Muscles Flashcards
Trapezius innervation
Motor: accessory nerve
Also receives proprioceptor fibers from C3 and C4 spinal nerves
Trapezius origin
Medial 1/3 of superior nuchal line (on skull), external occipital protuberance (also on skull), nuchal ligament, spinous processes of C7-T12
Trapezius attachment
Lateral 3rd clavicle, acromium and scapular spine
List Trapezius actions on __________:
On scapula*
Elevation/depression
Protraction/retraction
Upward rotation/downward rotation
Latissimus dorsi innervation
Thoracodosal nerve (C6-C8)
Latissimus Dorsi origin
Spinous processes T7-12, thoracolumbar fascia, iliac crest, inferior 3-4 ribs
Latissimus Dorsi insertion
Floor of intertubercular sulcus of humerus
Latissimus Dorsi actions
Extends humerus
Adductor humerus
Medially rotates humerus
Levator scapulae innervation
Dorsal scapular nerve (C5) and cervical spinal nerves (C3, C4)
Levator Scapulae origin
Transverse processes of C1-C4
Levator Scapulae insertion
Medial superior scapula
Levator scapulae action
Elevates scapula and rotates it downward
Rhomboid minor innervation
Dorsal scapular nerve
Rhomboid minor origin
Nuchal ligament, C7-T1 spinous processes
Rhomboid minor insertion
Medial scapula at spine border
Rhomboid major innervation
Dorsal scapular nerve
Rhomboid major origin
Spinous processes T2-T5
Rhomboid major insertion
Medial scapular border
Rhomboid major and minor action
Elevates scapula
Retracts scapula
Rotates scapula downward
Supraspinatus innervation
Supraspinatus nerve
Supraspinatus origin
Supraspinous fossa of the scapula
Supraspinatus attachment
Greater tubercle of the humerus
Supraspinatus action
Stabilizes the glenohumeral joint
Abducts the arm 0-15 degrees, and assists the deltoid for 15-90 degrees
Infraspinatous innervation
Suprascapular nerve
Infraspinatus origin
Infraspinous fossa of the scapula
Infraspinatus insertion
Greater tubercle of the humerus
Infraspinatus action
Stabilizes the glenohumeral joint
Laterally rotates the arm
Subscapularis innervation
Upper and lower subscapular nerve
Subscapularis origin
Subscapular fossa, costal surface of the scapula
Subscapularis insertion
Lesser tubercle of the humerus
Subscapularis action
Stabilizes the glenohumeral joint
Medially rotates the arm
Teres minor innervation
Axillary nerve
Teres minor origin
Posterior surface of the scapula adjacent to itslateral border
Teres minor insertion
Greater tubercle of the humerus
Teres minor action
Stabilizes the glenohumeral joint
Laterally rotates the arm
Serratus posterior superior muscle innervation
Intercostal nerves
Serratus posterior superior muscle origin
Lower part of the ligamentum nuchae and the cervical and thoracic spines (C7-T3)
Serratus Posterior Superior muscle insertion
Ribs 2-5
Serratus posterior superior action
Elevates ribs 2-5
Serratus posterior inferior muscle innervation
Intercostal nerves
Serratus posterior inferior muscle origin
Thoracic and lumbar spines (T11-L3)
Serratus posterior inferior muscle insertion
Ribs 9-12
Serratus posterior inferior muscle action
Depresses ribs 9-12
Splenius capitis innervation
Posterior rami of spinal nerves C3 and C4
Splenius capitis origin
Lower aspect of the ligamentum nuchae and the spinous processes of C7-T3/4 vertebrae
Splenius capitis insertion
Mastoid process and the occipital bone of the skull
Splenius capitis action
Rotate head to the same side
Also acts with splenius cervicis to extend the head and neck
Splenius cervicis innervation
Posterior rami of the lower cervical spinal nerves
Splenius cervicis origin
Spinous processes of T3-T-6 vertebrae
Splenius cervicis insertion
Transverse processes of C1-3/4
Splenius cervicis action
Rotate the head to the same side
Also acts with the splenius capitis to extend the head and neck
Muscles included in the erector spinae
Iliocostalis m, longissimus m, and spinalis m
Common origin of erector spinae muscles
Common tendinous origin that arises from:
Lumbar and lower thoracic vertebrae, sacrum, posterior aspect of iliac crest, sacroiliac and supraspinous ligaments
Erector spinae (I,L,S) muscle innervation
Posterior rami of the spinal nerves
Iliocostalis muscle insertion
Costal angle of the ribs and the cervical transverse processes
Longissimus muscle insertion
Lower ribs, the transverse processes of C2-T12 and the mastoid process of the skull
Semispinalis muscle insertion
Spinous processes of C2-T4 and to the occipital bone of the skull
Action of the erector spinae muscles
Unilaterally - act to laterally flex the vertebral column
Bilaterally - act to extend the vertebral column and head
Multifidus muscle innervation
Posterior rami of the spinal nerves
Multifidus muscle origin
Broad origin - sacrum, posterior iliac spine, common tendinous origin of the erector spinae, mamillary processes of lumbar vertebrae, transverse processes of C4-C7
Multifidus muscle insertion
Spinous processes of the vertebrae
Multifidus muscle action
Stabilizes the vertebral column
Rotatores muscles innervation
Posterior rami of the spinal nerves
Rotatores muscle origin
Vertebral transfers processes
Rotatores muscle insertion
Lamina and spinous processes of the immediately superior vertebrae
Rotatores muscle action
Stabilizes the vertebral column and has a proprioceptive function
Interspinales muscle: describe location and function
Span b/w adjacent spinous processes
Action: stabilize the vertebral column
Intertransversari muscle: describe location and function
Spans b/w adjacent transverse processes
Action: stabilize the vertebral column
Levatores costarum muscle: describe location and function
Origin: transfers processes of C7-T11
Insertion: attaches to the rib immediately below
Action: elevates ribs
Pectoralis major innervation
Lateral and medial pectoral nerves
Pectoralis major origin
Clavicular head: anterior surface of the medial clavicle
Sternocostal head: anterior surface of the sternum, superior six costal cartilages and the aponeurosis of the external oblique muscle
Pectoralis major insertion
Both heads attach to the intertubercular sulcus of the humerus
Pectoralis major action
Adducts and medially rotates the upper limb, draws the scapula anteroinferiorly. The clavicular head also acts to flex the upper limb.
Pectoralis minor innervation
Medial pectoral nerve
Pectoralis minor origin
3rd and 5th ribs
Pectoralis minor insertion
Coracoid process of the scapula
Pectoralis minor action
Stabilizes the scapula by drawing it anteroinferiorly against the thoracic wall
Serratus anterior innervation
Long thoracic nerve
Serratus anterior origins
Lateral aspects of ribs 1-8
Serratus anterior insertion
Costal (rib facing) surface of the medial border of the scapula
Serratus anterior action
Rotates the scapula, allowing the arm to be raised over 90 degrees. Also holds the scapula against the ribcage.
Subclavius innervation
Nerve to subclavius
Subclavius origin
Junction of the 1st rib and its costal cartilage
Subclavius insertion
Inferior surface of the middle third of the clavicle
Subclavius action
Anchors and depresses the clavicle
Deltoid innervation
Axillary nerve
Deltoid origin
Scapular spine, acromion, lateral third of clavicle
Deltoid insertion
Humerus (deltoid tuberosity)
Deltoid actions
Flexion, internal rotation, adduction, aBduction, extension, external rotation
Abduction takes over from the supraspinatus which abducts the first 15 degrees
Biceps brachii innervation
Musculocutaneous n.
Biceps tendon reflex tests spinal cord segment C6
Biceps brachii origin
Long head: Supraglenoid tubercle of scapula
Short head: coracoid process of scapula
Biceps brachii insertion
Radial tuberosity and biciptial aponeurosis
Biceps brachii action
Supination of the forearm, flexion of the arm at elbow and shoulder, adduction and internal rotation of the humerus
Brachialis innervation
Musculocutaneous n. (C5-C6) and Radial n. (C7, minor)
Brachialis origin
Humerus (distal half of anterior surface)
Brachialis insertion
Ulnar tuberosity
Brachialis action
Flexion at the elbow joint
Coracobrachialis innervation
Musculocutaneous n.
Corachobrachialis origin
Coracoid process of the scapula
Coracobrachialis insertion
Medial side of the humeral shaft (at the level of the deltoid tubercle)
Coracobrachialis action
Flexion of the arm at the shoulder and weak adduction
What artery supplies the BBC (biceps brachii, brachialis & coracobrachialis) muscles?
Brachial artery
Triceps brachii innervation
Radial nerve
A tap of the triceps tendon tests spinal segment C7
Triceps brachii origins
Long head: infraglenoid tubercle of scapula
Lateral head: posterior humerus (proximal to the radial groove)
Medial head: posterior humerus (distal to the radial groove)
Triceps brachii insertion
Olecranon of the ulna
Triceps brachii action
Extension of the arm at the elbow
What artery supplies the triceps brachii (the posterior side of the arm)?
Profound a brachii artery
Where does the common tendon for the flexor carpi ulnaris, palmaris longus, flexor carpi radialis and pronator teres originate?
Medial epicondyle of the humerus
Flexor carpi ulnaris innervation
Ulnar nerve
Flexor carpi ulnaris origin
Medial epicondyle of the humerus and long origin from the ulna
Flexor carpi ulnaris insertion
Pisiform carpal bone
Flexor carpi ulnaris action
Flexion and adduction at the wrist
Palmaris longus innervation
Median nerve
Palmaris longus origin
Medial epicondyle of the humerus
Palmaris longus insertion
Flexor retinaculum of the wrist
Palmaris longus action
Flexion at the wrist
What lies directly underneath the palmaris longus?
The median nerve
Fun fact: the palmaris longus muscle is absent in 15% of the population
Flexor carpi radialis innervation
Median nerve
Flexor carpi radialis origin
Medial epicondyle of the humerus
Flexor carpi radialis insertion
Base of metacarpals II and III
Flexor carpi radialis action
Flexion and abduction at the wrist
Pronator teres innervation
Median nerve
Pronator teres origin
Medial epicondyle of humerus & coronoid process of the ulna
Pronator teres insertion
Lateral radius, distal to supination insertion
Pronator teres action
Pronation of the arm
Flexor digitorum superficialis innervation
Median nerve
Flexor digitorum superficialis origins
Two heads: one originates from the medial epicondyle of the the humerus and the other from the radius
Flexor digitorum superficialis insertion
4 tendons that split at the wrist and travel through the carpal tunnel to insert on the middle phalanges of the 4 fingers
Flexor digitorum superficialis action
Flexes the metacarpophalangeal joint and proximal interphalangeal joint at the 4 fingers 7 flexes at the wrist
Flexor digitorum profundus innervation
Medial half (acts of the little and ring fingers) - ulnar nerve
Lateral half (acts on the middle and index fingers) - anterior interosseus branch of the median nerve
Flexor digitorum profundus origin
Ulna and interosseus membrane
Flexor digitorum profundus insertion
Splits into 4 tendons at the wrist that pass through the carpal tunnel and insert on the distal phalanges of the 4 fingers
Flexor digitorum profundus action
The ONLY muscle that can flex the distal interphalangeal joints of the fingers, also flexes at metacarpophalangeal joints and the wrist
Flexor pollicis longus innervation
Median nerve (anterior interosseus branch)
Flexor pollicis longus origin
Anterior surface of the radius and surrounding interosseus membrane
Flexor pollicis longus insertion
Base of the distal phalanx of the thumb
Flexor pollicis longus action
Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb
Pronator quadratus innervation
Median nerve (anterior interosseus branch)
Pronator quadratus origin
Anterior surface of the ulna
Pronator quadratus insertion
Anterior surface of the radius
Pronator quadratus action
Pronates the arm
Which nerve innervates all muscles in the posterior compartment of the forearm?
Radial nerve
Which superficial muscles of the posterior forearm share a common tendinous origin at the lateral epicondyle?
Extensor carpi radialis brevis m., extensor digitorum m., extensor carpi ulnaris m., and extensor digit minimi m.
Brachioradialis innervation
Radial nerve
Brachioradialis origin
Proximal aspect of the lateral supracondylar ridge of the humerus
Brachioradialis insertion
Distal end of the radius, just before the radial styloid process
Brachioradialis action
FLEXES at the ELBOW
*outlier because its origin and innervation (radial) are characteristic of an extensor muscle
What are sandwhiched between the brachioradialis and the deep flexor muscles in the distal forearm?
The radial artery and nerve
Extensor carpi radialis longus and brevis innervation
Radial nerve
Extensor carpi radialis longus and brevis origin
ECRL: supracondylar ridge of distal humerus, lateral intermuscular septum
ECRB: lateral epicondyle of humerus
Extensor carpi radialis longus and brevis insertion
Tendons attach to metacarpal bones II and III
Extensor radialis longus and brevis action
Extend and abduct the wrist
Extensor digitorum innervation
Radial nerve (deep branch)
Extensor digitorum origin
Lateral epicondyle of humerus
Extensor digitorum insertion
4 tendons that insert into the extensor hood of each finger
Extensor digitorum action
Extends medial 4 fingers at the MCP and IP joints
*main extensor of the fingers - to test the function of the muscle, the forearm is pronated and the fingers extended against resistance
Extensor digiti minimi innervation
Radial nerve (deep branch)
Extensor digiti minimi origin
Lateral epicondyle of the humerus
Extensor digiti minimi insertion
Into the extensor hood of the little finger (with the extensor digitorum tendon)
Extensor digiti minimi action
Extends the little finger, contributes to extension at the wrist
In some people, extensor digiti minimi and extensor digitorum muscle are fused, typically the extensor digiti minimi lies medially to the extensor digitorum m.
Extensor carpi ulnaris innervation
Radial nerve (deep branch)
Extensor carpi ulnaris origin
Lateral epicondyle of the humerus
Extensor carpi ulnaris insertion
Base of metacarpal V
Extensor carpi ulnaris action
Extension and adduction of wrist
Anconeus innervation
Radial nerve
Anconeus origin
Originates from the lateral epicondyle of humerus
Anconeus insertion
Posterior and lateral part of the olecranon of ulna
Anconeus action
Extends and stabilize the elbow joint, abducts the ulna during pronation of the forearm
The anconeus is blended in with the fibers of which muscle?
Triceps brachii
The two muscles are sometimes indistinguishable
Describe tennis elbow
Lateral epiconylitis refers to inflammation of the periosteum of the lateral epicondyle caused by repeated use of the superficial extensor muscles which strains their common tendinous attachment to the lateral epicondyle.
Supinator innervation
Radial nerve (deep branch)
Supinator origin
2 heads: one originates from the lateral epicondyle of the humerus, one from the posterior surface of the ulna
*the deep branch of the radial nerve passes between the heads
Supinator insertion
Posterior surface of the radius
Supinator action
Supinator the forearm
Abductor pollicis longus innervation
Radial nerve (posterior interosseus branch)
Abductor pollicis longus origin
Interosseus membrane and the adjacent posterior surfaces of the radius and ulna
Abductor pollicis longus insertion
Lateral side of the base of metacarpal I
Abductor pollicis longus action
Abducts the thumb
Extensor pollicis brevis innervation
Radial nerve (posterior interosseus branch)
Extensor pollicis brevis origin
Posterior surface of the radius and interosseus membrane
Extensor pollicis brevis insertion
Base of the proximal phalanx of the thumb
Extensor pollicis brevis action
Extends at the metacarpophalangeal and carpometacarpal joint of the thumb
Extensor pollicis longus innervation
Radial nerve (posterior interosseus branch)
Extensor pollicis longus origin
Posterior surface of the ulna and interosseus membrane
Extensor pollicis longus insertion
Distal phalanx of the thumb
Extensor pollicis longus action
Using the dorsal tubercle of the radius as a pulley for its tendon, the muscle extends all joints of the thumb: carpometacarpal, metacarpophalangeal and interphalangeal
Extensor indicis proprius innervation
Radial nerve (posterior interosseus branch)
Extensor indicis proprius origin
Posterior surface of the ulna and interosseus membrane, distal to the extensor pollicis longus
Extensor indicis proprius insertion
Extensor hood of the index finger
Extensor indicis proprius action
Extends the index finger
Injury to which nerve causes “wrist drop”?
Where does the injury typically happen?
Radial nerve injury proximal to the elbow
Axilla - injured via humeral dislocations or fracture of the proximal humerus
Radial groove of the humerus - injured via a humeral shaft fracture
Radial nerve innervates all muscles in the extensor compartment so with a lesion they are paralyzed, while the wrist flexors (innervated but the median nerve) are unaffected leading to unopposed flexion
Describe the borders of the anatomical snuff box
Medial/ulnar: tendon of the extensor pollicis longus
Lateral/radial: tendons of the abductor pollicis longus and extensor pollicis brevis
Proximal: styloid process of the radius
Floor: carpal bones; scaphoid and trapezium
Roof: skin
Describe the contents of the anatomical snuffbox
Radial artery, a branch of the radial nerve and the cephalic vein (more subcutaneous)
Subcutaneously, terminal branches of the superficial branch of the radial nerve run across the roof of the anatomical snuffbox providing innervation to the skin of the lateral 3 1/2 digits on the dorsal of the hand and associated palm area
Describe the potential severity of a scaphoid fracture
If localized pain is reported in the anatomical snuffbox after falling on an outstretched hand, it’s likely a fracture of the scaphoid.
Because the scaphoid unique blood supply runs distal to proximal, a fracture can disrupt the blood supply to the proximal portion - emergency! Failure to revascularize the scaphoid can lead to a vascular necrosis and future arthritis.
Opponens pollicis innervation
Median nerve
Opponens pollicis origin
Tubercle of the trapezium and the associated flexor retinaculum
(Part of the thenar eminence)
Opponens pollicis insertion
Lateral margin of the metacarpal of the thumb
Opponens pollicis action
Opposes the thumb by medially rotating and flexing the metacarpal on the trapezium
Abductor pollicis brevis innervation
Median nerve
Abductor pollicis brevis origin
Tubercle of the scaphoid and trapezium and from the associated flexor retinaculum
(Part of the thenar eminence)
Abductor pollicis brevis insertion
Lateral side of the proximal phalanx of the thumb
Abductor pollicis brevis action
Abducts the thumb
Flexor pollicis brevis innervation
Median nerve
Flexor pollicis brevis origin
Tubercle of the trapezium and from the associated flexor retinaculum
(Part of the thenar eminence)
Flexor pollicis brevis insertion
Base of the proximal phalanx of the thumb
Flexor pollicis brevis action
Flexes the metacarpophalangeal (MCP) joint of the thumb
Most distal of the thenar eminence muscles
Opponens digiti minimi innervation
Ulnar nerve
Opponens digiti minimi origin
Hook of hamate and associated flexor retinaculum
Deepest of the hypothenar muscles
Opponens digiti minimi insertion
Medial margin of metacarpal V
Opponens digiti minimi action
Rotates the metacarpal of the little finger towards the palm, producing opposition
Abductor digiti minimi innervation
Ulnar nerve
Abductor digiti minimi origin
Pisisform and tendon of the flexor carpi ulnaris
Most superficial of the hypothenar muscles
Abductor digiti minimi insertion
Base of the proximal phalanx of the little finger
Abductor digiti minimi action
Abducts the little finger
Flexor digiti minimi brevis innervation
Ulnar nerve
Flexor digiti minimi brevis origin
Hook of hamate and adjacent flexor retinaculum
Flexor digiti minimi insertion
Base of the proximal phalanx of the little finger
Flexor digiti minimi brevis action
Flexes the MCP joint of the little finger
Denervation of lumbrical muscles in the hand is the basis for what two “signs”?
Ulnar claw and hand of benediction
Lumbricals innervation
Medial 2 lumbricals (little and ring fingers): ulnar nerve
Lateral 2 lumbricals (index and middle fingers): median nerve
Lumbricals origin
Each originates from a tendon of the flexor digitorum profundus
Lumbricals insertion
Each passes dorsal and laterally around each finger and insert into the extensor hood
Lumbricals action
Flex at the MCP joint, extend at the IP (interphalangeal) joint of each finger
Dorsal Interossei innervation
Ulnar nerve
Dorsal interossei origin
Each interossei originates from the lateral and medial surfaces of the metacarpals
(Most superficial of the dorsal muscles)
Dorsal interossei insertion
Extensor hood and proximal phalanx of each finger
Dorsal interossei action
Abduct the fingers at the MCP joint
Palmar interossei innervation
Ulnar nerve
Palmar interossei origin
Medial or lateral surface of a metacarpal
Palmar interossei insertion
Extensor hood and proximal phalanx
Palmar interossei action
Adducts the fingers at the MCP joint
Palmaris brevis innervation
Ulnar nerve
Palmaris brevis origin
Palmar aponeurosis and flexor retinaculum
Palmaris brevis insertion
Dermis of the skin on the medial margin of the hand
Palmaris brevis action
Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip
Adductor pollicis innervation
Ulnar nerve
Adductor pollicis origin
2 heads: one originates from metacarpal III, the other from the capitate and adjacent areas of metacarpals II and III
Adductor pollicis insertion
Base of the proximal phalanx of the thumb
Adductor pollicis action
Adductor of the thumb
What passes anteriorly through the space between the two head of the adductor pollicis?
Radial artery - it then forms the deep palmar arch
