forelimb Flashcards
what is the locomotor system
musculoskeletal system that allows a wide range of animal movement
what are the three components of the musculoskeletal system
1) bones = act as rigid support/framework
2) joints = allows movement between bones
3) muscles = produces movement between bones
what are cursors
vertebrates that run on ground + are modified to enhance speed+ endurance. mostly predators or medium to large herbivores (common domestic species)
what are the cursorial adaptation of locomotor system
1) reduced pectoral skeleton (allows more cranial/caudal movement)
2) elongation at proximal end of limb (scapula lies laterally)
3) elongation at distal end of limb (lon metacarpals, walk on toes/hooves)
Describe how the pectoral skeleton is reduced in cursors
Clavicle is absent or vestigial.
No skeletal component attaching the forlimb to the trunk
Joint is purely muscular = synsarcosis
joint is called the omothoracic junction
Decribe how the proximal end of the limb is enlongated in cursors
scapula lies laterally
this allows increased stride length as the leg length is increase.
At the proximal end of the forelimb the scapula moves from lying flat across the back of a broad chest (humans) to lying flat agaisnt the sides of a deep narrow chest.
How is the distal end of the limb elongated
to increase leg length = increases stride length
as they have long metacarpals and walk on their toes or their hooves
What is flexion
folding limb (decreasing angle around the joint)
what is extension
stretching limb (increasing angle around the joint)
what is protraction
moving limbs forward
what is retraction
moving limbs backwards or fixing limb + moving trunk forwards towards the limb
How does trunk affect the locomotion of the species
locomotion + diet are linked in evolution
-herbivores with roughage diets and bulky abdominal viscera have less flexible trunks and rely more on limbs elongation
=cows, rigid = restricted movemnt
in horses they have a rigid vertebral column, propulsion/stride length comes from limbs, have a flexed suspension plate
- carnivores with small volume, run fast have flexible trunks with multipurpose limbs
e.g. cats = have flexible vertebral column allow limbs to swing more, acts like bow to increase propulsion/stride length from limbs and have flexed + extended suspension phase
what is a gait
sequence of limb movements
in equine what is a walk
4 beat gait
each limb move forward individually sequentially + hit ground separately (slow)
what is a trot
diagonal gait = 2 beat gate
two limb hit ground simultaneously
pairs are opposite diagonal limbs
what is a canter
3 beat gait
with one period of suspension
left lead = RH LH+Rf LF
right lead LH RH+LF RF
still diagonal pairing
what is a gallop
4 beat
left lead - RH LH RFLF
right lead - LH RH LF RF
fast
what is the axial skeleton
bones of vertebral column, skull and ribcage
what is the appendicular skeleton
all bones of fore and hind limbs
what are the 4 types of bones
1) flat (scapula/pelvis)
large surface area for muscle attachment and protects underlying structures
2) long (humerus/femur)
support and leverage in limbs , hole inside = blood cell production
3) short (carpus/tarsus)
large range of movement , anti-concussive , cluster
4() sesamoid bones(e.g. kneecap)
embedded in tendons, change in angle over bony surfaces, can redirect forces and reduce friction to prevent damage
3 bone general features
1) smooth surface areas
for passge of structures/tendons
articular surfaces : hyaline cartilage at weight bearing surfaces, resistant to deformation, no blood vessels or nerves, no periosteum
2) specific bony contours
tuberosities/tubers/tubercles/processes
provide site for attachment of important structures
3) rough surface areas
for general muscle attachment
in x-ray/radiographs what are the visible features of long bones
-diaphysis = shaft
- cortex = wall
- medullary cavity = hollow centre
- epiphysis = end (incorporated articular surfaces)
- metaphysis = transition zone
appear white as they reflect the x-rays (radio opaque)
where is the insertion of the muscle
distal
or where it is not fixed ( joint)
how can muscles be attached
1) directly to bone
size of area depends on muscle, rough surface, bony tuber
2) by tendons
condensation of deep fascia into cords, less bulky across joints. small area of attachment , may have separate centre of ossification
3) via aponeurosis
limited access to bone. Fibrous tissue arranged in thin sheets of tissue. condensation of deep fascia into sheets, long area of attachment, muscles in areas with limited access to bone
what are intrinsic muscles
origin and insertion with appendicular skeleton (within limbs)
movement of limb joints
flexion and extension
what are extrinsic muscles
origin on axial skeleton
insertion in appendicular skeleton
movement of limb relative to trunk
protaction and retraction of limb
in domestic animals is there a join between forelimb and trunk
no
muscular attachments oly
scapular glide over thorax pivotal point midway down scapula
what is the shoulder region called
omo
what is the arm region
brachium (region from shoulder to elbow)
what is the forearm region
antebrachium (region from elbow to carpus)
what is the wrist region
carpus
what is the hand region
manus (region distal to carpus)
what is the toe regin
digit
How does the scapula develop
has 2 centres of ossification
primary is in the body
secondary in the supraglenoid tubercule
open in a young animal
potential problem = tendon of orgigin of biceps brachii muscles
physis weak point can cause avulsion fracture
what bony structures of the scapula can we palpate
dorsal border
cranial border
cranial angle
spine
acromion (guide for locating shoulder joint)
caudal border is beneath muscle so difficult to palpate
what is the brachiocephalic muscle
extrinsic muscle runing from the head to the arm ( down the neck)
origin = cervio-thoracic fascia
insertion = humerus (aponeurosis)
function = protractor (raises arm)
what are 3 parts:
cleidocervicalis, cleidomastoideus, cleidobrachialis
with line of cartilage between brachialis and cervicalis bit = at shoulder (no bone)
what is the latissimus dorsi muscle
broadest muscle of the back
origin = thoracolumbar fascia
insertion = humerus (aponeurosis)
crosses shoulder joint caudally
function = retractor
propulsion (acts on forelimb and across shoulder)
what is the serratus ventralis muscle
located between forelimb and trunk
origin = thoracis wall (rib) and cervial vertebrae (neck)
insertion = proximal scapula (edial aspect)
proximal to pivotal point
function: cranially = retractor
caudally = protractor
what are 3 tpes of joints
fibrous
cartilagenous
synovial
what is the omo region
shoulder
what is the branchium region
arm
from shoulder to elbow
what is the antebrachium
forearm
elbow to carpus
what is the carpus region
wrist
what is the manus region
hand (region distal to carpus)
what is the digit region
toe
where is the scapula
shoulder blade
what does the lateral surface of the scapula
facing out
has spine running down the middle
cranial side is the suprasinous fossa
caudal is the infraspinous fossa
at end of spine is the acromion process
distal area: - cranial side has the supraglenoid tubercle, glenoid cavity and ventral angle
scapular notch is above the supraglenoid tubercle
what is the glenoid cavity
articular surface (shoulder joint)
concave
smooth surface
where does the biceps brachii muscle attach on the scapula
supraglenoid tubercle
what is on the medial surface ofo the scapula
cranial edge is the serrated edge with rough edge
has the subsacapula fossa
distal caudal aspect has the infraglenoid tubercle
beneath the supraglenoid tubercle has the coracoid process
dorsal = attachement of the serratus ventralis muscle
ventrally = subscapularis muscle
what muscles attach to the medial face of the scapula
dorsally is the serratus ventralis
ventrally is the subscapularis muscle
differences of the cat and dog
more rounded cranial angle than dog in a cat
cat has a suprahamate process which is proximal to the acromion process
what is the development of the scapula
has 2 centres of ossification :
- body
- supraglenoid tubercle
problem as tendon of origin of biceps brachi attaches to the supraglenoid tubercle but it is a weak point so has avulsion fracture
what bony structures of the scapula can we palpate in live animals
- dorsal border
-cranial border + angle
-spine - acromion (guide to locate shoulder joint)
- caudal border is difficult to palapte
what are the extrinsic muscles of the shoulder
- brachiocephalic muscle
- omotransversarius
- serratusventralis muscle
describe the brachiocephalic muscle
origin : cervico - thoracic fascia
insertion = humerus (aponeurosis)
function: acts as a protractor
has 3 parts: cleidocervicalis thick bit on neck, clediomastoidues thin bit on neck
both make up the cleidocephalicus
cleidobrachialis - bit along the arm
describe the omotransversarius muscle
goes underneath the brachiocephalic muscle along the neck
origin : transverse wing of the atlas C!
insertion: acromion process of the scapula
function: protracts forelimb
describe the latissimus dorsi muscle
‘broadest muscle of the back’
origin: thorcolumbar fascia
insertion: humerus (aponeurosis)
function: retraction
propulsion (also acts across the shoulder)
describe the serratus ventralis muscle
muscle located between the forelimb and trunk, runs under the medial aspect of the scapula
origin: - thoracic wall (rib) and the cervical vertebrae (neck)
insertion: proximal scapula (medial aspect, proximal to pivotal point)
function: cranial portion - retractor
caudal portion - protractor
think of the way it moves the scapula + what that results for the rest of the limb
describe abductors
muscles are located proximal to the pivotal point and limn ( dorsal aspect?)
move limb away from midline
describe adductors
move limb towards midline
located distal and medial to limb (ventral aspect)
kimited movement (more possible in small than large species)
describe the trapezius muscle
origin : cervicothoracic fascia
insertion = proximal scapular spine by aponeurosis
has 2 parts cranial and caudal
superficial, can be felt
triangle shape
causes abduction of scapula ?
no effect on shoulder
describe the rhomboideus muscle
lies deep to the trapezius
origing : cervicothoracis fascia
insertion: dorsal border of scapula
abductor of scapula
no effect on shoulder
describe the pectoral muscles
origin: sternum
insertion: humerus ( proximal )
has 2 heads , deep and superficial
causes adduction of the limb
what are intrinsic muscles
both origin and insertion are within appendicular skeleton (on limb)
no effect on limb relative to trunk = move joints within limb causing flexion and extension
what type of bone is the humerus
type of long bone
s-shaped
describe the proximal aspect of the humerus
head contains the greater tubercle laterally
and the lesser tubercle is on the medial aspect
neck
head is the articular surface, convex and smooth surface
articulates with glenoid cavity of scapula at shoulder joint
coming down from the greater tubercle on the cranial side is the tricipital line (raised) and then the deltoid tuberosity (small tubercles)
intertubercle groove is where tendon of the bicep brachii passes through
describe the distal aspect of the humerus
contains the musculospiral groove and at the bottom tuburcle is called the condyle
medial hald is larger than the lateral
it is the articular surface for the radius and ulna and is divided into 2 areas:
- trochlea , on the medial side, pulley like structure which is larger with a central depression and articulates with radius and ulna
- capitulum : located laterally and is smaller, articulates with the radius
in middle of the caudal aspect is the olecranon/ulnar fossa
in middle of the cranial aspect is the radial fossa
dogs contains the supratrochlear foramen beneath the fossas which has no function and may not be present in shortlegged dogs
what does the distal end of the humerus contain in a cat
the supracondyloid foramen
not the supratrochlear foramen
allows the brachial artery and the median nerve to pass through is vulnerable in fractures
what are the centres of ossification of the humerus
has 5
one in the proximal epiphyses (tubercle)
one in the body
3 in the condyle:
-medial epicondyle
-medial half of the condyle
-lateral half of the condyle
what are the palpation landmarks of the humerus
- greater tubercle, guide for locating shoulder joint
- lateral epicondyle
- medial epicondyle
how is the nerve supply to the muscles developed in the embryo
somites in the embryo (paired blocks of mesochyme) develop alon spinal cord
groups combine to form each forelimb and drag nerves with them
nerve supply reflects origin
which nerves supply the forelimb
C6 C7 C8 T1 and T2
ventral branches form brachial plexus, located in the axillary region
emerging nerves supply forelimb
what sections of the forelimb does the brachial plexus nerve supply
ulnar nerve
radial nerve
median nerve
axillary nerve
musculo-cutaneous nerve
what does the ulnar nerve affect
flexor carpii ulnaris muscle
deep digital flexor muscle
what does the radial nerve affect
tensor fasciae antebrachii muscle
triceps brachiim
anconeus muscle
extensor carpi radialis muscle
common digital extensor muscle
lateral digital extensor muscle
ulnaris lateralis muscle
abductor digitis longus
what does the median nerve affect
pronator teres muscle
flexor carpi radialis
superficial digital flexor muscle
deep digital flexor muscle
pronator quadratus
what does the axillary nerve affect
deltoideus msucle
teres minor muscle
subscapularis muscle
teres major muscle
what does the musculo-cutaneous nerve affect
coracobrachialis muscle
brachiialis muscle
what are mixed nerves
consist of both motor and sensory fibres , transmit messages in both directions at once
cause spinal reflexes
what is proprioception
location of limb in space
what muscles does the brachial plexus supply
all intrinsic muscles
some extrinisc:
- latissimus dorsi (retractor)
- serratus ventralis (protractor and retractor)
-pectorals (adductor)
doesn’t supply
- brachiocephalicus (protractor)
- trapezius and rhomboides (abductors)
what are the 3 types of joints
- fibrous
-cartilagenous - synovial
what is a fibrous joint
allows little movement
e.g. skull sutures
sydesmosis of the radius and ulna and equine metacarpal bones
what is a cartilagenous joint
allows little movement
- synchondrosis/synarthrosis
pelvic / mandibular symphysis
epiphysis/diaphysis in young
what does a synovial joint contain
allows large range of motion
found in most limb joints
contains: hyaline cartilage which covers articular surface (bones) , reduces friction and contains no blood vessels or nerve endings = no pain, in arthirits nerves are exposed
- synovial fluid is in joint cavity to lubricate joint and nourish the cartilage
- joint cavity is lined by synovial membrane that produces synovial fluid and is a physical barrier to contain fluid
- joint capsule covers it all , is a fibrous layer that is incorporated into the synovial membrane and attaches round the osteochondral junction
- ligaments laterally around joint capsule (formed from condensation of fibrous material) run from bone to bone, support joint and restirct movements between bones
what bones make up the shoulder joint
scapula and humerus
glenoid cavity articulates with the humerus head
glenoid cavity is concave , humerus head is convex
what can you palpate on the shoulder joint
acromion process of the scapule and the greater tubercle of the humerus
what is the bicipital bursa
allows movement of the tendon of the bicep brachii over the humeral tubercles
as joint capsule extends into the inter-tubercular grove and wraps around tendon of orgin of biceps brachii (origin is the supraglenoid tubercle of scapula)
held in place by the transverse ligament
what is the supraspinatus muscle
supports the shoulder laterally
on the cranial aspect
origin is the supraspinous fossa on the scapula
inserts on the greater tubercle of the humerus two heads?
allows extension of the shoulder joint
what is the infraspinatus muscle
supports the shoulder laterally on the caudal aspect
origin is the infraspinous fossa
inserts distally to the greater tubercle on the humerus
causes abduction of the shoulder
supplied by the suprascapular nerve, contains motor fibres only
what is the subscapularis muscle
supports the shoulder on the medial aspect
origin is the subscapular fossa on the scapula
inserts on the lesser tubercle on the humerus
causes adduction of the shoulder joint
supplied by the subscapular nerve which contains motor fibres only
what muscles extends the shoulder joint
shoulder extensors cross cranially to the shoulder joint
- brachiocephalicus (extrinisc muscle) nerve supply is not the brachial plexus
- biceps brachii muscle (one head in dog)
what is the biceps brachii muscle
intrinsice muscle
origin is the supraglenoid tubercle
insertion is the ulnar and radial tuberosities
shoulder extensor and elbow flexor
supplied by the musculocutaneous nerve
the bicipital bursa in the humerus protects the tendon of origin as it passes through the intertubercular groove
what muscles flex the shoulder joint
shoulder flexors cross caudally to the shoulder joint
- latissimus dorsi (extrinisc, nerve supply is the brachial plexus)
- teres major (intrisins)
- teres minor (intrinsic )
- deltoideus muscle (intrinsic)
- triceps (intrinsic)
what is the teres major muscle
on lateral aspect caudally of the shoulder joint
origin is the caudal border of the scapula
insertion is the medial humerus
nerve supply from the auxillary nerve
which contains both motor and sensory fibres
shoulder flexor
what is the teres minor
lies cranial to the teres minor but still caudal aspect of the scapula and humerus
origin is the infraspinous fossa of the scapula,, distal aspect
inserts on the medial humerus
supplied by the axillary nerve
shoulder flexor
what is the deltoideus muscle
has 2 heads
origins: scapular spine and acromion process
inserts: lateral aspect of humerus
nerve supply : axillary nerve, mxed type , both motor and sensory fibres
shoulder flexor
what is the triceps muscle
has 4 heads
one is major = ‘long head’ , most superficial and caudal
long head origin is the caudal border of the scapula
other heads origin is the humerus lateral and one medial
insert on the olecranon of the ulna
extends the elbow
nerve supple is the radial nerve which contains both motor and sensory fibres
what are the four parts of the hoof
- wall (toe, quarter = underneath, heal and bar
- periople
- sole
- frog
what is the frog
rubbery wedge shaped strucutre positioned between the bars
can expand hole when weight bearing, is very flexible and elastic in nature
in centre is the centre sulcus which either side has the sulci where you need to clear dirt out of these before shoeing or examining
what are the bars of the heel
there are two bars on each hoof, either side of the frog. they are triangular support that weight bearing so they are a hard structure
what is the sole
the sole covers the bottom offoot, (white bit round the front) / is concave so shouldn’t touch the ground)
what is the white line in the hoof
interconnected lamina between wall and sole
contains both sensitive and insensitive
what are the walls of the hoof
go round the outside
walls are the same basic structure as your finger and toe nails (weight bearing)
where are the heel bulbs
back of heel, round bit at the end
what is the coronary band
enitre boundary between skin and hoof, contains the periople
transition between skn and hoof wall
produces hoof wall
and marks boundary between skin and hoof
what is the periople
within the coronary band
the whiteish line round the middle
produces waterproof waxy layer that extends 2/3 way down hoof and prevents evaporation, wear and tear
what does the inside of the hoof contain
proximal phalanx, ,middle phalanx and distal phalanx
DIP and PIP joint
navicular one ( sesamoid bone of the phalanx)
DDFT ( deep digital flexor tendon)
navicular bursa = protects
digital cushion
what is the digital cushion
- deep to frog (behing the P2 and P3)
contains elastic tissue, blood vessels and fat
is a shock absorber (is equiv. of dog pad)
protects the DDFT, distal phalanx, navicular bursa and navicular bone
what is the clinical significance of the hoof contents
penetration injuries , depending on location and depth
abcess formation exerts pressure on the structures may need to apply poultice to soften horn
can sometime palpate
need to know where strucutures are to let out
what and where anf the lateral and ungual cartilages
either side of the DIP
cartialge plates, palmer processes
both medial and lateral aspects
for shock absorption
mineralise with age ( can be seen in xray if ossified) when they mineralise = called sidebone
how is hoof produced
the dermis corium covers the distal phalanx and digital cushion , is the deeper red layer that is senstitve as it contains blood and nerve supply (extensively vascularised) contains lots of curtain like folds, visible by microscopes
this supplies the germinative layer
germinative layer : produces epidermis layer at the coronary band and solar aspect ( bottom of hoof)
hoof wall ontop is keratinised to stop damage and is insensitive
how does the coronary band forms
dermisi firmed into conical shaped papillae
dermal papillae produces in the form of tubes of keratin which extend distally towards ground
which grow 5-6mm per moth
gaps are filled by intertubular horn which forms the hoof wall which is weight bearing surface
-epidermal horn tubes glide distally
internal surface interdigitates with dermal laminae and forms corresponding primary and secondary laminae known as epidermal/insensitive laminae
where does the dermis fuse and how does it form under the hoof
dermis is fused to the distal phalanx
primary lamina is macroscopic (bands of pink)
secondary is protusions into the insensitive lamina, only visible in the microscopic
this is the sensitive part below the hoof wall
the primary laminae are the folds you can see
what is the interdigitation
white line that prevents separation of epidermis from distal phalanx and transfers weight from hoof wall to distal phalanx
the solar surface (bottom) is the active germination layer and has a different composition to hoof wa;;
what is the sole composition
keratinised flakes
and no tubular horns
what is the composition of the frog
incomplete keratinisation and soft and elastic
what is the clinical significance of the lamina
introducing nail to attach shoe , if in interweaving bit animal wil go lame as nerve are hits
how does the weight bearing occur in the hoof
frog contacts ground first
and forces are passed to the digital cushion which pushes the blood back up leg and the lateral cartilages
when the hof wall contacts ground the weight is transferrred to distal phalanx then via laminae to hoof wall
extensive blood supply mean forces travel back up
what to be aware of for farriers
foot needs cutting continuously, as horn always grows
shoeing protects weight bearing wall, caudal aspect is oepn so shape doesn’t restirct heel
therapeutic shoes support heel
nails need to be careful and aim for only the insensitive laminae , so nails are sledge tipped nails then tips clipped and flattened form clenches. must ‘raise clenches’ before reomving
difference between ruminants hoof and horses hoof
ruminants have a cloven hoof with both medial and lateral claws with an interdigital cleft
has no frog and no angles and the bars
no lateral cartilages
wall of ruminant hood wall is concave inbetween digits
lateral wall is convex and is continuous with heel
medial part is vertical and stops at parapedal groove, transition hard to soft hors at top is prone to damage
how do ruminants absorb the shock
- bulbous heels with digital cushion
- digits splay and are supported by interdigital ligaments
have no lateral cartilages and no frog
clinical consideration with ruminant hoofs
horn is often overgrown if soft ground (forelimb inner claw is overgrown, hindlimb is outer claw)
can get solar ulcers especially with parapedal groove , secondary infection can track up deep digital flexor tendon sheath
can get interdigital dermatitis
white line disease
lamininits
how are sheep and goat hooves adapted
- goot hooves are well adapted for climbing, hard walls and softer soles for traction on steep inclines
same as cattle
skin gland is proximal to inter-digital cleft (waxy substances produced by sebaceous and serous gland)
overgrowth is a problem a trimmed
how are pigs hooves like
- similar to ruminants
have no ruminants and no frog
no lateral cartilages
has 4 digits
extra digits that are non-weight bearing and don’t touch the ground
