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2010-10-20 12:37:41

Forelimb Anatomy
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  1. Muscle characteristics
    • Individual muscle firbres arranged in parallel lines
    • collected into bundles
    • covered by fibrous tissue (fascia)
    • attached to rigid structure
    • origin- usually proximal
    • insertion- usually distal
  2. Attachments of skeletal muscle
    • Origin or insertion:
    • directly to bone (rough surface, boney tuberocity)
    • via tendons (condensation of deep fascia into cords, less bulky across joints, small area of attachment, may have separate centre of ossification)
    • via aponeurosis: (condensation of deep fascia into sheets, long area of attachment, muscles in areas w/ limited access to bone)
    • ex: superficial fascia, and cervico-thoraco-lumbar fascia
  3. Muscle actions:
    • Belly contracts and shortens muscle
    • pulls points of attachment close togeter
    • pivot at joint (decrease angle- flexion, increase angle- extension)
    • action depends on which joints crossed and aspect of joint
    • *antagonistic pairs of musciles- opposite action
  4. Intrinsic muscles
    • origin and insertion w/in appendicular skeleton
    • movement and extension
  5. Extrinsic muscles:
    • origin on axial skeleton
    • insertion in appendicular skeleton
    • movement of limb relative to trunk
    • protraction and retraction of limb
  6. Pivotal point (PP) of scapula
    • No joint present between forelimb and trunk in domestic animals
    • muscular attachements only
    • scapular glide over thorax
    • PP midway down scapula
  7. Brachiocehpalic muscle
    • Cephalic= head
    • brachium= arm
    • origin= cervicothoracic fascia
    • insertion= humerus (aponeurosis)
    • PROTRACTOR (also acts across shoulder)
    • (cleidocervicalis/cleidomastoideus/cleidobrachialis)
  8. Clavical
    • Dog: clavical insertion is a fibrous band
    • Cat: has a bony remnant visible on radiographs, cranial to shoulder
  9. Latissimus dorsi muscle
    • (extrinsic)
    • latus= broad
    • dorsi= back
    • "boradest muscle of the back"
    • origin= thoracolumbar fascia
    • insertion= humerus (aponeurosis)
    • RETRACTOR (also acts across shoulder)
    • propulsion
  10. Serratus ventralis muscle
    • Extrinsic
    • Origin: thoracis wall/ribs and cervical vertiebrae/neck
    • insertion: proximal scapula/medial aspect (proximal to pp)
    • *muscle is located between forelimb and trunk*
    • Function: cranial portion= Retractor, Caudal portion= Protractor
  11. Abductors vs adductors:
    • Abductors: move limb away from midline- muscles located proximal to PP and limb
    • Adductors: move limb towards midline- located distal to PP and medial to limb
  12. Trapezius Muscle
    • Origin= cervicothoracic fascia
    • insertion= proximal scapular spine
    • 2 parts (cranial and caudal)
    • no effect on shoulder
  13. Rhomboideus muscle
    • lies deep to trapezuius
    • origin= cervicothoracic fascia
    • insertion= dorsal border of scapula
    • abductors of limb
    • no effect on shoulder
  14. Pectoral Muscles
    • Origin= sternum
    • insertion= medial humerus
    • Deep and superficial groups
    • adductor of limb
  15. Intrinsic muscles
    • origin and insertion w/in appendicular skeleton
    • no effect on limb relative to trunk
    • move joints w/in limb
    • (flexion and extension)
  16. Humerus
    • Long Bone
    • S-shape
    • head, body condyle
    • brachial/musculospiral groove
    • proximal end: head (artivular surface, convex, smooth surface, articulates w/ glenoid cavity of scapula at shoulder joint, greater tubercle, greater tubercle-lateral, lesser tubercle-medial, intertubercular groove- smooth for tendon of otigin of biceps brachii muscle to pass through)
    • distal end: condyle (medial half larger than lateral), medial epicondlylle, lateral epicondyle, articular surface w/ elbow joint, trochlea (larger, located medially, central depression, articulates w/ radius and ulna), capitulum (smaller, located laterally, articulates w/ radius), olecranon/ulnar fossa-caudal, radial foss-cranial/proximal to articular surfaces, spratrochlear foramen (nothing passes through, may not be present in short legged dogs (only in dogs)
  17. Humerus differences in cats:
    • Proximal features and articular surfaces same as dog
    • distal end: olcranon fossa, radial fossa, NO supratrochlear foramen~!
    • instead they have a supracondyloid foramen (brachial artery, median nerve, vulverable in fractures)
  18. Humerus development and palpation
    • Centres of ossification: proximal epiphyses, body, condyle (medial epicondyle, medial half, lateral half) 5 total
    • Palpation: greater tubercle (shoulder joint), lateral epicondyle and medial epicondyle ( elbow oint
  19. Humerus trama
    • supratrochlear foramen= weak point
    • medial half of condyle larger than lateral half
    • fracture most commonly through lateral half
    • may involve joint- poorer outcome
    • no blood vessels thru
  20. Efferent Nerve Supply
    Brain to structure (motor fibres eg.. movement)
  21. Afferent nerve Supply
    • Structure to brain
    • sensory fibres eg. pain, temp, pressure, etc
    • Proprioception (location of limb in space- automatic)
  22. Motor Nerves
    carry efferent and afferent fibres to structure
  23. Mixed nerves
    carry afferent/sensory from the skin surface
  24. Spinal reflexes
    occur w/o brain being involved eg. patellar reflex
  25. Brachial plexus supply
    • Latissimus dorse (retractor), serratus ventralis (retractor and protractor), pectorals (adductor)
    • supplies ALL intrinsic muscles

    (DOES NOT supply Brachiocephalicus, trapezius and rhomboideus)
  26. Types of Joints:
    • Fibrous
    • Carilagenous
    • Synovial
  27. Fibrous Joints:
    Little Movement (eg. skull sutures)
  28. Carilagenous Joint
    • Synchondrosis/synarthrosis
    • Little movement
    • Pelvic/mandibular sumphysis
  29. Synovial Joint
    • Allows large range of motion between bones
    • most limb joints
    • typical features: Hyaine cartilage (covers articular surfaces, reduce friction, flexible, avascular, no nerves)
    • synovial fluid (viscus, nourishes cartilage, lubricates)
    • synovial membrane (produces synovial fluid, physical barrier to contain fluid)
    • Joint capsule (fibrous layer, incorporates synovial membrane, attaches round osteochondral junction (bone cartilage))
  30. Ligaments
    • Fibrous materal condenses to form ligaments
    • run from bone-bone
    • collateral ligaments support joints (medial and lateral ONLY)
  31. Joint Movement:
    • Flexion: decreased angle, folded limb, non weight bearing position
    • Extension: increased andly, streching limb, weight bearing
  32. Shoulder Joint components:
    • Scapula (glenoid cavity), humerus (head)
    • palpable landmarks (acromion process, greater tubercle)
    • Typical synovial joint features except: poorly developed collateral ligaments
    • Bicipital bursa
    • muscle support
  33. Bicipital Bursa (shoulder joint)
    • Joint capsule extends into intertubercular groove (between greater and lesser tubercles)
    • wraps around tendon of origin of biceps brachii (originates on supraglenoid tubercle)
    • Held in place by transverse ligament
  34. Lateral support of Shoulder joint
    • Supraspinatous muscle: supraspinous fossa-> I= Greater tubercle
    • Infraspinatous muscle: Infraspinous fossa-> I= Distal to greater tubercle
    • Suprascapular nerve- motor fibres ONLY
  35. Medial Support of Shoulder Joint
    • Subscapularis muscle
    • subscapular fossa-> I=lesser tubercle
    • subscapular nerve- motor fibres ONLY
  36. Shoulder Joint extensors
    • Cross cranial to shoulder joint:
    • Brachiocephalicus (extrinsic muscle) nerve non from brachial plexus
    • Biceps brachii muscle (O= supraglenoid tubercle, I= Proximal radius, intrinsic muscle) Motor nerve supply- musculocutaneous nerve, motor and sensory fibres
    • Bicipital bursa (protects tendon of origin, intertubercular groove, transverse ligament)
  37. Shoulder joint flexors
    • cross caudal to shoulder joint
    • Latissimus dorsi (extrinsic muscle) nerve from brachial plexus
    • Deltoideus muscle (2 heads) (O1-scapular spine, O2- acromion process, I- lateral aspect humerus)(intrinsic muscle) Axillary nerve, motor and sensory fibres
    • Teres Major (O- caudal border of scapula, I- medial humerus) axillary nerve, motor and sensory fibres
    • Teres Minor: overlies lateral aspect joint space
    • Triceps Muscle: multiple heads, long head: (O- caudal border scapula, I- Olecranon of Ulna) radial nerve motor and sensory fibres
  38. Clinical considerations
    • Osteochondrosis (OCD): developmental dz, erosion of articular cartilage, subchondral bone may be affected, visible on radiograph, characteristic location, pain causes lameness, leads to DJD/arthritis
    • Degenerative Joint Disease (DJD): new bone formation around joint capsule attachment, osteochondral junction, characteristic locations on rads, painful while forming, lameness
    • soft tissue conditions: bicipital bursitis- U/S used for Dx
  39. Radius and Ulna (breif)
    • Long bones
    • Paired
    • Radius is main weight bearing
    • Ulna is longer/ leverage
  40. Radius proximal end
    • Head
    • Fovea capitis, articular surface (elbow joint)
    • Neck
    • Body
  41. Radius Distal end
    • Trochlea (articular surface w/ carpus)
    • styloid process ("pen") medial, attachment medial collateral ligament or carpus
  42. Ulna Proximal end
    • Olecranon process
    • anconeal process (beak shaped, fits into olecranon/ulnar fossa of humerus)
    • trochlear notch (articular surface/elbow joint)
    • Lateral coronoid process
    • medial coronoid process
    • radial notch (articulates w/ radius)
    • Proximal articulation (radius/head, radial notch of ulna, held by annular ligament (runs lateral to medial coronoid process, rotation possible)
  43. Ulna Distal End
    • Styloid process (attachment lateral collateral ligament of carpus)
    • Distal articulation (fibrous joint, some rotation possible)
    • interosseous space (between bodies, interosseous ligament, fibrous joint)
  44. Evolution of Radius and Ulna
    • Toes rotated cranially
    • elbows rotated caudally
    • radius and ulna therefore rotate around eachother
    • Proximal: ulna most medial projection
    • Distal ulna most lateral projection
  45. Radium and ulna CAT
    • Square olecranon
    • radius and ulna similar diameter
  46. Radius and Ulna Palpation and Development
    • Palpation:
    • Ulna: Olecranon process, lateral styloid process
    • Radius: Medial Styloid Process
    • Development:
    • Radius: proximal epiphyses, body, distal epiphyses (3)
    • Ulna: Olecranon process, anconeal process, body, distal epiphyses (4)
  47. Radius and Ulna development clinical considerations
    • Large contribution to limb length
    • must grow together
    • growth plates= weak point= susceptible to damage
    • Ulna in particular due to shape
    • if one stops before other= angular limb deformaties
    • Fractures: radius bears most weight= requires fixation
    • Primary bone tumors (osteosarcoma)- predilection sites (proximal humerus, distal radius, distal ulna)
  48. Elbow Joint
    • Humerus w/ radius & ulna
    • Humerus: Trochlea, articulates w/ trochlear notch of ulna & fovea capitis of radius. Capitulum: articulates only w/ fovea capitis of radius
    • Typical features of synovial joint (joint capsule- osteochondral jnc, incorporates proximal radio-ulnar articulation)
    • stability: collateral ligaments (humerus- radius and ulna), Boney structures (anconeal process (ulna) Olecranon/ulnar fossa (humerous))
  49. Elbow Joint Movement (Humerus- radius & ulna)
    • Between humerus- radius & Ulna
    • Limited to flexion and extension
    • Ulna acts as lever
    • Elbow extensors insert into olecranon (avulsion possible)
  50. Elbow joint Movement (radius and ulna)
    • Rotation possible
    • annular ligament
    • interosseous ligament
    • fibrous joint distally (pronation= face down, Supination= face up)
    • dogs= rotation limited
    • cats= large amount rotation eg. climb trees!
  51. Elbow Joint Clinical Considerations
    • Elbow dysplasia
    • OCD
    • ununited anconeal process
    • fragmented medial coronoid process
    • elbow incongruity
    • DJD
  52. Elbow Joint Muscles Extensors (triceps):
    • Triceps Muscle (long head): O- caudal border scapula
    • (lateral head): O- Lateral aspect humerus (only part that effects shoulder)
    • (Medial head): O- Medial aspect humerus
    • (accessory head)
    • Radial nerve supply
  53. Elbow Joint Muscles Flexors
    • Triceps muscle
    • Biceps brachii (O- supraglenoid tubercle, I- Proximal radius) Musculocutaneous nerve
    • Brachialis muscle (O- caudal aspect humerus, I- proximal radius) follows musculospiral/brachial groove, musculocutaneous never supply
  54. Elbow Joint Muscles Rotators
    • Supinator Muscle (O- lateral epicondyle) radial nerve
    • Pronator teres muscle (O- medial epicondyle) median nerve
    • I- proximal radius
  55. Elbow Joint Muscle Clinical Considerations
    • Dissect between muscles (rather than cutting them)= less damage= faster healing
    • Proximal humerus: dissect between brachiocephalicus and deltoideus
    • Midshaft: between brachiocehpalicus and brachialis
    • distal humerus: between brachialis and triceps
  56. Forelimb Blood Supply
    • Limb naturally in extended position
    • blood vessels cross flexor aspects of joints (avoids stretching of vessels)
    • arterial supply (oxygenated blood from heart to peripheral tissues, major vessel runs down limb, changes name according to region)
  57. Forelimb Arterial Supply
    • Subclavial artery: runs round 1st rib- axila
    • Axillary arter: runs through axilla
    • Brachial artery: runs down brachium, branches
    • Branches into: Median artery: runs down medial aspect antebrachium, branches- radial artery, terminates in superfical palmar arch, (superficial palmar arch, palmar common digital arteries)
    • superficial brachial artery: runs down cranial aspect antebrachium (superficial dorsal supply, dorsal common digital arteries)
    • Radial artery: deep palmar arch, palmar metacarpal arteries, ddeep dorsal supply, dorsal metacarpal arteries.
  58. Forelimb arterial supply (arterial supply to digit)
    • 4 vessels per digit
    • palmar supply most important
    • axial palmar proper digital A largest
    • implications when wmputating toes
  59. Forelimb Venous Drainage
    • Veins- take deoxygenated blood back to heart
    • deep system: follows arterial supply
    • superficial system: cephalic vein, drains into jugular vein/vena cava
  60. Cephalic vain- clinical considerations
    • access to systemic circulation
    • pressure to raise vein
    • valves allow blood to pool
    • reslease pressure before inject
    • fluid enter vein not SQ tissues!!
    • radial nerve runs alongside it- providing cutaneous sensation to cranial aspect of forelimb
    • pain and necrosis...
  61. Carpus Terminology Changes
    • Composed of Carpal bones
    • short bones
    • no medullary cavity
    • centre= cancellous bone
    • Proximal, distal
    • dorsal, palmar
  62. Carpus Proximal row:
    • Radial/Intermediate carpal bone (fused) (RCB)
    • Ulnar carpal bone (UCB)
    • Accessory Carpal bone (ACB)
  63. Carpus Distal Row Bones
    • 1st carpal bone
    • 2nd carpal bone
    • 3rd carpal bone
    • 4th carpal bone
  64. Carpus development
    • single centre of ossification
    • except: accessory carpal bone= 2 on all species
    • fused radial/intermedial carpal bone=2 due to origin
  65. Carpal Joints (3)
    • Antebrachio-carpal joint: between antebrachium and carpus (radius- RCB & UCB) (Ulna- (UCB & ACB)
    • Middle carpal joint: proximal and distal rows
    • Carpo-metacarpal joint: distal row and metacarpal bones
    • (Intercarpal joints- vertical)
  66. Carpal joints- movement
    • Standing= extension
    • Large range of flexion: most moevement antebrachio-carpal joint, least carpo-metacarpal joint, some between bones)
    • ACB acts as lever for distal limb: insertion of some major carpal flexor, counteracting by palmar ligament
  67. Carpal Joint Support
    • Typical Synovial joint: single joint capsule extending proximally between radius and ulna, distally between metacarpal bones- poor communication between compartments)
    • Collateral ligaments: Lateral- ulna (lateral styloid process) to 5th metacarpal bone, Medial radius (medial styloid process) to 2nd metacarpal bone
    • Styloid processes vulnerable
    • Intracarpal ligaments
    • Palmar aspect: Fibrocartilagenous reinforcement (friction free, passive maintenance of joint extension, prevention of collapse)
    • Retinaculum= sleeve of deep fascia
    • Dorsal retinaculum: dorsal survace, jumps from bone to bone, allows flexion, forms transverse ligaments to hold tendons
    • Palmar/flexor retinaculum: runs down caudal surface, attaches to lateral aspect accessory carpal bone, crosses from ACB to medial aspect carpus, forms carpal canal
  68. Carpal Canal
    • Dorsal boundary: Fibrocartilagenous reingorcement of palmar aspect of carpal joint capsule
    • Lateral Boundary: ACB
    • Palmar boundary: Palmar/Flexor retinaculum

    Dog: Deep digital flexor tendon through tunnel, blood vessels and nerves, suprficial digital fleor tendon outside
  69. Carpus= Palpation
    • Accesory carpal bone
    • joint spaces (flexion)
    • medial stylid process (radius)
    • lateral styloid process (ulna)
  70. Manus
    • Dogs and Cats= digitigrade (bear weight on digits)
    • 4 weight bearing and 1 vestigial
    • numbered medial to lateral
    • Digit: proximal phalanx, middle phalanx, distal phalanx, sesamoids
  71. 1st digit= dew claw
    • Vestigial
    • medial aspect
    • non-weight bearing
    • has 3 elements (debate as to which is missing)
    • commonly removed in puppies
  72. Metacarpus
    • four metacarpal bones
    • long bones
    • convex dorsal surface
    • base=poximal end (forms carpo-metacarpal joint)
    • body= midshaft
    • head= distal end
    • raiesd sagittal ridge- extends to palmar aspect
  73. Digit (proximal and middle phalanx)
    • Proximal Phalanx (PP): long bone, sagittal groves at both ends
    • Middle Phalanx (MP): Long bone, proximal sagittal ridge, distal- sagittal groove
  74. Digit (distal phalanx)
    • Long bone debate
    • ungual process
    • ungual crest (round root of claw, very vascular)
    • extensor process (extensor tendons)
    • palmar process (flexor tendons)
  75. Metacarpus Sesamoid Bones
    • Metacarpo-phalangeal joint
    • 2 x proximal sesamoids: palmar aspect, either side of sagittal ridge, protect flexor tendons
    • 1 x dorsal sesamoid: protect extensor tendons
  76. Manus Development
    • MC(2) body and distal end
    • PP (2) Body and Proximal end
    • MP (2) Body and proximal end
    • DP (1)
  77. Joints of Manus
    • Metacarpo-phalangeal joint
    • Proximal Interphalangeal Joint
    • Dipstal interphalangeal joint
    • All typical synovial joints
    • flexion and extension
    • stability: collateral ligaments, sagittal ridge/groove
  78. Metacarpo-phalangeal joint
    • Resting position= extended
    • interosseous muscle and proximal sesamoids
    • sling configuration suspends Metacarpo-phalangeal joint
    • supported by metacarpal foot pad
  79. Distal Inter-Phalangeal Joint
    • Deep Digital Flexor Tendon
    • Common Digital extensory tendon
    • Dorsal elastic ligament (proximal end MP, extensor process DP)
    • Dog: forces balanced to maintain tip of claw above horizon problem if DDFT is severed
    • Cat: claws not visible- very strong dorsal elastic ligament, DIP joint hyperextended, claw rests in skin fold/sheath- not visible- remain sharp for hunting/climbing (to expose DDFT flexes joint, or manual pressure to digital pad)
  80. Muscles of Antebrachium
    • Affect joints of carpus and digits
    • muscle belly- antebracium
    • tendon of insertion- distal to carpus
    • extensors of distal limb: originate lateral epicondyle of humerus, run over dorsal aspect carpus, radial nerve
    • flexors of distal limb: originate medial epicondyle, run over palmar aspect carpus, median and ulnar nerves
  81. Extension of carpus
    • origin= lateral epicondyle, radial nerve
    • extensor arpi radialis muscle (I= metacarpal bones)
    • Abductor pollicus longus/Extrnsor carpi obliquus muscle: crosses at level of carpus- useful land mark, sesamoid in tendon of insertion
    • extensor carpi ulnaris/ulnaris lateralis muscle (I= 5th metacarpal bone and Accessory carpal bone
    • flexion or extension depending on position of limb
  82. Extension of carpus and digits
    • origin= lateral epicondyle, radial nerve
    • common digital extensor muscle (I= all digits), distal phalanx- extensor process, brances to all digits
    • lateral digital extensor muscle (I= 4th and 5th digits) distal phalanx- extensor process (lateral digits only)
  83. Flexion of Carpus
    • Origin= medial epicondyle, median and Ulnar nerves
    • Flexor Carpi Ulnaris muscle (O= olecranon, I= ACB 2 heads)
    • Flexor Carpi radialis muscle (I= metacarpal Bones)
  84. Flexion of carpus and digits
    • origin= medial epicondyle, median and ulnar nerves
    • Superficial digital flexor muscles (I= all digits (middle phalanx)) runs outwith carpal canal
    • deep digital flexor muscle (O- also radial and ulnar heads, I= All digits) distal phalanx- palmar process, tendon runs through carpal canal passes through SDFT
  85. Footpads
    • Carpal/stopper pad
    • metacarpad pad x 1
    • Digital pads x 4
    • functions: resistanct to trauma/wear & tear, traction, anti-concussive, protect deep structures, dupport digit
  86. Skin (Epidermis/dermis)
    • Epidermis: cells constantly produced by germinative later, cells age as move outwards, dead at surfact and slough, constant replacement, no blood supply, no nerve supply, insensitive and no bleeding
    • dermis: blood supply, nerve supply, sensitive and bleeds, supports germinative layer- active production of skin celss
  87. Footpad modifications
    Trauma resistance: increased skin thickness, increased turnover of cells, deposition of keratin, rough surface, sweat glands, variable amounts pigmentation
  88. Footpad components
    • Skin (epidermis, germinative layer, dermis)
    • superficial fascia
    • Digital cushion (fibrous tissue, elastic tissue, fat, vascular channels)
    • Function= shock absorption
  89. Footpad clinical considerations
    • Wounds (elastic tissue and vascular channels)
    • sweat (bandaging)
    • DDFT (stubbed toe)
  90. Claw
    • No superficial fascia
    • dermis (fused directly to periosteum of ungual process of DP)
    • germinative layer (active in 2 areas only)
    • epiermis (heavily keratinised= horn)
    • stratum tectorum (waterproof surface layer, produced by skin in ungual recesses)
  91. Germinative areas of Claw
    • Area 1: recess between claw and skin, horn grows over dorsal and lateral surfaces of ungual process, horse-shoe shaped in transverse section/short axis
    • area 2: palmar surface of ungual process, horn covers palmar surface
  92. Normal claw/growth
    • Tip touches ground
    • position maintained by dorsal elastic ligament, extensor tendons, balanced by DDFT
    • continuous growth
    • tips wear naturally
    • reduced wear (not walking, walking on soft ground, dew claw, DDFT damage)
    • Claw grows in circular fashion (can eventually grow into pad)
  93. Claw clinical considerations
    • Horn= epidermis (insensitive so can cut)
    • Dermis= contains blood and nerve supply- don't cut too far!
    • Non-pigmented claws (easier to clip)
    • Cats:
    • Pressure on pad- unsheath claw
  94. Lymphatic system/cardiovascular system
    Cardiovascular system: continuous system, leaky capillary bed, exchange of material (eg. fluid, protein), net loss, fluid accumulation (edema and swelling in peripheral tissues)
  95. Lymphatic system (basics)
    • Rocovery/scavenging system
    • series of individual vessels
    • thin walled
    • run from periphery to thoracic duct
    • thoracic duct empties into caudal vena cava
    • transports lost material back into systemic circulation
  96. Lymphatic system (lymph nodes)
    • Filters
    • located where lymph vessels converge
    • prevent contaminants reaching systemic circulation
    • remove invading organisms/bacteria
    • contain defence cells
    • forelimb lymph nodes (prescapular, axullary)
    • enlarge in response to infection
    • can use to differentiate between localised/generalised dz
    • important in large animals for meat inspection
  97. Nervous system- brachial plexus
    • Supplies:
    • Selected extrinsic muscles: pectoral, latissimus dorsi, serratus ventralis
    • all intrinsic muscles: subscapular nerve, suprascapular nerve, musculocutaneous nerve, axillary nerve, radial nerve, median and ulnar nerve
  98. Subscapular/suprascapuar nerves
    • Motor nerves only- no cutaneous sensation
    • subscapular nerve: medial shoulder support, subscapularis muscle
    • suprascpular nerve: laterl shoulder support, supraspinatous muscle, infraspinatous muscle
  99. Musculocutaneous nerve
    • Mixed Nerve
    • Sensory: cutaneous sensation to: cranial and medial aspect of elbow, medial aspect of antebrachium (see notes)
    • motor: elbow flexors (brachialis muscle, bicesps brachii muscle)
    • damage (no compensation- loss of elbow flexion)
  100. Axillary nerve
    • Mixed nerve
    • Sensory fibres: cutaneous sensation to: lateral aspects shoulder and brachium
    • motor supply: dedicated shoulder flexors (deltoideus muscle, teres major muscle)
    • damage: compensation by latissimus dorsi, long head triceps
  101. Median and Ulnar Nerves
    • Mixed Nerves
    • Sensory Fibres, cutaneous sensation to: caudal and palmar aspect limb, dorsal aspect 5th digit
    • motor supply: carpal and digital flexors (flexor carpi ulnaris muscle, flexor carpi radialis muscle, superficial digital flexor muscle, deep digital flexor muscle)
    • damage- no compensation- loss of distal limb flexion
  102. Radial Nerve
    • Mixed Nerve
    • sensory fibres, cutaneous sensation to: dorsal and cranial aspect limb except dorsal aspect 5th digit
    • motor supply: extensors of elbow (triceps muscle), extensors of carpus and digits (extensor carpi radialis, extensor carpi ulnaris, common digital extensor muscle, lateral digital extensor)
  103. Radial nerve route
    • Starts medial, passes caudal to shoulder, passes through triceps (supplies triceps)
    • follows musculospiral grove (and brachialis muscle)
    • branch- lateral epicondyle (supplies distal limb extensors)
    • branch- cranial/dorsal aspect limb (runs alongside cephalic vein, supplies cutaneous sensation)
    • Humeral fx most common cause of damage
    • deficits depend on level of damage
  104. Radial nerve damage motor losses
    • Proximal level:
    • all extensor muscles affected
    • cannot extend elbow, carpus, or digits
    • cannot weight bear
    • limb appears longer than opposite one
    • Distal Level:
    • Extensors of carpus and digits affected
    • cannot extend carpus/ digits
    • Triceps intact: can extend elbow, can weight bear if limb extended, can learn to swing leg to compensate
  105. Radial nerve damage sensory losses
    • Cranial and dorsal aspect limb
    • trauma to dorsal aspect paw if drags
    • self mutilation
    • check sensation using forceps
    • check pre-op humeral fracture repair so cannot be blamed
  106. Brachial plexus damage
    • Tear/avulsion= stretching: high imact collision, head/neck one direction- limb the other, variable degrees of damage, regeneration possible with time, mismatching may result in aberrant sensation
    • turnover- effects depend on which nerves affected
    • effect on limb: can protract/abduct limb
    • cannot retract/adduct limb
    • cannot extend/flex limb
    • cannot weight bear
    • no cutaneous sensation on limb or lateral thorax to level of 3rd intercostal space