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