Upper Limb Flashcards
Pectoralis Major
Most superficial muscle of reigon. Large & fan shaped.
Function
Adducts & medially rotates the upper limb and draws the scapula anterioinferiorly. Clavicular head also acts individually to flex upper limb.
Innervation
Lateral & medial pectoral nerves
Pectoralis Minor
Function
- Stabilises the scapula by drawing it anterioferiorly against the thoracic wall
- Protection of the scapula
- If arm & scapula are fixed, elevates the rib for deep breathing (runners etc)
Innervation
Medial pectoral nerve
Serratus Anterior
Function
- Rotates the scapula, allowing arm to be held above 90o
- Holds scapula against rib-cage
Innervation
- Long thoraic nerve
Subclavius
Small muscle underneath the clavicle, runs horizontally.
Function
- Anchors & depresses clavicle
- Provides minor protection to neurovasuclar structures underneath
Innervation
Nerve to Subclavius
Clinical Relevance - Winging of Scapula
- Serratus anterior holds scapula against the ribcage
- If there is damage to the thoraic nerve then serratus anterior becomes paralysed
- The scapula gives a winged appearance, no longer being held against ribcage
- Long thoraic nerve palsy is most commonly down to traction issues, where the upper limb is stretched violently
Trapezius
Superficial extrinsic muscle. Broad, flat & triangular
Function
- Upper fibres elevate scapula & rotates it during arm abduction
- Middle fibres retract scapula
- Lower fibres pull the scapula inferiorly
Innervation
Accessory nerve
Latissimus Dorsi
Covers wide area of lower back, fibres converge into tendon (twist) that attaches to humerus
Function
Extends, adducts & medially rotates the upper limb
Innervation
Thoracodorsal nerve
Levator Scapulae
Small, strap-like muscle
Function
Elevates the scapula
Retracts & rotates the scapula
Innervation
Rhomboid Major
Situated inferiorly to the rhomboid minor
Function
Retracts & rotates the scapula
Innervation
Dorsal scapular nerve
Rhomboid Minor
Situated superiorly to the major
Function
Retracts & rotates scapula
Innervation
Dorsal scapula nerve
Clinical Relevance - Testing Accessory Nerve
- Accessory nerve damage is usually iatrogenic (due to a medical procedure e.g lymph node biopsy, jugular vein cannular)
- To test nerve, trapezius function can be assessed
- Ask patient ot shrug their shoulders
- Other features of damage include: muscle atrophy, asymmetrical neckline & partial paralysis of the sternocleidmastoid
Deltoid
Can be divided into anterior, middle & posterior
Function
- Anterior fibres - flexion and medial rotation
- Posterior fibres - extension and lateral rotation
- Middle fibres - major abductor of the arm (takes over from supraspinatus, first 15o)
Innervation
Axillary nerve
Teres Major
Function
Adducts the shoulder & medially rotates the arm
Innervation
Lower subscapular nerve
Rotator Cuff
- A group of four muscles: supraspinatus, infraspinatus, subscapularis, teres minor
- Provides the glenohumeral joint with additional stability
- Collectively pulls the humeral head to the glenoid fossa
Supraspinatus
Attachments
Originates: supraspinous fossa of the scapula
Attaches: greater tubercle of the humerus
Function
Abducts the arm 0-15o, assists deltoid for 15-90o
Innervation
Suprascapular nerve
Infraspinatus
Attachments
Originates: Infraspinous fossa of scapula
Attaches: greater tubercle of the humerus
Function
Laterally rotates the arm
Innervation
Suprascapular nerve
Subscapularis
Attachments
Originates: subscapular fossa, on costal surface of the scapula
Attaches: lesser tubercle of the humerus
Function
Medially rotates the arm
Innervation
Upper & lower subscapular nerves
Teres Minor
Attachments
Originates: posterior surface of the scapula, adjacent to lateral border
Attaches: greater tubercle of the humerus
Function
Laterally rotates the arm
Innervation
Axillary nerve
Clinical Relevance - Tendonitis
- Rotator cuff tendonitis refers to the inflamation of the tendons of the rotator cuff muscles
- Secondary to repetitive use of shoulder joint
- Supraspinatus most commonly affected - rubs and causes degenerative changes
- Conservative treatment: rest, analgesia & physiotherapy
- Severe cases: steriod injections & surgery
Clinical Relevance - Suprascapular Ligament
- Can have ossification (calcification) which will compress the nerve/artery
- Can lead to atrophy of the intra/supraspinatus due to lack of innervation
Biceps Brachii
Function
Supination of the forearm & flexes arm at elbow & shoulder
Innveration
Musculotaneous nerve
Coracobrachialis
Function
Flexion of the arm at the shoulder & weak adduction
Innervation
Musculocutaneous nerve
Brachialis
Function
Flexion at elbow
Innervation
Musculotaneous nerve, with contribution from radial nerve
Clinical Relevance - Rupture of Biceps Tendon
- Long head of biceps brachii is a more common tendon to rupture
- When flexing elbow, characteristic is the ‘popeye sign’ - a bulge of the muscle belly
- Patient would not notice much weakness, due to brachialis & supinator muscle action
Triceps Brachii
Found in the posterior compartment of the upper arm. Made up of a long, lateral & medial head
Function
Extension of the arm at the elbow
Innervation
Radial nerve but in some individuals, long head is innervated by axillary nerve
Flexor Carpi Ulnaris
Function
Flexion & adduction at wrist
Innervation
Ulnar nerve
Palmaris Longus
Function
Flexion at wrist
Innervation
Median nerve
Pronator Teres
Forms the lateral border of the cubital fossa
Function
Pronation of forearm
Innervation
Median nerve
Flexor Digitorum Superficialis
Only muscle to make up the intermediate compartment - between superficial & deep layers
Function
Flexes metacarpophalangeal joints & proximal interphalangeal joints at 4 fingers
Flexes at wrist
Innervation
Median Nerve
Flexor Digitorum Profundus
Function
Only muscle that can flex interphalangeal finger joints
Flexes at metacarpophalangeal joints & at wrist
Innervation
Medial half (acts on little & ring finger) - ulnar nerve
Lateral half (middle & index finger) - anterior interosseous branch of median nerve
Flexor Pollicis Longus
Lies laterally to the Flexor Digitorum Profundus
Function
Flexes at the interphalangeal & metacarpophalangeal joint of the thumb
Innervation
Median nerve
Pronator Quadratus
Function
Pronates the forearm
Innervation
Median nerve
Brachioradialis
Paradoxical muscle - origin & innervation of an extensor muscle but is actually a flexor
Function
Flexes at elbow
Innervation
Radial nerve
Extensor Digitorum
Functions
Extends medial four fingers at MCP & IP joints
Innervation
Radial nerve (deep branch)
Extensor Carpi Radialis Longus & Brevis
Function
Due to position, able to extend & abducts the wrist
Innervation
Radial nerve
Extensor Digiti Minimi
Thought to originate from the extensor digitorum muscle - in some people they are fused together. Anatomically:
Function
Extends the little finger & contributes to extension at the wrist
Innervation
Radial nerve (deep branch)
Extensor Carpi Ulnaris
Function
Due to position, able to extend & adduct at wrist
Innervation
Radial nerve (deep branch)
Aconeus
Blended with fibres of the triceps brachii & the two muscles can be indistinguishable
Function
Extends & stabilises the elbow joint
Abducts the ulna during pronation of forearm
Innervation
Radial nerve
Clinical Relevance - Tennis Elbow
- Tennis Elbow aka Lateral Epicondylitis is inflammation of the posterium of the lateral epicondyle
- Peak age of onset: 40-50 years old
- Caused by repeated use of the supericial extensor muscles
- Strains their common tendious attachment to the lateral epicondyle
Supinator
Lies on the floor of the cubital fossa
Attachments
First head originates: lateral epicondyle of humerus
Second head originates: posterior surface of ulna
Inserts: together into posterior surface of radius
Function
Supinates forearm
Innervation
Radial nerve (deep branch)
Abductor Pollicis Longus
Function
Abducts the thumb
Innervation
Radial nerve (posterior interosseous branch)
Extensor Pollicis Longus
Function
Extends all joints of thumb: carpometacarpal, metacarpophalangeal & interphalangeal
Innervation
Radial nerve (posterior interossesous branch)
Extensor Indicis Proprius
Function
Extends the index finger
Innervation
Radial nerve (posterior interosseous branch)
Clinical Relevance - Wrist Drop
- Sign of radial nerve injury, proximal to elbow
Two common characteristic sites of damage:
- Axilla - injured via humeral dislocations/fractures
- Radial groove of humerous - injured via a humeral shaft fracture
In an event of a radial nerve lesion, all muscles in the extensor compartment of forearm get paralysed.
The flexor muscles remain unaffected (innervated by median nerve). Unopposed flexion at the wrist joint = wrist drop
Thenar Muscles
- Three short muscles located at the base of the thumb
- Bellies produce a bulge, thenar eminence
- Responsible for fine movements of the thumb
- All muscles innervated by the median nerve
Opponens Pollicis
Largest & lies underneath other two muscles
Function
Opposes the thumb by medially rotating and flexing the metacarpal on the trapezium
Innervation
Median nerve
Abductor Pollicis Brevis
Function
Abducts the thumb
Innervation
Median nerve
Flexor Pollicis Brevis
Function
Flexes the metacarpophalangeal (MCP) of thumb joint
Innervation
Median nerve. Deep head is innervated by the deep branch of ulnar nerve
Hypothenar Muscles
- Produce hypothenar eminence - muscular protusion on medial side of palm (base of little finger)
- Ulnar nerve innervates the three muscles
Opponens Digiti Minimi
Lies deep to other hypothenar muscles
Function
Rotates the little finger metacarpal towards the palm, producing opposition
Innervation
Ulna nerve
Abductor Digiti Minimi
Most superficial of hypothenar muscles
Function
Abducts little finger
Innervation
Ulna nerve
Flexor Digiti Minimi Brevis
Lies laterally to the abductor digiti minimi
Function
Flexes the MCP joint of little finger
Innervation
Ulnar nerve
Lumbricals
- Four lumbricals in hand, associated with a finger
- Crucial to finger movement - linking extensor tendons to flexor tendons
- Denervation of these muscles is basis for the unlar claw & hand of benediction
Function
Flexion at the MCP joint & extension at the interphalangeal (IP) joints of each digit
Innervation
Lateral two (index & middle): median nerve
Medial two (little & ring): ulnar nerve
Dorsal Interossei
Most superficial of all dorsal muscles - can be palpated on the dorsum of hand (4 in total)
Function
- adduct the fingers at MCP joint
- assist lumbricals in the flexion at MCP joints & extension of IP joints
Innervation
Ulnar nerve
Palmar Interossei
- three palmar interossei muscles
- located anteriorly on hand
Function
Adducts fingers at the MCP joint
Innervation
Ulnar nerve
Palmaris Brevis
Small thin muscle found superficially in the subcutaneous tissue of the hypothenar eminence
Function
- wrinkles skin of the hypothenar eminence
- deepens curvature of hand, improving grip
Innervation
Ulnar nerve
Adductor Pollicis
Large triangular muscle with two heads. Radial atery passes anteriorly through the space between two heads, forming deep plamar arch.
Function
Adductor of thumb
Innervation
Ulnar nerve
Axilla Region Borders
Apex - first rib, scapula, clavicle
Lateral wall - humerus
Medial wall - serratus anterior & thoracic wall (ribs & intercostal muscles)
Anterior wall - pectoralis major, minor & subclavius muscles
Posterior wall - subscapularis, teres major & lattisimus dorsi
Axilla Reigon Contents
- Axillary artery - 3 parts, one medial, one lateral & one posterior to pectoralis minor (medial & posterior travel in axilla)
- Axillary vein
- Brachial plexus
- Axillary lymph nodes
- Biceps brachii (short head)
- Coracobrachialis
Clinical Relevance
Thoracic Outlet Syndrome
- vessels & nerves of axilla may become compressed between bones in the apex
- common causes - trauma, repetitive motion, cervical rib
- presents with pain in the affected limb (dependent on nerve), tingling, muscle weakness & discolouration
Lymph Node Biopsy
- 75% of lymph from breast drains into the axilla lymph nodes
- Biospy to test for cancer, removal to prevent spreading (axillary clearance)
- Long thoraic nerve may become damaged, resulting in winged scapula
Cubital Fossa Borders
Lateral border - brachiodialis muscle
Medial border - pronator teres muscle
Superior border - hypothetical line between epicondyles of humerus
Floor - proximally by brachialis, distally by supinator muscle
Roof - consists of skin & fascia, reinforced by bicipital aponeurosis
Cubital Fossa Contents
- Radial nerve
- Biceps tendon
- Brachial artery
- Median nerve
Mneumonic - Really Need Beer To Be At My Nicest
Clinical Relevance - Cubital Fossa
Brachial Pulse & Blood Pressure
- Can be felt immeadiately when palpating medial to the biceps tendon in the cubital fossa
- When measuring blood pressure, stethoscope must be placed here to heat korotkoff sounds
Venepuncture
- Medial cubital vein located superficially in roof
- Connects basilic & cephalic veins
- Can be accessed easily - common site for venepuncture
Supracondular Fractures
- common in young people falling on hyper-extended elbow (sometimes flexed)
- displaced fracture fragments may impinge & damage cubital fossa
- direct damage/post-fracture swelling can cause lack of forearm blood supply from brachial artery
- ischaemia can cause Volkmann-s ischaemic contracture - uncrontrolled flexion of hand as flexors become short
- also can be damage to median or radial nerves
Carpal Tunnel Borders
- Narrow passageway found on anterior portion of wrist
- Entrance to palm for several tendons & median nerve
Carpal Arch
concave on palmar side, forming base & sides of carpal tunnel
lateral - scaphoid & trapezium tubercles
medial - hook of hamate & pisiform
Flexor Retinaculum
thick connective tissue that forms roof
turns carpal arch into tunnel by briding space between the medial & lateral parts
originates on lateral side & inserts into medial side of carpal arch
tCarpal Tunnel Contents
Tendons
- the tendon of flexor pollicis longus
- four tendons of flexor digitorum profundus
- four tendons of flexor digitorum superficialis
8 tendons surrounded by a single synovial sheath, 1 (flexor pollicis longus) surrounded by it’s own synovial sheath
Sheaths allow free movement of tendons
Median Nerve
- once it passes through the carpal tunnel, splits into two branches: reccurent branch & palmar digital nerves
- palmer digital nerves give sensory innervation to palmer skin, dorsal nail beds & lateral 3 1/2 digits
- palmer digital nerves give motor innervation to lateral two lumbricals
- recurrent branch supplies thenar muscle group
Clinical Relevance - Carpal Tunnel Syndrome
- Caused by compression of median nerve in carpal tunnel
- Most common mononeuropathy & can be caused by thickening of ligaments & tendon sheaths
- Left untreated can cause weakness to thenar muscles
- Clinical features include: numbness, tingling & pain along median nerve (forearm). Often wakes patients in sleep & is worse in mornings
Anatomical Snuffbox Borders
Ulnar (medial) border: tendon of extensor pollicis longus
Radial (lateral) border: tendons of extensor pollicis brevis & abductor pollicis longus
Proximal border: styloid process of the radius
Floor: carpal bones, scaphoid & trapezium
Roof: skin
Anatomical Snuffbox Contents
- Radial artery (pulse can be palpated in some individuals)
- Superficial branch of the radial nerve - found in skin & subcutaneous tissue
- Cephalic vein
Clinical Relevance - Scaphoid Fracture
- Most commonly fractured carpal bone (FOOSH - falling on outstreched hand)
- Causes pain & tenderness in anatomical snuffbox
- Risk of avascular necrosis - ‘retrograde blood supply’ at distal end that may interrupt blood supply to proximal part rendering it avascular
- Scaphoid is supplied by two vascular branches of radial artery - volar branch is weaker than dorsal branch
- avascular necrosis (death of bone tissue) can cause non-union (failure to heal fractures properly)
- Having a missed scaphoid fracture makes patient more likely to develop osteoarthritis of wrist in later life
Muscle Groups (& Blood Supply) - Anterior Compartment of Forearm
Pronators of Wrist
- pronator teres & quadratus
- median nerve
Flexors of Wrist
- flexor carpi ulnaris & radialis
- ulnar nerve
Flexors of Fingers
- flexor digitorum profundus & superficialis
- median nerve (flexor digitorum profundus is also innervated by ulnar nerve)
Flexors of Thumb
- flexor pollicis longus & brevis
- median nerve
General Blood Supply
Anterior Arm = brachial artery & veins
Anterior Forearm = radial/ulnar arteries & venae comitantes
Clinical Relevance - Tendon Injuries Hand
- Tendons of the digits may be severed when the hand is injured
- To find out what tendons have been damaged, the patient should be asked to flex the fingers at both the distal & proximal interphalangeal joints:
If there is movement only in the distal phalanges - flexor digitorum superficialis damaged
If there is movement in the only middle phalanges - flexor digitorum profundus damaged
If no movement at all - both damaged
Clinical Relevance - Linburg-Comstock
- Common anatomical variation in the hand - involuntary flexion of the index/middle finger when flexing thumb
- Caused by extra tissue holding tendons together so they cannot move independently
- Opperation to remove tissue possible - important for musicians
- Another common anatomical variation is the presence of a palmaris longus (seen when wrist flexed & thumb and little finger opposed)
Hand Innervation
- Medial side (1/2 ring & little finger) innervated by ulnar nerve
- Lateral side (thumb, index, middle & 1/2 ring finger) is innervated by median nerve
- Ring finger is innervated by both nerves
Carpal Tunnel Syndrome Tests
Phalen’s
- flex wrists maximally & push dorsal side of hands together for 1 minute
- if tingling is felt on lateral side of hand (thumb to 1/2 ring finger) carpal tunnel syndrome can be concluded
- pressure on median nerve
Tinel’s
- tap over carpal tunnel at wrist & whole distribution of median nerve from index finger to elbow
- Positive test if tingling or numbness is felt on the lateral fingers (thumb to 1/2 ring finger) - median nerve damage
Clinical Relevance - Allen’s Test
- shows anastomotic nature of the palmar arches - if there is a likely obstruction in the median or ulnar artery
- open & close hand quickly several times then squeeze hand tightly (clench fist)
- with thumbs, compress radial & ulnar arteries
- open hand & release one thumb (one artery at a time)
- if blood flows into hand quickly - healthy artery
- compare with other hand to see if an artery is impared
Supination VS Pronation
- Supination is a stronger movement - supinator muscles (supinator & biceps brachii) are larger & more developed so are more powerful and don’t tire easily
- Pronation is a weaker movement - pronator muscles are smaller & weaker (pronator teres & quadratus) so forearm will tire easily
- Reason why screws require an anti-clockwise movement (supination) to tighten
Muscle Groups - Hand
Lumbricals
- flex metacarpophalangeal joints & extend interphalangeal joints
- median & ulnar nerve
Palmar Interossei
- adducts digits 2-4
- ulnar nerve
Dorsal Interossei
- abducts digits 2-4
- ulnar nerve
Thenar Muscles
- fine movements of thumb
- median nerve
Hypothenar Muscles
- abducts, flexes and rotates 5th digit
- ulnar nerve
Clinical Relevance - Venous Patterns
- Important for venepuncture & intravenous access
- Cephalic & basilic veins are most prominent and superficial
- Basilic vein is larger than cephalic vein so is usually the most common vessel used for intravenous access (however there is anatomical variation between patients)
Interossei
Palmar Interossei
- anterior compartment of hand
- adduct digits
- PAD - Palmar interossei ADduct
Dorsal Interossei
- Posterior compartment of hand
- adbucts digits
- DAB - Dorsal interossei ABduct
General Nerves & Veins
Radial
- mainly extensor muscles
Median
- mainly flexor muscles
- thenar muscles
- 1st two lumbricals (little & ring)
Ulnar
- mainly intrinsic muscles of hand (hypothenar)
Musculotaneous
- three main muscles of anterior arm
Extensor Retinaculum
- thickened fibrous band that traverses wrist
- holds extensor tendons in position
- prevents bow-stringing - if reticulum was torn, tendons would come more superior & take the shortest route when digits extend
Tendons in Digits
- Two tendons & muscle bellies in the index (2nd) and little (5th) finger - move independently/more freely
- Interconnections in the dorsal of the hand - middle (3rd)/ ring (4th) finger cannot move alone as easily
