forelimb Flashcards
superior, inferior, anterior, posterior
superior = dorsal
inferior = ventral
anterior = cranial = cephalic
posterior = caudal
internal vs external
internal = deep = away from body surface
external = superficial = towards body surface
proximal + distal
toward/away from main mass of body
visceral + parietal
related to internal organs
related to body walls
articular vs non-articular bone features
articular = form joints w corresponding articular areas other bones
non-articular = serve for attachment muscle, ligament, tendon, fascia
fascia
sheet CT covering all organs in bod to provide support
head
of bone
round, smooth, v convex articular projecting process
* on end long bones, e.g. humerus, femur
condyle
smooth, convex, protruding articular projection at extermities long bones
facet
small, smooth articular surface
* flat, concave or convex
epicondyle
small, roughened non-articular projection above condyle
* usually attachment site musc + ligaments
process
vague name for non-articulating prominence
trochanter
specialised term for few blunt projection tuberosities on femur
* non-articulating
tubercle + tuberosity
both rounded, roughened non-articular processes
* attachment pts for ligaments/tendons
* sometimes interchangeable but tubercle usually larger/more prominent
crest
prominent linear sharp border/ridge
* non-articular prominence
line
less prominent faint ridge - a baby crest
* non-articular prominence
spine
sharp, slender process/elongated thin shelf-like projection
* non-articular prominence
neck
constricted attachment bet articulating head + shaft of bone - non-articular
fovea
small non-articular pit-like depression
* provide area for passage bvs/soft tiss
fossa
large non-articular basin depression
* provide area for passage bvs/soft tiss
notch
non-articular depression - C/U shaped
* area for passage bvs/soft tiss
groove = sulcus
furrow-like opening to accomodate soft tiss structures (bvs, nerves, tendons)
* non-articular depression
acetabulum
smooth, deep, articular depression
trochlea
pulley-like articular structure
cochlea
articular surface reciprocal to trochlea
glenoid cavity
smooth, shallow articular depression
foramen
hole/opening in bone for transmission bvs + nerves
sinus
large air-filled cavity w/in bone
* lined w mucous mem
* communicates w exterior (can secrete mucous for IS)
canal
foramen that extends through bone to make tube-like passageway
* passage bvs + nerves
fissure
narrow, slit-like opening bet adjacent parts bone
* bvs + nerves pass through
flexion + extension
decr + incr angle at joint
adduction vs abduction
move limb closer to/further from midline
add = closer
depression + elevation
refers to head: downward vs upward movement
supination vs pronation
supination = turning forearm/palm upwards
pronation = downwards
inversion + eversion
rotation plantar (sole) aspect internally/externally
external/internal rotation
rotate bone externally/internally around longitudinal axis
protraction + retraction
protraction = moving limb forwards
retraction = moving limb backwards/fixing limb + moving trunk forward relative
stride
+ how used incr speed
1 cycle limb movement at particular gait
* incr by incr stride length (by incr limb length anatomically or physiologically - more extension/flexion) or stride rate (decr limb mass, esp distally)
* length + rate antagonistic - incr 1 = other decr
how incr stride rate
- conc musculature proximally
- decr no. digits
- elongate distal, less massive segments limb (for incr stride length, as opposed proximal)
- physiologically: flex limb in protraction - more flexion the faster you go
role of forelimb + so anatomical features
- carry more static weight
- maximise gait efficiency by minimising up/down E expenditure = ligaments absorb KE of downward movement + store it as potentially E when stretched then rebound + E -> upward KE = thorax elevated w minimal musc movement
- shorter + straighter than hindlimb
- connected to trunk just by musc + ligament
- broader rounder hoof (horse)
forelimbs = thoracic limbs
role + general anatomical features hindlimb
motors of locomotion = drive trunk forward + propel body up
* longer + more angular
* osseus articulation to axial skeleton
* hip, stifle + hock can all extend at once
* narrower pointier hoof (horse)
hindlimbs = pelvic limbs
overarching limb diffs carnivores + herbivores
carnivores = limbs for running + manipulation (prey, fighting) so specialisation limited
* unguis not used locomotion so available as tool/weapon
* smaller intestinal mass = flexible trunk + spine = limbs can swing more = incr stride length = faster
* flexed + extended suspension phases (when lose contact w ground)
horses need continual grazing = ligament structures to allow prolonged standing w lil expenditure musc E
* just flexed suspension phase
locomotor sys
muscoskeletal sys that allows wide range animal movement
* bones (osteology) - rigid support
* joints (arthrology) - allow movement be bones
* musc (myology) - prods movement bet bones
cursorial meaning
animal w ability run fast (cheetah) or keep constant speed long distance
cursorial adaptations locomotor sys
- reduced pectoral skeleton - no/vestigial clavicle = no skeletal attachment bet forelimb + trunk = just muscular joint = free more caudal/cranial movement = incr stride length
- chest cavity compressed laterally (-> deep + narrow) = unrestricted movement limbs back + forth = incr stride length
- elongation at proximal end limb - scapula lies laterally = incr stride length
- elongation at distal end limb - long metacarpals + walk on toes/hooves = incr stride length
- brachium v muscular + relatively short = limb mass proximal = incr stride rate
- conversion musc -> ligament = decr mass + reliance on passive mechanics
- reduction digits in manus - stability over dexterity
- radius more dominant bone in antebrachium - stability over rotation for manipulation
incr stride length = run faster
digitigrade, unguligrade, plantigrade
digitigrade = ground contact made w digits w heel always up
unguligrade = ground contact made w hoof w carpus always raised
plantigrade = walking w heel (plantar side foot) on ground
synsarcosis
purely muscular joining bet parts skeleton
shoulder joint fancy name
omothoracic junction
gait
sequence limb movements
walk
as a gait
4 beat gait:
each limb moves forward individually + hits ground sep
sequential
slowest
trot
as a gait
diagonal gait = 2 beat gait
2 limbs hit ground simultaneously
2nd slowest
canter
as a gait
3 beat w one period suspension
L lead: RH, LH + RF, LF
R lead: LH, RH + LF, RF
gallop
as a gait
4 beat gait
L lead: RH, LH, RF, LF
R lead: LH, RH, LF, RF
division bod into 2 skeletons
axial = vertebral column, skull + ribcage
appendicular = limbs
bone types
- flat - large SA for musc attachment + protect underlying structures
- long - support bodyweight + allow movement
- short - large range movement (small but working together) + anti-concussive (== shock absorbing)
- sesamoid embedded in tendons in joints
* allow wide range movement
* redirect forces
* reduce friction to prevent damage
some others irregular for function, e.g. vertebrae
smooth vs rough SAs of bones
smooth = passage structures/tendons + articular surfaces
rough = musc attachment
features of articular surfaces
- hyaline cartilage covering if weight-bearing surface
- resistant deformation
- no bvs or nerves
- no periosteum
periosteum is + why
covers outer surface bone (except articular surfaces) + conts bvs/nerves
* important for fracture healing
* enters medullary cavity via nutrient foramen
how does bone form from embryo v simple
embryonic mesenchymal cells -> cartilagenous matrix
then mesenchymal -> osteoblasts
cartilage calcifies
how many ossification centres diff bones
short + sesamoid = 1 per bone
flat + long = >1
attachment sites for important may have more than one
how to identify physis/growth plate radiograph
cartilage bet bones appears black
how identify young vs old
young = open physes for incr bone length
mature = closed = physeal scars
diff ones close diff times depending on contrib to length = estimate age
most likely pts damage on bones animals diff ages
adults = shaft weakest pt so fractures
young = growth plate weakest - damage/separation (can cause premature closure)
tendon vs ligament
tendon = musc-bone
ligament = bone-bone
general structure sk musc
individual musc fibres arranged parallel lines collected in bundles covered by fibrous tiss (= deep fascia)
* attached rigid structures, usually bone
origin usually proximal
insertion usually distal
aponeurosis
thin flat sheet CT connect musc to bone when no space for tendon to attach
diff ways sk musc attaches to bone
- directly to bone on rough surface
- via tendon = condensation deep fascia into cords w smaller area attachment (= less bulky across joints)
- via aponeurosis if limited access to bone = condensation deep fascia into sheets (fibrous) - long attachment area
superficial fascia = subcut loose CT attaching skin-musc
overall musc action w part names
belly contracts + shortens = pts attachment drawn closer together
* pivots at joint to decr/incr angle of joint
* antagonistic pairs have opposite action, i.e. flexor + extensor of any given joint
description of sides of joint
flexor + extensor aspects where angle decr/incr
intrinsic vs extrinsic sk musc
INTRINSIC = origin + insertion w/in appendicular skeleton, moving limb joints - flexion + extension
EXTRINSIC = origin on axial, insertion on appendicular, movement limb relative to trunk - protraction/retraction
pivotal point
= PP
midway down scapula - pt around which it rotates + glides over thorax
regions of forelimb
- omo (shoulder) - scapula (+ clavicle in cats)
- brachium - humerus
- antebrachium - radius + ulna
- carpus - cluster small carpal bones
- manus - metacarpal bones
- digit - phalanges
structure scapula
lateral + medial - dog (reference pt)
glenoid cavity
smooth concave articular surface for attachment humerus in shoulder joint
superaglenoid tubercle
attachment biceps brachii musc
serrated face on proximal medial aspect scapula
where serratus ventralis attaches
where does subscapularis musc originate
lower 2/3 subscapular fossa
how is cat scapula diff to dog
- more rounded cranial angle
- suprahamate process = extra extension of spine to allow attachment musc
- vestigial clavicle
centres of ossification scapula
- body
- supraglenoid tubercle
= growth plates visible as line black on readiograph if young
how to find scapula
can palpate:
* dorsal border
* cranial border
* cranial angle
* spine
* acromion
caudal border beneath musc so difficult
extrinsic muscs of forearm
- brachiocephalic
- omotransversarius
- latissimus dorsi
- serratus ventralis
- trapezius
- rhomboideus
- pectoral
brachiocephalic musc
origin: cervico-thoracic fascia that sits on top whole neck region
insertion: humerus (aponeurosis)
protractor - acts across shoulder (also extensor)
3 parts:
1. Cleidocepahlicus = Cleidocervicalis (caudal) + Cleidomastoideus (cranial) - cervical + accessory nerves
3. Cleidobrachialis - distal - axillary nerve
omotransversarius
origin: transverse processes of 1st vertebra C1)
insertion: acromion process
protractor (+ flexes neck laterally)
innervated by accessory nerve
latissimus dorsi musc
origin: thoracolumbar fascia
insertion: humerus (aponeurosis) on teres major tuberosity
retractor - propulsion, + shoulder joint flexor
innervated by thoracodorsal nerve
serratus ventralis musc
origin: thoracic wall (ribs) + cervical vertebrae (neck)
insertion: proximal scapula - medial aspect, proximal to PP (facies serrata)
cranial part = RETRACTOR
caudal part = PROTRACTOR
bc inserts on proximal scapula
* cranial pulls dorsal side cranial so ventral side -> caudal = limb backward
* caudal pulls dorsal side caudal = ventral end cranial = limb forward
INNERVATED cervical nerves + long thoracic nerve
no effect on shoulder, also supports limb + involved inspiration
where would abductor + adductor muscs insert on scapula
abductors located proximal to PP + limb
adductors located distal to PP + medial to limb
Trapezius musc
origin: cervicothoracic fascia
insertion: proximal scapular spine
only abduction (no effect shoulder)
cranial + caudal part
innervation = accessory nerve
rhomboideus muscle
origin: cervicothoracic fascia
insertion: dorsal border scapula
abductor
innervated thoracic + cervical nerves
lies deep to trapezius
pectoral muscles
origin: sternum
insertion: humerus
2 heads: deep + superficial
adductor
superficial pectoral
cranial end sturnum -> major tubercle of humerus
adductor
inn: cranial pectoral nerve
deep pectoral musc
originates entire length sternum -> insert minor tubercle humerus
retractor AND adductor
inn: caudal pectoral nerve
larger than superficial pectoral
intrinsic muscs
origin + insertion w/in appendicular skeleton + no effect on limb relative to trunk
* only flexion + extension to move joints w/in limb
humerus structure proximal end
lateral + medial views
- head articulates w glenoid cavity of scapula at shoulder joint
- intertubercular groove = smooth where tendon of origin biceps brachii musc passes
long bone
distal end humerus structure
- medial epicondyle larger than lateral - on either side condyle
- condyle = articular surface for elbow joint, split:
1. trochlea = larger w central depression + articulates w radius + ulna
2. capitulum = lateral + articulates w radius - nothing through foramen + may not be in short-legged dogs
how is humerus cat different to dog
- no supratrochlear foramen
- supracondyloid foramen thru which pass brachial artery + median nerve
supracondyloid foramen vulnerable fractures
centres ossification humerus
- proximal epiphyses
- body
- medial epicondyle
- medial half condyle
- lateral half condyle
how is humerus situated
palpable landmarks humerus
- greater tubercle
- lateral epicondyle
- medial epicondyle
clinical considerations for humerus
- supratrochlear foramen = weak pt
- medial 1/2 condyle larger than lateral 1/2 so lateral more common fracture
somites in embryo giving rise sk musc
segmental axial structures
1. blocks musc tiss develop in pairs alongside spinal cord
2. grp combine form each forelimb
3. move + drag nerves w
4. so nerve supply reflects origin musc tiss
spinal nerves -> forelimb
- leave spinal cord thru intervertebral foramen
- paired L + R
- branches (dorsal supply dorsal structures)
- ventral branches from C6, C7, C8, T1, T2 form brachial plexus in axillary region
- emerging nerves supply forelimb
nerve numbered as vertebra it is just cranial to, e.g. C6 = just cranial to cervical vertebra 6 (-> thoracic -> lumbar)
nerves supplying forelimb
- ulnar
- radial
- median
- axillary
- musculocutaneous
proprioception
location of limb in space
mxed nerves
consist motor + sensory fibres = transmit messages both directions at once
* spinal reflexes - rapid involuntary responses mediated by spinal cord w/o input from brain
which of forelimb extrinsic muscs does brachial plexus supply
- latissimus dorsi
- serratus ventralis
- pectorals
not brachiocephalicus, trapezius, rhomboideus
supplies all intrinsic muscs of forelimb
types joint
- fibrous - v lil movement, e.g. skull sutures + syndesmosis (radius + ulna)
- cartilagenous - slightly more movement but lil, e.g. pelvic symphysis
- synovial
synovial joint
for large range motion bet bones = most limb joints w:
1. hyaline cartilage covering articular surfaces reduce friction + make flexible - avascular + no nerves
2. viscous synovial fluid to nourish cartilage (bc no bvs) + lubricate
3. synovial mem to prod fluid + physical barrier to contain it
4. joint capsule = fibrous layer incorping mem, attaching around osteochondral junction
why does hyaline cartilage in synovial joint have no nerve supply
would be painful when press applied (always)
structure + role ligaments
fibrous mat condenses to form = dense fibrous CT
* medial + lateral collateral ligaments support joint + hold bones together + restrict movement bet bones
flexion vs extension in terms weight bearing
flexion = non weight-bearing position, extension associated w weight bearing
components shoulder joint
concave glenoid cavity scapula + convex head humerus -> ball + socket joint
* palpable acromion process + greater tubercle
* glenohumeral ligaments v weak + poorly developed
bicipital bursa
extension joint capsule into intertubercular groove
* joint capsule extends round tendon of origin Biceps brachii - protects
* held in place by transverse ligament
arthrogram
radiograph where contrast agent was injected into joint
Supraspinatus musc
origin: supraspinous fossa
insertion: greater tubercle humerus
function: lateral support joint + extensor
innervation: suprascapular nerve
infraspinatus musc
origin: infraspinous fossa
insertion: distal to greater tubercle
function: lateral support joint + abductor + both flex + extend shoulder depending limb position
nerve supply: suprascapular nerve - motor fibres only
subscapularis musc
origin: subscapular fossa
insertion: lesser tubercle humerus
function: medial support shoulder joint, extensor + adductor
nerve supply: subscapular nerve - motor fibres only
biceps brachii musc
origin: supraglenoid tubercle
insertion: proximal radial tuberosity + ulna tuberosity (2 tendons) = on proximal medial aspects of bones
function: shoulder joint extensor, elbow flexor
nerve supply: musculocutaneous nerve - motor only
1 head in dog, starts w long tendon, runs craniomedially down brachium
Teres Major
origin: caudal border scapula
insertion: medial humerus (Teres major tuberosity)
function: shoulder joint flexor
nerve supply: axillary nerve - motor + sensory fibres
where do shoulder flexors + extensors cross joint
extensors cross cranial to joint
flexors cross caudal
Teres Minor
origin: distal1/3 caudal edge scapula
insertion: tuberosity teres minor in middle lateral humerus (proximal to deltoid tuberosity
function: shoulder joint flexor
crosses over flexor side joint
innervation: axillary nerve
deltoideus musc
2 heads:
origins: scapular spine (1) + acromion process (2)
insertion: lateral aspect humerus (deltoid tuberosity)
function: shoulder joint flexor
nerve supply: axillary nerve - mixed
sits on top of infraspinatus musc (wide aponeurosis)
triceps musc
from shoulder joint perspective
4 heads, only ‘long head’ relates shoulder joint
origin: caudal border scapula
insertion: olecranon of ulna (common tendon)
function: shoulder joint flexor + elbow extensor
nerve supply: radial nerve - motor + sensory fibres
radius + ulna respective roles
paired long bones that cross each other obliquely
* ulna = longer, acts as lever
* radius = shorter, main weight bearing
radius structure
styloid process = attachment medial collateral ligament of carpus
structure ulna
styloid process = attachment lateral collateral ligament of carpus
articulation of radius + ulna
PROXIMAL: head of radius -> radial notch on ulna
* held by annular ligament running lateral to medial coronoid process
* rotation poss
DISTAL: fibrous joint, lil rotation poss
* interosseus ligament
* interosseous space bet bodies
evolution in relation radius + ulna
- toes rotated cranially
- elbows rotated caudally
== ulna + rad rotate around each other
proximal = ulna most medial
distal = ulna most lateral
what can you palpate radius + ulna
ULNA:
* olecranon process
* lateral styloid process
RADIUS:
medial styloid process
how do cat radius + ulna differ
- square olecranon
- radius + ulna similar diameter
elbow joint loads rotation climb + stuff when dogs rotation limited
centres ossification radius
- proximal epiphyses
- body
- distal epiphyses
ulna centres ossification
- olecranon process
- anconeal process
- body
- distal epiphyses (cone shape)
predilection sites osteosarcoma
= primary bone tumour
* proximal humerus
* distal ulna
* distal radius
articulation in elbow joint
- humerus trochlea w trochlear notch ulna + fovea capitis radius
- capitulum humerus w fovea capitis radius
- olecranon fossa humerus w anconeal process ulna
synovial joint w extensive capsule
how is elbow joint made stable
- collateral ligaments
- anconeal process -> ulnar/olecranon fossa
omly flexion/extension + rotation
triceps musc
from elbow joint perspective
4 heads, all insert on olecranon process
1. long head o = caudal border scapula
2. lateral head o = lateral aspect humerus
3. medial head o = medial aspect humerus
4. accessory head o = proximal caudal humerus
function = elbow extensors
nerve supply = radial nerve
visualising triceps heads
long and lateral visible lateral view
accessory underneath
medial visible from medial view
elbow extensors vs flexors
extensors are caudal to joint
flexors are cranial to joint
brachialis musc
origin: caudal humerus
insertion: proximal ulna (ulnar tuberosity)
follows musculospiral/brachial groove
function: elbow flexor
nerve supply: musculocutaneous nerve
coracobrachialis musc
coracoid process of scapula -> minor tubercle humerus
shoulder extensor + adductor + rotates joint outwards
innerv: musculocutaneous
capsular musc of shoulder
anconeus musc
distal 1/3 caudal humerus -> olecranon
elbow extensor
innerv: radial nerve
capsular musc of elbow
tensor fascia antebrachii
origin: latissimus dorsi
insertion: olecranon
broad, flat musc = main tensor of antebrachial fascia
innerv: radial nerve
elbow joint rotator muscles
- supinator: lateral epicondyle -> proximal radius (radial nerve)
- pronator teres: medial epicondyle -> radius, on top (median nerve)
considerations for surgery
accessing humerus
dissect bet muscles, don’t cut them = less damage = faster healing
* proximal: bet brachiocephalicus + deltoideus
* midshaft: bet brachiocephalicus + brachialis
* distal: bet brachialis + triceps
where do bvs run + why
limb naturally extended so bvs cross flexor aspects joints to avoid stretching
also nerves - vein, artery + nerve run together = NV bundle
main arterial supply whole forelimb
1 major vessel running down limb, changing name according region (branches off loads ofc)
1. subclavian 1st rib -> axilla
2. axillary through axilla
3. brachial down brachium
then 3 main branches:
* median down medial aspect antebrachium
* radial terminates superficial palmar arch
* superficial brachial down cranial aspect antebrachium
palmar blood supply
- median artery -> superficial palmar arch -> palmar common digital arteries
- caudal interosseus artery -> deep palmar arch -> palmar common digital arteries
dorsal blood supply
superficial brachial artery -> dorsal common digital arteries + dorsal digital artery
what happens to blood supply at digits
supplies fuse then branch again -> 4 vessels per digit
* palmar supply extensive + most important
* axial palmar supply most important (palmar on side closest trunk)
venous supply forelimb
- deep sys follows arterial supply (VAN) - same names + all
- superficial sys = cephalic vein -> jugular vein/vena cava
radial nerve alongside cephalic vein for cutaneous sensation - injection
carpal bones
proximal row, PR w:
1. radial/intermediate bone (fused) (RCB)
2. ulnar carpal bone (UCB)
3. accessory carpal bone (ACB)
distal row, DR w 1st, 2nd, 3rd, 4th carpal bones
all short bones
carpus centres ossification
each bone single centre ossification except ACB = 2, + fused R/ICB = 2
carpal joints
- antebrachio-carpal joint bet antebrachium + carpus
- middle carpal joint bet PR + DR
- carpo-metacarpal joint bet DR + metacarpal bones
movement carpal joints
large range flexion
* most movement antebrachio-carpal joint
* least in carpo-metacarpal joint
* some bet carpal bones
ACB = insertion major carpal flexor musc
- counteraction by palmar ligament
standing = extension = weight-bearing position
extent carpal synovial joint
joint capsule extends proximally bet radius + ulna + distally bet metacarpal bones
poor comms bet compartments
collateral ligaments carpal joint
lateral = lateral styloid process ulna -> 5th metacarpal bone
medial = medial styloid process radius -> 2nd metacarpal
styloid processes vulnerable (esp lateral) so also intracarpal ligaments
retinaculum
deep fascia sleeve (fibrous CT) enclosing carpal region to support joint from lateral aspect ACB -> medial aspect carpus
at palmar + dorsal surface
carpal canal
tunnel gap bet
* palmar ligament (dorsal)
* ACB (lateral)
* palmar retinaculum (palmar)
deep digital flexor tendon (DDFT), bvs + nerves pass thru
* superficial digital flexor tendon (SDFT) outside in dogs
palmar ligament
fibrocartilagenous reinforcement carpal joint capsule
* = friction-free surface for passage tendons
* passive maintenance joint extension
* prevents collapse into hyperextension
dorsal boundary carpal canal
what can you palpate carpal joint
- ACB
- joint spaces (in flexion)
- medial styloid process radius
- lateral styloid process ulna
components of manus
- 5 metacarpal bones (MC), numbered medial -> lateral
- sesamoid bones
- then digits w proximal (PP, P1), middle (MP, P2) + distal phalanx (DP, P3) (no middle on 1) - long bones
digitigrade = 4 weight bearing - no.1 vestigial
1st digit
= dew claw on medial aspect
* vestigial + non weight bearing
* commonly removed in puppies
centres ossification in manus
MC: body + proximal end
PP: body + proximal end
MP: body + proximal end
DP: body
DP structure
ungual crest v vascular - root of claw
* claw held in place bt CT bet it + bone
debate if long bone
joints w/in manus
- metacarpo-phalangeal (MCP)
- proximal interphalangeal (PIP)
- distal interphalangeal (DIP)
all synovial w extension + flexion
stability joints in manus
- collateral ligaments
- sagittal ridge/groove over MCP on palmar side prevent hyperextension w spring-like mech
MCP joint
- 2 proximal sesamoids on palmar aspect either side sagittal ridge protect flexor tendons
- 1 dorsal sesamoid protect extensor tendons
- supported metacarpal foot pad
- interosseus musc + tendon
resting = extended
attachments DIP
forces balanced to maintain claw tip above horizontal = problem if DDFT severed bc toe too far up = ‘stubbed toe’
differences in cat claws
v strong dorsal elastic ligament = DIP hyperextended = claw in sheath, not visible
* remains sharp for hunting, climbing
manual press on digital pad = DDFT flexes joint = exposed
overall on muscs affecting joints carpus + manus
belly in antebrachium then tendon of insertion distal to carpus
extensors distal limb general facts
origin: lateral epicondyle humerus
run over dorsal aspect carpus
controlled radial nerve - ALL so damage = no extension at all
flexors distal limb general facts
origin: medial epicondyle
run over palmar aspect carpus
median nerve innervates superficial, + ulnar nerve deeper musc
carpus extensors
- extensor carpi radialis
- abductor pollicus longus (= extensor carpi obliquus)
- extensor carpi ulnaris (ulnaris lateralis in ungulates)
- common digital extensor
- lateral digital extensor
carpus flexors
- flexor carpi ulnaris (2 heads)
- flexor carpi radialis
- superficial digital flexor
- deep digital flexor (3 heads)
extensor carpi radialis musc
origin: lateral epicondyle humerus
inserts on metacarpal bones
carpus extensor, elbow flexor
innerv = radial nerve
abductor pollicus longus musc
== extensor carpi obliquus
inserts on proximal end metacarpal 2
* crosses at level of carpus
* sesamoid in tendon of insertion
carpus extensor
extensor carpi ulnaris musc
**= ulnaris lateralis **
origin: lateral epicondyle humerus
inserts on proximal end 5th metacarpal + ACB
flexion/extension carpus depending on limb position
innerv: radial
common digital extensor musc
origin: lateral epicondyle humerus
inserts on all digits - DP on extensor process
extends: carpus + digits II -> V
innerv: radial
lateral digital extensor musc
origin: lateral epicondyle humerus
inserts on DP extensor process digits II, IV + V
digits II, IV + V extensor
innerv: radial
flexor carpi ulnaris musc
origin olecranon asw as epicondyle humerus (2 heads)
insertion ACB
carpus flexor
innerv: ulnar nerve
ulnar head = weaker
flexor carpi radialis musc
origin: medial epicondyle
inserts on palmar aspect metacarpal II + III
innerv: median
carpus flexor
superficial digital flexor musc
origin: medial epicondyle of humerus
inserts on middle phalanx all digits (not I) - palmar proximal
flexor of carpus + digits II, III, IV + V
innerv: median
deep digital flexor musc
3 heads: origin medial epicondyle (strongest) + radial (medial border, weakest) + ulnar (caudal border) heads
inserts on DP all digits (not I) - palmar process
flexor of carpus + digits (not I)
innerv: median nerve
3 heads unite -> strong tendon, thru carpal canal -> splits, insert DPs
pronator quadratus musc
arises on ulna, inserts on radius, filling space bet 2
rotates paw inwards
innerv: median
interossei muscs
- 4 in total from palmar aspect metacarpals II, III, IV + V
- distally each divides into 2 short tendons that attach proximal end P1
- each tendon has sesamoid bone embedded in it
flexion metacarpophalangeal joints
innerv: ulnar nerve
supinator musc
lies lateral on cranial surface elbow
origin: lateral collateral ligament + lateral epicondyle humerus
inerts: cranial surface radius
function: rotate paw so palmar surface medial-facing (supination)
innerv: radial
abductor digiti longus musc
= extensor carpi obliquus in domestics, abductor pollicis longus -horses
origin: craniolateral surface of ulna
inserts: medial proximal metacarpal I/II - small sesamoid near point of insertion
extends carpus + abducts 1st digit
innerv: radial
pronator teres musc
medial epicondyle of humerus -> cranial radius = lies medially on cranial surface of elbow
rotates paw so palmar surface in contact w ground
innerv: median
how do radius + ulna articulate w carpus
radius w R/UCB
ulna w UCB + ACB
footpads where + names
- carpal/stopper pad protects ACB
- metacarpal pad over MCP joint
- 4 digital pads over DIP joints
functions footpads
- resistance trauma/wear + tear
- traction - prevent slipping
- anti-concussive = shock absorption
- protect deep structures (sesamoid bones)
- support digit to allow weight bearing
integumentary sys
epidermis facts
cells constantly proded germinative layer + move outwards as age
* dead at surface + slough
* constant replacement
avascular + no nerve supply
stratified squamous keratinised epithelium
dermis
vascular CT layer w nerve supply
* supports germinative layer epidermis w active production skin cells
how is epidermis of footpad modified
- incr skin thickness
- incr cell turnover = active germinative layer
- deposition lots keratin as hard proteinaceous mat
- rough surface = grip
- lots sweat glands for heat loss (= bandaging tricky)
- hairless
=== trauma resistance
components footpad
digital cushion = fibro-elastic tiss w fat + loads bvs (= v vascular tiss)
* shock absorption
claw structure
- no superficial fascia
- dermis fused periosteum CT of ungual process
- epidermis v keratinised -> horn
- germination active 2 places only
- stratum tectorum = oily waterproof surface layer nourishing + preventing brittle proded by skin in ungual recesses
germinative areas of claw
- recess bet claw + skin -> horn over dorsal + lateral surfaces ungual process (horse-show shape in TS)
- palmar surface ungual process to grow horn over it
how is claw held in place
common digital extensor tendon + dorsal elastic ligament (balanced by deep digital flexor tendon)
* so tip just touches ground
how does claw grow
circular fashion + can grow into pad but wears naturally unless:
* not walking
* walking on soft ground
* dew claw
* DDFT damage -> ‘stubbed toe’
horn = epidermis = insensitive = can cut + wear down (dermis sensitive)
lymph nodes role
filters where lymph vessels converge
* prevent contaminants reaching systemic circulation, removing invading orgs like bac
* contain defence cells
which muscles/nerves does brachial plexus supply
extrinsic: pectoral, latissimus dorsi, serratus ventralis
all intrinsic forelimb muscs:
* subscapular nerve -> subscapularis
* suprascapular nerve -> supraspinatus + infraspinatus
* musculocutaneous nerve -> BBC
* axillary nerve -> all on antebrachial (= shoulder flexors)
* radial nerve -> extensors of elbow, carpus, digits
* median + ulnar nerves -> flexors carpus + digits
BBC = biceps brachii, brachialis, coracobrachialis
subscapular nerve
- motor only (no cutaneous sensation)
- only innervates subscapularis musc = medial shoulder support
suprascapular nerve
motor only (no cutaneous sensation)
-> supraspinatus + infraspinatus = lateral shoulder support
musculocutaneous nerve
cutaneous sensation:
* cranial + medial aspect elbow
* medial aspect antebrachium
motor = elbow flexors (BBC):
* brachialis
* biceps brachii
* coracobrachialis
damage = no compensation = no elbow flexion
axillary nerve
sensory fibres to:
lateral aspect shoulder + brachium
motor = shoulder flexors:
* deltoideus
* teres major
damage = compensation by latissimus dorsi + long head triceps
median + ulnar nerve
cutaneous sensation:
* caudal + palmar aspect limb
* dorsal aspect 5th digit
motor = carpal + digital flexors:
* flexor carpi ulnaris
* flexor carpi radialis
* superficial digital flexor
* deep digital flexor
damage = no compensation = no flexion distal limb
radial nerve
sensory fibres:
* dorsal + cranial aspect limb
* EXCEPT dorsal 5th digit
motor = extensors elbow (triceps) + extensors carpus + digits:
* extensor carpi radialis
* extensor carpi ulnaris/ulnaris lateralis
* common digital extensor
* lateral digital extensor
proximal damage = no elbow or carpus, distal = elbow ye carpus/digits no
route of radial nerve
- medial
- caudal to shoulder
- thru triceps
- follows musculospiral groove + brachialis musc
branch -> lateral epicondyle supplies distal limb extenders
branch -> cranial/dorsal aspect limb alongside cephalic vein for cutaneous
humeral fracture most common cause damage
causes brachial plexus damage
- tear bc stretched - head + neck one way, limb other
- high impact collision
- tumours
poss regen
effect on limb of brachial plexus damage
- can protract/abduct
- can’t retract/adduct
- can’t extend/flex
- can’t weight bear
- no cutaneous sensation on limb/lateral thorax -> 3rd intercostal space
quite protected by scapula tho
which cutaneous areas are innervated by which nerves
Origin vs insertion of musc
origin end music usually fixed in place - attachment site static during contraction
insertion attachment site moves as musc contracts
insertion usually distal end, origin proximal
Vein setup
2 sets:
1. Deep - follow path of arteries
2. Superficial - run just under skin, mainly involved thermoregulation
proximal veins w paths
- cephalic - up cranial aspect then proximally runs deep to brachiocephalicus + joins jugular
- axillobrachial runs bet cephalic + axillary veins at shoulder
- omobrachial from axillobrachial -> cephalic
pronator quadratus
fills interosseus space bet radius + ulna
* pronator of limb
describe artery path
- right brachial enters antebrachium, gives off common interosseus
- rb continues as median into manus
- interosseus gives 3 branches: ulnar, cranial interosseus + caudal interosseus
caudal interosseus runs in interosseus space bet ulna + radius = protected blood source to manus
general differences horse forelimb
- unguligrade - weight-bearing DP 3rd digit
- same bones, joints, muscs
- manus expanded - metacarpal bones long to incr limb length = incr stride length
- 2nd + 4th metacarpals v reduced
extra vestigial structures horse
- chestnut = vestigial toe over 1st metacarpal bone
- ergot = keratinised horny lump on palmar aspect MCP joint = vestigial metacarpal pad
* hidden by ‘feathers’ = long hairs
how is humerus different in horses
+ so biceps brachii
has intermediate tubercle in the middle of intertubercular groove = 2 intertubercular grooves
* = tendon biceps brachii split in 2
* = bicipital bursa sep from shoulder joint capsule
lacertus fibrosis
fibrous CT extension over biceps + extensor carpi radialis
* inserts proximal MC3
* if shoulder extended then carpus extended too = stay apparatus
in horse
how are radius + ulna diff in horse
+ triceps
- fused = no rotation, no annular ligament
- ulna v reduced (no distal) - radius = main weight-bearing bone
triceps only 3 heads - no accessory
bursa of elbow joint
fluid filled cushions to protect tendons
1. tricipital bet triceps tendon + olecranon process - excess fluid = pain, lameness
2. subcut bet skin + tendon of tricep insertion - excess = swelling but not so painful
how is carpus diff in horses
all carpal bones present except 1st (may be vestigial but tiny) - RCB + ICB sepped
* 3rd carpal bone largest
most movement at antebrachio-carpal joint
least at carpometacarpal joint
both DDFT + SDFT in carpal canal
tendon sheaths in carpus horse
protects tendon in confined spaces w transparent CT sheath
1. dorsal aspect = around extensor tendons
2. palmar aspect = around DDFT + SDFT
thoroughpin
inflammation of carpal canal bc incr press = bulges = ‘thoroughpin’
in horse
how are metacarpal bones horses different
3rd = ‘cannon’ bone - weight bearing
* distal articular surface = sagittal ridge
2nd + 4th = ‘splint’ bones - vestigial + non-weight-bearing
* palpable ‘button’ at distal end
fibrous joints bet MCs = syndesmosis
* mineralise as age
no dorsal sesamoid bones - only palmar
phalanges in horses
- proximal = long pastern bone w raised ‘V’ on palmar surface = attach oblique distal sesamoidean ligament
- middle = short pastern
- distal = coffin bone (w/in hoof capsule)
bony contours for attachment collateral ligaments
coffin bone
- extensor process for attachment common digital extensor tendon
- palmar processes support lateral cartilages
- solar surface attachment DDFT
- striations dorsal surface for hoof attachment + bvs
- nutrient foramens = vascular channels for bvs enter
horse - w/in hoof capsule
centres ossification manus horse
MC 3: body + distal epiphysis
MC 2 + 4: proximal epiphysis + body
PP: proximal epiphysis + body
MP: proximal epiphysis + body
DP: body
proximal sesamoid bones horse
palmar to distal end MC3 on either side sagittal ridge, embedded in suspensory ligament
* protect + support SDFT + DDFT
no dorsal sesamoid bones
distal sesamoid horse
== navicular bone
* 2 flat articular surfaces
* covered hyaline cartilage - under lots press from bodyweight whole bod
* cancellous centre = spongy, porous, bone tiss filled red BM
* vascular channs
* on palmar aspect DIP joint
dorsal surface articulates w MP + DP
pamlar surface guides DDFT over DIP joint
navicular disease syndrome
erosion bony matrix w age = visible radiograph
metacarpophalangeal joint horse
== fetlock bet MC3 + PP
synovial joint w extensive capsule
1. large dorsal pouch w synovial fluid to protect extensor tendons
2. large palmar pouch w synovial fluid incorporating proximal sesamoids
no dorsal sesamoid
structure MCP joint horse
natural position = extension - only flexion + extension
* tendency collapse into hyperextension
* sesamoidean ligaments
* suspensory ligament = interosseus musc dogs
suspensory ligaments
horse
origin proximal palmar MC3 to fill area bet splint bones, then bifurcates to:
* abaxial aspect each of proximal sesamoids -> dorsal aspect + fuses w common digital extensor tendon
prevent collapse MCP = hyperextension -> normal extended (relies stability proximal sesamoids)
equiv interosseus musc
inter-sesamoidean ligament
= proximal scutum (shield)
* reinforced fibrocartilage for passage DDFT + SDFT over sesamoids (= on palmar aspect)
* support carpal joint
collateral sesamoidean ligaments
proximal sesamoids -> MC + PP
* support carpal joint + hold proximal sesamoids in place
distal sesamoidal ligaments horse
- paired cruciate = prox sesamoids, diagonally cross, -> PP
- short = proximal sesamoids -> PP (deepest)
- paired oblique = proximal sesamoids -> V-shaped trough on PP
- straight = proximal sesamoids -> MP, inserting w SDFT
proximal interphalangeal joint horse
pastern joint - flexion + extension only
* sagittal groove on distal PP -> sagittal ridge on proximal MP
* collateral ligaments bet PP + MP w extension -> navicular bone
distal interphalangeal joint horse
sagittal ridge + groove
* broad = some rotation - accomodate uneven ground
common digital extensor tendon + DDFT but NO dorsal elastic ligament
collateral ligaments bet MP + DP
ligaments of navicular bone
- collateral ligament PP -> distal sesamoid
- impar ligament DP -> distal sesamoid
navicular bursa
== podotrochlear bursa
fluid filled pocket bet navicular bone + DDFT
* sepped from DIP joint by impar ligament
* protects DDFT
lateral cartilages
== ungual cartilages, on palmar processes DP
* medial + lateral
* project above level of hoof
* shock absorption
not visible radiograph bc cartilage but ossifies + mineralises as age -> ‘sidebone’ (visible)
proximal part palpable
extensor tendons distal forelimb horse
- common digital extensor (CDE) across dorsal aspect carpus joined by 2 branches suspensory ligament + inserts PP, MP + DP
- lateral digital (LDE) inserts PP
muscs distal forelimb horse
below carpus = only fibrous tiss (tendons, ligaments), musc bellies in antebrachium
* stay apparatus - can stand + weight not on musc
flexor tendons distal forelimb horse
- SDFT - thru carpal canal, splits allow DDFT pass thru, inserts MP
- DDFT - thru carpal canal, thru split in SDFT, over navicular bone + bursa, inserts DP
- each have accessory check ligament (CL)
* for SDFT originates proximal to carpal canal + fuses w SDFT just distal of carpus
* for DDFT originates fibrocartilage of palmar ligament on carpus + fuses w DDFT halfway down MC
both palmar aspect
can easily palpate all tendons + ligaments palmar aspect distal forelimb horse
tendons on ultrasound
lesions hypoechoic (= darker) bc inflammation + necrosis
white lines = normal collagen fibres
lesions = needs rest
extra CT structures digital region horse
- scutum = cartilage shield on palmar aspect joints = smooth passage tendons
- annular ligaments (AL) hold SDFT + DDFT against bones
- tendon sheath extends distally from annular ligament, shared by SDFT + DDFT (palmar to suspensory ligament)
scutum on MCP joint = intersesamoidean ligament
stay apparatus is?
most weight borne on forelimb so need mech for passive weight bearing
mechs of stay apparatus
- serratus ventralis suspends bodyweight bet forelimbs
- biceps brachii maintains shoulder in extension
- collateral ligaments elbow maintain extended
- lacertus fibrosis = carpus extended when shoulder extended
how does stay apparatus prevent hyperextension carpus
- palmar fibrocartilage joint reinforcement
- SDFT + check ligament
- retinaculum
how does stay apparatus prevent hyperextension MCP
- suspensory ligament
- common digital extensor
- proximal sesamoids
- distal sesamoidean ligaments
how does stay apparatus prevent hyperextension MCP, PIP + DIP
- DDFT + SDFT + check ligaments
- annular ligaments
arterial supply forelimb horse
- brachial artery at medial aspect elbow (palpable pulse)
- medial + lateral digital arteries on abaxial aspect proximal sesamoids (palpable pulse)
neous drainage similar to dogs
how is nerve supply different in horses
different sensory areas
* distal to carpus median + ulnar nerves combine to supply pastern + foot combined w musculocutaneous nerve
same motor function
major branches median + ulnar nerves after combined in horse
- palmar metacarpal nerves - paired medial + lateral, bet MC3 + splint bones, emerging distal end to supply dorsal aspect digit
- palmar nerves - paired medial + lateral, bet suspensory ligament + SDFT, crossing abaxial aspect aspect proximal sesamoids
* become palmar digital nerves w dorsal + palmar branches to supply hoof contents
use nerve blocks in horses
localise area of lameness - give 1 bit distal, still lame = more slightly proximally still lame = more proximal + so on until not lame anymore = know where area of issue + pain is (bc know supplied by that specific branch of nerve)
injecting local anaesthetic
palmar digital nerve block
on palmar digital nerves adjacent digital arteries just above coronary band
* both medial + lateral injections to block palmar 1/2 foot inc navicular bone
abaxial sesamoid nerve block
palmar digital nerves + dorsal branches on abaxial aspect sesamoids
* medial + lateral injections to block whole foot
palmar metacarpal nerve block
= ‘4 point block’
- palmar nerves bet suspensory ligament + flexor tendons
- AND palmar metacarpal nerves at distal end splint bones (2cm proximal to distal sesamoids)
* medial + lateral injections to block entire digit
label whole distal forelimb horse
overall hoof structures
diagrams
4 parts:
1. wall (toe, quarters, heel, bar) - weight bearing
2. periople - junction bet hoof wall + skin to protect new wall growth (waxy) - prods waterproof layer 2/3 way down to prevent evap, wear, tear
3. sole - shouldn’t touch ground
4. frog - anticoncussive (rubbery)
digital cushion
deep to frog in hoof made elastic tiss w bvs + fat
* for shock absorption (cf digital pads dog)
* protects DDFT, DP, navicular bone + bursa
clinical significance digital cushion hoof
- penetration injuries
- abcess formation = pododermatitis - significant pain + palpable digital pulses - need dig remove pus (may need poultice to soften horn)
layers hoof
- dermis (corium) covers DP + digital cushion w blood + nerve supply (also supplies germinative layer)
- germinative prods epidermis
* active in coronary band + solar surface
structure coronary band + how prods hoof
- dermis formed conical shaped papillae
- prod epidermis in form keratin tubes
- tubes extend distally towards ground
always growing + gaps filled intertubular horn
structure hoof wall
dermis fused DP
* surface forms vertical ridges = primary laminae (macroscopic)
* secondary laminae on 1 (microscopic)
then epidermal horn tubes gliding distally bet laminae w internal surface interdigitating w dermal laminae (== epidermal/insensitive laminae)
dermal laminae sensitive (cont blood + nerves)
white line of hoof
= interdigitation to prevent separation epidermis from DP
* transfers weight hoof wall -> DP
how is structure sole + frog diff hoof wall
sole:
keratinised flakes + no tubular horns
frog: incomplete keratinisation = soft + elastic
weight bearing in hoof
- frog contacts ground 1st
- forces passed -> digital cushion (= blood forced back up leg) + lateral cartilages
- then hoof wall touches ground + weight transferred -> DP -> laminae -> hoof wall
laminitis
inflammation digital laminae = fluid accumulates bet dermal + epidermal laminae
* severe pain, lameness, incr hoof temp
* also causes altered bloodflow
* -> DP rotates + sinks (radiography)
role farrier
- foot trimming as hoof grows continuously
- shoeing to protect weight bearing wall - shape means no restrist heel
putting in nails for horse shoe
into insensitive laminae (white line)
* sledge tipped nails then tips clipped + flattened -> clenches (need be ‘raised’ b4 can remove shoe)
traditionally shod hoofs =?
- front weightbearing - broad, round, 1 or 2 toe clip
- back for propulsion = narrow, pointed, 2 toe clips
* lateral wall more angled + rounded w 4 nails
* medial more upright, straighter, 3 nails
how are ruminant hoofs different
cloven hoof w medial + lateral claws + interdigital cleft
* sole but no frog, no bars
lateral wall = convex + continuous w heel
medial wall = vertical up to parapedal groove bet it + heel bulb
otherwise same as horse
how is ruminant hoof wall diff to horse
only part dermis covered laminae + only primary not secondary
* still have sensitive + insensitive interdigitating
still grows from coronary band, still sensi w insensi in bet + covering
how does bovine hoof absorb shock
- bulbous heels
- digital cushion
- digits splay, supported by interdigital ligaments
no lateral cartilages or frog
problems w ruminants hoofs
- horn overgrowth bc soft ground - FL = inner claw, HL = outer
- solar ulcers, esp parapedal groove -> 2ndary infection if track up DDFT sheath
- interdigital dermatitis
- white line disease
- laminitis
sheep + goat hooves
same as cattle w skin gland proximal to interdigital cleft prod substance from sebaceous + serous gland
goat well adapted climbing = hard walls, softer soles for traction on steep incline
overgrowth a problem - need to trim
pig hoof
similar ruminants w no frog or lateral cartilages
scapula dog
looking from comparative anatomy angle
- acromion process
- tuber spine absent
- supraglenoid tubercle part glenoid cavity
scapula horse
looking from comparative anatomy angle
- narrow supraspinous fossa
- acromion process absent
- prominent tuber spine
- supraglenoid tubercle sep from glenoid cavity
- glenoid notch present
scapula cow
looking from comparative anatomy angle
- broad dorsal border + larger infraspinous fossa
- acromion process blunt + doesn’t reach level of glenoid cavity
- tuber spine less prominent/absent
- indistinct glenoid notch
pig scapula
looking from comparative anatomy angle
- rounded cranial margin
- poorly defined acromion
- prominent tuber
dog humerus
looking from comparative anatomy angle
- single greater tubercle
- supratrochlear foramen
horse humerus
from comparative anatomy angle
- cranial + caudal parts to greater tubercle, level w humeral head
- lesser tubercle similar size greater
- intermediate tubercle + double intertubercular groove
- no supratrochlear foramen
- v prominent deltoid tuberosity
cow humerus
from comparative anatomy angle
- greater tubercle w cranial (massive, overhanging intertubercular groove) + caudal parts above level humeral head + pointy
- single intertubercular groove
- circular area for insertion infraspinatus m. on lateral aspect greater tubercle
- deltoid tuberosity smaller than horse
- no supratrochlear foramen
pig humerus
from comparative anatomy angle
- greater tubercle cranial + caudal parts, higher than humeral head, rounded, almost enclosing intertubercular groove
- single intertubercular groove
- no supratrochlear foramen
dog + cat radius + ulna
from comparative anatomy angle
2 complete sep bones = rotation possible
horse radius + ulna
from comparative anatomy angle
- proximal ulna present + fused radius
- body ulna absent
- distal ulna present + fused radius = lateral styloid process
- no rotation
- radius at distal end = medial styloid process
ruminant radius + ulna
from comparative anatomy angle
- 2 complete bones
- fuse as animal ages
- no rotation
pig radius + ulna
from comparative anatomy angle
- 2 complete sep bones
- ulna same diameter as radius
- no interosseus space
- no rotation
comparative antomy carpus dog/cat, horse, pig, ruminant
dog/cat:
radial + intermediate fused, distal row all present
horse:
all present but variable 1st CB
pig:
all present
ruminant:
proximal row all present, no 1st CB + 2nd/3rd fused in distal row
comparative anatomy carpal canal
dog/cat = only DDFT through
horse = both DDFT + SDFT
ruminant/pig = DDFT + 1/2 SDFT (splits)
comparative anatomy manus
dog = digitigrade = weight on digit (2nd-5th), 1st vestigial
horse = unguligrade = weight on distal phalanx (3rd MC + digit only), 2nd + 4th vestigial, no 1st or 5th
ruminants = unguligrade - 3rd + 4th digits present, weight bears on distal phalanx
metacarpal bones in ruminants
1 + 2 gone, 5= vestigial spur
3 + 4 sep in foetal life but fuse in uterus
* axial bony septum
* proximal end = 1 articular surface
* distal end = 2 articular surfaces
* 4 centres ossification
* 2 medullary cavities (hollow part bone cont BM)
ruminant digits
everything double horse:
* 2 MCP joints
* 2 pairs proximal sesamoids
* no dorsal sesamoids
* PIP joints
* 2 DIP joints
* 2 distal sesamoid bones
MCP joint support ruminants
- medial + lateral collateral ligaments - axial fused proximally
- intersesamoidean ligaments = 2x proximal scuta
- AND interdigital intersesamoidean ligament
- distal sesamoidean ligaments - only short, cruciate, no oblque + straight
- interdigital phalangeal sesamoidean ligament from axial aspect sesamoid -> opp PP, holding PPs together
difference in digits small vs large ruminants
large = large weight pushes digits apart = need strong atatchments
small = less weight so less firmly attached
* means accomodate rough ground better
digit ligaments ruminants
proximal interdigital ligament bet PPs (not in small)
distal interdigital ligament bet MPs, cross over (in small + large)
suspensory ligament ruminants
similar arrangement to horses w 2 branches
* wraps round DDFT
* fuses w SDFT, acting like check ligament
pig digits
bony els for 4th digits
3rd + 4th weight bearing
* 2nd + 5th vestigial + no touch ground
artiodactyla = even no. digits on ungulate
digital amputation
thru MP removing DIP
* remember interdigital ligaments
local anaesthesia - specific nerve blocks
