MSK Anatomy Flashcards
Joint types
Fibrous: cranial sutures, interosseus membrane
Cartilagenous:
- Primary (hyaline only): ossify - growth plates
- Secondary (+ fibrocartilage): midline - pubic symphysis
Synovial:
- Plane
- Hinge
- Condylar
- Ball and socket
- Saddle
- Pivot
Joint stability
- Articular surface
- Capsule and ligaments
- Muscles
Cartilage Structure
Superficial layer: flattened chondrocytes that produce collagen and glycoproteins (lubricin) - parallel collagen
Transitional layer: round chondrocytes that produce proteoglycans (aggrecan)
Deep layer: horizontal collagen
75% water
Cartilage Function
Provide a smooth, lubricated surface for low friction articulation and facilitation of load transmission
- Glycoproteins (lubricin):»_space; protein
- Proteoglycans (aggrecan)»_space; carb
- GAGs (hyaluronic acid)»_space;> carb
Synovial fluid components and function
- Hyaluronic acid
- Lubricin
- Blood plasma
Nutrition of cartilage, waste removal, lubrication (boundary, hydrodynamic, weeping)
Bursae
Fluid-filled sacs that reduce friction
Bone development
- Hyaline cartilage model
- Primary ossification centre develops at centre
- Secondary ossification centre develops at ends
- Medullary cavity forms in primary ossification centre
Bone structure
Epiphysis: articular cartilage, spongy/cancellous bone
Epiphyseal growth plate
Metaphysis
Diaphysis: medullary cavity, compact/cortical bone
Cortical/compact bone
Lamellae
- Concentric: central canal with blood vessels
- Interstitial
- Circumferential
Biologically inactive
Resists bending and torsion
Spongy/cancellous bone
Trabeculae
- Resists/absorbs compression
- Very biologically active - osteoclasts, osteoblasts, osteocytes
Tendon structure and function
Collagenous structure
- Vinculum: blood supply
Connects muscle to bone
Ligament structure and function
Collagenous structure
Connects bone to bone (span a joint)
Axilla boundaries
Apex: lat. border of 1st rib, scapula, clavicle
Base: axillary fascia
Anterior: pectoralis major + minor
Posterior: subscapularis, teres major, latissimus dorsi
Medial: thoracic wall, serratus anterior
Lateral: neck/shaft of humerus
Axilla contents
- Axillary artery
- Axillary vein
- Brachial plexus
- Axillary lymph nodes
Brachial plexus roots
C5-T1
Brachial plexus trunks
- Superior: C5-6
- Middle: C7
- Inferior: C8-T1
Brachial plexus cords
Named for position in relation to axillary artery
- Lateral cord: anterior divisions of upper and middle trunk
- Posterior cord: posterior divisions of all trunks
- Medial cord: anterior division of lower trunk
Musculocutaneous nerve
C5-7
- Originates from lateral cord
- Anterior compartment of arm (BBC)
Course:
- Perforates coracobrachialis
- Descends between biceps brachii and brachialis
- Crosses elbow
- Terminal branch in forearm: lateral cutaneous nerve
Axillary nerve
C5-6
- Originates from posterior cord
- Deltoid and teres minor
Course:
- Exits axilla via quadrangular space
- Passes medially to surgical neck of humerus
- Divides into 3 terminal branches: anterior, posterior, articular
Radial nerve
C5-T1
- Originates from posterior cord
- BEST: brachioradialis, extensors (wrist), supinator, triceps (posterior compartment of arm)
Course:
- Enters anterior to medial head of triceps and runs with profunda brachii artery
- Descends down midshaft humerus in radial groove
- Lies between brachialis and brachioradialis
- Anterior to lateral epicondyle
- Cubital fossa and then terminates (deep and superficial branch)
a. Deep branch (aka posterior interosseus nerve) runs deep to supinator (pierces to enter posterior compartment)
b. Superficial branch runs deep to brachioradialis and enters hand above anatomical snuff box (dorsum of hand)
Median nerve
C5-T1
- Originates from lateral and medial cord
- Anterior compartment of forearm
Course:
- Descends along lateral side of axillary/brachial artery
- Crosses to medial brachial artery in middle part of arm
- Enters cubital fossa
- Heads under pronator teres
- Descends between flexor digitorum superficialis and profundus
- Enters carpal tunnel deep to flexor retinaculum
Ulnar nerve
C8-T1
- Originates from medial cord
- Intrinsic muscles of the hand
Course:
- Descends along medial side of brachial artery
- Enters posterior compartment of arm through medial intermuscular septum and runs along medial head of triceps
- Passes medial epicondyle posteriorly
- Passes between heads of flexor carpi ulnaris
- Descends to wrist medial to ulnar artery
- Enters hand superficial to flexor retinaculum
Arterial supply of upper limb
- Subclavian
- Axillary - at lateral border of the 1st rib
- Brachial - lower margin of teres major. Gives off profunda brachii (passes deep to triceps with radial nerve)
Radial (lateral)
- Starts under brachioradialis
- Runs over pronator teres, flexor pollicis longus and distal radius
- Forms deep palmar arches
Ulnar (medial)
- Runs distal with ulnar nerve between flexor carpi ulnaris and flexor digitorum profundus
- Runs through wrist and forms superficial palmar arch
Palmar arches anastomose
Common digital artery
Proper palmar digital artery
Posterior interosseus artery - branch of ulnar artery
Venous drainage of upper limb
- Dorsal venous arch
- Cephalic (lateral)
- Basilic (medial)
- Median cubital (communicating vein in ante-cubital fossa:
cephalic -> basilic) - Axillary vein
Cephalic vein pierces clavipectoral fascia
Basilic vein becomes axillary at lower border of teres minor
Dermatomes of upper limb
C5 - deltoid (regimental badge) C6 - thumb C7 - middle finger C8 - little finger T1 - medial antecubital fossa
Lymphatic drainage of upper limb
Axillary lymph nodes:
- Anterior/Pectoral: anterior thoracic wall
- Posterior/Subscapular: posterior thoracic wall
- Lateral/Brachial: lateral axillary wall
- ^^ all drain to central nodes at base of axilla.
- ^^ drains to apical nodes at apex of axilla
Pectoral (shoulder) girdle
Connect bilateral upper limbs to axial skeleton
- Clavicle
- Scapula
- Acromioclavicular joint (plane)
- Sternoclavicular joint (plane with fibrocartilage disc)
Clavicle
Connects to manubrium of sternum (SC) and acromion of scapula (AC).
- Shaft is weakest
- Conoid tubercle on inferior surface
Scapula
- Acromion
- Coracoid process
- Spine and spinous process
- Supra/infraspinous fossa (posterior)
- Subscapular fossa, lateral/medial border and superior/inferior angle (anterior)
- Glenoid cavity and supra/infraglenoid tubercles
Coracoid process attachments
3 muscles
- Pectoralis minor
- Biceps brachii (short head)
- Coracobrachialis
3 ligaments
- Coracohumeral
- Coracoacromial
- Coracoclavicular
Scapulo-humeral rhythm
Abduction
- First 30 degrees caused by muscles acting at gleno-humeral joint
- > 30 degrees requires scapula-thoracic movement: elevation and lateral rotation
Elevation (superomedial) of scapula
- Trapezius (superior fibres)
- Levator scapulae
- Rhomboid minor and major
All medial border of scapula insertion
Depression of scapula
- Gravity
- Latissimus dorsi
- Serratus anterior
- Pectoralis major and minor
- Trapezius (inferior fibres)
Protraction (forward movement) of scapula
- Serratus anterior
2. Pectoralis major and minor
Retraction (backward movement) of scapula
- Trapezius (middle fibres)
- Rhomboid major and minor
- Latissimus dorsi
Lateral (upward) rotation - elevate glenoid cavity
- Trapezius
2. Serratus anterior
Medial (downward) rotation - depress glenoid cavity
- Gravity
- Levator scapulae
- Rhomboids
- Pectoralis minor
Gleno-humeral joint
Ball and socket synovial joint.
Glenoid labrum is a rim of cartilage that deepens the socket providing stability
Ligaments of shoulder joint
- Coracoacromial arch (superior)
- Coracohumeral (superior)
- Glenohumeral (anterior)
- Transverse humeral (stabilises long head of biceps)
Bursae of shoulder joint
Subacromial (subdeltoid)
- Between infra-/supraspinatus muscles and deltoid to reduce friction beneath deltoid (promoting movement of rotator cuff muscles)
- Injury by repetitive overhead movements
Subscapular
- Communicate with joint cavity
Rotator Cuff muscles (SITS)
Stabilise the gleno-humeral joint
Innervation: C5-6
External (lateral) rotators:
- Infraspinatus
- Infraspinous fossa
- Greater tuberosity of humerus - Supraspinatus
- Supraspinous fossa
- Greater tuberosity of humerus - Teres minor
- Lateral border of scapula
- Greater tuberosity of humerus
Internal (medial) rotator:
- Subscapularis
- Subscapular fossa of scapula
- Greater tubercle of humerus (anterior)
Shoulder dislocation
Weakest part of capsule is anteroinferior.
Anterior more common
Axillary nerve damage (loss of sensation at regimental badge area)
Deltoid muscle
- Origin: lateral spine of scapula
Passes across acromion to lateral third of clavicle - Insertion: deltoid tuberosity of humerus
- Function: flexion, abduction and extension
- Innervation: axillary nerve
Pectoralis major
- Origin: medial third of clavicle, sternum and costal cartilage of ribs 1-6 and rectus sheath
- Insertion: lateral lip of bicipital groove of humerus
- Function: adduct, flex and medially rotate humerus
Pectoralis minor
- Origin: 3-5th ribs
- Insertion: coracoid process
- Function: stabilise scapula (with serratus anterior), splits axillary artery into 3
Serratus anterior
Stabilise and protraction of scapula.
- Long thoracic nerve (C5-7)
- Dysfunction leads to winging (long thoracic nerve damage during breast surgery common)
Trapezius
- Origin: occipital, spinous process T1-12
- Insertion: lateral 1/3 clavicle, acromion, spine of scapula
- Function: elevate (superior), retract (middle) and depress (inferior) scapula
- Innervation: CNXI
Flexion of shoulder
- Deltoid
- Pectoralis major
- Corachobrachialis
Extension of shoulder
- Deltoid
- Latissimus dorsi
- Teres major and minor
Adduction of shoulder
- Pectoralis major
- Latissimus dorsi
- Teres major
- Triceps brachii
Abduction of shoulder
0-90: supraspinatus, deltoid
90-180: trapezius, serratus anterior
Medial/internal rotation of shoulder
- Subscapularis
- Latissimus dorsi
- Pectoralis major
- Teres major
Lateral/external rotation of shoulder
- Infraspinatus
- Supraspinatus
- Teres minor
Latissimus dorsi
- Origin: broad - T7-12 spinous processes, ileal crest, ribs 9-12
- Insertion: Intertubercular sulcus of humerus (anterior)
- Function: Depression, internal rotation, adduction, extension
Humerus
Anterior:
- Greater (SIT) and lesser tubercle
- Intertubercular groove (t. major and lat dorsi)
- Deltoid tuberosity
- Coronoid fossa
- Radial fossa
- Trochlea
- Capitulum
Posterior:
- Head
- Neck (anatomical then surgical)
- Shaft
- Radial groove
- Olecranon fossa
- Medial epicondyle
Elbow joint
Synovial hinge (180 degrees)
- Trochlear notch (ulna) and trochlea
- Head of radius and capitulum
Bursae: intratendinous, subtendinous, subcutaneous (olecranon)
Elbow ligaments
- Radial collateral ligament (medial epicondyle and coronoid process -> olecranon of ulna)
- Ulnar collateral ligament (lateral epicondyle -> annular ligament of radius)
Epicondylitis
Repetitive overused of forearm muscles results in inflammation of muscle tendons attached to epicondyles
Lateral: tennis elbow
Medial: golfer’s elbow
Radio-ulnar joints
- Proximal (annular ligament keeps radius in place) and distal
- Pivot-type to allow supination and pronation
Anterior compartment of the arm
Biceps brachii, coracobrachialis and brachialis
- Musculocutaneous (BBC) nerve
- Flexion
Biceps brachii
- Long head: supraglenoid tubercle (intertubercular groove)
- Short head: coracoid process
- Radial tuberosity
- Bicipital aponeurosis to deep fascia of forearm
- Flexion of elbow + arm
- Supination of forearm
Coracobrachialis
- Coracoid process
- Mid-shaft humerus (medial)
- Flexion and adduction of arm
Brachialis
- Distal shaft humerus (anterior)
- Coranoid process of ulna
- Flexion of elbow
Posterior compartment of arm
Triceps brachii and anoceus
- Radial nerve
- Extension of forearm (+ arm)
Triceps brachii
- Long head: Infraglenoid tubercle
- Lateral head: Posterior humerus (above radial groove)
- Medial head: Posterior humerus (below radial groove)
- Olecranon process of ulna
Ancoceus
- Lateral epicondyle of humerus
- Olecranon process of ulna
Cubital fossa
Boundaries
- Lateral: medial brachioradialis muscle
- Medial: lateral border of pronator teres muscle
- Superior: imaginary line between epicondyles
- Floor: brachialis and supinators
- Roof: skin and fascia
Contents:
- Radial nerve
- Biceps tendon
- Brachial artery - bifurcation at radial neck
- Median nerve
Note: Median cubital vein lies anterior. Cephalic lies laterally and basilic lies medially
Supination
Biceps brachii and supinator
Pronation
Pronator teres and pronator quadratus
Anterior compartment of the forearm
Flexion of wrist and pronation of forearm
Superficial:
- Brachioradialis
- Pronator teres
- Flexor carpi radialis
- Flexor carpi ulnaris
- Palmaris longus
Intermediate:
- Flexor digitorum superficialis
All except brachioradialis originate from medial epicondyle (common flexor origin)
Deep:
- Flexor digitorum profundus
- Flexor pollicis longus
- Pronator quadratus
All median nerve except ulnaris, brachioradialis and some of FDP
Pronator teres
Anterior compartment of forearm
- Medial epicondyle
- Radius (lateral)
- Pronation and elbow flexion
- Median nerve
Flexor carpi radialis
Anterior compartment of forearm
- Medial epicondyle
- Metacarpals 2-3
- Wrist flexion, abduction (radial deviation)
- Median nerve
Flexor carpi ulnaris
Anterior compartment of forearm
- Medial epicondyle
- Pisiform, hamate, metacarpal 5
- Wrist flexion, adduction (ulnar deviation)
- Ulnar nerve
Flexor digitorum superficialis
Anterior compartment of forearm (intermediate)
- Medial epicondyle
- Intermediate phalanges of digits 2-5. Note: makes tunnel for FDP tendons
- Wrist and finger flexion
- Median nerve
Flexor digitorum profundus
Anterior compartment of forearm (deep)
- Ulna + interosseus membrane
- Distal phalanges 2-5 (palmar)
- Flexion: metacarpophalangeal, interphalangeal, wrist
- Dual nerve supply: median (2-3) and ulnar (4-5)
Flexor pollicis longus
Anterior compartment of forearm (deep)
- Radius + interosseus membrane
- Distal phalanx of thumb
- Flexion of thumb: metacarpophalangeal, interphalangeal
- Median nerve
Pronator quadratus
Anterior compartment of forearm (deep)
- Distal anterior ulna
- Distal anterior radius
- Pronation (with pronator teres)
- Median nerve
Brachioradialis
- Lateral supracondylar ridge of humerus
- Styloid process of radius
- Elbow flexion (lies in posterior compartment) and pronation
- Radial nerve
Carpal tunnel
Passageway from forearm to hand passing deep to the flexor retinaculum (fibrous band)
- 4 carpal bones: scaphoid and trapezium (lateral) and pisiform and hamate (medial)
Function: transmits structures
- 4 FDS tendons
- 4 FDP tendons
- 1 tendon of FPL
- Median nerve
Thenar compartment of the hand
Control thumb movement
- Abductor pollicis brevis
- Flexor pollicis brevis
- Opponens pollicis (deep)
- Median nerve
- Ulnar nerve: deep belly of FPB
Hypothenar compartment of the hand
Control 5th digit movement
- Abductor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi
- Ulnar nerve
Central compartment of the hand
- Flexor tendons from forearm: FDS, FDP, FPL
- Lumbricals - 4 muscles that arise from the medial and lateral aspects of the FDP tendon between the 1st-5th metacarpals
Lumbricals:
- Flexion at metacarpophalangeal 2-5
- Extend at interphalangeal 2-5
- 3,4 - ulnar
- 1,2 - median
Adductor compartment of the hand
Adductor pollicis
- Oblique and transverse head
- Adduction of thumb
- Ulnar nerve
Interosseus compartment of the hand
Lie between metacarpal bones
4 dorsal: abduct fingers (DAB)
- 1 -> 2nd digit
- 2,3 -> 3rd digit
- 4 -> 4th digit
3 palmar: adduct fingers (PAD)
- 1 -> 2nd digit
- 2 -> 4th digit
- 3 -> 5th digit
- Ulnar nerve (deep branch)
Upper limb motor nerve testing
Axillary: abduct shoulders (deltoid)
Musculocutaneous: flex elbow (ant. compartment arm)
Radial: extend wrist (post. compartment forearm)
Ulnar: spread your fingers (intrinsic hand)
Median: thumb towards nose (abductor pollicis brevis)
Upper limb sensory nerve testing
Axillary: regimental badge area
Musculocutaneous: lat. aspect of forearm
Radial: post. arm, forearm, dorsal lateral 3 1/2 fingers
Ulnar: palmar/dorsal aspect of medial 1 1/2 fingers
Median: palmar lateral 3 1/2 fingers
Radius and ulna
Radius
- Radial tuberosity
- Styloid process
- Head
Ulna
- Olecranon process
- Trochlear notch
Wrist
Carpal bones
- Scaphoid (most commonly fractured) and lunate - articulates with radius
- Triquetrum
- Pisiform
- Hamate
- Capitate
- Trapezoid
- Trapezium
Between ulna and carpal bones is triangular fibrocartilage complex (TFCC)
Movements of wrist
Flexion: anterior compartment of forearm
Extension: posterior compartment of forearm
Adduction (ulnar deviation): flexor/extensor carpi ulnaris
Abduction (radial deviation): flexor/extensor carpi radialis
Circumduction
Hand
Carpals
- Carpometocarpal joint
Metacarpals
- Metacarpophalangeal joint
Proximal phalanges
Middle phalanges - 2-5 only
Distal phalanges
- Interphalangeal joint
Posterior compartment of forearm
Extend wrist joint
- Extensor carpi radialis longus - abduct
- Extensor carpi radialis brevis - abduct
- Extensor carpi ulnaris - adduct
Extend medial 4 digits
- Extensor digitorum
- Extensor indices
- Extensor digiti minimi
Extend or abduct thumb
- Abductor pollicis longus
- Extensor pollicis longus
- Extensor pollicis brevis
Supinator - supination
- Radial nerve (C5-8)
Medial epicondyle attachments
Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficiales
Lateral epicondyle attachments
Extensor carpi radialis brevis
Extensor carpi ulnaris
Extensor digitorum
Supinator
Anatomical snuff box
Medial: Extensor pollicis longus (EPL) tendon (inside)
Lateral: Extensor pollicis brevis tendon and abductor pollicis longus tendon (outside)
Floor: scaphoid and trapezium and radial artery
Proximal: styloid process of radius
Dorsal digit (extensor) expansion
Formed by flattening of four extensor digitorum tendons
- At base of proximal phalanx
- Extensor digitorum carries on and crosses base of middle (middle conjoint tendon) and distal (terminal conjoint tendon) phalanx.
Muscles attached to extensor expansion:
- Lumbricals
- Interosseus
- Flexor digitorum superficialis
- Flexor digitorum profundus
Extensor retinaculum
Provides stability and a tunnel for extensor tendons
Curvature in the spine
Cervical (1-7) and lumbar (1-5): lordosis
Thoracic (1-12): kyphosis
Vertebrae structure
- Superior/inferior articular process (facet synovial joint)
- Lamina of vertebral arch
- Intervertebral foramen
- Intervertebral disc (secondary cartilaginous)
- Spinous process
- Transverse process
- Vertebral body
Spinal muscles
- Longissimus/semispinalis capitis
- Longissimus/semispinalis/iliocostalis cervicis
- Longissimus/semispinalis/iliocostalis/ spinalis thoracis
- Erector spinae: longissimus, iliocostalis, spinalis
- Iliocostalis/quadratus lumborum
- Multifidus
- External oblique
- Psoas major and minor
Ligaments of the spine
- Anterior/posterior longitudinal ligaments
- Ligamentum flavum
- Inter/supraspinous ligaments
- Intertransverse ligaments
Myotome
Group of muscles innervated by a single spinal nerve
Dermatome
Area of skin innervated by a single spinal nerve
Spinal cord
Ends at L1
- becomes conus medularis
Intervertebral disc
- Secondary cartilaginous joint
- Structure: annulus fibrosis and nucleus pulposus
- Function: shock absorber, resists rotation
- Ageing: decreased water content -> degenerative changes
