Upper Body O, I, A, N Flashcards
Trapezius Origin
Medial 1/3 of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7-T12
Trapezius Insertion
Lateral 1/3 of clavicle; acromion process; spine of scapula
Trapezius Action
Descending part: elevates shoulder
Ascending part: depresses shoulder
Middle part or all: retracts scapula
Ascending & descending together: rotate glenoid superiorly
Trapezius Innervation
Spinal accessory nerve (Cranial XI) and C3&C4 spinal nerves
Latissimus Dorsi Origin
Spinous processes of T7-T12; thoracolumbar fascia; iliac crest; ribs 9-12
Latissimus Dorsi Insertion
Floor of intertubercular sulcus of humerus
Latissimus Dorsi Action
Extends, adducts, and medially rotates shoulder joint; raises body during climbing
Latissimus Dorsi Innervation
Thoracodorsal nerve (C6, C7, C8)
Rhomboid Major Origin
Spinous processes of T2-T5
Rhomboid Major Insertion
Medial border of scapula from spine to inferior angle
Rhomboid Major Action
Retracts scapula; rotates to depress glenoid cavity; holds scapula to body wall
Rhomboid Major Innervation
Dorsal scapular nerve (C4, C5)
Rhomboid Minor Origin
Nuchal ligament; spinous processes of C7-T1
Rhomboid Minor Insertion
Scapula at medial end of scapular spine
Rhomboid Minor Action
Retracts scapula; rotates to depress glenoid cavity; holds scapula to body wall
Rhomboid Minor Innervation
Dorsal scapular nerve (C4, C5)
Levator Scapulae Origin
Posterior tubercles of transverse processes of C1-C4
Levator Scapulae Insertion
Medial border of scapula from superior angle to spine
Levator Scapulae Action
Dorsal scapular (C5) and cervical (C3,C4) spinal nerves
Levator Scapulae Innervation
Elevates scapula; rotates glenoid inferiorly
Erector Spinae: Origin
Iliocostalis
Longissimus
Spinalis
Broad tendon from posterior iliac crest, posterior sacrum, sacro-iliac ligaments, inferior lumbar and sacral spinous processes, and supraspinous ligament
Erector Spinae: Inseriton
Iliocostalis
Longissimus
Spinalis
Iliocostalis: run superiorly to angles of ribs and transverse processes of cervical verts
Longissimus: run superiorly to ribs between tubercles and angles; to transverse processes on thoracic and cervical verts; and to mastoid process
Spinalis: run superiorly to spinous processes of upper thoracic and cervical verts
Erector Spinae: Action
Iliocostalis
Longissimus
Spinalis
Extend head and vertebral column; laterally flex vertebral column
Erector Spinae: Innervation
Iliocostalis
Longissimus
Spinalis
Dorsal (posterior) rami of spinal nerves
Splenius Capitis
Splenius Cervicis
Origin
Nuchal ligament and spinous processes of C7-T6
Splenius Capitis
Splenius Cervicis
Insertion
Capitis: superolaterally to mastoid process and lateral 1/3 of nuchal line
Cervicis: tubercles of transverse processes of C1-C4
Splenius Capitis
Splenius Cervicis
Action
Flex neck; rotate head; extend head and neck
Splenius Capitis
Splenius Cervicis
Innervation
Dorsal (posterior) rami of spinal nerves
Semispinalis Capitis Origin
Transverse processes of C7-T6; articular processes of C4-C6
Semispinalis Capitis Insertion
Occipital bone
Semispinalis Capitis Action
Extends head
Semispinalis Capitis Innervation
Dorsal (posterior) rami of spinal nerves
Serratus Posterior Superior Origin
Nuchal ligament; spinous processes of C7-T3
Serratus Posterior Superior Insertion
Ribs 2-4 on superior borders
Serratus Posterior Superior Action
Elevate ribs
Serratus Posterior Superior Innervation
2nd-5th intercostal nerves
Serratus Posterior Inferior Origin
Spinous processes of T11-L2
Serratus Posterior Inferior Insertion
Ribs 8-12 on inferior borders near their angles
Serratus Posterior Inferior Action
Depresses ribs
Serratus Posterior Inferior Innervation
9th-11th intercostal nerves, subcostal (T12) nerve
Semispinalis Origin
Transverse processes of C4-T10
Semispinalis Insertion
Occipital bone and spinous processes in upper thoracic and cervical regions 4-6 segments superior
Semispinalis Action
Extends head + thoracic and cervical regions of vertebral column; rotates column contralaterally
Semispinalis Innervation
Dorsal (posterior) rami of spinal nerves
Multifidus Origin
Posterior sacrum; PSIS of ilium; aponeurosis of erector spinae; sacro-iliac ligaments; mammillary processes of lumbar verts., transverse processes of thoracic verts., articular processes of C4-C7
Multifidus Insertion
Spinous processes of vertebrae 2-4 segments superior
Multifidus Action
Stabilizes vertebrae during movements of vertebral column; rotates column contralaterally
Multifidus Innervation
Dorsal (posterior) rami of spinal nerves
Rotatores Origin
Transverse processes of vertebrae
Rotatores Insertion
Junctions of lamina and either transverse processes or spinous processes 1 (brevis)-2 (longus) segments superior.
Rotatores Action
Stabilizes vertebrae during movements of vertebral column; rotates column contralaterally; may be organs of proprioceptions
Rotatores Innervation
Dorsal (posterior) rami of spinal nerves
Interspinales Origin
Superior surfaces of spinous processes of cervical and thoracic vertebrae
Interspinales Insertion
Inferior surfaces of spinous processes of vertebrae superior to vertebra of origin.
Interspinales Action
Extension and rotation of vertebral column
Interspinales Innervation
Dorsal (posterior) rami of spinal nerves
Intertransversarii Origin
Transverse processes of cervical and thoracic verts
Intertransversarii Insertion
Transverse processes of adjacent vertebrae
Intertransversarii Action
Dorsal (posterior) and ventral (anterior) rami of spinal nerves
Intertransversarii Innervation
Lateral flexion of vertebral column; stabilize vertebral column
Levatores Costarum Origin
Tips of transverse processes of C7 + T1-T11
Levatores Costarum Insertion
Pass inferolaterally and insert on rib between tubercle and angle
Levatores Costarum Action
Elevate ribs, assisting in respiration; lateral flexion of vertebral column
Levatores Costarum Innervation
Posterior rami of C8-T11 spinal nerves
External intercostal Origin
Inferior border of ribs
External intercostal Insertion
Superior border of ribs inferiorly
External intercostal Action
During forced inspiration – elevate ribs
External intercostal Innervation
Intercostal nerve
Internal intercostal Origin
Inferior border of ribs
Internal intercostal Insertion
Superior border of ribs inferiorly
Internal intercostal Action
During forced respiration – interosseus part depresses ribs, interchondral part elevates ribs
Internal intercostal Innervation
Intercostal nerve
Innermost intercostal Origin
Inferior border of ribs
Innermost intercostal Insertion
Superior border of ribs inferiorly
Innermost intercostal Action
During forced respiration – interosseus part depresses ribs, interchondral part elevates ribs
Innermost intercostal Innervation
Intercostal nerve
Transversus thoracis Origin
Posterior surface of inferior sternum
Transversus thoracis Insertion
Internal surface of costal cartilages 2-6
Transversus thoracis Action
Weakly depresses limbs
Transversus thoracis Innervation
Intercostal nerve
Subcostal Origin
Internal surface of lower ribs near their angles
Subcostal Insertion
Superior borders of 2nd or 3rd ribs below
Subcostal Action
Probably during forced respiration – interosseus part depresses ribs, interchondral part elevates ribs
Subcostal Innervation
Intercostal nerve
Pectoralis Major Origin
Clavicular head: anterior surface of medial half o clavicle
Sternocostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle
Pectoralis Major Insertion
Lateral lip of intertubercular sulcus of humerus
Pectoralis Major Action
Adducts and medially rotates shoulder joint, draws scapula anteriorly and inferiorly
Clavicular head: flexes shoulder joint
Sternocostal head: extends shoulder joint from the flexed position
Pectoralis Major Innervation
Lateral and medial pectoral nerves, clavicular head (C5, C6), sternocostal head (C7, C8, T1)
Pectoralis Minor Origin
3rd-5th ribs near their costal cartilages
Pectoralis Minor Insertion
Medial border and superior surface of coracoid process of scapula
Pectoralis Minor Action
Stabilizes scapula by drawing inferiorly and anteriorly against thoracic wall; depresses shoulder
Pectoralis Minor Innervation
Medial pectoral nerve (C8, T1)
Subclavius Origin
Junction of 1st rib and its costal cartilage
Subclavius Insertion
Inferior surface of middle third of clavicle
Subclavius Action
Anchors and depresses clavicle
Subclavius Innervation
Subclavian nerve (C5, C6)
Serratus Anterior Origin
External surfaces of lateral parts of 1st-8th ribs
Serratus Anterior Insertion
Anterior surface of medial border of scapula
Serratus Anterior Action
Protracts scapula and holds against thoracic wall; rotates scapula
Serratus Anterior Innervation
Long thoracic nerve (C5, C6, C7)
Deltoid Origin
Lateral third of clavicle; acromion; spine of scapula
Deltoid Insertion
Deltoid tuberosity of humerus
Deltoid Action
Clavicular (anterior): flexes and medially rotates shoulder
Acromial (middle) or all together: abducts shoulder joint after first 15°
Spinal (posterior): extends and laterally rotates shoulder joint
Deltoid Innervation
Axillary nerve (C5, C6)
Supraspinatus Origin
Supraspinous fossa of scapula
Supraspinatus Inseriton
Superior facet of greater tubercle of humerus
Supraspinatus Action
Initiates (first 15°) and assists deltoid in abduction of shoulder joint; part of rotator cuff
Supraspinatus Innervation
Suprascapular nerve (C4, C5, C6)
Infraspinatus Origin
Infraspinous fossa of scapula
Infraspinatus Insertion
Middle facet of greater tubercle of humerus
Infraspinatus Action
Laterally rotates shoulder joint; part of rotator cuff
Infraspinatus Innervation
Suprascapular nerve (C4, C5, C6)
Teres Major Origin
Middle part of lateral border of scapula
Teres Major Insertion
Inferior facet of greater tubercle of humerus
Teres Major Action
Laterally rotates shoulder joint; part of rotator cuff
Teres Major Innervation
Axillary nerve (C5, C6)
Teres Minor Origin
upper two-thirds of the lateral border of scapula
Teres Minor Insertion
Medial lip of intertubercular sulcus of humerus
Teres Minor Action
Adducts and medially rotates shoulder joint
Teres Minor Innervation
Lower subscapular nerve (C5, C6)
Subscapularis Origin
Subscapular fossa
Subscapularis Insertion
Lesser tubercle of humerus
Subscapularis Action
Medially rotates and adducts shoulder joint; part of rotator cuff
Subscapularis Innervation
Upper and lower subscapular nerves (C5, C6, C7)
Biceps brachii Origin
Short head: tip of coracoid process of scapula
Long head: supraglenoid tubercle of scapula
Biceps brachii Insertion
Tuberosity of radius and fascia of forearm via bicipital aponeurosis
Biceps brachii Action
Supinates forearm and, when it is supinated, flexes elbow joint. Flexes shoulder joint. Short head resists shoulder dislocation.
Biceps brachii Innervation
Musculocutaneous nerve (C5, C6)
Brachialis Origin
Distal half of anterior surface of humerus
Brachialis Insertion
Coronoid process and tuberosity of ulna
Brachialis Action
Flexes elbow joint
Brachialis Innervation
Musculocutaneous nerve (C5, C6)
Coracobrachialis Origin
Tip of coracoid process of scapula
Coracobrachialis Insertion
Middle third of medial surface of humerus
Coracobrachialis Action
Flexes and adducts shoulder joint; resists shoulder dislocation
Coracobrachialis Innervation
Musculocutaneous nerve (C5, C6)
Triceps brachii Origin
Long head: infraglenoid tubercle of scapula
Lateral head: posterior surface of humerus superior to radial groove
Medial head: posterior surface of humerus inferior to radial groove
Triceps brachii Insertion
Proximal end of olecranon of ulna and fascia of forearm
Triceps brachii Action
Chief extensor of elbow joint
Long head: extends shoulder joint and resists dislocation of humerus (esp during abduction)
Triceps brachii Innervation
Radial nerve (C6, C7, C8)
Anconeus Origin
Lateral epicondyle of humerus
Anconeus Insertion
Lateral surface of olecranon and superior part of posterior surface of ulna
Anconeus Action
Assists triceps in extending elbow joint; stabilizes elbow joint; abducts ulna during pronation
Anconeus Innervation
Radial nerve (C7, C8, T1)
Pronator Teres (PT) Origin
Ulnar head: coronoid process of ulna
Humeral head: medial epicondyle of humerus
Pronator Teres (PT) Insertion
Middle of convexity of lateral surface of radius
Pronator Teres (PT) Action
Pronates and flexes forearm
Pronator Teres (PT) Innervation
Median nerve (C6, C7)
Flexor carpi radialis (FCR) Origin
Medial epicondyle of humerus
Flexor carpi radialis (FCR) Insertion
Base of 2nd (3rd) metacarpal
Flexor carpi radialis (FCR) Action
Flexes and abducts hand at wrist
Flexor carpi radialis (FCR) Innervation
Median nerve (C6, C7)
Palmaris longus Origin
Medial epicondyle of humerus
Palmaris longus Insertion
Distal half of flexor retinaculum, palmar aponeurosis
Palmaris longus Action
Flexes hand at wrist and tenses palmar aponeurosis
Palmaris longus Innervation
Median nerve (C7, C8)
Flexor carpi ulnaris
Humeral head and ulnar head
Origin
Ulnar head: Olecranon and posterior border of ulna (via aponeurosis)
Humeral head: medial epicondyle of humerus
Flexor carpi ulnaris
Humeral head and ulnar head
Insertion
Pisiform, hook of hamate, 5th metacarpal
Flexor carpi ulnaris
Humeral head and ulnar head
Action
Flexes and adducts hand at wrist
Flexor carpi ulnaris
Humeral head and ulnar head
Innervation
Ulnar nerve (C7, C8)
Flexor digitorum superficialis (FDS) Origin
Humero-ulnar head: medial epicondyle of humerus and coronoid process of ulna
Radial head: oblique line of radius
Flexor digitorum superficialis (FDS) Insertion
Shafts (bodies) of middle phalanges of medial four digits
Flexor digitorum superficialis (FDS) Action
Flexes wrist joint
Flexes proximal interphalangeal joins of middle four digits; also flexes proximal phalanges at metacarpophalangeal joints
Flexor digitorum superficialis (FDS) Innervation
Median nerve (C7, C8, T1)
Flexor digitorum profundus (FDP) Origin
Proximal 3/4 of medial and anterior surfaces of ulna and interosseous membrane
Flexor digitorum profundus (FDP) Insertion
Bases of distal phalanges of medial four digits
Flexor digitorum profundus (FDP) Action
Flexes wrist joint
Flexes distal interphalangeal joints of medial four digits; assists with writs flexion
Flexor digitorum profundus (FDP) Innervation
Lateral part (digits 2-3): Median nerve (C8, T1) (anterior interosseous branch) Medial part (digits 4-5): Ulnar nerve (C8, T1)
Flexor pollicis longus (FPL) Origin
Anterior surface of radius and adjacent interosseous membrane
Flexor pollicis longus (FPL) Insertion
Base of distal phalanx of thumb
Flexor pollicis longus (FPL) Action
Flexes wrist
Flexes metacarpophalangeal and interphalangeal joints of the thumb
Flexor pollicis longus (FPL) Innervation
Anterior interosseous nerve from Median nerve (C8, T1)
Pronator Quadratus Origin
Distal quarter of anterior surface of ulna
Pronator Quadratus Insertion
Distal quarter of anterior surface of radius
Pronator Quadratus Action
Pronates forearm. Deep fibers bind radius and ulna together.
Pronator Quadratus Innervation
Anterior interosseous nerve from Median nerve (C8, T1)
Brachioradialis Origin
Proximal 2/3 of lateral supraepicondylar ridge of humerus
Brachioradialis Insertion
Lateral surface of distal end of radius proximal to styloid process
Brachioradialis Action
Relatively weak flexion of elbow joint, maximal when forearm is in midpronated position
Brachioradialis Innervation
Radial nerve (C5, C6, C7)
Extensor carpi radialis longus Origin
Lateral supra-epicondylar ridge of humerus
Extensor carpi radialis longus Insertion
Dorsal aspect of base of 2nd metacarpal
Extensor carpi radialis longus Action
Extend and abduct wrist joint
Extensor carpi radialis longus Innervation
Radial nerve (C6, C7)
Extensor carpi radialis brevis Origin
Lateral epicondyle of humerus
Extensor carpi radialis brevis Insertion
Dorsal aspect of base of 3rd metacarpal
Extensor carpi radialis brevis Action
Extend and abduct wrist joint; active during fist clenching.
Extensor carpi radialis brevis Innervation
Deep branch of radial nerve (C7, C8)
Extensor digitorum Origin
Lateral epicondyle of humerus
Extensor digitorum Insertion
Extensor expansions of medial four fingers
Extensor digitorum Action
Extend wrist joint.
Extend medial four fingers primarily at metacarpophalangeal joints, secondarily at interphalangeal joints.
Extensor digitorum Innervation
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
Extensor digiti minimi Origin
Lateral epicondyle of humerus
Extensor digiti minimi Insertion
Extensor expansion of 5th finger
Extensor digiti minimi Action
Extends wrist joint.
Extends 5th finger primarily at metacarpophalangeal joint, secondarily at interphalangeal joint
Extensor digiti minimi Innervation
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
Extensor carpi ulnaris Origin
Lateral epicondyle of humerus; posterior border of ulna via a shared aponeurosis
Extensor carpi ulnaris Insertion
Dorsal aspect of base of 5th metacarpal
Extensor carpi ulnaris Action
Extends and adducts wrist joint; active during fist clenching
Extensor carpi ulnaris Innervation
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
Supinator Origin
Lateral epicondyle of humerus; radial collateral and anular ligaments; supinator fossa; crest of ulna
Supinator Insertion
Lateral, posterior, and anterior surfaces of proximal third of radius
Supinator Action
Supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
Supinator Innervation
Deep branch of radial nerve (C7, C8)
Abductor pollicis longus Origin
Posterior surface of proximal halves of ulna, radius, and interosseous membrane
Abductor pollicis longus Insertion
Base of 1st metacarpal
Abductor pollicis longus Action
Extends wrist joint
Abducts thumb and extends it at carpometacarpal joint
Abductor pollicis longus Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor pollicis longus Origin
Posterior surface of middle third of ulna and interosseous membrane
Extensor pollicis longus Insertion
Dorsal aspect of base of distal phalanx of thumb
Extensor pollicis longus Action
Extends wrist joint
Extends distal phalanx of thumb at interphalangeal joint, extends metacarpophalangeal and
Extensor pollicis longus Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor pollicis brevis Origin
Posterior surface of distal third of radius and interosseous membrane
Extensor pollicis brevis Insertion
Dorsal aspect of base of proximal phalanx of thumb
Extensor pollicis brevis Action
Extends wrist joint
Extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint
Extensor pollicis brevis Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor Indicis Origin
Posterior surface of distal 1/3 of ulna and interosseous membrane
Extensor Indicis Insertion
Extensor expansion of 2nd finger
Extensor Indicis Action
Extends wrist joint
Extends 2nd finger (enabling its independent extension); helps extend hand at wrist.
Extensor Indicis Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Opponens pollicis Origin
Flexor retinaculum and tubercles of scaphoid and trapezium
Opponens pollicis Insertion
Lateral side of 1st metacarpal
Opponens pollicis Action
To oppose thumb, it draws 1st metacarpal medially to center of palm and rotates it medially
Opponens pollicis Innervation
Recurrent branch of median nerve (C8, T1)
Abductor pollicis brevis Origin
Flexor retinaculum and tubercles of scaphoid and trapezium
Abductor pollicis brevis Insertion
Lateral side of base of proximal phalanx of thumb
Abductor pollicis brevis Action
Abducts thumb, helps oppose it
Abductor pollicis brevis Innervation
Recurrent branch of median nerve (C8, T1)
Flexor pollicis brevis:
superficial head, deep head
Origin
Flexor retinaculum and tubercles of scaphoid and trapezium
Flexor pollicis brevis:
superficial head, deep head
Insertion
Lateral side of base of proximal phalanx of thumb
Flexor pollicis brevis:
superficial head, deep head
Action
Flexes thumb
Flexor pollicis brevis:
superficial head, deep head
Innervation
Superficial head: Recurrent branch of median nerve (C8, T1)
Deep head: Deep branch of ulnar nerve (C8, T1)
Adductor pollicis:
oblique head, transverse head
Origin
Bases of 2nd and 3rd metacarpals, capitate, adjacent carpals.
Anterior surface of shaft of 3rd metacarpal.
Adductor pollicis:
oblique head, transverse head
Insertion
Medial head side of base of proximal phalanx of thumb
Adductor pollicis:
oblique head, transverse head
Action
Adducts thumb toward lateral border of palm
Adductor pollicis:
oblique head, transverse head
Innervation
Deep branch of ulnar nerve (C8, T1)
Abductor digiti minimi Origin
Pisiform
Abductor digiti minimi Inseriton
Medial side of base of proximal phalanx of 5th finger
Abductor digiti minimi Action
Abducts 5th finger, assists in flexion of its proximal phalanx
Abductor digiti minimi Innervation
Deep branch of ulnar nerve (C8, T1)
Flexor digiti minimi Origin
Hook of hamate and flexor retinaculum
Flexor digiti minimi Insertion
Medial side of base of proximal phalanx of 5th finger
Flexor digiti minimi Action
Flexes proximal phalanx of 5th finger
Flexor digiti minimi Innervation
Deep branch of ulnar nerve (C8, T1)
Opponens digiti minimi Origin
Hook of hamate and flexor retinaculum
Opponens digiti minimi Insertion
Medial border of 5th metacarpal
Opponens digiti minimi Action
Draws 5th metacarpal anterior and rotates it, bringing 5th finger into opposition with thumb
Opponens digiti minimi Innervation
Deep branch of ulnar nerve (C8, T1)
Lumbricals 1-2 Origin
Lateral two tendons of flexor digitorum profundus (as unipennate muscles)
Lumbricals 1-2 Insertion
Lateral sides of extensor expansions of 2nd – 5th fingers
Lumbricals 1-2 Action
Flex metacarpophalangeal joints, extend interphalangeal joints of 2nd - 5th fingers
Lumbricals 1-2 Innervation
Median nerve (C8, T1)
Lumbricals 3-4 Origin
Medial three tendons of flexor digitorum profundus (as bipennate muscles)
Lumbricals 3-4 Insertion
Lateral sides of extensor expansions of 2nd – 5th fingers
Lumbricals 3-4 Action
Flex metacarpophalangeal joints, extend interphalangeal joints of 2nd - 5th fingers
Lumbricals 3-4 Innervation
Deep branch of ulnar nerve (C8, T1)
Dorsal interossei 1-4 Origin
Adjacent sides of two metacarpals (as bipennate muscles)
Dorsal interossei 1-4 Insertion
Bases of proximal phalanges, extensor expansions of 2nd – 4th fingers
Dorsal interossei 1-4 Action
Abduct 2nd – 4th fingers from axial line, act with lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints
Dorsal interossei 1-4 Innervaition
Deep branch of ulnar nerve (C8, T1)
Palmer interossei 1-4 Origin
Palmar surfaces of 2nd, 4th, and 5th metacarpals (as unipennate muscles)
Palmer interossei 1-4 Insertion
Bases of proximal phalanges, extensor expansions of 2nd , 4th , 5th fingers
Palmer interossei 1-4 Action
Adduct 2nd , 4th , 5th fingers toward axial line, assist lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints
Palmer interossei 1-4 Innervation
Deep branch of ulnar nerve (C8, T1)