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Flashcards in UL Bones, Muscles Deck (63):
1

Shoulder girdle

two bones: Clavicle and Scapula

2

Clavicle

Parts:
Medial end, lateral end and shaft.
• Medial end (sternal) is rounder and articulates with sternum.
• Lateral end (acromial) is flat and articulates with acromion process of scapula.
• Shaft is “S” shaped and divided into medial 2/3 part (convex anteriorly) and lateral 1/3 part (concave)
• Inferior surface of the shaft has subclavian groove, conoid tubercle and trapezoid line

Is a long bone and it has some special characteristics:
• It is placed horizontally
• It is subcutaneous
• It has no medullar cavity
• Greater part of it is ossified in membrane. Clavicle is the only long bone which is ossified in membrane.
• It transmits the weight of the appendicular skeleton to the axial skeleton.
• It is a curved bone and protects the underlying vessels and nerves.
• It is weak where two curves meet at the junction of the medial ⅔ with the lateral ⅓.
• It is usually fractured at the junction of medial 2/3 and lateral 1/3
• It is the most commonly fractured upper limb bone because of its shape and subcutaneous location.
• Whenever a person falls on the outstretched hand or on the side of the shoulder, it tends to get fractured.
• Brachial plexus and subclavian vessels can get damaged by fractured segments.
• Can cause pulmonary embolism (Embolism-obstruction of an artery, typically by a clot of blood or an air bubble; sudden blockage in a lung artery, usu from vein in leg)
• Green stick fracture of clavicle in young children: Clavicle is bent like a young, tender green stick (not fractured). Common in children
• When the clavicle is fractured in its middle, the medial segment is elevated and lateral segment is depressed because the medial segment is elevated by the sternocleidomastoid and lateral segment is depressed by gravity.
Joints of the clavicle:
• Medially – sternoclavicular joint (synovial, saddle type)
• Laterally – acromioclavicular joint (Synovial, plane type)

Ligaments attached to the medial end:
• Sternocalvicular ligament
• Costoclavicular ligament

Ligaments attached to the lateral end:
• Acromioclavicular ligament
• Coracoclavicular ligament

Muscles attached to the clavicle:
• Medially: Sternocleidomastoid and Pectoralis major
• Laterally: Deltoid and Trapezius
• Inferiorly: Subclavius

3

Scapula

• It is a flat triangular bone.
It has two surfaces: Ventral and dorsal
• Ventral surface has subscapular fossa which gives origin to subscapularis muscle
• The dorsal surface has a spine.
• Superior to the spine of the scapula, there is Supraspinous fossa and inferior to the spine there is Infraspinous fossa.
• Supraspinatus muscle arises from the Supraspinous fossa while the infraspinatus muscle arises from the Infraspinous fossa.
It has two notches:
• Suprascapular notch –on the upper border
• Spinoglenoid notch- between the spine and the glenoid cavity
It has three borders: Medial, lateral and superior
• To the medial border muscles are inserted
• Ventral surface of the medial border: insertion of serratus anterior.
• Dorsal aspect of medial border: insertion of levator scapulae, rhomboid minor and rhomboid major muscles
• Muscle originate from the lateral border:
• Long head of triceps (from the infraglenoid tubercle), Teres minor, Teres major
• Superior border has a notch: Suprascapular notch.
• Suprascapular ligament bridges the notch and converts it into a suprascapular foramen through which Suprascapular nerve passes.
• The Suprascapular artery passes superior to the ligament. (Remember the mnemonic that Army walks over the bridge and Navy goes under the bridge).
• Suprascapular nerve supplies the supraspinatus and then passes through the spinoglenoid notch to supply the infraspinatus muscle.

It has three angles:
• Superior, inferior and lateral
• The lateral angle corresponds to the Glenoid cavity.
• The Glenoid cavity joins the head of the humerus to form the glenohumeral (shoulder joint)
• Supraglenoid tubercle gives origin to the long head of biceps brachii.
• It is important to note that the origin of the long head of biceps is intracapsular.

It has two processes:
• Coracoid and Acromion
• The coracoid process gives attachment to the coracoclavicular ligament and insertion of pectoralis minor.
• The tip of the coracoid process gives origin to short head of biceps and coracobrachialis.
• Acromion gives attachment to deltoid and trapezius muscles

4

Humerus

Nerves related to the humerus:
• Axillary nerve (with post circumflex humeral vessels)- To the surgical neck
• Radian nerve (with deep artery of the arm, profunda brachii): Radial grove/Spiral grove (shaft of humerus)
• Ulnar nerve: Behind the medial epicondyle
• Medial nerve: Lower part of the shaft anteriorly (supracondylar fracture)
• In case of fracture, these nerves can be damaged.
Tennis elbow: Inflammation of common extensors
Golfer's elbow: Inflammation of common flexors

• Long bone, bone of arm.
• It has upper end, shaft and lower end.

The upper end:
• Has head, neck and two tubercles.
• The head is smooth and it forms the glenohumeral joint (shoulder joint) with the scapula.
• The constriction around the head is called the anatomical neck of the humerus. Fibrous capsule of the shoulder joint (glenohumeral) is attached to the anatomical neck.
• Surgical neck of the humerus: It is at the junction of the upper end with the shaft. It is a common site of fracture. Axillary nerve and the posterior circumflex humeral vessels wind around the surgical neck of the humerus.
• There are two tubercles:
• Greater tubercle: Insertions of Supraspinatus, Infraspinatus and Teres minor (SIT)
• Lesser tubercle: Insertion of the subscapularis
• Intertubercular sulcus or bicipital groove (btwn 2 tubercles): Insertions of pectoralis major (lateral lip), Teres major (medial lip) and Latissimus dorsi (between the lips).
• Long head of biceps and ascending branch of anterior circumflex humeral artery run in the bicipital groove.
• Shaft: Has 3 borders (anterior, medial and lateral) and 3 surfaces (anteromedial, anterolateral and posterior)
• The shaft receives the attachment of deltoid muscle on the middle of the lateral side (deltoid tuberosity), and coracobrachialis on the medial side. Lower part of the front of the shaft gives origin to brachialis. Posterior surface of the shaft gives origin to lateral and medial heads of the triceps brachii. Radial groove lies between the two origins. Radial nerve and profunda brachii vessels run in the radial groove.

The lower end has the following parts:
• Medial and lateral epicondyles
• Medial epicondyle gives origin to the common flexors of the forearm
• Lateral epicondyle gives origin to the common extensors of the forearm
• Anconeus muscle arises from the posterior surface of the lateral epicondyle.
• The condyle has the following parts;
• Capitulum and Trochlea – Capitulum articulates with the head of the radius. Trochlea articulates with the trochlear notch of the ulna.
• The medial edge of the trochlea projects beyond the rest of the bone and this causes the angulation present between the long axis of humerus and long axis of ulna when the elbow is extended. This is called carrying angle. The carrying angle is more marked in the female (10 - 15¬¬0 in male, > 15¬¬0 in female)
• There is a large olecranon fossa on the posterior aspect of the lower end. The head of the humerus is directed medially and the olecranon fossa posteriorly.

5

Radius

• Long bone with upper end, shaft and lower end
• Upper end: has head, neck and tuberosity:
• Head articulates with ulna medially (radial notch of ulna) and capitulum of the humerus superiorly
• The head of the radius is held by annular ligament. This ligament is NOT attached to the radius
• Radial tuberosity: Insertion of brachialis muscle
• Radius and ulna connected by interosseous membrane
• Lower end:
• Radial artery can be compressed against its anterior surface (radial pulse)
• Articulates with scaphoid, lunate and triquetral to form wrist joint
• Dorsal surface has grooves for extensor tendons
• Lateral part extends to form styloid process (articulates w carpal bones to form wrist joints)
• Shaft:
• Has anterior, posterior and lateral surfaces
• Has anterior, posterior and medial border (interosseous border)
• Colles fracture:
• Fracture of the lower end of the radius and may be the styloid process of ulna
• Fall on the hand with palm facing the ground (radius lower end breaks off dorsally)
• Hand look like a dinner fork!
• Smith’s fracture:
• Fracture of the lower end of the radius (breaks off ventrally) and may be the styloid process of ulna
• Fall on the hand with the dorsum of the hand facing the ground

6

Ulna

• Parts: Upper end, shaft and lower end
• Upper end:
• Has olecranon process, coronoid process, trochlear notch, radial notch, ulnar tuberosity and supinator crest
• Trochlear notch articulates with trochlea of the humerus to form elbow joint
• Shaft: 3 surfaces (anterior, posterior & medial)
• 3 borders (anterior, posterior & lateral/ interosseous border )
• Lower end:
• Head & styloid process
• Head articulates with lower end of the radius

7

Carpal bones

• 8 in number
• 4 in proximal row
• 4 in distal row
• Named from lateral to medial (She Looks Too Pretty; Try To Catch Her!)
• Proximal row: Scaphoid, Lunate, Triquetral, Pisiform
• Distal row: Trapezium, Trapezoid, Capitate, Hamate
• Scaphoid (navicular-shaped) is most commonly fractured and can undergo avascular necrosis (death of bone tissue due to a lack of blood supply)
• Lunate is most commonly dislocated and can compress median nerve leading to carpel tunnel syndrome.
• Hamate has a hook; Capitate- biggest
• Pisiform is a sesamoid bone. Ulnar nerve and vessels are related to this.
• Metacarpals: 5 in number and numbered from lateral to medial
• Bennett’s fracture: Fracture of the base of the first metacarpal
• Boxer’s fracture: Fracture of 4th or 5th metacarpal
• Phalanges: 14 in total, 2 for thumb (proximal & distal), 3 for digits (proximal, middle and distal)

8

Deltopectoral groove

In pectoral region:
-lies between the pectoralis major and deltoid muscles
• This groove contains:
• Cephalic vein
• Deltopectoral lymph nodes and lymph vessels accompanying it
• Deltoid branch of Thoracoacromial artery

9

Pectoralis major

• Action: flexor of the shoulder joint; helps in the adduction and medial rotation of the shoulder joint.
• Nerve supply: lateral and medial pectoral nerves.
• Artery: Pectoral branch of thoracoacromial

-removal of pec major mostly affects arm adduction

• This has two parts:
• Clavicular part and sternocostal part
• Clavicular part origin: from the anterior surface of the medial half of the clavicle
• Sternocostal origin: from the anterior surface of the sternum and upper six costal cartilages
• It is inserted into the lateral lip of the bicipital groove.
• It crosses the shoulder joint
• The clavicular fibers help in the flexion of the shoulder joint.

10

Pectoralis minor

• It depresses the scapula
• Nerve supply: It is supplied by the lateral and medial pectoral nerves. Medial pectoral nerve mainly supplies it as it pierces it.
• Artery: Pectoral branch of thoracoacromial

-muscle tear that resulted directly from the superolateral distraction of a fractured coracoid process: pec minor torn

• It arises from the 3rd, 4th and 5th ribs near their costal cartilages.
• It is inserted into the coracoid process of the scapula

11

Subclavius m.

• Axn: Depresses lateral part of clavicle
• It is supplied by the nerve to subclavius (C5 & C6) which arises from the upper trunk of the brachial plexus
• Artery: Clavicular branch of thoracoacromial artery

• It arises from the 1st rib and its costal cartilage.
• inserted to the subclavian groove on the middle ⅓ of the inferior surface of the clavicle.

12

Deltoid

Intrinsic Muscle of UL
• Nerve supply: Axillary nerve. (C5, 6)
• Artery- Posterior circumflex humeral artery, deltoid branch of thoracoacromial artery

*Origin:
• Lateral ⅓ of the clavicle (anterior border) - Anterior fibres
• Lateral border of the acromion – Middle fibres.
• Lower lip of the crest of the spine of the scapula - Posterior fibres
Insertion:
• Deltoid tuberosity of the humerus*

Action:
• Anterior fibres- flexor, adductor and medial rotator of the arm
• Middle fibres- Abductor of the arm (15°-90°)
• Posterior fibres- Extensor, adductor and lateral rotator of the arm
• Anterior and posterior fibers alternately contract while walking
• Middle fibers are main abductor of the shoulder joint.
• Deltoid is the major abductor (15 – 90°) of the arm. It is assisted by the supraspinatus in the initial 15° abduction.
• Testing the function of deltoid (or axillary nerve) - The patient is asked to abduct the arm from 15°-against resistance.
o *rmbr shoulder abduction done at 3 stages (initial: 0-15 deg by supraspinatus Muscle, 15 deg to 90 deg (horiz)-by deltoid, horiz to vertical (>90d, overhead abduction)-scapula rotate by traps and serratus anterior)
• Deltoid atrophies when the axillary nerve is damaged.
• As the deltoid atrophies, the rounded contour of the shoulder disappears.

• Powerful muscle, large and triangular.
• It is called deltoid because it is shaped like inverted Greek letter delta.
• It is responsible for the smooth round contour of the shoulder
• It is the principle abductor of the shoulder
• It overlaps the upper end of the humerus. Axillary nerve and posterior circumflex humeral vessels lie deep to the muscle.

13

Rotator cuff m.

*KNOW ATTACHMENTS*
Nerve supply of the muscles of rotator cuff:
• Supraspinatus and infraspinatus – suprascapular nerve
• Teres minor – axillary nerve
• Subscapularis – upper and lower subscapular nerves

Three muscles are inserted into the greater tubercle
• Supraspinatus
• Infraspinatus
• Teres minor (SIT muscles)
Subscapularis is inserted into the lesser tubercle

Rotator cuff injuries

• Rotator cuff tears are problems of the rotator cuff muscles of the shoulder.
• One or more rotator cuff tendons may become inflamed from overuse, aging, a fall on an outstretched hand, or a collision.
• Sports requiring repeated overhead arm motion or occupations requiring heavy lifting also place a strain on rotator cuff tendons and muscles.
• Normally, tendons are strong, but a longstanding wearing down process may lead to a tear.
• Typically, a person with a rotator cuff injury feels pain over the deltoid muscle at the top and outer side of the shoulder, especially when the arm is raised or extended out from the side of the body.
• Motions like getting dressed can be painful!
• The shoulder may feel weak, especially when trying to lift the arm into a horizontal position.
Arm drop test: to test the supraspinatus muscle

• They act like expansible ligaments and protect the shoulder joint. The tonic contraction of the muscles help keep the head of the humerus opposed to the glenoid cavity.

14

Supraspinatus

Intrinsic Muscle of UL
Nerve supply: Suprascapular nerve (C5, 6)
Artery: Suprascapular artery

Action:
• Assists deltoid in abduction.
• Initiates abduction of arm from 0° -15 ° at shoulder joint.
• Test the function – asks the patient to abduct from full adducted position against resistance.
• Clinical: subacromial bursitis. Pain is felt during 50-130 degree abduction when supraspinatus is in intimate contact with the acromion- Painful arc syndrome.
• If supraspinatus alone is torn or diseased, when the patient is asked to lower the fully abducted arm slowly and smoothly from 90 degree position, the limb will suddenly drop to the side.

o most commonly injured in rotator cuff injuries bc rubs against acromion process, thus subacromial bursa (most commonly inflamed bursa)
rotator cuff injuries common in baseball
initiates process of abduction of arm; during arm abduction against resistance, can palpate muscle; NOT innervated by nerve that also supplies cutaneous innervation to lateral surface of proximal arm (axillary nerve)

• Located on the dorsal surface of the scapula above the spine.

*Origin: from the supraspinous fossa of scapula
Insertion: Superior facet on greater tubercle of humerus*

15

Infraspinatus

Intrinsic Muscle of UL
Located on the dorsal surface of the scapula below the spine.

*Origin: Infraspinous fossa of the scapula
Insertion: to the middle facet on the greater tubercle of humerus*
Nerve supply: Suprascapular nerve (C5, 6)
Artery: Suprascapular artery
Action: Lateral rotation of the arm at the shoulder joint.

16

Subscapularis

Intrinsic Muscle of UL
Forms the posterior wall of the axilla and lies on the costal surface of scapula.

*Origin: from the subscapular fossa
Insertion: lesser tubercle of humerus. It passes in front of the fibrous capsule of the shoulder joint.*

Nerve supply: Upper and lower subscapular nerves
Artery: Subscapular artery, lateral thoracic artery
Action: Medial rotation and adduction of arm at the shoulder joint.

17

Teres minor

Intrinsic Muscle of UL
*Origin: upper ⅔ of the lateral border of scapula, below the infraglenoid tubercle.
Insertion: to the inferior facet on greater tubercle of humerus*
Nerve supply: Axillary nerve (C5, 6)
Artery: Circumflex scapular artery
Action: Lateral rotation of the arm

18

Teres major

Intrinsic Muscle of UL
Thick rounded muscle. Along with latissimus dorsi, forms the posterior fold of axilla.
Origin: from the oval area on the posterior surface of the inferior angle of scapula.
Insertion: Medial lip of intertubercular sulcus of humerus
Nerve supply: Lower subscapular nerve
Artery: Circumflex scapular artery
Action: Adduction, medial rotation and extension of the arm at the glenohumeral joint.

19

Serratus anterior

Nerve supply: Long thoracic nerve (nerve of Bell) C 5, 6, 7.
Artery: Lateral thoracic a.

Action:
• It protracts (dragging it forwards) the scapula around the chest wall - pushing and punching movements.
• This action is antagonized by the contractions of rhomboids and trapezius, which act as retractors of scapula.
• Paralysis of serratus anterior results in winging of the scapula and arm cannot be raised above 90° abduction
• To test the serratus anterior (or the function of the long thoracic nerve), the hand of the outstretched limb is pushed against a wall.

• Broad sheet of muscle. Forms the medial wall of the axilla. It has saw-tooth (serratus) appearance. “Boxer’s muscle”
Origin: by 8 fleshy digitations from the upper 8 ribs.
Insertion: to the costal surface of the medial border of the scapula.

20

Biceps brachii

It has two heads: a short and a long head.
*Origin:
• Short head arises from the tip of the coracoid process along with the coracobrachialis
• Long head arises from the supraglenoid tubercle and it lies inside the capsule of the shoulder joint
• The tendon of long head of biceps is intracapsular and extrasynovial
• It emerges through the intertubercular groove and joins the short head
Insertion:
• Biceps is inserted into the posterior part of the radial tuberosity and deep fascia of forearm via bicipital aponeurosis*
• It crosses the shoulder joint, elbow joint and superior radioulnar joint

Innervation: musculocutaneous n.
Artery: Muscular branches of brachial artery

Action on the shoulder joint:
• Flexion of the shoulder joint
Action on the elbow joint:
• It flexes the elbow joint
Action on the superior radioulnar joint:
• It supinates the forearm in a semiflexed elbow. “Screwing!”
• It is a powerful supinator and that is the reason why all screws are tightened by supination and loosened by pronation.

Biceps tendonitis:
• The tendon of the long head of the biceps brachii moves back and forth in the Intertubercular sulcus, which can lead to wear and tear resulting in the shoulder pain.
• Inflammation of the tendon (bicepital tendinitis) can occur bc of repetitive microtrauma as is common in sports involving throwing and use of racquet.
• Tenderness and crepitus (crackling/popping sensation due to the presence of air in the subcutaneous tissue) can be observed.

21

Coracobrachialis

• It arises from the tip of the coracoid process along with the short head of the biceps. It is inserted into the middle of the medial side of the humerus.
• It crosses the shoulder joint anteromedially, therefore it is flexor & adductor of the shoulder.
• It is pierced by the musculocutaneous nerve
Innervation: musculocutaneous n.
Artery: Muscular branches of brachial artery

22

Brachialis

• *It arises from the lower part of the front of the humerus
• It is inserted into the ulnar tuberosity of ulna (In front of coronoid process of ulna)*
• It is supplied by two nerves: musculocutaneous nerve and radial nerve – radial nerve supplies the lateral part of the muscle.
• Artery: Radial recurrent artery, muscular branches of brachial artery
• It helps to flex the elbow joint.

23

Triceps

• It has three heads:
• Long head: it arises from the infraglenoid tubercle
• Lateral head: It arises from the posterior surface of the shaft of the humerus superior to the radial groove
• Medial head: It arises from the lower part of the posterior surface of the humerus below the radial groove
• Insertion: All three heads join to form the belly of triceps and it is inserted into the olecranon process of ulna
• Nerve supply: Radial nerve
• Artery: Branch of profunda brachii artery
• Action: extension of elbow joint
• Notes- -Medial head is functional counterpart of chief flexor- brachialis
o -Medial head is misnamed. It lies deep not medial
o Tapping triceps tendon elicits triceps reflex- testing C7 and C8

24

Forearm flexors summary

5 Superficial muscles (arise from the medial epicondyle of the humerus):
• Pronator teres
• Flexor carpi radialis
• Palmaris longus
• Flexor digitorum superficialis
• Flexor carpi ulnaris

3 Deep muscles:
• Flexor pollicis longus
• Flexor digitorum profundus
• Pronator quadratus

25

Pronator teres

• It arises from the medial epicondyle of the humerus
• It also arises from the medial border of olecranon process of ulna
• Therefore it has two heads: the humeral (superficial) and ulnar (deep) heads
• Median nerve runs between its two heads and it is the site where the compression of median nerve can occur here. (Pronator syndrome)
• Deep head of pronator teres separates the median nerve from the ulnar artery
• Ulnar artery lies deep to the deep head of pronator teres
• It is inserted into the maximum convexity on the lateral surface of the shaft of the radius.
• It is supplied by the median nerve.
• A: Ulnar a., anterior ulnar recurrent a.
• It acts as a pronator of the forearm
• It forms the medial boundary of the cubital fossa

26

Flexor carpi radialis

• It arises from the medial epicondyle of the humerus
• It lies within a separate compartment deep to the flexor retinaculum
• It is inserted into the base of second metacarpal bone
• It is supplied by the median nerve
• A: Ulnar a
Action:
• Acting with flexor carpi ulnaris, it flexes the wrist
• Acting with extensor carpi radialis, it abducts the wrist

27

Palmaris longus

• It arises from the medial epicondyle of the humerus
• It lies superficial to the flexor retinaculum and is inserted into the palmar aponeurosis
• It is often absent and it is supplied by the median nerve
• A: Ulnar a
• It flexes the wrist
• To test this muscle: The wrist is flexed and pads of little finger and thumb are pinched together.

28

Flexor carpi ulnaris

• It has two heads of origin: Humeral and ulnar head
• It arises from:
• The medial epicondyle of the humerus
• It also arises from the medial border of the olecranon
• The posterior border of the ulna by common aponeurosis along with extensor carpi ulnaris and flexor digitorum profundus
• A: Ulnar a
• Innerv: Ulnar nerve passes between the two heads of the flexor carpi ulnaris.
• It is the site where compression of ulnar nerve can occur (Cubital tunnel syndrome)
• It is inserted into the pisiform bone
• Acting with flexor carpi radialis, it flexes the wrist joint
• Acting with the extensor carpi ulnaris, it adducts the wrist joint

29

Flexor digitorum superficialis

*• It arises from three bones:
• Medial epicondyle of humerus
• Ulna
• Oblique line of radius
• It runs deep to the flexor retinaculum and divides into four tendons
• The four tendons go to the medial four digits of the hand.
• Each tendon splits into two and is attached to the sides of the middle phalanx.*

• The tendon of the flexor digitorum profundus passes deep to the two slips in each finger
• Innerv: median nerve
• A: Ulnar a
• It flexes the proximal interphalangeal joint.
• It also assists in the flexion of the metacarpophalangeal joint and wrist joint
• To test this muscle:
• One finger is flexed at the proximal interphalangeal joint against resistance while the other fingers are held in an extended position to inactivate the flexor digitorum profundus muscle.

30

Flexor digitorum profundus

*• It arises from ulna only. It also arises from the adjoining interosseous membrane
• It passes deep to the flexor retinaculum and divides into four tendons for the medial four digits.
• The tendons give origin to four lumbricals in the palm of the hand
• The tendons of flexor digitorum profundus is inserted into the base of the distal phalanx*

• It is supplied by two nerves:
• Medial half is supplied by the ulnar nerve while the lateral half is supplied by the anterior interosseous nerve (branch of median nerve).
• A: Ulnar artery and anterior interosseous artery
• It mainly flexes the distal interphalangeal joint
• It also assists to flex the proximal interphalangeal, metacarpophalangeal and wrist joint

To test this muscle:
• The proximal interphalangeal joint is held in extended position while the person attempts to flex the distal interphalangeal joint.
• When this test is done with the index finger, which becomes a test for the median nerve while the same test done with the little finger becomes a test for the ulnar nerve.

31

Flexor pollicis longus

• It arises from the radius only. It also arises from the adjoining interosseous membrane.
• It passes deep to the flexor retinaculum and is inserted into the base of the distal phalanx of thumb.
• It flexes the interphalalngeal joint of thumb
• It is supplied by the anterior interosseous nerve (branch of median nerve)
• A: Anterior interosseous artery (from common interosseous a., which is from ulnar a.)
• To test this muscle: the proximal phalanx of the thumb is held and the distal phalanx is flexed against resistance.

32

Pronator quadratus

• It is a quadrilateral muscle.
• It is present in the distal part of the forearm
• It arises from the ulna and is inserted into the radius.
• Its action is pronation
• It is supplied by the anterior interosseous nerve of forearm
• A: Anterior interosseous artery (from common interosseous a., which is from ulnar a.)
• All deep flexors of the forearm are supplied by the anterior interosseous (branch of median nerve) nerve except the medial half of the flexor digitorum profundus which is supplied by the ulnar nerve.

• All supinators and pronators are inserted into the radius. Can you tell me why?
• It is the radius which moves over stationary ulna in these movements
• Therefore all supinators and pronators are inserted into the radius.

33

Medial epicondylitis/Golfer's elbow

• It is also called Golfer’s elbow
• It is due to the inflammation of tendon of origin of flexor muscles from the medial epicondyle of the humerus.

34

Flexor retinaculum of wrist

• It is thickened band of deep fascia which bridges the concavity of carpal bones.
• It is attached medially to the pisiform and hook of the hamate bones
• It is attached laterally to the scaphoid and trapezium bones
• The flexor retinaculum bridges across the carpal bones and converts the space into carpal tunnel.
• Compression of the median nerve can occur here (carpal tunnel syndrome) leading to clinical symptoms associated with median nerve lesion.

The following structures lie superficial to the flexor retinaculum of the wrist:
• Ulnar nerve
• Ulnar artery
• Palmar cutaneous branch of ulnar nerve
• Palmaris longus tendon
• Palmar cutaneous branch of median nerve
• Superficial palmar branch of radial artery
Clinical:
• The ulnar nerve and ulnar artery run in a tunnel superficial to the flexor retinaculum.
• This is called canal of Guyan.
• Ulnar nerve may be compressed here (handle bar neuropathy)

The following structures lie deep to the flexor retinaculum of wrist:
• The median nerve
• Four tendons of flexor digitorum superficialis
• Four tendons of flexor digitorum profundus
• Tendon of flexor pollicis longus
• Tendon of flexor carpi radialis lies in a separate compartment
Clinical:
• Carpal tunnel syndrome

Synovial sheaths of the flexor tendons:
• As the long flexor tendons run into the palm, they are covered by synovial sheaths.
• One for the flexor pollicis longus (radial bursa)
• One for the common tendons of the Flexor digitorum superficialis and profundus.(ulnar bursa)
• The sheath extends to the distal phalanx on flexor pollicis longus (radial bursa) and that of the little finger (ulnar bursa).
• Infection may spread through these sheaths.
• If it is inflamed at the fingers, it may compress the blood vessels to the tendons causing necrosis of the tendons to the digit.

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Forearm extensors summary

7 Superficial muscles: (Boiling 5 Eggs Again!)
• Brachioradialis
• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor digiti minimi
• Extensor carpi ulnaris
• Anconeus
5 deep muscles: (Savor All 3 Eggs! / Suspend All 3 Engineers!)
• Supinator
• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor indicis

Superficial muscles of the back of the forearm:
• Two muscles arise from the lateral supracondylar ridge.
• Brachioradialis and extensor carpi radialis longus.
• These two are supplied by the radial nerve in the front of the arm.
• Anconeus is another superficial muscle which arises from the back of the lateral epicondyle and is inserted into the ulna.
• It is supplied by a branch of radial nerve.

• The remaining superficial muscles arise from the lateral epicondyle of the humerus by a common tendinous origin.
They are:
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor digiti minimi
• Extensor carpi ulnaris
• They are supplied by the posterior interosseous nerve.

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Brachioradialis

• Origin: upper part of the lateral supracondylar ridge
• Insertion: inserted into the lateral surface of distal end of radius near the base of the styloid process
• Nerve supply: Radial nerve
• A: Radial recurrent artery
• It is the only muscle which is grouped under the extensors as it arises from the lateral supracondylar ridge and is supplied by the radial nerve but acts as flexor of the elbow.
• Action: It flexes the mid-prone forearm efficiently (to drink beer!)

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Extensor carpi radialis longus

• Origin: lower part of the lateral supracondylar ridge
• Insertion: inserted into the base of the second metacarpal bone
• Nerve supply: Radial nerve
• A: Radial a.
• Action: it acts as the extensor of the wrist. It also helps in the abduction acting with the flexor carpi radialis and extensor carpi radialis brevis

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Extensor carpi radialis brevis

• It arises from the lateral epicondyle of the humerus by a common extensor tendinous origin.
• It is inserted into the base of the third metacarpal bone
• It is supplied by the posterior interosseous nerve (deep branch of the radial nerve)
• A: Radial a.
• It acts as extensor of the wrist and also helps in the abduction of the wrist

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Extensor digitorum

• It arises from a common tendinous origin attached to the lateral epicondyle of the humerus
• It divides into four tendons to the medial four digits and takes part in their extensor expansion & through this, inserted to the dorsum of middle and terminal phalanges.
• It helps in the extension of metacarpo-phalangeal and extension of interphalangeal joints
• It is supplied by the posterior interosseous nerve (deep branch of radial nerve)
• A: Interosseous recurrent a. (from posterior interosseous a.) and posterior interosseous a. (from common interosseous a., which is from ulnar a.)

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Extensor digiti minimi

• It arises from the common tendinous origin attached to the lateral epicondyle of the humerus.
• It is inserted into the little finger and takes part in its extensor expansion
• Nerve supply: posterior interosseous nerve (deep branch of radial nerve)
• A: Interosseous recurrent artery (from posterior interosseous a.)

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Extensor carpi ulnaris

• It arises from the common extensor tendinous origin attached to the lateral epicondyle of the humerus
• It is inserted into the base of the fifth metacarpal bone
• It extends and adducts the wrist
• It is supplied by the posterior interosseous nerve (deep branch of radial nerve)
• A: ulnar a.

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Anconeus

superficial muscle which arises from the back of the lateral epicondyle and is inserted into the ulna.
• It is supplied by a branch of radial nerve.
• A: Deep brachial artery, recurrent interosseous artery
• Action: Assists triceps brachii in extending forearm

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Supinator

• It arises from the lateral epicondyle, annular ligament of the superior radio-ulnar joint, and supinator crest of the ulna.
• It is inserted into the upper part of the lateral surface of the radius (above the insertion of the pronator teres).
• Axn: supinates the pronated forearm in all positions of the forearm (biceps brachii is most powerful but can only work in flexed position)
• It crosses the superior radio-ulnar joint and acts on that.
• Supination and pronation take place in the superior and inferior radio-ulnar joints.
• It is supplied by the posterior interosseous nerve (deep branch of radial nerve)
• A: Posterior interosseous artery (from common interosseous a., which is from ulnar a.), which pierces supinator

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Abductor pollicis longus

• It arises from the posterior surface of the radius & ulna and adjoining interosseous membrane
• It is inserted into the base of the 1st metacarpal bone.
• It is supplied by the posterior interosseous nerve (deep branch of radial nerve)
• A: Posterior interosseous artery (from common interosseous a., which is from ulnar a.)
• Action: it abducts the thumb

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Extensor pollicis brevis

• It arises from the posterior surface of the radius and is inserted into the base of the proximal phalanx of the thumb
• It is supplied by the posterior interosseous nerve (deep branch of radial nerve)
• A: Posterior interosseous artery (from common interosseous a., which is from ulnar a.)
• It extends the metacarpo-phalangeal joint of the thumb

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Extensor pollicis longus

• It arises from the posterior surface of the ulna
• It is inserted into the base of the distal phalanx of the thumb
• Action; it extends the interphalangeal joint of the thumb
• Nerve supply: the posterior interosseous nerve (deep branch of radial nerve)
• A: Posterior interosseous artery (from common interosseous a., which is from ulnar a.)

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Extensor indicis

• It arises from the posterior surface of the ulna
• It takes part in the dorsal extensor expansion along with the tendon of extensor digitorum for the index finger.
• It extends the index finger (indpt ext)
• Nerve supply: the posterior interosseous nerve (deep branch of radial nerve)
• A: Posterior interosseous artery (from common interosseous a., which is from ulnar a.)

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Muscles inserted into thumb (insertions and n. supply)

Lobo: (I don’t recommend memorizing thenar m. attachments!)

• Base of the first metacarpal bone- abductor pollicis longus- Posterior interosseous branch of radial nerve

• Shaft of the first metacarpal bone- opponens pollicis- Recurrent branch of median nerve

• Medial part of the base of the proximal phalanx of the thumb – adductor pollicis- Deep branch of ulnar nerve

• Lateral part of the front of the base of the proximal phalanx of the thumb – abductor pollicis brevis- Recurrent branch of median nerve

• Front of the base of the proximal phalanx of the thumb – flexor pollicis brevis- Recurrent branch of median nerve

• Dorsal part of the base of the proximal phalanx of thumb – extensor pollicis brevis- Posterior interosseous branch of radial nerve

• Dorsal part of the base of the distal phalanx of thumb – extensor pollicis longus- Posterior interosseous branch of radial nerve

• Anterior part of the base of the distal phalanx of thumb – flexor pollicis longus- Anterior interosseous branch of median nerve

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Tennis Elbow

Elbow tendonitis or lateral epicondylitis:
• Repeated forceful flexion and extension of the wrist strain the common extensor origin, producing inflammation of the periosteum of the lateral epicondyle
• Pain radiates down from the lateral epicondyle to the posterior surface of the forearm.
• Pain is felt while lifting a glass or opening a door.
• Focus point of pain: lateral epicondyle / common extensor origin

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Extensor retinaculum of the wrist

• It is a thickened band of deep fascia on the back of the wrist
• It is oblique. It is oblique because it is disposed perpendicular to the pull of the tendons of the back of the wrist
Attachments:
• Lateral: lower end of radius
• Medial: styloid process of ulna, pisiform and triquetral bones
• All extensor tendons pass deep to the extensor retinaculum.
• There are six compartments deep to the extensor retinaculum.
• They are usually numbered from the lateral to medial side.
The first compartment contains the following two tendons:
• Abductor pollicis longus
• Extensor pollicis brevis

The second compartment contains the following two tendons:
• Extensor carpi radialis longus
• Extensor carpi radialis brevis

The third compartment contains:
• Extensor pollicis longus tendon

The fourth compartment contains the following 4 structures:
• Extensor digitorum
• Extensor indicis
• Posterior interosseous nerve
• Anterior interosseous artery

The fifth compartment contains:
• Extensor digiti minimi tendon

The sixth compartment contains:
• Extensor carpi ulnaris tendon

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Dorsum of the hand

• The skin is loosely attached to the underlying fascia.
• Swelling on the dorsum of the hand is extensive because of this.
• The structures present in the dorsum of the hand are:
• Dorsal digital veins
• Dorsal metacarpal veins
• Dorsal venous arch
• Cephalic vein begins from the lateral side of the dorsal venous arch while the basilic vein begins from the medial side of the dorsal venous arch.
• Radial artery gives the first dorsal metacarpal artery and dips into the palm of the hand between the two heads of the first dorsal interosseous muscle
• Radial artery also gives the dorsal carpal branch which anastomoses with the dorsal carpal branch of the ulnar artery and forms the dorsal carpal arterial arch.
• This gives three dorsal metacarpal arteries.

The nerve supply of the skin of the dorsum of the hand:
• The medial ⅓ is supplied by the dorsal branches of the ulnar nerve
• The lateral ⅔ of the dorsum of the hand are supplied by the (superficial branch of) radial nerve.
• Medial 1½ fingers are supplied by the ulnar nerve
• Lateral 3½ fingers are supplied by the radial nerve
• However, the skin over the distal phalanges of the lateral 3½ fingers is supplied by the branches of median nerve.
• Nail beds are not supplied by radial nerve!

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Extensor (dorsal digital) expansion

Following structures contribute to the extensor expansion:
• Tendon of extensor digitorum
• Lumbrical muscle
• Palmar and dorsal interossei
• In the index finger – the tendon of extensor indicis joins the expansion
• In the little finger – the tendon of extensor digiti minimi joins the expansion
• Hood is an expansion of the tendon of extensor digitorum over the dorsum of the proximal phalanx and metacarpo-phalangeal joint
• It is joined on either side by the lumbrical and interossei
• Then the hood divides into three parts:
• The central part which is attached to the base of the middle phalanx
• The lateral parts join and form one median part which is inserted into the base of the distal phalanx.
• By this arrangement, the lumbricals can flex the metacarpo-phalangeal joint and extend the interphalangeal joint. This action is assisted by the interossei muscles.

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Mallet finger

• The extensor digitorum tendon insertion to the terminal phalanx might get avulsed resulting in the mallets finger.
• This happens when direct force hits the terminal phalanx

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Palm

• The skin of the palm is thick and hairless.
• Sweat glands are present but no sebaceous glands, do you know why?
• There are creases in the palm- palmar creases.
• There are two separate horizontal creases but in most cases of the Down syndrome, the two are fused and is called simian crease.
• Astrology/ palm reading? I can, lolz, My PhD thesis is on dermatoglyphics!

From superficial to deep, the following structures are seen in the palm of the hand:
• The skin
• Tough superficial fascia
• Palmar aponeurosis
• Superficial palmar arch and its common digital branches
• Digital branches of ulnar and median nerves
• Tendons of flexor digitorum superficialis
• Tendons of flexor digitorum profundus & Lumbricals- 4
• Deep palmar arch and the deep branch of ulnar nerve lie deep to the tendons
• Interossei- 3/4 palmar and 4 dorsal
• Thenar eminence: Elevation on the lateral side of the palm proximal to the thumb
• Hypothenar eminence: Elevation on the medial side of the palm proximal to the little finger.
• Cutaneous nerve supply of the fingers: Ulnar nerve supplies the skin of the medial one and half digits while the median nerve supplies the lateral three and half digits.

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Palmar aponeurosis

• It is a triangular strong and well defined part of the deep fascia of the palm
• Covers the soft tissue and overlies the tendons of the palm of the hand
• The proximal end is apex and is continuous with the flexor retinaculum & the tendon of palmaris longus
• Distally it forms the four digital bands for the medial four digits
• It sends in a medial vertical septum which is attached to the fifth metacarpal bone
• The lateral vertical septum is attached to the first metacarpal bone
• An intermediate septum is attached obliquely to the third metacarpal bone

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Dupuytren’s contracture

• It is the progressive shortening and thickening and fibrosis of the palmar aponeurosis.
• Not neurological.
• Little and ring fingers are partially flexed.
• Surgical excision of fibrotic part is curative

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Palmaris brevis

• Is a small muscle in the subcutaneous tissue of the hypothenar eminence.
• It is attached laterally to the medial border of the palmar aponeurosis and medially to the skin on the medial border of the hand.
• It wrinkles the skin on hypothenar eminence and covers the ulnar nerve and artery.
• It is supplied by the ulnar nerve (superficial branch)

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Lumbricals

Four lumbricals.
• They arise from the tendons of the flexor digitorum profundus..
• Lumbricals are numbered from the lateral to medial side.
• The lateral two (1st and 2nd) (unipennate) are supplied by the median nerve while the medial two (3rd and 4th) (bipennate) are supplied by the ulnar nerve.
• They are inserted to the radial side of the extensor expansion (dorsal digital expansion) and the radial side of the proximal phalanx of the finger.
• They flex the metacarpophalangeal joint and extend the interphalangeal joints. Hit a salute!

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Interossei

• Remember PAD & DAB for their actions
• There are three (four according to some!) palmar and four dorsal interossei.
• Palmar interossei are adductors (PAD), unipennate, 2,4,5
• There is no palmar interosseous for the middle finger.
• Thumb has its OWN adductor, so x need palmar interossei
• Dorsal interossei are abductors (DAB), bipennate, 2,3,4
• There are two dorsal interossei for the middle finger and no dorsal interossei for the thumb and little fingers.
• Thumb and little finger have their OWN abductors, so they don’t need dorsal interossei!
• Interossei are inserted to the extensor expansion and the side of the proximal phalanx of the finger.
• Hence, they also flex the metacarpophalangeal joints and extend the interphalangeal joints.
• All interossei are supplied by the ulnar nerve (deep branch of the ulnar nerve)

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Thenar m.

Lobo: (I don’t recommend memorizing these attachments!)

Four short muscles of the thumb.
• Abductor pollicis brevis
• Flexor pollicis brevis
• Opponens pollicis
• Adductor pollicis
• All thenar muscles are supplied by the median nerve (by its recurrent branch) except the adductor pollicis which is supplied by the ulnar nerve (deep branch of ulnar nerve)
• Abductor pollicis brevis: it arises from the trapezium and flexor retinaculum. It is inserted into the lateral side of the base of the proximal phalanx of the thumb
• Flexor pollicis brevis arises from the flexor retinaculum and trapezium and it is inserted into the base of the proximal phalanx of the thumb
• Opponens pollicis arises from the flexor retinaculum and trapezium and is inserted into the shaft of the first metacarpal bone.
• Adductor pollicis has two heads of origin:
• Oblique head - from 2nd and 3rd metacarpals, capitate & hamate
• Transverse head – from anterior surface of the shaft of 3rd metacarpal
• Insertion: medial side of base of proximal phalanx of thumb
• Action: the name of the muscles indicates its action.
• The opponens pollicis opposes the thumb with other digits.

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Hypothenar m.

Lobo: (I don’t recommend memorizing these attachments!)

3:
• Abductor digiti minimi
• Flexor digiti minimi
• Opponens digiti minimi

• All these three muscles arise from the flexor retinaculum and the hamate bone.
• They are inserted into the little digit as follows:
• The opponens digiti minimi is inserted into the shaft of the fifth metacarpal bone
• The flexor digiti minimi is inserted into the base of the proximal phalanx of the little finger.
• Abductor digiti minimi is inserted into the base of the proximal phalanx of the little finger.
• All of them are supplied by the ulnar nerve (deep branch of the ulnar nerve).

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Hand m. supplied by median n.

Regarding the nerve supply of the muscles of the hand, five muscles are supplied by the median nerve while all the remaining muscles are supplied by the ulnar nerve.

• Flexor pollicis brevis
• Abductor pollicis brevis
• Opponens pollicis
• First lumbrical
• Second lumbrical

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Hand m. supplied by ulnar n.

Regarding the nerve supply of the muscles of the hand, five muscles are supplied by the median nerve while all the remaining muscles are supplied by the ulnar nerve.

• Palmaris brevis
• Flexor digiti minimi
• Abductor digiti minimi
• Opponens digiti minimi
• Third lumbrical
• Fourth lumbrical
• Adductor pollicis
• Palmar interossei
• Dorsal interossei

• Note: Palmaris brevis is supplied by the superficial branch. All other muscles are supplied by the deep branch of the ulnar nerve.