  • Pectoral Girdle (Right)

    • Scapula

    • Clavicle

  • Free Part of Upper Limb (Right)

    • Humerus

    • Ulna

    • Radius

    • Carpals

    • Metacarpals (I–V)

    • Phalanges

  • Additional Structure:

    • Manubrium of Sternum

    • Clavicle

Specific Bone Identification in Upper Extremity

Bone Count Per Upper Limb

  • Pectoral Girdle: 1 Clavicle & 1 Scapula

  • Arm (Brachial Region): 1 Humerus

  • Forearm (Antebrachial): 1 Radius & 1 Ulna

  • Hand:

    • 8 Carpals

    • 5 Metacarpals

    • 14 Phalanges

Clavicle (Right)

Structural Orientation

  • Posterior Medial Aspect:

    • Sternal End

  • Lateral Anterior Aspect:

    • Acromial End

  • Superior & Inferior View:

    • Further detailing the orientations of the clavicle with respect to the manubrium of the sternum.

Related Anatomy of the Scapula

Detailed Features of Scapula

  • Acromion

  • Coracoid Process

  • Glenoid Cavity

  • Spine

  • Supraspinous Fossa

  • Infraspinous Fossa

  • Subscapular Fossa

  • Borders:

    • Medial, Lateral, and Posterior

Specific Features and Their Relevance

  1. Spine of Scapula

    • Helpful for partial attachment of the Trapezius & Deltoid muscles.

  2. Acromion

    • Meaning: “Highest”, referring to the shoulder. This site provides partial attachment for Trapezius & Deltoid.

  3. Supraspinous Fossa

    • Meaning: “Above” the spine; serves as proximal attachment for the Supraspinatus muscle.

  4. Infraspinous Fossa

    • Meaning: “Below” the spine; proximal attachment for Infraspinatus muscle.

  5. Subscapular Fossa

    • Means “Under”; primarily an anterior surface, this feature provides proximal attachment for Subscapularis muscle.

  6. Coracoid Process

    • Meaning: “Like a Raven’s beak”; serves as an attachment for 3 muscles.

  7. Glenoid Cavity

    • Meaning: “Socket-like”; articulates with the head of humerus, forming the shoulder joint.

Humerus

Proximal Humerus Features

  • Anterior View:

    • Anatomical Neck: Area between the head and tubercles.

    • Greater Tubercle: Larger and more lateral than the Lesser Tubercle.

    • Lesser Tubercle: Anteriorly located; serves as a distal attachment for one of four rotator cuff muscles.

    • Surgical Neck: Region that is more prone to fractures than the anatomical neck.

    • Intertubercular Sulcus: Means “between” tubercles; acts as a passageway for a tendon, specifically the long head of the biceps brachii muscle.

Distal Humerus Features

  • Distal Anatomical Structures:

    • Capitulum: Means “head”; articulates with the head of the radius.

    • Trochlea: Derived from “pulley”, articulates with the trochlear notch of the ulna; serves as a structural pivot point for the elbow joint.

    • Epicondyle(s): Literally “above the knuckle/joint”; key points for the proximal attachment of muscle groups in the forearm.

Radius & Ulna

Proximal Radius & Ulna Features

  • Anterior View Features:

    • Head of Radius

    • Neck

    • Radial Tuberosity: Serves as a distal attachment point for the Biceps brachii muscle.

    • Coronoid Process: Feature contributing to elbow articulation.

    • Trochlear Notch: Engages with the trochlea of the humerus during elbow flexion and extension.

    • Olecranon (Process): Forms the Elbow, providing distal attachment for Triceps Brachii muscle.

Distal Radius & Ulna Features

  • Distal View:

    • Radial Styloid Process: Recognized as a vertical pillar, serves as a distal attachment for ligaments of the wrist.

    • Head of Ulna: Distally located head.

    • Ulnar Styloid Process: Analogous to the radial styloid, also serving as attachment for wrist ligaments.

Hand Anatomy

Phalanges (Bones of Fingers)

  • Bones Identified:

    • Distal Phalanx (DP)

    • Middle Phalanx (MP)

    • Proximal Phalanx (PP)

  • Notes:

    • Digit 1 has only PP & DP

    • Digits 2-5 consist of PP, MP, & DP.

Metacarpals (Bones of Palm/Dorsum)

  • Metacarpal I (MC1): Located within thumb pad.

  • Metacarpal V (MC5): The last metacarpal on the pinky side.

Carpals (Wrist Bones)

Rows of Carpals

  • Row 1: S: Scaphoid, L: Lunate, Tri: Triquetrum, P: Pisiform

  • Row 2: T1: Trapezium, T2: Trapezoid, C: Capitate, H: Hamate

  • Notes:

    • Carpals are ordered from lateral to medial; Pisiform fuses to Triquetrum and is superimposed in X-ray images.