Raftery Upper Limb Flashcards
What is the female breast made of?
Fat
Fibrous tissue
Glandular tissue (15-20 lobules)
What are the lobules of glandular tissue in the breast separated by?
By fibrous septa running from subcutaneous tissues to the fascia of the chest wall (i.e. ligaments of Astley Cooper)
What does each gland in the breast drain into?
Lactiferous duct, which converges towards the nipple. Each duct becomes dilated to form a lactiferous sinus beneath the areola.
What are glands of Montogomery in the breast?
Large modified sebaceous glands that lubricate the areola
Arterial supply of breast
Axillary artery via lateral thoracic and acromiothoracic branches
Internal mammary (thoracic) artery via its perforating branches
Intercostal arteries via perforating branches
(Venous drainage to corresponding veins)
Lymphatic drainage of breast
Axillary LNs along tributaries of axillary vein
Internal mammary chain along tributaries of internal mammary vessels
(free communication between lymphatic vessels between breast lobules, but lateral part tends to drain towards axilla and medial part towards internal mammary chain)
Anatomical classification of axillary nodes
Anterior (pectoral) - 3-5 nodes lie deep to pec major in medial wall of axilla along lower border of pectoralis major, related to lateral thoracic artery. Receive lymph mainly from anterior thoracic wall including most of breast.
Posterior (subscapular) - 6-7 nodes along posterior axillary fold and subscapular vessels. Lymph from posterior thoracic wall and scapular region.
Lateral (humeral) - 4-6 nodes posterior to axillary vein, most lymph drained from UL
Central - 3-4 large nodes near base of axilla (deep to pec minor, close to 2nd part of axillary artery) in axillary fat. Lymph from efferent vessels from pectoral, subscapular and humeral axillary LN groups
Apical - immediately behind clavicle at apex of axilla above pectoralis minor. Close to axillary vein (all other axillary nodes drain down this group and also from lymph vessels accompanying cephalic veins)
Surgical classification of axillary nodes
Level 1 nodes - below and lateral to inferolateral border of pec minor (lateral, anterior and posterior nodes)
Level 2 nodes - behind pec minor (central and some apical nodes)
Level 3 nodes - above upper border of pec minor (apical and infraclavicular nodes)
How may a male breast cancer spread when it has infiltrated the normal pathways of lymphatic drainage?
Lymphatics of opposite breast
Contralateral axillary nodes
Inguinal lymph nodes
Cervical lymph nodes
How are incisions in the breast made?
Radially, to avoid cutting across the line of the ducts
What is dimpling of the skin over a carcinoma of the breast?
It is the result of malignant infiltration and contraction of Cooper’s ligaments
What is the shape of the axilla?
Pyramidal, with a base, apex and 4 walls
Contents of the axilla
Axillary artery (3 parts) - medial, posterior and lateral to pectoralis minor (medial and posterior parts travel in axilla)
Axillary vein - lies in apex of axilla, continuation of basilic vein, becomes subclavian vein at outer border of 1st rib
Brachial plexus
Axillary lymph nodes - lymph from UL and pectoral region
Biceps brachii (short head) and coracobrachialis - attach to coracoid process of scapula
Long thoracic nerve (of Bell) - derived from C5-7, passes behind brachial plexus to enter axilla. Lies on medial chest wall, supplies serratus anterior. Damage during axillary surgery causes winging of scapula.
Thoracodorsal nerve and trunk - innervate and vascularise latissimus dorsi
Intercostobrachial nerves - traverse the axillary LNs, often divided during axillary surgery, provide cutaneous sensation to axillary skin
Fat
Borders of the axilla
Medial - thoracic wall, serratus anterior
Lateral - bicipital/intertubercular groove of humerus/humeral head
Anterior - lateral border of pec major, pec minor, subclavius muscles
Posterior - subscapularis, teres major, lat dorsi
Apex (axillary inlet) - lateral border of 1st rib, superior border of scapula, posterior border of clavicle
Fascia - clavipectoral fascia
Boundaries of antecubital fossa
Medial - lateral border of pronator teres
Lateral - medial border of brachioradialis
Superior - horizontal line between epicondyles of humerus
Floor - brachialis (proximally) and supinator (distally)
Roof - bicipital aponeurosis, fascia, subcutaneous fat, skin
Contents of antecubital fossa
(Lateral to medial)
Radial nerve - along lateral border of cubital fossa, divides into superficial and deep branches, motor and sensory function in posterior arm and hand
Biceps tendon - passes centrally through fossa, attaches the radial tuberosity (immediately distal to radial neck), gives rise to bicipital aponeurosis which contributes to roof of cubital fossa
Brachial artery - divides into radial and ulnar arteries at apex of fossa, brachial pulse can be felt by palpating medial to biceps tendon
Median nerve - travels medially through fossa, exiting by passing through 2 heads of pronator teres, motor and sensory function in anterior arm and hand
Roof of cubital fossa also contains a few superficial veins - median cubital vein connecting basilic and cephalic veins
Boundaries of carpal tunnel
Roof - flexor retinaculum
Floor and walls - concavity of carpal bones (medial to lateral: trapezium, trapezoid, capitate, hamate)
Contents of carpal tunnel
Median nerve
9 tendons surrounded by synovial sheaths: FDS (4), FDP (4), flexor pollicis longus
Former 2 surrounded by single synovial sheath, latter has its own sheath - sheaths allow free movement of tendons
Note: flexor carpi radialis is located within the flexor retinaculum and not within carpal tunnel itself
Why is there no sensory impairment on lateral side of the palm if the median nerve is compressed in the carpal tunnel?
The superficial palmar branch innervating the lateral palm is given off proximal to the flexor retinaculum
Borders of anatomical snuffbox (radial fossa)
Medial - EPL
Lateral - abductor pollicis longus, EPB
Proximal - styloid process of radius
Floor - trapezium, scaphoid
Contents of anatomical snuffbox (radial fossa)
Radial artery - crosses floor of anatomical snuffbox, then turns medially and travels between heads of adductor pollicis muscle
Superficial branch of radial nerve - innervates dorsal surface of lateral 3.5 digits
Cephalic vein
Which structure is close to the dorsal branch of the radial artery?
Cephalic vein - site for creating AV fistula for dialysis
Lymphatics of upper limb (broadly speaking)
Superficial - accompany veins, very few in UL mainly epitrochlear nodes
Efferents from epitrochlear nodes pierce the deep fascia and end in axillary nodes
Deep - accompany arteries
Which structures do the axillary nodes drain?
Breast Pectoral region Upper abdominal wall down to umbilicus Skin of back down to iliac crest Upper limb
What emerges from the axillary nodes?
Subclavian lymph trunk
Overview of arteries of the upper limb
Subclavian Axillary Brachial Radial Ulnar
Start and end points of axillary artery
Starts at lateral border of 1st rib (from subclavian artery)
Ends at lower border of teres major (as brachial artery)
Parts of axillary artery
Divided into 3 parts by pec minor: 1st part (proximal) - superior thoracic artery
2nd part (posterior) - thoracoacromial and lateral thoracic artery
3rd part (distal) - subscapular, anterior and posterior circumflex arteries (latter form anastomotic network around surgical neck of humerus, can be damaged in fractures)
Relations of axillary artery
Brachial plexus cords (lateral, medial, posterior) surround the artery
Start and end points of brachial artery
Starts at lower border of teres major (from axillary artery)
Ends in cubital fossa at level of neck of radius (divides into radial and ulnar artery)
Where does the brachial artery lie in its course?
Immediately below the deep fascia in most of its course where it is readily accessible e.g. for brachial embolectomy.
What crosses the brachial artery superficially from lateral to medial side?
Median nerve at level of mid-humerus
Start and end points of radial artery
Starts at neck of radius lying on biceps tendon
Distal to the wrist, give off branches contributing to superficial palmar arch
Where does the radial artery lie in its course?
Overlapped by brachioradialis in its upper half
In distal forearm - lies between the brachioradialis and FCR (can palpate at wrist)
Closely related to radial nerve in middle of forearm
Passes deep to tendons of APL and EPB to enter anatomical snuffbox
Pierces first dorsal interosseous and adductor pollicis to contribute to deep palmar arch
Start and end points of ulnar artery
Starts at neck of radius in middle of antecubital fossa
Passes obliquely downward, reaching ulnar side of forearm midway between elbow and wrist
Crosses in front of flexor retinaculum to divide into superficial and deep volar arches, and form superficial palmar arch with superficial branch of radial artery
Where does the ulnar artery lie in its course?
Passes deep to muscles from common flexor origin
Lies on FDP, overlapped by FCU
Median nerve at medial side of artery for ~2.5cm, then crosses it superficially
In distal forearm - becomes superficial between tendons of FDP and FCU
Ulnar nerve lies at medial side in distal 2/3 of forearm and across the flexor retinaculum
What separates the median nerve from the ulnar artery?
Deep head of pronator teres
What are the veins in UL important for?
Cannulation
Creation of AV fistula for dialysis
Overview of veins of the upper limb
Superficial - cephalic, basilic (combine to form median cubital vein)
Deep (venae comitantes accompanying arteries)
Start and end points of superficial veins in upper limb
Starts as dorsal venous network on dorsum of hand
Dorsal venous network drains into lateral cephalic vein and dorsal basilic vein
Where does the cephalic vein lie in its course?
Lies subcutaneously just behind radial styloid
Runs up anterior aspect of forearm
Lies in along lateral border of biceps in upper arm
Passes to deltopectoral triangle (superficial until reaches here)
Pierces clavipectoral fascia to enter axillary vein
Path of basilic vein
Originates on medial side of dorsal venous network of the hand
Passes MEDIALLY up forearm and arm (most of its course is superficial), runs in groove along medial border of biceps
Joins cephalic vein near region anterior to cubital fossa
Passes deep under the muscles midway up the humerus
Anterior and posterior circumflex humeral veins feed into it at lower border of teres major
Often joined by medial brachial vein (venae comitantes of brachial artery) before draining into axillary vein
Which vein connects the cephalic and basilic vein?
Median cubital vein
What separates the median cubital vein at the elbow from the underlying brachial artery?
Tough bicipital aponeurosis
What are the components of the brachial plexus and their locations?
Roots - between scalenus anterior and scalenus medius
Trunks - posterior triangle of neck
Divisions - behind clavicle
Cords - in axilla
Roots of the brachial plexus
Anterior primary rami of C5-8 and T1
Trunks of the brachial plexus
Superior - C5-6
Middle - C7-8
Inferior - C8-T1
Divisions of the brachial plexus
Each trunk divides into anterior and posterior divisions
Cords of the brachial plexus
Lateral - fused anterior divisions of upper and middle trunks
Medial - anterior division of lower trunk
Posterior - fusion of all 3 posterior trunks
What are the nerves that arise from each cord?
Lateral cord - musculocutaneous nerve
Medial - ulnar nerve
Posterior - radial, axillary nerve
Cross-communication between lateral and medial cords - median nerve
What is the radius?
One of 2 long forearm bones extending from lateral side of elbow to thumb side of wrist. Has 2 expanded ends, distal end is larger.
Relations of radius at its upper end
Articular cartilage - covers medial > lateral side
Articulates with radial notch of ulna by annular ligament
Biceps brachii attaches to radial tuberosity
Muscle attachment at shaft of radius
Upper 1/3 of body - supinator, FDS, FPL
Middle 1/3 of body - pronator teres
Lower 1/4 of body - pronator quadratus, tendon of supinator longus
Relations of lower end of radius
Quadrilateral
Anterior surface - capsule of wrist joint
Medial surface - head of ulna
Lateral surface - ends in styloid process
Posterior surface - 3 grooves containing: tendons of extensor carpi radialis brevis and longus, EPL and extensor indicis
Which nerve forms the terminal branch of the posterior cord of the brachial plexus?
Axillary nerve (C5-6) - divides into anterior and posterior branches
What does the axillary nerve innervate?
Deltoid muscle, small patch of skin over deltoid
Course of axillary nerve
Descends posterior to axillary artery at lower border of subscapularis, then passes through quadrangular space with posterior circumflex humeral vessels
Relations of brachial artery
Posterior - long head of triceps, with radial nerve and profunda vessels intervening
Anterior - overlapped by medial border of biceps, crossed by median nerve in middle of arm
In cubital fossa it is separated from median cubital vein by bicipital aponeurosis
Basilic vein is in contact at most proximal aspect of cubital fossa and lies medially
Origin of trapezius muscle
Medial 1/3 of superior nuchal line of occiput
External occipital protruberance
Ligamentum nuchae
Spines of C7 and all thoracic vertebrae and all intervening interspinous ligaments
Insertion of trapezius muscle
Posterior border of lateral 1/3 of clavicle
Medial border of acromion
Upper border of crest of spine of scapula
Nerve supply of trapezius
Spinal portion of accessory nerve (CN XI)
Actions of trapezius muscle
Elevation of shoulder girdle
Lateral rotation of scapula
Relations of ulnar artery
Deep to - pronator teres, FCU, palmaris longus
Lies on - brachialis, FDP
Superficial to flexor retinaculum at wrist
Branch of ulnar artery
Anterior interosseous artery
Course of long thoracic nerve
Derived from ventral rami of C5-7, close to their emergence from intervertebral foramina
Runs downward and passes either anterior or posterior to middle scalene muscle
Reaches upper tip of serratus anterior muscle and descends on outer surface of this muscle, giving branches to it
When does winging of scapula occur?
Long thoracic nerve injury - commonest
Spinal accessory nerve injury - denervates trapezius
Dorsal scapular nerve injury
What is the anterior (volar) interosseous nerve a branch of?
Median nerve
What does the anterior interosseous nerve supply?
PURE MOTOR
Deep muscles in anterior compartment of forearm:
- FPL
- Pronator quadratus
- Radial half of FDP (lateral 2/4 tendons)
Course of anterior interosseous nerve
Accompanies anterior interosseous artery along anterior of interosseous membrane of forearm, in the interval between FPL and FDP
Ends below in pronator quadratus and wrist joint
Which joint does the axilla lie under?
Glenohumeral joint, at the junction between UL and thorax
Passageways exiting axilla
3 main routes:
1. Immediately inferiorly and laterally, into the UL (majority)
- Quadrangular space (gap in posterior wall of axilla, structures passing through include axillary nerve and posterior circumflex humeral artery - branch of axillary artery)
- Clavipectoral triangle (gap in anterior wall) - bounded by pec major, deltoid and clavicle. Cephalic vein enters axilla here, while the medial and lateral pectoral nerves leave
What happens when vessels and nerves become compressed between the bones (clavicle, 1st rib, scapula) in the apex of axilla?
Thoracic outlet syndrome
Common causes of thoracic outlet syndrome
Trauma e.g. fractured clavicle
Repetitive movements - commonly in jobs with arm lifting
Cervical rib - extra rib from C7 vertebra
What is a supracondylar fracture?
Fracture of the distal humerus - usually transverse or oblique
Commonest mechanism of injury in supracondylar fracture
FOOSH, commoner in children than adults
What can happen if damage to the brachial artery is not repaired?
Volkmann’s ischaemic contracture (uncontrolled hand flexion) as forearm flexors become fibrotic and short
Damage to which structures can occur in supracondylar fracture?
Brachial artery
Anterior interosseous nerve (branch of median nerve) - weakness of flexor pollicis longus
Ulnar nerve
Radial nerve
What is the ulnar (cubital) tunnel?
A fibro-osseous space located on the posteromedial aspect of elbow
Transmits the ulnar nerve from arm into forearm
Borders of cubital tunnel
Medial - medial epicondyle of humerus
Lateral - olecranon of ulna
Floor - elbow joint capsule and medial collateral ligament of elbow
Roof - ligament spanning between medial epicondyle and olecranon (cubital tunnel retinaculum aka arcuate ligament of Osborne - band of fascia running between ulnar and humeral heads of flexor carpi ulnaris)
Contents of cubital tunnel
Ulnar nerve
After the tunnel, nerve travels between the 2 heads of flexor carpi ulnaris and continues into forearm and hand
What is cubital tunnel syndrome?
Compression of the ulnar nerve within the ulnar tunnel.
2nd commonest peripheral neuropathy of UL
What is the ulnar (Guyon’s) canal?
A fibro-osseous tunnel located at the level of the palm. Transmits ulnar neurovascular bundle from forearm into hand
Length of ulnar canal
About 4cm long, extends from proximal aspect of pisiform bone to origin of hypothenar muscles at hook of hamate
Borders of ulnar canal
Medial - pisiform, pisohamate ligament, abductor digiti minimi
Lateral - hook of hamate
Roof - palmar carpal ligament
Floor - flexor retinaculum, hypothenar muscles
Contents of ulnar canal
Ulnar nerve - divides within canal into superficial (sensory) and deep (motor) branches
Ulnar artery - located on radial aspect of ulnar nerve, gives rise to deep palmar branch, continues laterally across palm as superficial palmar arch
Venae comitantes of ulnar artery
Lymphatic vessels
Commonest causes of ulnar canal syndrome
Ganglion cyst
Lipoma
Trauma
Layers of carpal tunnel
Deep carpal arch - forms concave surface, converted into tunnel by overlying flexor retinaculum (transverse carpal ligament)
Superficial flexor retinaculum
What is the carpal arch of carpal tunnel formed by?
Lateral - scaphoid, trapezium tubercles
Medial - hook of hamate, pisiform
Divisions of median nerve once it passes through carpal tunnel
2 branches:
Recurrent branch - supplies thenar muscles
Palmar digital nerve - sensory innervation to palmar skin and dorsal nail beds of lateral 3.5 digits, motor innervation to lateral 2 lumbricals
Origin of subclavian artery
Right - brachiocephalic trunk
Left - directly from aortic arch
Parts of subclavian artey
1st part - origin of subclavian artery to medial border of anterior scalene
2nd part - posterior to anterior scalene
3rd part - lateral border of anterior scalene to lateral border of 1st rib (becomes axillary artery)
Which structure can be compressed in axillary artery aneurysm?
Brachial plexus, causing paraesthesia and muscle weakness
Which artery does the brachial artery give rise to immediately distal to teres major?
Deep artery (profunda brachii) - supplies structures in posterior aspect of upper arm (e.g. triceps brachii)
What does the profunda brachii travel with in the radial groove of humerus?
Radial nerve
What does the radial artery supply?
Posterolateral aspect of forearm
Contributes to anastomotic networks surrounding elbow joint and carpal bones
What does the ulnar artery supply?
Anteromedial aspect of forearm
Contributes to anastomotic network surrounding elbow joint
What does the ulnar arteries divide into?
Anterior and posterior interosseous arteries - supply deeper structures in forearm
What is formed when the radial and ulnar arteries anatosmose in the hand?
Superficial and deep palmar arches
Where does the ulnar artery enter the hand?
Anterior to flexor retinaculum, lateral to ulnar nerve
Where does the radial artery enter the hand?
Dorsally, crossing the floor of the anatomical snuffbox. Then turns medially and travels between heads of adductor pollicis muscle
Radial artery supplies 1 branch to the thumb, index finger and the superficial palmar arch, then continues as deep palmar arch
Origins of basilic and cephalic vein
Dorsal venous network of the hand
Where does the basilic vein travel in the arm?
Ascends the medial aspect of upper limb, moves deep into arm at border of teres major
What happens to the basilic vein at the border of teres major?
Basilic vein moves deep into the arm i.e. combines with brachial veins from deep venous system to form axillary vein
Where does the cephalic vein travel in the arm?
Ascends the anterolateral aspect of upper limb, passing anteriorly at the elbow.
Where does the cephalic vein travel at the shoulder?
Between the deltoid and pectoralis major (deltopectoral groove)
Enters axilla region via clavipectoral triangle where it empties into axillary vein
What is the deep venous system of the upper limb formed by?
Paired veins that accompany and lie on either side of an artery (brachial, ulnar, radial) - vena comitantes
What connects the deep and superficial veins of the upper limb?
Perforating veins
What is formed from the efferent vessels from apical axillary nodes?
Efferent vessels from apical axillary nodes travel through the cervico-axillary canal and converge to form the subclavian lymphatic trunk
What structures do the right and left subclavian trunks drain into?
Right subclavian trunk - right lymphatic duct, enters right venous angle directly (junction of internal jugular and subclavian veins)
Left subclavian trunk - thoracic duct
Common causes of axillary lymphadenopathy
Infection of UL resulting in lymphangiitis - lateral (humeral) group usually affected first
Infections of pectoral region and breast
Metastases of breast cancers
What is at risk of damage during axillary lymph node dissection?
Long thoracic nerve (causing winged scapula)
Thoracodorsal nerve
Where do the superficial lymphatic vessels of the UL arise from?
Lymphatic plexuses in the skin of hand (networks of lymphatic capillaries beginning in extracellular spaces)
Where do the superficial lymphatic vessels of the UL travel?
They travel up the arm in close proximity to major superficial veins
Basilic vein - enter cubital lymph nodes found medial to vein and proximal to medial epicondyle of humerus. They continue up the arm, ending in lateral (humeral) axillary lymph nodes
Cephalic vein - cross proximal part of arm to enter apical axillary lymph nodes, but some enter the more superficial deltopectoral lymph nodes
Where do the deep lymphatic vessels of the UL terminate?
Lateral (humeral) axillary lymph nodes
From which structures is lymph drained from by the deep lymphatic vessels of the UL?
Joint capsules
Periosteum
Tendons
Muscles
Which muscle originates from the subscapular fossa (anterior surface)
Subscapularis
Which muscles attach to the coracoid process of the scapula?
Pectoralis minor
Coracobrachialis
Short head of biceps brachii
Bony landmarks of scapula and their muscle attachments
Glenoid fossa - articulates with head of humerus to form glenohumeral joint
Supraglenoid tubercle - long head of biceps brachii
Infraglenoid tubercle - long head of triceps brachii
Landmarks of posterior surface of scapula and muscle attachments (if any)
Spine - most prominent feature, runs transverse across scapula, dividing it into supraclavicular and infraclavicular fossae
Acromion - projection of spine arching over glenohumeral joint and articulates with clavicle at acromioclavicular joint
Infraspinous fossa - origin of infraspinatus
Supraspinous fossa - origin of supraspinatus
Where does serratus anterior originate from and attach to?
Ribs 1-8, attaches to costal surface of scapula
Functions of clavicle
Long bone, attaches UL to trunk as part of ‘shoulder girdle’
Protects underlying NV structures supplying UL
Transmits force from UL to axial skeleton
Parts of clavicle
Sternal (medial) end
Shaft
Acromial end
Commonest mechanism of injury for fracture of clavicle
FOOSH or onto the shoulder
Commonest fracture in middle third (80%), followed by lateral and medial
What happens to orientation of arm after a clavicle fracture?
Lateral end displaced inferiorly by weight of arm
Displaced medially by pec major
Medial end pulled superiorly by sternocleidomastoid
Where does the costoclavicular ligament attach to?
Inferior surface of sternal end of clavicle
Which muscles attach to the shaft of clavicle?
Trapezius Deltoid Subclavius Pec major Sternocleidomastoid Sternohyoid
Which ligaments attach to the acromial end of clavicle?
Conoid ligament (medial part of coracoclavicular ligament, extrinsic) - attached to conoid tubercle
Trapezoid ligament (lateral part of coracoclavicular ligament, extrinsic) - attached to trapezoid line
Acromioclavicular ligament (intrinsic) - horizontally from acromion to lateral clavicle, covers joint capsule, reinforcing its superior aspect
What does the pectoral girdle consist of?
Scapula
Clavicle
Origin of scapula
Extends from 2nd to 7th rib
Attachment of clavicle
Attached to 1st rib by costoclavicular ligament
Which bone is the first bone to ossify in a fetus?
Clavicle
Which is the only long bone to develop in membrane?
Clavicle
Which nerves may pierce the clavicle?
Supraclavicular nerves
Proximal landmarks of humerus
Head - faces medially, upwards and backwards
Anatomical neck - separates head from greater and lesser tubercles
Surgical neck - runs from just distal to tubercles to shaft of humerus
Greater tubercle
Lesser tubercle
Intertubercular sulcus/bicipital groove - separates the 2 tubercles (edges are called lips)
Which muscles attach to the greater tubercle of the humerus?
Supraspinatus
Infraspinatus
Teres minor
What muscle attaches to the lesser tubercle of the humerus?
Subscapularis
Which muscles insert into the lips of the intertubercular sulcus?
Pec major
Teres major
Lat dorsi
Which tendon runs through the intertubercular sulcus?
Long head of biceps brachii
Which structures lie against the surgical neck of the humerus?
Axillary nerve - paralysis of deltoid and teres minor
Posterior circumflex artery
What attaches to the lateral side of the humeral shaft (deltoid tuberosity)?
Deltoid muscle
What is the radial (spiral) groove?
A shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity
Which structures lie in the radial groove on the posterior surface of the humerus?
Radial nerve
Pronfunda brachii
(Risk of damage from midshaft humeral fractures)
What muscles attach to the anterior surface of humeral shaft?
Deltoid
Brachialis
Brachioradialis
Coracobrachialis
What muscles attach to the posterior surface of humeral shaft?
Medial and lateral head of the triceps (spiral groove demarcates their origins)
What are the articulations at the elbow joint (distal humerus)?
Capitulum of humerus articulates with head of radius
Trochlea of humerus articulates with trochlear notch of ulna
What do the lateral and medial borders of the distal humerus form?
Lateral and medial supracondylar ridges (lateral more roughened, site of common origin of forearm extensors)
What passes in a groove on the posterior aspect of the medial epicondyle (distal humerus)?
Ulnar nerve
What are the depressions located on the distal humerus?
Coronoid
Radial
Olecranon fossae
Accommodate forearm bones during flexion/extension of elbow
Parts of radius
Head
Neck
Radial tuberosity
Shaft
What attaches to the radial tuberosity?
Biceps brachii muscle
What attaches to the middle of the lateral surface of radial shaft where there is a small roughening?
Pronator teres
What parts are found at the distal end of radius?
Styloid process
Ulnar notch - articulates with head of ulna, forming distal radioulnar joint
2 facets for articulation with scaphoid and lunate carpal bones (make up wrist joint)
What attaches the radius and ulna together?
Interosseous membrane
What is a Monteggia fracture?
Fracture of proximal shaft of ulna + anterior dislocation of head of radius at elbow
What is a Galeazzi fracture?
Fracture to the distal radius + dislocation of ulna head at distal radio-ulnar joint
Important landmarks of proximal ulna
Olecranon Coronoid process Trochlear notch Radial notch Ulnar tuberosity
Surfaces of ulnar shaft and their muscle attachments
Anterior - pronator quadratus (distally)
Posterior - many
Medial - unremarkable
3 borders of ulnar shaft
Anterior - unremarkable
Interosseous - attachment of interosseous membrane
Posterior - palpable along entire length of forearm posteriorly
What muscle attaches to the olecranon of ulna?
Triceps brachii
What muscle attaches to the ulnar tuberosity?
Brachialis
Carpal bones in order (lateral to medial)
Scaphoid
Lunate
Triquetrum
Pisiform (sesamoid bone, formed within tendon of flexor carpi ulnaris)
Trapezium
Trapezoid
Capitate
Hamate
What bones does the radio-carpal joint consist of?
Radius
Scaphoid
Lunate
What is a Boxer’s fracture?
Fracture of the 5th metacarpal neck, usually caused by clenched fist striking a hard object. Distal part of fracture is displaced anteriorly, producing shortening of affected finger
What is a Bennett’s fracture?
Fracture of the 1st metacarpal base, caused by forced hyperabduction of the thumb. Fracture extends into 1st MCP joint leading to instability and subluxation of joint.
Hence, often needs surgical repair.
Arterial supply to acromioclavicular joint
Suprascapular - from subclavian artery at thyrocervical trunk
Thoracoacromial - from axillary artery
Nerve supply of acromioclavicular joint
Articular branches of suprascapular and lateral pectoral nerves - both arise directly from brachial plexus
Ligaments of sternoclavicular joint
Sternoclavicular ligaments (anterior and posterior)
Interclavicular ligament - spans gap between sternal ends of each clavicle and reinforces joint capsule superiorly
Costoclavicular ligament - bind at 1st rib and cartilage inferiorly, and to the anterior and posterior borders of clavicle superiorly
Arterial supply to sternoclavicular joint
Internal thoracic artery
Suprascapular artery
Nerve supply of sternoclavicular joint
Medial supraclavicular nerve (C3-4)
Nerve to subclavius (C5-6)
Which ligament acts as a pivot for movements of the clavicle?
Coracoclavicular ligament
Bursae at glenohumeral (shoulder) joint
Subacromial - located deep to deltoid and acromion, superficial to supraspinatus tendon and joint capsule. Reduces friction beneath deltoid, promoting free motion of rotator cuff tendons.
Subscapular - between subscapularis tendon and scapula, reduces wear and tear at joint
Ligaments at shoulder joint
Glenohumeral (superior, middle, inferior)
What type of joint is the shoulder (glenohumeral) joint?
Ball and socket - inherently unstable, capable of wide ROM
What stabilises the shoulder joint?
Muscles of rotator cuff that pass from scapula to insert into greater tuberosity of humerus (except subscapularis - inserts into lesser tuberosity)
What is the glenoid labrum?
A fibrocartilaginous rim attached to the free edge of the glenoid cavity
What arises from within the joint from the supraglenoid tubercle?
Tendon of long head of biceps
What muscle attaches to the infraglenoid tubercle?
Long head of triceps
Attachments of fibrous capsule of shoulder joint
Scapula external to glenoid labrum and to labrum itself (postero-superiorly)
Humerus at level of anatomical neck superiorly and surgical neck inferiorly
Relations of fibrous capsule of shoulder joint
Anterior - subscapularis tendon
Superior - supraspinatus tendon
Posterior - infraspinatus and teres minor tendons
How many defects are there in the fibrous capsule of shoulder joint
2 defects - superiorly for tendon of biceps, anteriorly defect beneath subscapularis tendon
What is the inferior extension of the fibrous capsule of shoulder joint closely related to?
Axillary nerve at surgical neck of humerus, at risk of damage in anteroinferior dislocations
Shoulder joint FLEXORS
Anterior deltoid
Pec major
Coracobrachialis
(Biceps)
Shoulder joint EXTENSORS
Posterior deltoid
Teres major
Lat dorsi
Shoulder joint ADDUCTORS
Pec major
Lat dorsi
(Teres major, coracobrachialis)
Shoulder joint ABDUCTORS
Supraspinatus (first 15deg)
Mid deltoid
Shoulder joint MEDIAL ROTATION
Subscapularis Anterior deltoid Pec major Teres major Lat dorsi
Shoulder joint LATERAL ROTATION
Posterior deltoid
Infraspinatus
Teres minor
Important anatomical relations of shoulder joint
Anterior - brachial plexus, axillary artery and vein
Posterior - suprascapular nerve and vessels
Inferior - axillary nerve, circumflex humeral vessels
Elbow joint FLEXORS
Biceps
Brachialis
Brachioradialis
(Pronator teres)
Elbow joint EXTENSORS
Triceps
Anconeus
Elbow joint PRONATORS
Pronator teres
Pronator quadratus
Elbow joint SUPINATORS
Biceps
Supinator
Root values of ulnar nerve
C8-T1
Muscles supplied by ulnar nerve
(No muscles in upper arm)
Flexor carpi ulnaris Flexor digitorum profundus (medial half) Flexor digiti minimi Abductor digiti minimi Opponens digiti minimi Adductor pollicis Interossei muscles 3rd and 4th lumbricals Palmaris brevis
Path of ulnar nerve
Posteromedial aspect of upper arm to flexor compartment of forearm, then along ulnar
Passes below FCU
Passes superficial to flexor retinaculum into palm
Branches of ulnar nerve
Muscular branch Palmar cutaneous branch (arises near middle of forearm) Dorsal cutaneous branch Superficial branch Deep branch
Areas supplied by branches of ulnar nerve
Muscular - FCU, medial half of FDP
Palmar cutaneous - skin on medial part of palm
Dorsal cutaneous - dorsal surface of medial part of hand
Superficial - cutaneous fibres to anterior surfaces of medial 1.5 digits
Deep - hypothenar muscles, all interossei, 3rd and 4th lumbricals, adductor pollicis, medial head of flexor pollicis brevis
Effects of injury to ulnar nerve at wrist
Wasting and paralysis of hypothenar and intrinsic hand muscles (claw hand)
Loss of sensation of medial 1.5 fingers
Effects of injury to ulnar nerve at elbow
Radial deviation of wrist
LESS clawing in 4th-5th fingers (as flexor digitorum profundus affected)
Branches of thoracoacromial artery
Pectoral
Clavicular
Acromial
Deltoid
Path of thoracoacromial artery
Projects forward to upper border of pec minor and pierces coracoclavicular fascia before dividing into its 4 branches
Description of pectoral branch of thoracoacromial artery
Descends between 2 pectoral muscles
Distributed to the pectoral muscles and breast
Anastomose with intercostal branches of internal thoracic artery and with lateral thoracic
Description of clavicular branch of thoracoacromial artery
Runs upwards and medially to the sternoclavicular joint
Supplies sternoclavicular joint and subclavius
Description of acromial branch of thoracoacromial artery
Runs laterally over coracoid process and under the deltoid (to which it gives branches)
Pierces deltoid
Ends on acromion in an arterial network formed by branches from: suprascapular, thoracoacromial, posteriorr circumflex humeral arteries
Description of deltoid branch of thoracoacromial artery
Arises with acromial branch
Crosses over pec minor
Passes in same groove as cephalic vein, between pec major and deltoid (giving branches to both muscles)
What is the anterior interosseous nerve a branch of?
Median nerve
What does the anterior interosseous nerve innervate?
- 5 muscles (in deep level of anterior compartment of forearm):
- Flexor pollicis longus
- Pronator quadratus
- Radial half of flexor digitorum profundus (lateral 2/4 tendons)
Root values of axillary nerve
C5-6
Terminal branch of posterior cord of brachial plexus
Path of axillary nerve
Descends posterior to axillary artery at lower border of subscapularis
Passes through quadrangular space with posterior circumflex humeral vessels
Divides into anterior and posterior branches
Actions of interossei muscles
Palmar interossei - adduction of fingers
Dorsal interossei - abduction of fingers
PAD DAB
Flexion of MCP joint, extension of PIP and DIP joints (together with lumbricals) - claw hand seen if paralysed (digits pulled into hyperextension)
How many interossei muscles are there in total?
4 palmar
4 dorsal
They occupy the spaces between the metacarpal bones
Origins and insertions of interossei muscles
Palmar - originates from metacarpal of digit on which it acts
Dorsal - originates from surface of adjacent metacarpal on which it acts (hence 2x the size of palmar)
Interossei tendons (except 1st palmar) pass to one or other side of MCP joint posterior to deep transverse metacarpal ligament. They insert into the base of the proximal phalanx and partly into the extensor hood.
Origins of triceps
Long head - infraglenoid tubercle of scapula
Lateral head - dorsal surface of humerus, lateral and proximal to groove of radial nerve
Medial head - posterior surface of humerus on inferomedial side of radial groove and both of the intermuscular septae
Insertion of triceps
Olecranon process of ulna
Some fibres insert into deep fascia of forearm, posterior capsule of elbow
Nerve supply of triceps
Radial nerve
Blood supply of triceps
Profunda brachii
Action of triceps
Elbow extension
Note: long head can adduct the humerus and extend it from a flexed position
Relations of triceps
Radial nerve and profunda brachii lie between lateral and medial heads
Nerve supplies of rotator cuff muscles
Supraspinatus, infraspinatus - suprascapular nerve
Teres minor - axillary nerve
Subscapularis - superior and inferior subscapular nerves
Where is the pectoral region located?
Anterior chest wall
Muscles of the pectoral region
Pectoralis major
Pectoralis minor
Serratus anterior
Subclavius
Parts of pectoralis major
Sternal head
Clavicular head
Attachments of heads of pectoralis major
Clavicular - from anterior surface of medial clavicle
Sternal - from anterior surface of sternum, superior 6 costal cartilages and aponeurosis of external oblique muscle
Both to intertubercular sulcus of humerus
Function of pectoralis major
Adduction and medial rotation of UL
Draw scapula anteroinferiorly
Clavicular head acts individually to flex UL
Nerve supply of pectoralis major
Lateral and medial pectoral nerves
Where does the pectoralis minor lie?
Underneath its larger counterpart, pectoralis major
Both form part of anterior wall of axilla
Attachments of pectoralis minor
From ribs 3-5 to coracoid process of scapula
Function of pectoralis minor
Stabilise the scapula by drawing it anteroinferiorly against the thoracic wall
Nerve supply of pectoralis minor
Medial pectoral nerve
Where does the serratus anterior lie?
More laterally in the chest wall
Forms medial border of axilla region
Attachments of serratus anterior
Several strips, originate from lateral aspects of ribs 1-8, to costal surface of medial border of scapula
Function of serratus anterior
Rotate scapula, allowing arm to be raised >90 degrees
Hold scapula against ribcage
Nerve supply of serratus anterior
Long thoracic nerve
Where does the subclavius lie?
Directly underneath the clavicle, running horizontally
Attachments of subclavius
From junction of 1st rib and its costal cartilage, to inferior surface of middle 3rd of clavicle
Function of subclavius
Anchors and depresses the clavicle
Nerve supply of subclavius
Nerve to subclavius
Groups of muscles of the shoulder
Extrinsic (aka superficial back muscles) - originate from trunk and insert into bnoes of shoulder (clavicle, scapula, humerus)
Intrinsic - originate from scapula/clavicle and attach to humerus
Layers of extrinsic muscles of shoulder
Superficial layer
Deep layer
What are the superficial extrinsic muscles of shoulder?
Trapezius (most superficial of all back muscles)
Latissimus dorsi
Attachments of trapezius
Originate from skull, nuchal ligament and spinous processes of C7-12
Attach to clavicle, acromion and scapula spine
Innervation of trapezius
Motor - accessory nerve
Sensory (proprioception) - C3-4 spinal nerves
Actions of trapezius
Upper fibres - elevate scapula and rotate it during abduction of arm
Middle fibres - retract scapula
Lower fibres - pull scapula inferiorly
What is the commonest cause of accessory nerve damage?
Iatrogenic e.g. cervical LN biopsy, cannulation of internal jugular vein
Signs of accessory nerve damage
Inability to shrug shoulders
Muscle wasting
Partial paralysis of SCM
Asymmetrical neckline
Attachments of latissimus dorsi
Originate from spinous processes of T7-12, iliac crest, thoracolumbar fascia and inferior 3 ribs
Converge into a tendon that inserts into intertubercular sulcus of humerus
Innervation of latissimus dorsi
Thoracodorsal nerve
Actions of latissimus dorsi
Extension, adduction, medial rotation of UL
What are the deep extrinsic muscles of shoulder?
Levator scapulae
Rhomboid major
Rhomboid minor
Attachments of levator scapulae
Originate from transverse processes of C1-4 vertebrae
Attach to medial border of scapila
Innervation of levator scapulae
Dorsal scapular nerve
Action of levator scapulae
Elevation of scapula
Where is the rhomboid minor located in relation to the other deep extrinsic shoulder muscles?
Above rhomboid major, below levator scapulae
Attachments of rhomboid major
Originate from spinous processes of T2-5 vertebrae
Attach to medial border of scapula, between scapula spine and inferior angle
Innervation of rhomboid major
Dorsal scapular nerve
Action of rhomboid major
Retraction and rotation of scapula
Attachments of rhomboid minor
Originate from spinous processes of C7-T1 vertebrae
Attach to medial border of scapula, at level of spine of scapula
Innervation of rhomboid minor
Dorsal scapular nerve
Action of rhomboid minor
Retraction and rotation of scapula
What are the intrinsic shoulder muscles also known as?
Scapulohumeral group
What are the intrinsic muscles of shoulder?
Deltoid
Teres major
4 rotator cuff muscles
Parts of deltoid muscle
Anterior
Middle
Posterior
Attachments of deltoid
Originate from lateral 3rd of clavicle, acromion and spine of scapula
Attach to deltoid tuberosity on lateral aspect of humerus
Innervation of deltoid
Axillary nerve
Actions of deltoid
Anterior fibres - flexion, medial rotation
Posterior fibres - extension, lateral rotation
Middle fibres - abduction
Attachments of teres major
Originate from posterior surface of inferior angle of scapula
Attach to medial lip of intertubercular groove of humerus
Innervation of teres major
Lower subscapular nerve
Actions of teres major
Adduction and extension at shoulder
Medial rotation of arm
Attachments of supraspinatus
Originate from supraspinous fossa of scapula
Attach to greater tubercle of humerus
Innervation of supraspinatus
Suprascapular nerve
Action of supraspinatus
Abduction of arm (1st 15 degree)
Attachments of infraspinatus
Originate from infraspinous fossa of scapula
Attach to greater tubercle of humerus
Innervation of infraspinatus
Suprascapular nerve
Action of infraspinatus
Lateral rotation of arm
Attachments of subscapularis
Originate from subscapular fossa, on costal surface of scapula
Attach to lesser tubercle of humerus
Innervation of subscapularis
Upper and lower subscapular nerves
Action of subscapularis
Medial rotation of arm
Attachments of teres minor
Originate from posterior surface of scapula, adjacent to its lateral border
Attach to greater tubercle of humerus
Innervation of teres minor
Axillary nerve
Action of teres minor
Lateral rotation of arm
What is the muscle most commonly affected in rotator cuff tendonitis?
Supraspinatus
During abduction, it ‘rubs’ against the coracoacromial arch - over time, causes inflammation and degenerative changes in tendon itself
Muscles in upper arm
Anterior compartment - biceps brachii, brachialis, coracobrachialis
Posterior compartment - triceps brachii
Innervation of muscles in anterior compartment of upper arm
Musculocutaneous nerve
Arterial supply to anterior compartment of upper arm
Muscular branches of brachial artery
Does the biceps brachii attach to humerus?
No. Although majority of the biceps muscle is located in front of the humerus, it has no attachment to the bone itself
What forms the bicipital aponeurosis?
It is a connective tissue sheet that is given off when the tendon of biceps brachii enters the forearm
What does the bicipital aponeurosis demarcate?
It forms the roof of the cubital fossa
Blends with deep fascia of anterior forearm
Attachments of biceps brachii
Long head originate from supraglenoid tubercle of scapula
Short head originate from coracoid process of scapula
Both heads insert distally into radial tuberosity and fascia of forearm via bicipital aponeurosis
Action of biceps brachii
Supination of forearm
Flexion of arm at elbow and shoulder
Innervation of biceps brachii
Musculocutaneous nerve
What spinal cord segment is the biceps tendon reflex?
C6
Where does the coracobrachialis lie in relation to biceps brachii?
Deep to biceps brachii in arm
Attachments of coracobrachialis
Originate from coracoid process of scapula
Pass through axilla
Attaches to medial side of humeral shaft at level of deltoid tubercle
Action of coracobrachialis
Flexion of arm at shoulder
Weak adduction
Innervation of coracobrachialis
Musculocutaneous nerve
Where does the brachialis lie in relation to biceps brachii?
Deep to biceps brachii
Found more distally than other arm muscles
Forms floor of cubital fossa
Attachments of brachialis
Flexion at elbow
Innervation of brachialis
Musculocutaneous nerve
Contributions from radial nerve
What sign can you see with rupture of the long head of biceps brachii?
Sign on flexing elbow - bulge where muscle belly is (Popeye sign)
Arterial supply to posterior compartment of arm
Profunda brachii
Attachments of triceps brachii
Long head - originate from inglenoid tubercle
Lateral head - from humerus, above radial groove
Medial head - from humerus, below radial groove
All converge into 1 tendon distally and insert into olecranon of ulna
Function of triceps brachii
Extension of arm at elbow
Innervation of triceps brachii
Radial nerve
Note: in some people, long head of triceps tendon is innervated by axillary nerve
What spinal cord segment is the triceps tendon reflex?
C7
Categories of muscles in anterior compartment of forearm
Superficial
Intermediate
Deep
Superficial muscles in anterior compartment of forearm
(Medial to lateral) Flexor carpi ulnaris Palmaris longus Flexor carpi radialis Pronator teres
All originate from common tendon arising from medial epicondyle of humerus
Attachments of FCU
Originate from medial epicondyle of humerus
Another long origin from ulna
Pass into wrist
Attach to pisiform
Action of FCU
Flexion and adduction at wrist
Innervation of FCU
Ulnar nerve
Attachments of palmaris longus
Originate from medial epicondyle of humerus
Attach to flexor retinaculum
Action of palmaris longus
Flexion at wrist
Innervation of palmaris longus
Median nerve
Attachments of FCR
Originate from medial epicondyle
Attach to base of metacarpals 2 and 3
Action of FCR
Flexion and abduction at wrist
Innervation of FCR
Median nerve
What is the pronator teres a landmark of?
Its lateral border forms the medial border of the cubital fossa
Attachments of pronator teres
2 origins: from medial epicondyle and coronoid process of ulna
Attach laterally to midshaft of radius
Action of pronator teres
Pronation of arm
Innervation of pronator teres
Median nerve
Muscles in anterior intermediate compartment of forearm
Flexor digitorum superficialis
can sometimes be classed as superficial, but lie between deep and superficial layers in most
Why is the flexor digitorum superficialis a good anatomical landmark in the forearm?
Median nerve and ulnar artery pass between its 2 heads, then travel posteriorly
Attachments of FDS
2 heads - one from medial epicondyle of humerus, and other from radius
Split into 4 tendons at wrist
Travel through carpal tunnel
Attach to middle phalanges of 4 fingers
Action of FDS
Flexion of MCP and PIP joints at 4 fingers
Flexion at wrist
Innervation of FDS
Median nerve
Muscles in deep anterior compartment of forearm
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
Attachments of FDP
Originate from ulna and associated interosseous membrane
Split into 4 tendons at wrist
Travel through carpal tunnel
Attach to distal phalanges of 4 fingers
Action of FDP
Only muscle that can flex DIP joints of fingers
Flexion of MCP joints and wrist
Innervation of FDP
Medial half by ulnar nerve
Lateral half by anterior interosseous branch of median nerve
Where is the flexor pollicis longus in relation to the FDP?
Lateral to FDP
Attachments of FPL
Originate from anterior surface of radius and surrounding interosseous membrane
Attach to base of distal phalanx of thumb
Action of FPL
Flexion of MCP and IP joints of thumb
Innervation of FPL
Anterior interosseous branch of median nerve
Where is the pronator quadratus in relation to the FDP and FPL?
Square-shaped muscle deep to tendons of FDP and FPL
Attachments of pronator quadratus
Originate from anterior surface of ulna
Attach to anterior surface of radius
Action of pronator quadratus
Pronation of forearm
Innervation of pronator quadratus
Anterior interosseous branch of median nerve
Layers of posterior compartment of forearm
Superficial
Deep
Both layers separated by a layer of fascia
Superficial muscles in posterior compartment of forearm
Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum communis Extensor digiti minimi Extensor carpi ulnaris Anconeus
Radialis brevis, ulnaris, digitorum communis and digiti mini share a common tendinous origin at lateral epicondyle of humerus
Why is the brachioradialis a paradoxical muscle?
Its origin and innervation are characteristic of an extensor muscle
It’s actually a flexor at the elbow
When is the brachioradialis muscle most visible?
When forearm is half-pronated, and flexing at elbow against resistance
Attachments of brachioradialis
Originate from proximal aspect of lateral supracondylar ridge of humerus
Attach to distal end of radius, just before styloid process
Action of brachioradialis
Flexion at elbow
Innervation of brachioradialis
Radial nerve
Attachments of extensor carpi radialis longus and brevis
ECRL originate from supracondylar ridge
ECRB originate from lateral epicondyle
Tendons attach to metacarpal bones 2 and 3
Action of of extensor carpi radialis longus and brevis
Extension and abduction at wrist
Innervation of extensor carpi radialis longus and brevis
Radial nerve
Which muscle the main extensor of fingers?
Extensor digitorum communis
Attachments of extensor digitorum communis
Originate from lateral epicondyle
Continue into distal part of forearm, where it splits into 4
Insert into extensor hood of each finger
Action of extensor digitorum communis
Extension of fingers at MCP and IP joints
Innervation of extensor digitorum communis
Deep branch of radial nerve
Anatomically, where does the extensor digiti minimi lie?
Medial to extensor digitorum
Attachments of extensor digiti minimi
Originate from lateral epicondyle of humerus
Attach into extensor hood of fingers with extensor digitorum tendon
Action of extensor digiti minimi
Extension of little finger
Contribute to extension at wrist
Innervation of extensor digiti minimi
Deep branch of radial nerve
Attachments of ECU
Originate from lateral epicondyle of humerus
Attach to base of metacarpal 5
Action of ECU
Extension and adduction of wrist
Innervation of ECU
Deep branch of radial nerve
Where is the anconeus located in the extensor compartment of forearm?
Superiorly and medially
Blended with fibres of triceps brachii (the 2 can be indistinguishable)
Action of anconeus
Extension and stabilisation of elbow
Abduction of ulna during forearm pronation
Innervation of anconeus
Radial nerve
Muscles in deep compartment of posterior forearm
Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis
Where does the supinator lie in the deep posterior compartment of forearm?
In the floor of cubital fossa
How many heads does the supinator have and what passes in between them?
2 hears with deep branch of radial nerve passing in between
Attachments of supinator
1 head from lateral epicondyle of humerus, other from posterior surface of ulna
Attach together to posterior surface of radius
Action of supinator
Supination of forearm
Innervation of supinator
Deep branch of radial nerve
Where is the abductor pollicis longus located in relation to the supinator?
Immediately distal to supinator
Attachments of APL
Originate from interosseous membrane and adjacent posterior surfaces of radius and ulna
Attaches to lateral side of base of metacarpal 1
Action of APL
Abduction of thumb
Innervation of APL
Posterior interosseous branch of radial nerve
Where is the extensor pollicis brevis located in relation to the APL?
Medial and deep to the abductor pollicis longus
Attachments of EPB
Originate from posterior surface of radius and interosseous membrane
Attach to base of proximal phalanx of thumb
Innervation of EPB and EPL
Posterior interosseous branch of radial nerve
Attachments of EPL
Originate from posterior surface of ulna and interosseous membrane
Attach to distal phalanx of thumb
Action of EPB
Extension at MCP and CMC joints of thumb
Action of EPL
Extension of all thumb joints: CMC, MCP, IP joints
What makes the extensor indicis propius unique?
It allows the index finger to be independent of other fingers during extension
Attachments of extensor indicis propius
Originate from posterior surface of ulna and interosseous membrane, distal to EPL
Attach to extensor hood of index finger
Action of extensor indicis propius
Extension of index finger
Innervation of extensor indicis propius
Posterior interosseous branch of radial nerve
What is wrist drop a sign of?
Radial nerve injury proximal to elbow
What are the 2 common characteristic sites of damage of radial nerve?
Axilla - injured via humeral dislocations or fractures of proximal humerus
Radial groove of humerus - injured via humeral shaft fracture
Groups of muscles acting on the hand
Extrinsic - located in anterior and posterior compartments of forearm, control crude movements and produce forceful grip
Intrinsic - located within hand itself, for fine motor functions
Nerve roots of axillary nerve
C5-6
Sensory function of axillary nerve
Gives rise to upper lateral cutaneous nerve of arm
Innervate skin over lower deltoid (‘regimental badge area’)
Motor function of axillary nerve
Deltoid
Teres minor
Anatomical course of axillary nerve
Direct continuation of posterior cord of brachial plexus
In axilla - posterior to axillary artery and anterior to subscapularis
Exits axilla at inferior border of subscapularis via quadrangular space
Pass medial to surgical neck of humerus
What happens to the axillary nerve at the surgical neck of humerus?
Divides into 3 branches:
- Posterior terminal branch
- Anterior terminal branch
- Articular branch
Function of posterior terminal branch of axillary nerve
Motor innervation to posterior aspect of deltoid and teres minor
Sensory innervation to skin over inferior part of deltoid
Function of anterior terminal branch of axillary nerve
Motor innervation to anterior part of deltoid
Terminates with cutaneous branches to anterior and anterolateral shoulder
Function of articular branch of axillary nerve
Supplies glenohumeral joint
What is the quadrangular space?
A gap in the muscles of the posterior scapular region
Pathway for NV structures to move from axilla anteriorly to posterior shoulder and arm
Boundaries of quadrangular space
Superior - inferior border of teres minor
Inferior - superior border of teres major
Lateral - surgical neck of humerus
Medial - long head of triceps brachii
Anterior - subscapularis
What happens after the posterior terminal branch of axillary artery has innervated the teres minor?
It continues as the upper lateral cutaneous nerve of arm
What is Erb’s palsy?
A condition due to damage from C5-6 roots
Axillary nerve is affected, person unable to abduct or externally rotate shoulder joint
Nerve roots of musculocutaneous nerve
C5-7
Motor function of musculocutaneous nerve
Muscles in anterior compartment of upper arm (biceps, brachialis, coracobrachialis)
Sensory function of musculocutaneous nerve
Gives rise to lateral cutaneous nerve of forearm which innervates lateral aspect of forearm