Untitled

• The muscles of the upper limb are detailed

Shoulder Muscles

• Deltoid (9, 10, 11) abducts, flexes, and extends the arm.
• Teres Major (8) adducts and medially rotates the arm.
• Supraspinatus initiates abduction of the arm.
• Infraspinatus externally rotates the arm

Deltoid Muscle

• Originates from the clavicle, acromion, and spine of the scapula.
• Inserts on the deltoid tuberosity of the humerus.
• Clavicular part causes anteversion, internal rotation, and adduction.
• Acromial part causes abduction (from 15°-100°).
• Spinal part causes retroversion, external rotation, and adduction.

Teres Major Muscle

• Originates on the posterior surface of the inferior angle of the scapula.
• Inserts on the intertubercular sulcus of the humerus.
• Functions include adduction and internal rotation.

Supraspinatus Muscle

• Originates from the supraspinous fossa of the scapula.
• Inserts on the greater tubercle of the humerus.
• Initiates arm abduction from 0°-15°.

Infraspinatus Muscle

• Originates from the infraspinous fossa of the scapula.
• Inserts on the greater tubercle of the humerus.
• Functions in external rotation.

Teres Minor Muscle

• Originates from the axillary (lateral) border of the scapula.
• Inserts on the greater tubercle of the humerus.
• Functions in adduction and external rotation.

Subscapularis Muscle

• Originates from the subscapular fossa.
• Inserts on the lesser tubercle of the humerus.
• Functions include adduction and internal rotation.

Rotator Cuff Muscles

• Includes the Supraspinatus (12), Infraspinatus (13), Teres Minor (14), and Subscapularis (15).
• These muscles provide supportive cuff around the anterior, posterior, and superior aspects of the shoulder joint.

Rotator Cuff Tears

• Most common in older patients
• Usually involve the supraspinatus tendon

Spaces of the Posterior Shoulder Region

• Scapular notch contains the suprascapular nerve and suprascapular artery.
• Quadrangular space contains the posterior circumflex humeral artery and axillary nerve.
• Triangular space contains the circumflex scapular artery.
• Triceps hiatus contains the radial nerve and deep brachial artery.

Anterior Arm Muscles

• Includes the Biceps (1,2), Brachialis (3), and Coracobrachialis (4)
• Action: Flexes the glenohumeral and elbow joints and supinates the radioulnar joint.

Biceps Brachii

• Long head originates from the supraglenoid tubercle of the scapula.
• Short head originates from the coracoid process of the scapula.
• Insertion: Radial tuberosity.
• Innervation: Musculocutaneous nerve (C5-C6).
• Action: Elbow joint flexion and supination, shoulder joint flexion, stabilization of humeral head during deltoid contraction, abduction, and internal rotation of the humerus.

Brachialis

• Origin: Distal half of the anterior surface of the humerus.
• Insertion: Ulnar tuberosity.
• Innervation: Musculocutaneous nerve (C5-C6) and radial nerve (C7, minor).
• Action: Flexion at the elbow joint.

Coracobrachialis

• Origin: Coracoid process of the scapula.
• Insertion: Humerus (in line with crest of lesser tuberosity).
• Innervation: Musculocutaneous nerve (C6, C7).
• Action: Flexion, adduction, and internal rotation.

Posterior Arm Muscles

• Triceps brachii (5,6,7)
• Anconeus (8)
• Action: Extend the glenohumeral and elbow joints

Triceps Brachii

• Long head: Originates from the scapula (infraglenoid tubercle); Action is elbow joint extension, shoulder joint extension and adduction.
• Medial head: Originates from the posterior humerus, distal to radial groove; medial intermuscular septum, action is elbow extension
• Lateral head: Originates from the posterior humerus; proximal to radial groove; lateral intermuscular septum; Action is elbow extension
• Insertion: Olecranon of ulna
• Innervation Radial nerve (C6-C8)

Anconeus

• Originates from the lateral epicondyle of humerus (variance: posterior joint capsule)
• Insertion: Olecranon of ulna (radial surface)
• Action: Extends the elbow and tightens its joint.

Superficial Muscles of the Anterior Compartment of Forearm

• Pronator teres (1), Flexor carpi radialis (2), Palmaris longus (3), Flexor carpi ulnaris (4)

Pronator Teres

• Origin: Humeral head is the medial epicondyle of humerus.
• Origin: Ulnar head is the coronoid process.
• Insertion: Lateral radius (distal to supinator insertion).

Flexor Carpi Radialis

• Origin: Medial epicondyle of humerus.
• Insertion: Base of 2nd metacarpal; variance being base of the 3rd metacarpal.

Palmaris Longus

• Origin: Medial epicondyle of humerus.
• Insertion: Palmar aponeurosis.

Flexor Carpi Ulnaris

• Origin: Humeral head is the medial epicondyle; Ulnar head is the olecranon.
• Insertion: Pisiform, hook of hamate and base of the 5th metacarpal.

Intermediate Muscle of Anterior Compartment of Forearm

• Flexor digitorum superficialis (5).

Flexor Digitorum Superficialis

• Origin: Humeral-ulnar head from medial epicondyle of humerus, radial head from upper half of anterior border of radius
• Inserts on sides of middle phalanges of 2nd to 5th digits

Deep Muscles of Anterior Compartment of Forearm

• Flexor digitorum profundus (6), Flexor pollicis longus (7), Pronator quadratus (8)

Flexor Digitorum Profundus

• Origin: Ulna (two thirds of flexor surface) and interosseous membrane.
• Insertion: Distal phalanges of 2nd to 5th digits (palmar surface).

Flexor Pollicis Longus

• Origin: Radius (midanterior surface) and adjacent interosseous membrane.
• Insertion: Distal phalanx of thumb (palmar surface).

Pronator Quadratus

• Origin: Distal quarter of ulna (anterior surface).
• Insertion: Distal quarter of radius (anterior surface).

Superficial Muscles of Posterior Compartment of Forearm

• Extensor digitorum (1), Extensor digiti minimi (2), Extensor carpi ulnaris (3)

Extensor Digitorum

• Origin: Common head (lateral epicondyle of humerus).
• Insertion: Dorsal digital expansion of 2nd to 5th digits.

Extensor Digiti Minimi

• Origin: Common head (lateral epicondyle of humerus).
• Insertion: Dorsal digital expansion of 5th digit.

Extensor Carpi Ulnaris

• Origin: Common head (lateral epicondyle of humerus), Ulnar head (dorsal surface)
• Insertion: Base of 5th metacarpal.

Deep Muscles of Posterior Compartment of Forearm

• Supinator (4), Abductor pollicis longus (5), Extensor pollicis brevis (6), Extensor pollicis longus (7), Extensor indicis (8)

Supinator

• Origin: Olecranon, lateral epicondyle of humerus, radial collateral ligament, annular ligament of radius.
• Insertion: Radius (between radial tuberosity and insertion of pronator teres).

Abductor Pollicis Longus

• Origin: Radius and ulna (dorsal surfaces, interosseous membrane).
• Insertion: Base of 1st metacarpal.

Extensor Pollicis Brevis

• Origin: Radius (posterior surface) and interosseous membrane.
• Insertion: Base of proximal phalanx of thumb.

Extensor Pollicis Longus

• Origin: Ulna (posterior surface) and interosseous membrane.
• Insertion: Base of distal phalanx of thumb.

Extensor Indicis

• Origin Ulna (posterior surface) and interosseous membrane.
• Insertion: Posterior digital extension of 2nd digit.

Radialis Muscle Group of Posterior Compartment of Forearm

• Brachioradialis (9), Extensor carpi radialis longus (10), Extensor carpi radialis brevis (11)

Brachioradialis

• Origin: Distal humerus (distal surface), lateral intermuscular septum.
• Insertion: Styloid process of the radius.

Extensor Carpi Radialis Longus

• Origin: Lateral supracondylar ridge of distal humerus; lateral intermuscular septum.
• Insertion: 2nd metacarpal (base).

Extensor Carpi Radialis Brevis

• Origin: Lateral epicondyle of humerus.
• Insertion: 3rd metacarpal (base).

Thenar Compartment

• Contains muscles that abduct, flex, and oppose the thumb
• Muscles include: Adductor pollicis, Abductor pollicis brevis, Flexor pollicis brevis, and Opponens pollicis

Adductor pollicis

• Origin: Transverse head: 3rd metacarpal (palmar surface). Oblique head: capitate bone, 2nd and 3rd metacarpals (bases)
• Insertion: Thumb (base of proximal phalanx) via the ulnar sesamoid

Abductor pollicis brevis

• Origin: Scaphoid bone and trapezium, flexor retinaculum
• Insertion: Thumb (base of proximal phalanx) via the radial sesamoid

Flexor pollicis brevis

• Origin: Superficial head: flexor retinaculum. Deep head: capitate bone, trapezium
• Insertion: Thumb (base of proximal phalanx) via the radial sesamoid

Opponens pollicis

• Origin: Trapezium
• Insertion: 1st metacarpal (radial border)

Adductor Compartment

• Muscles adduct the thumb.
• Contains: adductor pollicis muscle

Hypothenar Compartment

• Flexes, abducts, and opposes the 5th digit.
• Includes: Opponens digiti minimi (5), Flexor digiti minimi brevis (6), Abductor digiti minimi (7), Palmaris brevis

Opponens digiti minimi

• Origin: Hook of hamate, flexor retinaculum
• Insertion: 5th metacarpal (ulnar border)

Flexor digiti minimi brevis

• Origin: Hook of hamate, flexor retinaculum
• Insertion: 5th proximal phalanx (base)

Abductor digiti minimi

• Origin: Pisiform bone
• Insertion: 5th proximal phalanx (ulnar base) and dorsal digital expansion of 5th digit

Palmaris brevis

• Origin: Palmar aponeurosis (ulnar border)
• Insertion: Skin of hypothenar eminence

Central Compartment

• Contains lumbricals that flex and extend joints of the fingers.

Interosseous Compartment

• Interossei muscles (3 palmar, 4 dorsal) abduct and adduct the fingers.