Muscles of the Upper Extremity

Vocabulary flashcards covering the anatomical structure, actions, functions, and nerve innervations of the upper extremity muscles (shoulder, arm, forearm, and hand).

Trapezius (Axioscapular Muscle):

Shrugs Shoulders & extends the head

Innervated by the Spinal Accessory Nerve.

Subclavius (Axioscapular Muscle):

Anchors and depresses the clavicle

Innervated by the Nerve to Subclavius.

Pectoralis Minor (Axioscapular Muscle):

Pulls the shoulder girdle down and forward to stabilize the scapula.

Innervated by the Medial Pectoral Nerve (aka Medial Anterior Thoracic Nerve).

Serratus Anterior (Axioscapular Muscle):

Pulls the shoulder down and forward, abducts and upwardly rotates the scapula, and prevents winging of the scapula.

Innervated by the Long Thoracic Nerve.

Levator Scapulae (Axioscapular Muscle):

Elevates and retracts the scapula, and performs cervical side bending (SB).

Innervated by the Dorsal Scapular Nerve.

Rhomboid Major (Axioscapular Muscle):

Retracts, rotates, and fixes the scapula.

Innervated by the Dorsal Scapular Nerve.

Rhomboid Minor (Axioscapular Muscle):

Retracts, rotates, elevates, and fixes the scapula.

Innervated by the Dorsal Scapular Nerve.

Pectoralis Major (Axiohumeral Muscles):

Flexes, horizontally adducts, and internally rotates the arm;

innervated by the Medial & Lateral Pectoral Nerves (aka Medial & Lateral Anterior Thoracic Nerves).

Latissimus Dorsi (Axiohumeral Muscles):

Extends, adducts, and internally rotates the arm; brings body toward arms when climbing.

Innervated by the Thoracodorsal Nerve.

Deltoid (Scapulohumeral Muscle):

Clavicular, acromial, and spinal parts that abducts the arm and assists in flexion, extension, and rotation.

Innervated by the Axillary Nerve.

Coracobrachialis (Scapulohumeral Muscle):

Adducts the arm, assists in flexion, and resists shoulder dislocation.

Innervated by the Musculocutaneous Nerve.

Rotator Cuff (SITS) Muscles

The four rotator cuff muscles:

Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis:

whose tendons surround the humeral head to prevent displacement.

SITS muscles.

Whose tendons surround the humeral head to prevent displacement?

What are the SITS muscles?

Supraspinatus

Infraspinatus

Teres Minor

Subscapularis

Supraspinatus (SITS)

Abduction of the arm.

Innervated by the Suprascapular Nerve.

Infraspinatus (SITS)

External rotation of the arm.

Innervated by the Suprascapular Nerve.

Teres Major (Scapulohumeral Muscle):

Adducts, medially rotates, and assists slightly in extension of the arm.

Innervated by the Lower Subscapular Nerve.

Teres Minor (SITS Muscles)

A rotator cuff muscle responsible for external rotation of the arm; innervated by the Axillary Nerve.

Subscapularis (SITS Muscles)

medial rotation of the arm and holding the head of the humerus in the glenoid cavity.

Innervated by Upper & Lower Subscapular Nerves.

Biceps Brachii (Upper Arm that moves Forearm):

Long and short heads that flexes supinated forearm, supinates forearm and hand, and resists shoulder dislocation.

Innervated by the Musculocutaneous Nerve.

Triceps Brachii (Upper Arm that moves Forearm):

Long, medial, and lateral heads that extends the forearm and resists dislocation of the humerus during adduction.

Innervated by the Radial Nerve.

Brachialis (Upper Arm that moves Forearm):

Flexes the pronated forearm.

Innervated by the Musculocutaneous Nerve.

Anconeus (Upper Arm that moves Forearm):

Assists the triceps with extension, stabilizes the elbow joint, and may abduct the ulna during pronation

Innervated by the Radial Nerve.

Pronator Teres (Anterior Forearm & 1st Layer):

Superficial anterior forearm muscle with ulnar and humeral heads, pronates and flexes the forearm.

The Median Nerve passes between its heads.

Flexor Carpi Radialis (FCR) (Anterior Forearm & 1st Layer):

A superficial anterior forearm muscle that flexes and abducts the hand.

Innervated by the Median Nerve.

Palmaris Longus (Anterior Forearm & 1st Layer):

A superficial anterior forearm muscle that flexes the hand, tenses the palmar aponeurosis, and crosses the carpal tunnel.

Innervated by the Median Nerve.

Flexor Carpi Ulnaris (FCU) (Anterior Forearm & 1st Layer):

A superficial anterior forearm muscle with humeral and ulnar heads that flexes and adducts the hand.

Innervated by the Ulnar Nerve.

Flexor Digitorum Superficialis (FDS) (Anterior Forearm& 2nd Layer)

An intermediate anterior forearm muscle that flexes middle phalanges at PIP joints and proximal phalanges at MCP joints of the middle 4 digits.

Innervated by the Median Nerve.

Flexor Digitorum Profundus (FDP) (Anterior Forearm & 3rd Layer):

A deep anterior forearm muscle with medial and lateral parts that flexes distal phalanges 2-5 at DIP joints.

Innervated by the Ulnar Nerve.

Flexor Pollicis Longus (FPL) (Anterior Forearm & 3rd Layer):

A deep anterior forearm muscle that flexes the phalanges of the thumb.

Innervated by the Anterior Interosseous Nerve (from Median Nerve).

Pronator Quadratus (Anterior Forearm & 3rd Layer):

A deep anterior forearm muscle that pronates the forearm and binds the radius and ulna together.

Innervated by the Anterior Interosseous Nerve (from Median Nerve).

Brachioradialis (Posterior Forearm & Superficial Layer):

A posterior forearm muscle that performs forearm flexion from a neutral position.

Innervated by the Radial Nerve.

Extensor Carpi Radialis Longus (ECRL) (Posterior Forearm & Superficial Layer):

A superficial posterior forearm muscle that extends and abducts the wrist, and is active during fist clenching.

Innervated by the Radial Nerve.

Extensor Carpi Radialis Brevis (ECRB) (Posterior Forearm & Superficial Layer):

A superficial posterior forearm muscle that extends and abducts the wrist.

Innervated by the Radial Nerve.

Extensor Digitorum (Posterior Forearm & Superficial Layer):

A superficial posterior forearm muscle that extends the middle 4 digits at MCP and IP joints.

Innervated by the Radial Nerve.

Extensor Digiti Minimi (EDM) (Posterior Forearm & Superficial Layer):

A superficial posterior forearm muscle that extends the 5th digit at MCP and IP joints.

Innervated by the Radial Nerve.

Extensor Carpi Ulnaris (ECU) (Posterior Forearm & Superficial Layer):

A superficial posterior forearm muscle that extends and adducts the wrist, active during fist clenching.

Innervated by the Radial Nerve.

Supinator (Posterior Forearm & Deep Layer):

A deep posterior forearm muscle that supinates the forearm.

Innervated by the Radial Nerve.

Extensor Indicis (Posterior Forearm & Deep Layer):

A deep posterior forearm muscle that extends the 2nd digit independently and helps extend the wrist.

Innervated by the Radial Nerve.

Abductor Pollicis Longus (APL) (Posterior Forearm & Deep Layer):

A deep posterior forearm muscle that abducts the thumb and extends it at the CMC joint.

Innervated by the Radial Nerve.

Extensor Pollicis Longus (EPL) (Posterior Forearm & Deep Layer):

A deep posterior forearm muscle that extends the thumb at the IP, MCP, and CMC joints.

Innervated by the Radial Nerve.

Extensor Pollicis Brevis (Posterior Forearm & Deep Layer):

A deep posterior forearm muscle that extends the thumb at the CMC and MCP joints.

Innervated by the Radial Nerve.

Muscles of the Hand:

Extrinsic:

Muscles that originate from outside the part of the skeleton being moved; “From the outside.”

Intrinsic:

Muscles that originates within the part being moved; “From within”

In general, muscles on the anterior forearm are:

Flexors

In general, muscles on the posterior forearm are:

Extensors

Opponens Pollicis (Intrinsic Muscles of Hand):

Opposes the thumb to the fingers.

Innervated by the Median Nerve.

Abductor Pollicis Brevis (Intrinsic Muscles of Hand):

Abducts the thumb.

Innervated by the Median Nerve.

Adductor Pollicis (Intrinsic Muscles of Hand):

Oblique and transverse heads that adducts the thumb.

Innervated by the Ulnar Nerve.

Flexor Pollicis Brevis (Intrinsic Muscles of Hand):

Superficial and deep heads that flexes the thumb.

Innervated by Median & Ulnar Nerves.

Abductor Digiti Minimi (Intrinsic Muscles of Hand):

Abducts and flexes the 5th digit,

Innervated by the Ulnar Nerve.

Flexor Digiti Minimi Brevis (Intrinsic Muscles of Hand):

Flexes the proximal phalanx of the 5th digit.

Innervated by the Ulnar Nerve.

Opponens Digiti Minimi (Intrinsic Muscles of Hand):

Helps oppose the 5th finger slightly.

Innervated by the Ulnar Nerve.

Palmar Interossei (Intrinsic Muscles of Hand):

Adduct the 2nd, 4th, and 5th fingers.

Innervated by the Ulnar Nerve.

Dorsal Interossei (Intrinsic Muscles of Hand):

Abduct the 2nd, 3rd, and 4th fingers.

Innervated by the Ulnar Nerve.

Lumbricals (Intrinsic Muscles of Hand):

Flex proximal phalanges and extend middle and distal phalanges.

Innervated by the Median Nerve (digits 2 & 3) and Ulnar Nerve (digits 4 & 5).

Carpal Tunnel Syndrome

A repetitive motion injury characterized by tenosynovitis (swelling of tendon sheaths around finger flexors) that compresses the Median Nerve, causing pain, weakness, and tingling.

Extrinsic vs. Intrinsic Hand Muscles

Extrinsic muscles originate in the forearm and move parts in the hand, whereas intrinsic muscles originate within the hand itself.