Upper limb

Bones

  • Clavicle
    • Connect trunk (sternoclavicular joint) to upper limb (acromioclavicular joint)
    • Medial 2/3 convex anteriorward and arches anterior to brachial plexus and subclavian vessels
      • Also attachment for costoclavicular ligament and subclavius (attach to 1st rib) (muscle pulls the clavicle down; ligament resists downward movement)
    • Lateral 1/3 concave anteriorward and flattened.
      • Also attachment of coracoclavicular ligament (attach to coracoid process) (keeping clavicle in place resisting upward movement)
    • First bone to begin ossification
  • Scapula
    • Connects the clavicle to humerus, resting on the superior part of the posterolateral thorax
    • The dorsal surface is divided by a spine- with a supraspinatous fossa above and an infraspinatous fossa below
    • The trapezius and deltoid attach to the crest of the spine
  • Humerus
    • Articulates with the scapula at the glenoid (shoulder) and the radius and ulna
    • Proximal end consists of head, anatomical neck (the surgical neck is different- where the superior part meets the shaft- the axillary nerve lies in contact with this), and greater and lesser tubercles (separated by intertubercular groove)
      • The greater tubercle projects laterally beyond the acromion and is covered by the deltoid
      • The lesser tubercle projects anteriorly
      • The intertubercular groove provides origin for the tendon of the long head of the biceps
    • The deltoid muscle inserts into the deltoid tuberosity on the anterolateral surface of the shaft near the middle
    • The radial nerve runs inferiorward and lateral on the posterior surface in a groove of the humerus
    • Distal end consists of lateral and medial epicondyles separated by capitulum and trochlea
      • The lateral epicondyle gives origin to supinator and extensor muscles
      • The capitulum articulates with the head of the radius
      • The trochlea is a pulley-shaped projection that articulates with the ulna (trochlear notch of ulna)
      • A deeper olecranon fossa is located posteriorly and superiorly
      • The medial epicondyle gives origin to the flexor muscles of the forearm
        • The ulnar nerve lies in a groove posterior to the medial epicondyle (funny bone)
  • Radius
    • Proximal end articulates with humerus, medial aspect with the ulna and distally with the carpi bones
    • Proximal end consist of head, neck and tuberosity.  Articulates with the capitulum of the humerus
    • The medial (interosseus) surface of the shaft connects with the lateral (interosseus) surface of the ulna via an interosseus membrane
    • Distal end consists of styloid process laterally- gives attachment to radial colateral ligament of the wrist; and ulnar notch medially which articulates with the ulna
  • Ulna
    • Longer and medial to radius; and articulates with the humerus proximally, radius laterally and articular disc distally
    • Proximal end includes olecranon and coronoid process.
      • Olecranon is prominence of the elbow.  The superior part receives insertion of the tendon of the triceps.  The anterior part forms part of the trochlear notch, articulating with the humerus.
      • The coronoid process completes the trochlear notch and also forms a radial notch laterally for articulation with the radius
    • Distal end includes the styloid process and the head
      • Styloid process is posteromedially
      • The head articulates with the ulnar notch of the radius and the inferior aspect articulates with the articular disc (separating from the carpi)
  • Carpal Bones
    • Mnemonic (from lateral to medial, proximal row first then distal row)
      • “Some lovers try positions that they can’t handle”
        • Scaphoid
        • Lunate (articulates with radius)
        • Triquetrum
        • Pisiform
        • Trapezium (articulates with the first (thumb) MC)
        • Trapezoid
        • Capitate (largest- articulates with 3rd MC)
        • Hamate (gives attachment to flexor retinaculum)
      • NB the trapezium and scaphoid make up the floor of the anatomical snuff box- the radial artery crosses it

Veins

  • Superficial
    • Variable but two large superficial veins can usually be found in most- the cephalic and basilic
      • Cephalic vein begins posterior to the styloid of the radius, winds anteriorly around the lateral border of the forearm, reaches the antecubital fossa lateral to the elbow, ascends laterally to the biceps, then in the groove between the deltoid and pectoralis major and drains into the axillary vein
      • Basilic vein curve anteriorly round the medial border of the forearm up to the medial epicondyle, ascends medial to the biceps, pierces the fascia and accompanies the brachial artery to the axilla, where it joins the brachial veins and becomes axillary vein
    • In the cubital fossa, they are often joined by via a medial cubital vein
  • Deep 
    • Largely accompany arteries

Arteries

  • In order (proximal to distal)-
    • Subclavian, axillary and brachial
      • Subclavian arches above the first rib to become the axillary.
        • The axillary apex is the interval between the clavicle, superior border of scapular and external border of the 1st rib.  The axillary vessels/nerve pass through this
        • Pec minor crosses the axillary, dividing is into 3 (medial, posterior and lateral)
      • At the base of the axilla (inferior border of teres major), the axillary becomes the brachial.
        • NB the brachial artery supplies the deep flexor muscles of the forearm (injury results in flexion deformities)
    • Immediately distal to the elbow, the brachial divides into radial and ulnar arteries
      • the radial artery lies lateral to the flexor carpi radialis tendon and can be readily palpated at the wrist here.

Nerves

  • Arise from brachial plexus (posterior triangle of neck, under the clavicle with the axillary artery under the pec major in the axilla- C5-T1)
  • Divides into
    • Trunks
      • Upper (C5, 6- flexion)
      • Middle (C7- pronation and supination)
      • Lower (C8, T1- extension)
    • Trunks-> cords
      • Upper and middle anterior divisions form lateral cord (in relation to axillary artery)
      • Lower anterior division forms medial cord
      • Posterior divisions from all trunks forms posterior cord (supplies the dorsal arm)
    • Cords -> branches
      • Lateral cord
        • Musculocutaneous (C5-7)
          • Pierces corachobrachialis; may carry all or part of the lateral head of the median nerve
          • Supplies flexor muscles (biceps, coracobrachialis and brachialis) of the anterior arm and the skin on the lateral forearm
          • Terminates as the antebrachial cutaneous nerve
        • Median (C6-T1)
          • Arises from both lateral and medial cords (lateral and medial heads of median nerve)
          • Supplies flexors and pronators in the forearm, most of the thumb muscles and skin of the lateral (radial) hand
          • Doesn’t give off any branches in the arm, but crosses anteriorly and descends medially before entering the forearm in the antecubital fossa between the heads of pronator teres muscle and descends between the bones of the forearm until it reaches the styloid processes where it moves anteriorly between the flexor digitorum superficialis (medially) and flexor carpi radialis (laterally).  It enters the hand through the ‘carpal tunnel’ posterior to the flexor retinaculum and anterior to the flexor tendons.
      • Medial cord
        • Ulnar nerve (C7-T1)
          • Supplies some of the flexor muscles of forearm, short muscles of the hand and skin of the ulnar and dorsal aspect of the hand
          • The ulnar nerve does not give off any branches in the arm but enters the forearm between the heads of the flexor carpi ulnaris at the posterior surface of the medial epicondyle.  It travels down the medial forearm towards the hamate/pisiform.  It lies between the flexor digitorum superficialis (laterally) and the flexor carpi ulnaris (medially) and passes anterior to the flexor retinaculum
      • Posterior
        • Axillary (C5,6)
          • Transverses through the quadrangular space between the long and lateral heads of the triceps
          • Anterior branch winds around the surgical neck of humerus and supples deltoid
          • Posterior branch supplies teres minor and deltoid and becomes the upper lateral brachial cutaneous nerve (supplying the ‘badge-patch’ area of skin over the lateral upper arm)
        • Radial (C5-T1)
          • Continuation of posterior cord
          • Spirals round posterior aspect of humeral shaft under the long and lateral head of triceps, deep into the antecubital fossa between the brachioradialis and brachialis muscles.  At the antecubital fossa it divides into deep and superficial branches, the former supplying cutaneous innervation to the dorsum of the hand and the latter winds round the radius between layers of supinator close to the radius (can be injured) to supply posterior muscles of the forearm as the posterior interosseus nerve
          • Supplies the extensors and supinators of the posterior arm and forearm and the skin on the posterior arm, forearm and over the anatomical snuffbox of the hand

Muscles of the Shoulder/Axilla

  • Upper limb connected to the trunk ventrally by
    • Pectoralis major
      • Origin: Medial half of clavicle (head); anterior sternum; costal cartilages; aponeurosis of external oblique
      • Insertion: Lateral lip of intertubercular groove of the humerus
      • Innervation: Lateral and medial pectoral nerves (from lateral and medial cords of plexus, respectively; C5, 6 and 7, and C8 and T1, respectively)
      • Action: Arm adductor
    • Pectoralis minor
      • Origin: Ribs 2-5
      • Insertion: Coracoid process (scapula)
      • Innervation: medial and lateral pectoral
      • Action: adducts and depresses shoulder
    • Subclavius
    • Serratus anterior
      • Origin: Ribs 1-8
      • Insertion: Costal aspect of the superior, medial and inferior angles/borders of the scapula
      • Innervation: Long thoracic nerve (C5-7)
      • Action: rotates scapula (paralysis causes ‘winging’)
  • Muscles of the back
    • Latissimus dorsi and trapezius (also levator scapulae and rhomboid muscles)
      • Trapezius
        • Large, superficial triangular muscle
        • Origin: Spines of cervical vertebrae (C7,8) and thoracic vertebrae T1-12
        • Insertion: Lateral third of clavicle, acromion and spine of scapula
        • Innervation: CNXI and C3,4
        • Action: Elevates shoulder and retracts and rotates scapula
      • Latissimus dorsi
        • Origin: Spines of T7-12; iliac crest; lower ribs and inferior angle of scapula
        • Insertion: intertubercular groove of humerus
        • Innervation: thoracic nerves
        • Action: Adducts and extends arm
  • Muscles of the shoulder
    • Deltoid
      • Origin: Lateral third of clavicle, acromion and spine of scapula
      • Insertion: deltoid tuberosity of humerus
      • Innervation: Axillary nerve (posterior cord: C5/6)
      • Abducts arm (30-120°)
    • Supraspinatous
      • Origin: Supraspinatous fossa of scapula
      • Insertion: greater tubercle of humerus
      • Innervation: suprascapular nerve (C3-4)
      • Action: abducts arm (0-30°)
    • Infraspinatous
      • Origin: infraspinatous fossa
      • Insertion: greater tubercle
      • Innervation: suprascapular nerve
      • Action: Externally rotates shoulder
    • Teres minor
      • Origin: Lateral part of dorsal surface of scapula
      • Insertion: Greater tubercle
      • Innervation: Axillary nerve (C5/6)
      • Action: external rotation
    • Teres major (NB divided from teres minor by the long head of the triceps, which forms a triangular space medially (subscapular artery space) and quadrangular space medially (posterior circumflex humeral artery and axillary nerve space)
      • Origin: Dorsal inferior angle of scapula
      • Insertion: Medial lip of intertubercular groove of humerus
      • Innervation: Lower subscapular
      • Action: Adducts arm
    • Subscapularis
      • Origin: Subscapular fossa of scapula
      • Insertion: Lesser tubercle
      • Innervation: Subscapular (upper and lower: c5/6)
      • Action: Internal rotation

Muscles of the Arm

  • Biceps, coracobrachialis and brachialis (musculocutaneous nerve); Triceps (radial nerve)
    • Separated (anterior and posteriorly) by intermuscular septa
  • Biceps brachii
    • Origin: Supraglenoid tubercle of scapula (long/lateral head) and tip of coracoid process (short/medial head)
    • Insertion: Tuberosity of radius, fascia of forearm, and ulna (bicipital aponeurosis)
      • NB the brachial artery and median nerve lie medial to the biceps tendon in the cubital fossa
    • Innervation: Musculocutaneous (c5-7)
    • Action: Flexes arm and supinates forearm
  • Coracobrachialis
    • Origin: Tip of coracoid process
    • Insertion: medial border of humerus
    • Innervation: musculocutaneous (pierces the muscle)
    • Action: assists in flexion
  • Brachialis
    • Origin: Anterolateral (next to deltoid insertion) and anteromedial surfaces of humerus
    • Insertion: Front or coranoid process and tuberosity of ulna
    • Innervation: musculocutaneous
    • Action: Flexes forearm
  • Triceps brachii
    • Origin: Infraglenoid tubercle of scapula (long head) and posterior surfacne of humerus (lateral and medial heads)
    • Insertion: Upper surface of olecranon and fascia of forearm
    • Innervation: Radial (C5-T1)
    • Action: extends forearm

Muscles of the Forearm

  • Split into 2 compartments: ventromedial or flexor (anterior), and dorsolateral or extensor (posterior)
  • NB Most of the anterior superficial group arise from common flexor tendon (medial epicondyle) and most of the posterior superficial group arise from common extensor tendon (lateral epicondyle)
  • Anterior (superficial)
    • Pronator teres
      • Origin: Medial supracondylar ridge and coranoid process of ulna (deep head)
      • Insertion: lateral surface of radius
      • Innervation: Median (C6-T1)
      • Action: Pronates and flexes forearm
    • Flexor carpi radialis
      • Origin: medial epicondyle
      • Insertion: bases of 2/3rd MCs
      • Innervation: median
      • Action: Flexes and abducts hands
    • Palmaris longus
      • Origin: Medial epicondyle
      • Insertion: Flexor retinaculum and palmar aponeurosis
      • Innervation: median
      • Action: hand flexion
    • Flexor carpi ulnaris
      • Origin: Medial epicondyle and olecranon
      • Insertion: pisiform, hamate and 5th MC
      • Innervation: Ulnar (C7-T1)
      • Action: Flexes and adducts the hand
  • Intermediate
    • Flexor digitorum superficialis
      • Origin: Medial epicondyle and anterior border of radius
      • Insertion: Middle phalanges of digits 2-5
      • Innervation: Median
      • Action: Flexes middle fingers
  • Deep
    • Flexor digitorum profundus
      • Origin: Front of ulna and interosseous membrane
      • Insertion: distal phalanges of digits 2-5
      • Innervation: Anterior interosseous (median)
      • Action: Flexes distal phalanges
    • Flexor pollicis longus
      • Origin: Front of radius and interosseous membrane
      • Insertion: Distal phalanx of thumb
      • Innervation: anterior interosseous
      • Action: Flexes distal phalanx of thumb
    • Pronator quadratus
      • Origin: Front of distal ulna
      • Insertion: Front of distal radius
      • Innervation: anterior interosseous
      • Action: pronates forearm
  • Posterior (superficial)
    • Brachioradialis
      • Origin: Lateral supracondylar ridge
      • Insertion: Lateral distal radius
      • Innervation: radial
      • Action: Flexes forearm
    • Extensor carpi radialis longus
      • Origin: Lateral supracondylar ridge
      • Insertion: Base of 2nd MC
      • Innervation: Radial
      • Action: Extend and abducts hand
    • Extensor carpi radialis brevis (NB common site for ganglion formation)
      • Origin: Lateral epicondyle
      • Insertion: Bases of 2/3rd MC
      • Innervation: Radial
      • Action: Extends and abducts hand
    • Extensor digitorum
      • Origin: Lateral epicondyle
      • Insertion: Middle and distal phalanges of 2-5
      • Innervation: Deep branch of radial
      • Action: Extends proximal phalanges
    • Extensor digiti minimi
      • Origin: Lateral epicondyle
      • Insertion: Extensor expansion of 5th finger
      • Innervation: deep branch of radial
      • Action: Extends proximal phalanx of 5th finger
    • Extensor carpi ulnaris
      • Origin: Lateral epicondyle and posterior border of ulna
      • Insertion: base of 5th MC
      • Innervation: deep branch of radial
      • Action: extends and adducts hand
    • Anconeus
      • Origin: Lateral epicondyle
      • Insertion: olecranon
      • Innervation: radial
      • Action: stabilise elbow
  • Deep
    • Supinator
      • Origin: lateral epicondyle
      • Insertion: Upper third of radius
      • Innervation: Deep branch of radial
      • Action: supinates forearm
    • Abductor pollicis longus
      • Origin: Interosseous membrane, radius and ulna
      • Insertion: Base of 1st MC
      • Innervation: Posterior interosseous (deep branch of radial)
      • Action: Abducts 1st phalanx
    • Extensor pollicis brevis
      • Origin: Interosseous membrane and radius
      • Insertion: proximal phalanx of thumb
      • Innervation: posterior interosseous
      • Action: Extends thumb
    • Extensor pollicis longus
      • Origin: Interosseous membrane and ulna
      • Insertion: Distal phalanx of thumb
      • Innervation: Posterior interosseous
      • Action: Extends distal thumb
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