Bones & Joints of the Upper Limb – Comprehensive Study Notes

Objectives

  • Identify and name every bone of the pectoral girdle and upper limb.
  • Recognize the key surface landmarks of the long bones (e.g.
    • condyle, epicondyle, tubercle, tuberosity, olecranon).
  • Recall the eight carpal and five metacarpal bones in sequence.
  • Summarize the construction and stabilizers of the major upper-limb joints:
    • Shoulder (glenohumeral) – incl. rotator-cuff ("SITS") muscles.
    • Elbow (humeroulnar–humeroradial + proximal radioulnar).
    • Wrist (radiocarpal) – incl. collateral and radiocarpal ligaments.

Skeletal Overview of the Upper Limb

  • Appendicular skeleton portion.
  • Each limb = 30 bones
    • 1 humerus
    • 1 radius + 1 ulna
    • 8 carpals
    • 5 metacarpals
    • 14 phalanges (2,3,3,3,3)(2,3,3,3,3)
  • Pectoral (shoulder) girdle attaches limb to axial skeleton:
    • Clavicle – anterior strut
    • Scapula – posterior, muscularly suspended

Pectoral (Shoulder) Girdle

Clavicle
  • S-shaped, subcutaneous, two ends & shaft
    • Medial (sternal) end – articulates with manubrium
    • Lateral (acromial) end – articulates with acromion
  • Surface landmarks
    • Superior surface: acromial facet
    • Inferior surface: conoid tubercle (attachment for conoid ligament)
Sternoclavicular (SC) Joint
  • Synovial saddle joint; only true axial–appendicular articulation.
  • Articulating surfaces: medial clavicle, clavicular notch of sternum, 1st costal cartilage.
  • Intra-articular fibrocartilaginous disc ⇒ ↑ congruence, allows ↑/↓\uparrow/\downarrow, AP glide.
  • Capsule reinforced by:
    • Anterior & posterior SC ligs.
    • Interclavicular lig.
    • Costoclavicular lig.
  • Blood supply: internal thoracic & suprascapular aa.
  • Innervation: medial supraclavicular nn., nerve to subclavius.
  • Movements occur during elevation, depression, protraction, retraction of shoulder.
Scapula
  • Flat, triangular; spans ribs 2–7; inferior angle at T7T7 level.
  • Bony landmarks
    • Spine, acromion, coracoid process
    • Glenoid cavity (lateral), supra-/infra-spinous fossae, subscapular fossa
    • Borders: superior, medial (vertebral), lateral (axillary)
    • Angles: superior, inferior
  • Muscular suspension = NO bony articulation with axial skeleton posteriorly.
Acromioclavicular (AC) Joint
  • Synovial plane joint between acromion & lateral clavicle.
  • Capsule + synovial membrane.
  • Ligaments
    • AC ligament (horizontal, capsular).
    • Coracoclavicular lig. (strong accessory) → divided into:
    • Trapezoid lig. → trapezoid line of clavicle.
    • Conoid lig. → conoid tubercle.
  • Innervation: suprascapular n. • Vascular: thoracoacromial & suprascapular aa.
  • Small gliding during scapular rotation or clavicular elevation/depression.

Arm – Humerus

Proximal End
  • Head (articulates with glenoid).
  • Anatomical neck (capsular attachment).
  • Greater & lesser tubercles separated by intertubercular (bicipital) groove.
  • Surgical neck (common fracture site).
Shaft
  • Three borders: anterior, lateral, medial.
  • Three surfaces: anterolateral, anteromedial, posterior.
  • Deltoid tuberosity (lateral) & radial groove (posterior; radial n. + profunda brachii a.).
Distal End
  • Condyles
    • Capitulum (lateral; articulates with radius).
    • Trochlea (medial; articulates with ulna).
  • Fossae (anterior): radial & coronoid; (posterior): olecranon.
  • Epicondyles: medial (ulnar n. groove) & lateral.

Glenohumeral (Shoulder) Joint

  • Synovial ball-and-socket.
  • Articular surfaces: large humeral head vs. shallow glenoid cavity.
  • Glenoid labrum (fibrocartilage) deepens socket.
  • Capsule: thin, lax → attached medial to glenoid labrum & lateral to anatomical neck; inferiorly descends on shaft.
  • Synovial membrane features
    • Sheath for tendon of long head of biceps.
    • Communicates with subscapular bursa.
Intrinsic Ligaments (Capsular Thickenings)
  • Superior, Middle, Inferior Glenohumeral (GH) ligs.
  • Coracohumeral lig. (coracoid → greater tubercle) supports superiorly.
  • Transverse humeral lig. bridges bicipital groove → retains biceps tendon.
Accessory Ligament
  • Coracoacromial arch (coracoid → acromion) acts as "roof" preventing superior dislocation.
Bursae Around Joint
  • Subacromial / subdeltoid bursa (NOT communicating with joint).
  • Subscapular bursa (communicates).
Rotator-Cuff (Musculotendinous Cuff) – "SITS"
  • Supraspinatus, Infraspinatus, Teres minor, Subscapularis.
  • Blend with capsule, hold humeral head in glenoid during motion.
  • Additional stabilizer: tendon of long head of biceps passes intracapsularly.
Vascular & Neural Supply
  • Anterior & posterior circumflex humeral aa.; suprascapular a.
  • Suprascapular, axillary, upper & lower subscapular nn. (muscular branches to cuff also supply capsule).
Movements & Prime Movers
  • Flexion: Pectoralis major (clav. head), anterior deltoid, coracobrachialis, biceps brachii.
  • Extension: Latissimus dorsi, teres major, posterior deltoid.
  • Abduction: Supraspinatus 0–15∘0–15^{\circ}, middle deltoid 15–90∘15–90^{\circ}, trapezius + serratus anterior (scapular rotation >90^{\circ}).
  • Adduction: Pectoralis major, latissimus dorsi, teres major.
  • Medial (internal) rotation: Subscapularis, pectoralis major, lat. dorsi, teres major, anterior deltoid.
  • Lateral (external) rotation: Infraspinatus, teres minor.
  • Circumduction = sequential combination.

Forearm Bones

Radius (lateral)
  • Proximal: head (articulates with capitulum & radial notch), neck, radial tuberosity (biceps insertion).
  • Shaft: borders (anterior, posterior, interosseous); surfaces (anterior, lateral, posterior).
  • Distal: styloid process (lateral), Lister’s dorsal tubercle, ulnar notch (medial), inferior articular surface (scaphoid & lunate).
Ulna (medial)
  • Proximal extremity
    • Olecranon & coronoid processes forming trochlear notch.
    • Radial notch (lateral) for radial head.
  • Shaft: borders (interosseous, anterior, posterior); surfaces (anterior, medial, posterior).
  • Distal: small rounded head + styloid process; articular disc attaches.
Interosseous Membrane
  • Fibrous sheet binding shafts; force transmission radius → ulna → humerus.
Proximal Radioulnar Joint
  • Synovial pivot, shares capsule with elbow.
  • Radial head spins within annular ligament against radial notch of ulna.
Distal Radioulnar Joint
  • Synovial pivot between ulnar head & ulnar notch of radius; reinforced by anterior & posterior ligs.
  • Articular disc (triangular fibro-cartilage) separates from wrist joint.
Movements at Both Radioulnar Joints
  • Supination (palm anterior/superior): Biceps brachii, supinator.
  • Pronation (palm posterior/inferior): Pronator teres, pronator quadratus.

Elbow Complex

Humeroulnar & Humeroradial (Elbow) Joint
  • Synovial hinge allowing flexion/extension.
  • Articulation: trochlea ↔ trochlear notch; capitulum ↔ radial head.
  • Capsule
    • Anterior attached above coronoid & radial fossae → coronoid process & annular lig.
    • Posterior attached above olecranon fossa → olecranon.
  • Synovial membrane continuous with proximal radioulnar cavity.
Collateral Ligaments
  • Ulnar (medial) collateral ligament (triangular): anterior, posterior, transverse bands.
  • Radial (lateral) collateral ligament: lateral epicondyle → annular ligament.
Annular Ligament
  • Encircles radial head; maintains contact with ulna.
  • Clinical: "pulled elbow" (radial head subluxation) in children when traction tears distal attachment of annular lig.
Movements & Muscles
  • Flexion: Brachialis, biceps brachii, brachioradialis (+ pronator teres synergist).
  • Extension: Triceps brachii, anconeus.
  • Stability: osseous congruity (ulna-humerus), capsule, collateral ligaments.

Wrist & Hand

Carpal Bones (8)

Mnemonic: "Stop Letting Those People Touch The Cadaver's Hand"

  • Proximal (lat→med): Scaphoid, Lunate, Triquetrum, Pisiform (sesamoid).
  • Distal (lat→med): Trapezium, Trapezoid, Capitate, Hamate.
Carpal Arch / Carpal Tunnel Borders
  • Lateral pillars: tubercles of scaphoid & trapezium.
  • Medial pillars: pisiform & hook of hamate.
Metacarpals
  • Five, numbered lateral (thumb) to medial.
  • Each has base, shaft, head (distal knuckle).
Phalanges
  • 14 per hand: thumb = 2 (proximal, distal); fingers = 3 each.
Radiocarpal (Wrist) Joint
  • Synovial ellipsoid between distal radius + articular disc (ulna) & proximal row scaphoid, lunate, triquetrum.
  • Capsule encloses; synovial membrane lines.
  • Ligaments:
    • Palmar radiocarpal
    • Dorsal radiocarpal
    • Radial collateral (lat.)
    • Ulnar collateral (med.)
  • Movements
    • Flexion / extension
    • Abduction (radial deviation) / adduction (ulnar deviation)
    • Circumduction (combined).

Summary of Key Clinical/Functional Points

  • SC joint disc = shock absorber; only joint linking upper limb to trunk skeleton → mobility > stability.
  • AC joint supported primarily by coracoclavicular lig.; disruption ⇒ "shoulder separation".
  • Glenohumeral joint trades stability for range; rotator-cuff tears & subacromial impingement common.
  • Surgical neck fractures endanger axillary n.; mid-shaft humeral fractures risk radial n. in radial groove.
  • Pulled (nursemaid’s) elbow: sudden traction → radial head slips from annular ligament in children.
  • Scaphoid fractures disrupt radial a. branches → risk of avascular necrosis of proximal fragment.
  • Colles’ fracture: distal radius dorsal displacement; affects radiocarpal alignment.

Integrated Functional Chain

  • Shoulder girdle positioning (SC + AC + scapulothoracic glide) essential for full 180∘180^{\circ} arm elevation.
  • Force transmission path in fall on outstretched hand: hand → carpals → radius → interosseous membrane → ulna → humerus → shoulder girdle.
  • Muscular synergy: rotator-cuff holds head while deltoid abducts; trapezius/serratus rotate scapula beyond 90∘90^{\circ}.

Ethical / Practical Implications

  • Understanding joint congruency & ligamentous support guides orthopedic repair (e.g.
    • reconstructing UCL in throwers – "Tommy John" surgery).
  • Knowledge of neurovascular supply critical for surgical approaches and avoiding iatrogenic injury.
  • Anatomical variations (e.g.
    • accessory ossicles, bifid median n.) require imaging correlation to prevent misdiagnosis.