Muscles of upper limb

Pectoral region

• Located in the anterior chest wall

• Contains the breast and four muscles

• Pectoralis major, pectoralis minor, serratus anterior and subclavius

Clavipectoral fascia

• Fibromuscular sheet situated deep to the clavicular portion of pectoralis major

• Vertically- superiorly splits to enclose subclavius muscle and attached to clavicle

• Horizontally- medially attached to 1st rib, costocoracoid ligament

• Laterally- attached to coracoid process and blends with coracoclavicular ligament

• Pierced by- lateral pectoral nerve, cephalic vein, thoracoacromial vessels and lymphatics

Muscles of pectoral region

	ORIGIN	INSERTION	ACTION	INNERVATION
Pectoralis major
Clavicular head Sternocostal head	Anterior surface of medial ½ of clavicle Anterior surface of sternum, 2nd to 6th costal cartilages	Lateral lip of bicipital groove	Adduction and medial rotation of shoulder	Lateral and medial pectoral nerve
Pectoralis minor	From 3rd to 5th rib near the costochondral junction	Medial border and superior surface of coracoid process	Draws scapula forward, depresses the point of the shoulder	Lateral and medial pectoral nerve
Subclavius	1st rib at costochondral junction	Subclavian groove of inferior surface of clavicle	Steadies clavicle during movement	Nerve to subclavius
Serratus anterior	8 digitations from the outer surface of the upper 8 ribs	1st attached to superior angle 2-3 attached to lateral border last 4-5 attached to inferior angle	Protracts scapula around chest wall	Long thoracic nerve

Axilla

• Has apex, base and 4 walls

Apex

• In front clavicle

• Behind superior border of scapula

• Medially outer border of 1st rib

Anterior wall

• Pectoralis major and minor, clavipectoral fascia and subclavius

Posterior wall

• Subscapularis, teres major and latissimus dorsi

Medial wall

• Upper 4 ribs with their intercostal muscles

Lateral wall

• Formed by upper part of shaft of humerus and coracobrachialis

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Contents of axilla

• Axillary artery

• Axillary vein

• Infra-clavicular part of brachial plexus

• Axillary lymph nodes (anterior, posterior, lateral, central, apical)

• Long thoracic nerve

• Intercostobrachial nerve

• Axillary pad of fat

Brachial plexus

• Formed from ventral rami C5 to T1

• Pre-fixed, C5 large, C4 present, T1 small and T2 absent

• Post-fixed, T1 large, T2 present, C5 small and C4 absent

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Branches from cord

Lateral cord

• Lateral pectoral nerve

• Lateral root of median nerve

• Musculocutaneous nerve

Medial cord

• Medial root of median nerve

• Medial cutaneous nerve of arm

• Medial cutaneous nerve of forearm

• Medial pectoral nerve

• Ulna nerve

Posterior cord

• Upper subscapular

• Lower subscapular

• Thoracodorsal nerve

• Radial nerve

• Axillary nerve

Erb’s point

Consists of C5, C6 ventral and dorsal division of upper trunk, suprascapular and nerve to subclavius

Clinical anatomy of brachial plexus

Muscles of back

Superficial- latissimus dorsi and trapezius

Deep- levator scapulae, rhomboid major and minor

	ORIGIN	INSERTION	ACTION	INNERVATION
Trapezius	Ligamentum nuchae, superior nuchal line, external occipital protuberance, spinous process of C7 to T12	Lateral 1/3 of clavicle, medial margin of acromion, upper lip of crest of spine of scapula	Superior fibres elevate Middle fibres retract Inferior fibres depress	Spinal part of accessory nerve
Latissimus dorsi	Spinous process of lower 6 thoracic vertebrae, inferior angle of scapula, posterior 1/3 of outer lip of iliac crest, posterior layer of thoracolumbar fascia	Floor of bicipital groove	Extends, adducts and medially rotates humerus	Thoracodorsal nerve
Levator scapulae	Posterior tubercle of transverse process of C1 to C4	Superior surface of medial border of scapula	Elevates scapula and tilts glenoid cavity inferiorly	Dorsal scapula nerve
Rhomboid	Minor- lower ligamentum nuchae, spinous process of C7 & T1 Major- spinous process of T2-T5	Medial border of scapula from level of spine to inferior angle	Retracts scapula and/ rotates it to depress glenoid cavity	Dorsal scapular nerve

Muscles of scapular region

	ORIGIN	INSERTION	ACTION	INNERVATION
Supraspinatus	Supraspinous fossa	Superior facet of greater tubercle	Initiates and assists deltoid with abduction	Suprascapular nerve
Infraspinatus	Infraspinous fossa	Middle facet of greater tubercle	Laterally rotates arm	Suprascapular nerve
Teres minor	Superior part of lateral border of scapula	Inferior facet of greater tubercle	Laterally rotates arm	Axillary nerve
Teres major	Dorsal surface of inferior angle of scapula	Medial lip of bicipital groove	Medially rotates and adducts	Lower scapular nerve
Subscapularis	Subscapular fossa	Lesser tubercle	Medially rotates and adducts	Upper and lower scapular nerve
Deltoid	Acromion process, anterior border of lateral 1/3 clavicle, lower lip of crest of spine	Deltoid tuberosity	Anterior flexes and medially rotates Middle abducts Posterior extends and laterally rotates	Axillary nerve

Intermuscular spaces

Formed by scapular muscles, humerus and long head of triceps

• Quadrangular space

• Upper triangular space

• Lower triangular space

Quadrangular space

• Superior- subscapularis, capsular ligament of shoulder joint, teres minor

• Inferior- teres major

• Medial- long head of triceps

• Lateral- surgical neck of humerus

• Contents- axillary nerve and posterior circumflex humeral vessels

Upper triangular space

• Medial- teres minor

• Lateral- long head of triceps

• Inferior- teres major

• Contents- circumflex scapular artery

Lower triangular space

• Medial- long head of triceps

• Lateral – medial border of humerus

• Superior – teres major

• Contents – radial nerve and profunda brachii vessels

Clinical correlation of shoulder

Compartments of arm

Medial and lateral intermuscular septae arises from deep fascia and divides arm into flexor and extensor compartment

Contents of flexor compartment

• Muscles- biceps brachii, coracobrachialis and brachialis

• Nerve- musculocutaneous

• Artery- brachial

Contents of posterior compartment

• Muscles- triceps

• Nerve- radial

Muscles of arm

Flexor compartment

	ORIGIN	INSERTION	ACTION	INNERVATION
Coracobrachialis	Tip of coracoid process	Middle 1/3 of medial border of humerus	Flexes and adducts arm	Musculocutaneous nerve
Biceps brachii	Short head- tip of coracoid process Long head- supraglenoid tubercle	Tuberosity of radius and deep fascia of forearm	Supinator of forearm Flexor of elbow	Musculocutaneous nerve
Brachialis	DIstal half of anteromedial and anterolateral surface of humerus Medial and lateral intermuscular septae	Coronoid process and tuberosity of ulna	Major flexor of forearm	Musculocutaneous nerve

Posterior compartment

	ORIGIN	INSERTION	ACTION	INNERVATION
Triceps brachii	Long head- infraglenoid tubercle Lateral head- posterior surface of humerus, superior to radial groove Medial head- posterior surface of humerus, inferior to radial groove	Posterior part of superior surface of olecranon process of ulna	Chief extensor of forearm	Radial nerve

Cubital fossa

• Triangular hollow region situated in front of the elbow joint

Boundaries

• Laterally- medial border of brachioradialis

• Medially- lateral border of pronator teres

• Base- directed upwards and formed by an imaginary line joining two epicondyles

• Apex- directed downwards and formed by overlapping of medial and lateral boundaries

• Roof- skin, superficial fascia with its contents, deep fascia

• Floor- brachialis above and supinator below

Contents

• Median nerve

• Tendon of biceps brachii

• Termination of brachial artery

• Ulnar artery

• Radial artery

• Radial nerve

Forearm

Contains anterior and posterior compartment

Anterior compartment

• Superficial- pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor carpi ulnaris

• Deep- flexor policis longus, flexor digitorum profundii, pronator quadratus

• Radial and ulnar arteries

• Median, ulnar and radial nerves

Posterior compartment

• Superficial- anconeus, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris

• Deep- supinator, abductor pollicis longus, extensor policis brevis, extensor indicis

Flexor muscles of forearm

	ORIGIN	INSERTION	ACTION	INNERVATION
Pronator teres	Medial epicondyle and coronoid process of ulna	Middle 1/3 of lateral surface of radius	Pronates and flexes forearm at elbow	Median nerve
Flexor carpi radialis	Medial epicondyle	Base of 2nd and 3rd metacarpal bone	Flexes and abducts hand at wrist	Median nerve
Palmaris longus	Medial epicondyle	Distal half of flexor retinaculum and apex of palmar aponeurosis	Flexes hand at wrist and tightens palmar aponeurosis	Median nerve
Flexor digitorum superficialis	Humeroulnar- medial epicondyle, ulnar collateral ligament and coronoid process of ulnar Radial- upper half of anterior border of radius	Bodies of phalanges 2-3	Flexes middle phalanges at proximal interphalangeal joint	Median nerve
Flexor carpi ulnaris	Humeral- medial epicondyle Ulnar- olecranon and posterior border of ulnar	Pisiform bone, hook of hamate and 5th metacarpal	Flexes and adducts at wrist	Ulnar nerve
Flexor digitorum profundus	Proximal ¾ of medial and anterior surface of ulnar and interosseous membrane	Base of distal phalanx 2-5	Flexes distal phalanges at distal interphalangeal joint	Medial- ulnar nerve Lateral- anterior interosseous branch of median nerve
Flexor pollicis longus	Anterior surface of radius and interosseous membrane	Base of distal phalanx of thumb	Flexes phalanges of 1st digit	Anterior interosseous nerve from median nerve
Pronator quadratus	Distal ¼ of anterior surface of ulna	Distal ¼ of anterior surface of radius	Pronates forearm	Anterior interosseous nerve from median nerve

Flexor retinaculum

Fibrous band which bridges anterior concavity of carpals and creates a tunnel

Attachment

• Medially- pisiform bone and hook of hamate

• Laterally- tubercle of scaphoid and crest of trapezium

Structures superficial

• Tendon of palmaris longus

• Palmar cutaneous branch of median and ulnar nerve

• Ulnar vessels

Structures deep

• Median nerve

• Ulnar bursa

• Tendons of FDS, FPL, FDP

Carpal tunnel syndrome

Extensor muscles of the forearm

	ORIGIN	INSERTION	ACTION	INNERVATION
Aconeus	Posterior aspect of lateral epicondyle	Lateral surface of olecranon and superior part of posterior surface of ulna	Weak extensor of elbow, stabilizes joint	Radial nerve
Brachioradialis	Proximal 2/3 of lateral supracondylar ridge of humerus and lateral intermuscular septum	Lateral surface of distal end of radius just above styloid process	Flexor of forearm	Radial nerve
Extensor carpi radialis longus	Lower 1/3 of lateral supracondylar ridge of humerus, lateral intermuscular septum	Dorsal surface of base of 2nd metacarpal bone	Extension and abduction of hand at wrist	Radial nerve
Extensor carpi radialis brevis	Common extensor origin and radial collateral ligament below elbow	Dorsal aspect of base of 2nd and 3rd metacarpals	Extension and abduction of hand at wrist	Posterior interosseous nerve
Extensor digitorum	Common extensor origin	Extensor expanasion of medial 4	Extension of interphalangeal, metacarpophalangeal and wrist joint	Posterior interosseous nerve
Extensor digiti minimi	Common extensor origin	Extensor expansion of 5th	Extends 5th digit at metacarpophalangeal and interphalangeal joint	Posterior interosseous nerve
Extensor carpi ulnaris	Common extensor origin and posterior border of ulna	Medial side of base of 5th	Extends and adducts at wrist	Posterior interosseous nerve

	ORIGIN	INSERTION	ACTION	INNERVATION
Supinator	Lateral epicondyle, radial collateral and annular ligaments, supinator fossa and crest of ulna	Lateral, posterior and anterior surfaces of proximal 1/3 of radius	Supination of forearm	Posterior interosseous nerve
Abductor pollicis longus	Posterior surfaces of ulnar, radius and interosseous membrane	Base of 1st metacarpal and trapezium	Abducts thumb and extends it at carpometacarpal joint	Posterior interosseous nerve
Extensor pollicis brevis	Posterior surfaces of radius and interosseous membrane	Base of proximal phalanx of thumb	Extends proximal phalanx of thumb at carpometacarpal	Posterior interosseous nerve
Extensor pollicis longus	Posterior surface of middle 1/3 of ulna and interosseous membrane	Base of distal phalanx of thumb	Extends distal phalanx of thumb at carpometacarpal and interphalangeal joints	Posterior interosseous nerve
Extensor indicis	Distal 1/3 of posterior surface of ulna and interosseous membrane	Middle and distal phalanx of 2nd digit	Extends index finger	Posterior interosseous nerve

Extensor retinaculum

Thick fibrous band present on back of wrist joint

Attached laterally to the lower part of the anterior border of the radius, medially to the styloid process of the ulna, triquetral and pisiform bones.

Clinical correlation of hand

Intrinsic muscles of hand

Four thenar muscles

• Abductor pollicis brevis

• Flexor pollicis brevis

• Opponens pollicis brevis

• Adductor pollicis brevis

Four hypothenar muscles

• Palmaris brevis

• Abductor digiti minimi

• Flexor digiti minimi

• Oppenens digiti minimi

Four lumbricals

Three palmar interossei

Four dorsal interossei

Thenar muscles

	ORIGIN	INSERTION	ACTION	INNERVATION
Abductor pollicis brevis	Flexor retinaculum and tubercle of scaphoid and crest of trapezium	Lateral of base of proximal phalanx of thumb	Abducts the thumb at metacarpophalangeal and carpometacarpal joint	Median nerve
Flexor pollicis brevis	Superficial head- flexor retinaculum and crest of trapezium Deep- trapezoid and capitate bone	Lateral side of base of proximal phalanx	Flexes thumb	Median nerve
Opponens pollicis	Flexor retinaculum and crest of trapezium	Lateral side of 1st metacarpal	Draws 1st metacarpal to oppose thumb	Median nerve
Adductor pollicis	Oblique- base of 2nd and 4rd metacarpals, capitate and adjacent carpals Transverse- palmar surface of 3rd metacarpal	Medial side of base of proximal phalanx of thumb	Muscle adducts thumb from flexed or abducted position	Deep branch of ulnar nerve

Hypothenar muscles

	ORIGIN	INSERTION	ACTION	INNERVATION
Abductor digiti minimi	Pisiform bone	Medial side of base of proximal phalanx of little finger	Abducts little finger	Deep branch of ulnar nerve
Flexor digiti minimi	Hook of hamate a/nd flexor retinaculum	Medial side of base of proximal phalanx of little finger	Flexes little finger at metacarpophalangeal joint	Deep branch of ulnar nerve
Opponens digiti minimi	Hook of hamate and flexor retinaculum	Medial border of shaft of 5th metacarpal	Draws 5th metacarpal anteriorly and rotates it laterally, opposes thumb	Deep branch of ulnar nerve
Palmaris brevis	Flexor retinaculum and palmar aponeurosis	Skin along medial border of hand	Helps with gripping	Superficial branch of ulnar nerve

Interossei, palmar and lumbricals

	ORIGIN	INSERTION	ACTION	INNERVATION
Dorsal interossei (4)	Adjacent sides of two metacarpals	Extensor expansions and base of proximal phalanges of digit 2-4	Abduct digits from axial line Act with lumbricals to flex metacarpophalangeal joint and extend interphalangeal joint	Deep branch of ulnar nerve
Palmar interossei	Palmar surfaces of 2nd, 4th and 5th metacarpals	Extensor expansions of digit and bases of proximal phalanges	Adduct digits towards axial line Assist lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints	Deep branch of ulnar nerve
Lumbrical muscles	From tendon of flexor digitorum profundus	Dorsal digital expansion	Flex the metacarpophalangeal joints and extend the interphalangeal joints	1st and 2nd lumbricals by median nerve 3rd and 4th lumbricals by deep branch of ulnar nerve