Muscles of the Upper Limb Flashcards
What are the 4 muscles within the pectoral region?
- Pectoralis major
- Pectoralis minor
- Subclavius
- Serratus anterior
What are the attachments of pectoralis major?
Clavicular head:
- originates from the anterior surface of the medial clavicle
Sternocostal head:
- originates from the anterior surface of the sternum, the superior 6 costal cartilages and the aponeurosis of the external oblique muscle
Insertion:
- intertubercular sulcus of humerus
What is the function and innervation of pectoralis major?
Function:
- adducts and medically rotates the upper limb
- draws the scapula anteroinferiorly
- clavicular head will flex the upper limb
Innervation:
- lateral and medial pectoral nerves
What are the attachments, function and innervation of pectoralis minor?
Origin:
- 3rd to 5th ribs
Insertion:
- coracoid process of the scapula
Function:
- stabilises the scapula by drawing it anteroinferiorly against the thoracic wall
Innervation:
- medial pectoral nerve
What are the attachments, function and innervation of serratus anterior?
Origin:
- muscular strips originate from the lateral aspects of ribs 1-8
Insertion:
- costal surface of medial border of the scapula
Functions:
- rotates the scapula, allowing the arm to be raised over 90 degrees
- holds the scapula against the rib cage
Innervation:
- long thoracic nerve
What are the attachments, function and innervation of subclavius?
Origin:
- junction of the 1st rib and its costal cartilage
Insertion:
- inferior surface of the middle third of the clavicle
function:
- Anchors and depresses the clavicle
Innervation:
- nerve to subclavius
What is the difference between extrinsic and intrinsic muscles of the shoulder?
Extrinsic muscles:
- originate from the torso and attach to the bones of the shoulder (clavicle, scapula or humerus)
Intrinsic muscles:
- originate from the scapula and/or clavicle and attach to the humerus
What are the 2 superficial extrinsic muscles of the shoulder?
- Trapezius
- Latissimus dorsi
What are the attachments, innervation and actions of trapezius?
Origin:
- skull, nuchal ligament and spinous processes of C7 - T12
Insertion:
- clavicle, acromion and the scapula spine
Innervation:
- motor innervation is from the accessory nerve
Actions:
- upper fibres elevate the scapula and rotate it during abduction of the arm
- middle fibres retract the scapula
- lower fibres pull the scapula inferiorly
What are the attachments, innervation and actions of latissimus dorsi?
Origin:
- spinous processes of T7-T12, iliac crest, thoracolumbar fascia and inferior 3 ribs
Insertion:
- intertubercular sulcus of the humerus
Innervation:
- thoracodorsal nerve
Actions:
- extends, adducts and medically rotates the upper limb
What are the 3 deep extrinsic muscles of the back?
- Levator scapulae
- Rhomboid minor
- Rhomboid major
These are situated in the upper back, underneath the trapezius
Label the extrinsic muscles of the shoulder
What are the attachments, innervation and actions of levator scapulae?
Origin:
- transverse processes of C1-C4 vertebrae
Insertion:
- medial border of the scapula
Innervation:
- dorsal scapular nerve
Actions:
- Elevates the scapula
What are the attachments, innervation and actions of rhomboid major?
Origin:
- spinous processes of T2-T5 vertebrae
Insertion:
- medial border of scapula, between scapula spine and inferior angle
Innervation:
- dorsal scapular nerve
Action:
- retracts and rotates the scapula
What are the attachments, innervation and actions of rhomboid minor?
Origin:
- spinous processes of C7-T1 vertebrae
Insertion:
- medial border of the scapula, at the level of the spine of the scapula
Innervation:
- dorsal scapular nerve
Actions:
- retracts and rotates the scapula
What are the 6 intrinsic muscles of the shoulder?
- Deltoid
- Teres major
and the 4 rotator cuff muscles:
- Supraspinatus
- Infraspinatus
- Subscapularis
- Teres minor
What are the attachments and innervation of deltoid?
Origin:
- lateral third of the clavicle, acromion and spine of scapula
Insertion:
- deltoid tuberosity on lateral aspect of humerus
Innervation:
- axillary nerve
What are the actions of the different fibres of the deltoid?
Anterior fibres:
- flexion and medial rotation
Posterior fibres:
- extension and lateral rotation
Middle fibres:
- the major abductor of the arm
- it takes over from supraspinatus (which abducts the first 15 degrees)
What muscle forms the inferior border of the quadrangular space?
teres major
this is the gap that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapula region
What are the attachments, innervation and actions of teres major?
Origin:
- posterior surface of the inferior angle of the scapula
Insertion:
- medial lip of the intertubercular groove of the humerus
innervation:
- lower subscapular nerve
Actions:
- adducts the shoulder
- medially rotates the arm
What muscles are shown here?
What is the collective function of the rotator cuff muscles?
Where do they originate and insert?
They originate from the scapula and insert onto the humeral head
They “pull” the humeral head into the glenoid fossa
This gives the glenohumeral joint a lot of additional stability
What are the attachments, innervation and actions of supraspinatus?
Origin:
- supraspinous fossa of the scapula
Insertion:
- greater tubercle of the humerus
Innervation:
- suprascapular nerve
Actions:
- abducts the arm 0-15 degrees
- assists deltoid for 15-90 degrees
What are the attachments, innervation and actions of infraspinatus?
Origin:
- infraspinous fossa of the scapula
Insertion:
- greater tubercle of the humerus
Innervation:
- suprascapular nerve
Action:
- laterally rotates the arm
What are the attachments, innervation and actions of subscapularis?
Origin:
- subscapular fossa of the scapula
Insertion:
- lesser tubercle of humerus
Innervation:
- upper and lower subscapular nerves
Actions:
- medially rotates the arm
What are the attachments, innervation and actions of teres minor?
Origin:
- posterior surface of scapula, adjacent to its lateral border
insertion:
- greater tubercle of the humerus
Innervation:
- axillary nerve
Actions:
- laterally rotates the arm
Label the rotator cuff muscles:
What are the 4 muscles of the upper arm?
Anterior compartment:
- brachialis
- coracobrachialis
- biceps brachii
Posterior compartment:
- Triceps brachii
What is the arterial and nervous supply of the anterior compartment of the arm?
musculocutaneous nerve
muscular branches of the brachial artery
What are the attachments, actions and innervation of biceps brachii?
Origins:
- long head - supraglenoid tubercle of scapula
- short head - coracoid process of scapula
Insertion:
- radial tuberosity
Actions:
- supination of the forearm
- flexion of the arm at the elbow and at the shoulder
Innervation:
- musculocutaneous nerve
What is the bicipital aponeurosis and how is it formed?
as the tendon of biceps brachii enters the forearm, it gives off a connective tissue sheet (bicipital aponeurosis)
this forms the roof of the cubital fossa and blends with the deep fascia of the anterior forearm
What are the attachments, function and innervation of coracobrachialis?
Origin:
- coracoid process of scapula
Insertion:
- It passes through the axilla to attach to the medial side of the humeral shaft, at the level of the deltoid tubercle
Innervation:
- musculocutaneous nerve
Actions:
- flexion of the arm at the shoulder
- weak adduction of the arm
What forms the floor of the cubital fossa?
brachialis
What are the attachments, functions and innervation of brachialis?
Origin:
- medial and lateral surfaces of humeral shaft
Insertion:
- ulna tuberosity
Function:
- flexion of the elbow
Innervation:
- musculocutaneous nerve
- contributions from the radial nerve
Label the anterior compartment arm muscles
What is meant by “Popeye sign” and what causes it?
it is caused by rupture of the biceps tendon
there is a bulge where the muscle belly is upon flexing the elbow
the patient does not notice much weakness in the upper limb due to the actions of brachialis and supinator muscles
What is the blood supply to the posterior compartment of the arm?
Profunda brachii artery
What are the attachments of triceps brachii?
Long head:
- infraglenoid tubercle of the scapula
Lateral head:
- humerus - superior to the radial groove
Medial head:
- humerus - inferior to the radial groove
Insertion:
- olecranon of the ulna
What are the actions and innervation of triceps brachii?
Actions:
- extension of the arm at the elbow
Innervation:
- radial nerve
In general, what are the actions of the muscles in the anterior compartment of the forearm?
flexion of the wrist and fingers
pronation
What are the 4 superficial compartment muscles of the forearm?
Where do they all originate from?
- Flexor carpi ulnaris
- Flexor carpi radialis
- Palmaris longus
- Pronator teres
They all arise from the medial epicondyle of the humerus
What are the attachments, actions and innervation of flexor carpi ulnaris?
Origin:
- medial epicondyle of humerus
Insertion:
- Pisiform bone
Actions:
- flexion and adduction of the wrist
Innervation:
- ulnar nerve
What are the attachments, actions and innervation of palmaris longus?
Origin:
- medial epicondyle of humerus
Insertion:
- flexor retinaculum of the wrist
Actions:
- flexion of the wrist
Innervation:
- median nerve
What are the attachments, actions and innervation of flexor carpi radialis?
Origin:
- medial epicondyle of humerus
Insertion:
- base of metacarpals II and III
Actions:
- flexion and abduction at the wrist
Innervation:
- median nerve
What are the attachments, actions and innervation of pronator teres?
Origin:
- one origin is from the medial epicondyle
- one origin is from the coronoid process of the ulna
Insertion:
- attaches laterally to the mid-shaft of the radius
Actions:
- pronation of the forearm
Innervation:
- median nerve
Label the superficial muscles of the anterior forearm
What is the muscle in the intermediate compartment of the forearm?
Why is it a good anatomical landmark?
Flexor digitorum superficialis
The median nerve and the ulnar artery pass between its two heads, and then travel posteriorly
What are the attachments of flexor digitorum superficialis?
Origin:
- one head originates from the medial epicondyle
- one head originates from the radius
Insertion:
- the muscle splits into 4 tendons, which travel through the carpal tunnel
- they attach to the middle phalanges of the 4 fingers
What are the actions and innervation of flexor digitorum superficialis?
Actions:
- flexes metacarpophalangeal joints and proximal interphalangeal joints of 4 fingers
- flexes the wrist
Innervation:
- median nerve
What are the 3 muscles in the deep compartment of the forearm?
- Flexor digitorum profundus
- Flexor pollicis longus
- Pronator quadratus
What are the attachments of flexor digitorum profundus?
Origin:
- ulna and associated interosseous membrane
Insertion:
- at the wrist, it splits into 4 tendons that pass through the carpal tunnel
- they attach to the distal phalanges of the 4 fingers
What are the actions and innervation of flexor digitorum profundus?
Actions:
- it is the only muscle that can flex the distal interphalangeal joints of the fingers
- flexes metacarpophalangeal joints
- flexes the wrist
Innervation:
- Medial half - ulnar nerve
- lateral half - anterior interosseous branch of the median nerve
What are the attachments, actions and innervation of flexor pollicis longus?
Origin:
- anterior surface of radius and interosseous membrane
Insertion:
- base of distal phalanx of the thumb
Actions:
- flexes interphalangeal joint and metacarpophalangeal joint of the thumb
Innervation:
- anterior interosseous branch of the median nerve
What are the attachments, innervation and actions of pronator quadratus?
Origin:
- anterior surface of the ulna
Insertion:
- anterior surface of the radius
Actions:
- pronates the forearm
Innervation:
- anterior interosseous branch of the median nerve
Label the muscles of the deep compartment of the forearm
Label the prosection image
Label the prosection images
Label the prosection image
What are the general functions of the posterior compartment forearm muscles?
What is their innervation?
they extend the wrist and fingers
they are all innervated by the radial nerve
What superficial posterior compartment muscles share a common tendinous origin?
- Extensor carpi radialis brevis
- Extensor digitorum
- Extensor carpi ulnaris
- Extensor digiti minimi
They share a common tendinous origin at the lateral epicondyle
Why is brachioradialis called a “paradoxical muscle”?
Its origin and innervation are characteristic of an extensor muscle, but it is actually a flexor at the elbow
What are the attachments, actions and innervation of brachioradialis?
Origin:
- proximal aspect of lateral supracondylar ridge of humerus
Insertion:
- distal end of the radius, just before radial styloid process
Actions:
- flexes the elbow
Innervation:
- radial nerve
Label the muscles in the superficial layer of the posterior forearm
What are the attachments, actions and innervation of extensor carpi radialis longus and extensor carpi radialis brevis?
Origin:
- ECRL - supracondylar ridge
- ECRB - lateral epicondyle
Insertion:
- metacarpal bones II and III
Actions:
- extends and abducts the wrist
Innervation:
- radial nerve
What are the attachments, actions and innervation of extensor digitorum?
Origin:
- lateral epicondyle
Insertion:
- the tendon continues into the distal part of the forearm and splits into four
- it inserts into the extensor hood of each finger
Actions:
- extends medial four fingers at the MCP and IP joints
Innervation:
- Deep branch of radial nerve
What are the attachments, actions and innervation of extensor digiti minimi?
Origin:
- lateral epicondyle of humerus
Insertion:
- it attaches, with the extensor digitorum tendon, into the extensor hood of the little finger
Actions:
- extends the little finger
- contributes to extension at the wrist
Innervation:
- deep branch of the radial nerve
What are the attachments, actions and innervation of extensor carpi ulnaris?
Origin:
- lateral epicondyle of the humerus
Insertion:
- base of metacarpal V
Actions:
- extension and adduction of the wrist
Innervation:
- deep branch of the radial nerve
What are the attachments, actions and innervation of anconeus?
Origin:
- lateral epicondyle
Insertion:
- posterior and lateral part of the olecranon
Actions:
- extends and stabilises the elbow joint
- abducts the ulna during pronation of the forearm
Innervation:
- radial nerve
