A24 - Statics of the fore- and hindlimbs; types of gait, walk, stride Flashcards
1
Q
Statics of the forelimb
General
A
- Major role: support the weight of the body
- Reduction in the skeletal structure of the shoulder girdle, where only the scapula, and in some species a much reduced clavicle
- Eq: Carry 55% of the body weight
- FL has less musculature than HL
- Elastic, springlike apparatus
- Scapula is attached to the trunk at the cranial end of the bow and string construction
- Restricted movement in large animals due to:
- Fascia
- Ligaments
- Shock-absorber system
- Proximal:
- Buffer the power from the weight → ground
- M. biceps brachii: tendon of origin, tendon of insertion
- M. triceps brachii, caput longum
- Lecertus fibrousus
- M. extensor carpi radialis
- M. flexor carpi ulnaris
- Distal:
- Elastic support
- Sesamoid ligaments
- Deep flexor tendon
- Superficial flexor tendon
- Tractus appositus (goes to cranial), holds against collaps
- Proximal:
- Three jointed column
- In normal position the point of impact of load on the scapula lies at the middle of the insertion area of the m. serratus ventralis
- The bearing area of the foot (paw, hoof) lies vertically below this impact point
2
Q
Statics of the forelimb
Stay apparatus
A
- Horse
- FL and HL
- Tendinous-ligamentous support mechanism
- Allows the body to carry its body weight with a minimum of muscular effort and reduces muscular fatigue
- Tendon of m. biceps brachii of lacertus fibrosus prevents the shoulder joint from locking
- Weight of body = flexion of shoulder
- Isometric contraction starts to increase to prevent flexing of sholuder in:
- M. supraspinatus
- M. biceps brachii
-
SDF and DDF:
- Tensed by dorsoflexion of fetlock joint
- Passive tension will maintain the elbow extension through caput humeri
- Isometric contraction of m. triceps brachii
- Isometric contraction starts to increase to prevent flexing of sholuder in:
- Weight of body = flexion of shoulder
- Vertical line between radius and cannon bone leads to less effort for carpus
- To pervent the sholuder joint from collapsing they are supported by strong collateral ligaments:
- M. infraspinatus
- M. supraspinatus
- The elbow joint will remain in equilibrium ad long as the vertical line of impact and the foot maintain its position
- The elbow joint must be prevented from building foreward, which is provided by:
- M. trceps brachii (by isometric contraction)
- M. flexor digitorum longus
-
Lacertus fibrosus:
- Keeps the carpus from collapsing forward
- Arises from m. biceps brachii
- Inserts on cannon bone
- The carpal joint protected against overextension by:
- Ligaments of the caudal aspect of the carpus
- Ligaments of the accessory bone
-
Check ligament of:
- M. flexor digitorum superficialis
- M. flexor digitorum profundus
-
Suspensory ligaments of the palmar and plantar aspect of the metacarpus/tarsus:
- Main support of the fetlock
- Prevents overextension
-
SDF and DDF:
- Suplements the suspensory ligament
- Accessory ligament: distal end of radius → SDF tendon (proximal check ligament)
- Accessory ligament: carpus → DDF tendon (distal check ligament)
3
Q
Statics of the forelimb
Statics
A
- Shoulder girdle muscles lifts the limb of the groud
- Flexion of all joints
-
M. brachiocepalicus draws the flexed limb cranially
- The action is complemented by:
- M. omotransversarius
- M. trapezius
- They rotate the distal end of scapula craniodorsally, and the caudal angle caudovenrrally → swing phase of locomotion
- The action is complemented by:
- All jounts gets extended, through the action of:
- M. triceps brachii
- Radial extensor muscles of the carpus
- Digital extensor muscles
- Limb hits the ground in front, weight is transformed
- Draws scapula in opposite direction by:
- M. rhomboideus
- M. pectoralis profundus
- Limb gets ready to be lifted again
- SDF tendon & suspensory ligament: relaxed
- Coffin joint: extended maximally
- DDF tendon & check ligament: tensed
- Phalangeal joints flex immediatly when the foot is lifted off the ground
4
Q
Statics of the hindlimb
General
A
- Bear less bodyweigth and are more angled than FL
- Fixation of the other joints of the HL is mainly done without any muscular effort – almost exclusively by tendons and ligaments
- Proximal HL: thight suspension between sacrum and inner surface of ala iliaca (sacroiliac joint)
- Ensures an effective transmission of the thrust of the HL onto the trunk
- Better developed musculature in the HL
5
Q
Statics of the hindlimb
Patellar lock
A
- Locking of patella → mobilization of stifle → mobilization of hock
- In normal flexion and extension of the stifle joint, the patella glides in the trochlear groove
- Extension beyond the proximal extremity of the groove, together with a medial twist of the patella → medial ridge of the femur protruding between the medial and middle patellar ligament
- The parapatellar cartilage becomes hooked over the tubercle of the trochlea → locking the stifle in an extended position
- M. vastus medialis actively keeps the medial loop formed by the middle and medial patellar ligament, and the patellar and parapatellar cartilage in position
- Release: the weight is shiflte to the other limb and the m. quadriceps femoris draws the patella proximally
- By a lateral twist, the patella returns to the trochlear groove
6
Q
Statics of the hindlimb
Reciprocal apparatus
A
- Stifle and hock is linked
- M. peroneus tertius: cranially
- M. gastrocnemius: caudally
- SDF: caudally
- Flexion of stifle = flexion of hock
- Extension of stifle = extension of hock
7
Q
Statics of the hindlimb
Statics
A
- Joints are flexed
- Limb moves forward as the following muscles contracts:
- Tensor muscles of the fascia lata
- M. gluteus superficialis
- M. sartorius
- M. iliopsoas
- The abductionary effect of m. iliopsoas is counteracted by the following muscles (situated on the medial side of the tight):
- M sartorius
- M. pectineus
- M. gracilis
- At the end of the swing phase, joints are extended again
- M. quadriceps stabilises the stifle
- During the stance phase, the body is propelled foreward through the contraction of the extensors of the:
- Hip (m. gluteus medius)
- Stifle (m. quadriceps femoris)
- Hock (m. gastrocnemius)
- Assisted by the hamstring muscles, which hold the stifle caudally relative to the forward moving body
8
Q
Gait, walk, stride
Name the different gaits
A
- Movement without change in location:
- Sitting
- Lying down
- Movement with change in location:
- Walk
- Trot
- Gallop
- Canter (collected gallop)
- Backwards
- Pass
9
Q
Gait, walk, stride
Walk
A
- 1 supporting and 1 swinging limb = 2 feets always in contact with the ground, there is no suspension period
- 4 beat gait
- RH - LF → LH - LF
- Head and neck are lowered at each swing phase of the FL and lifted during each support pahse
- Types of walk:
- Quick walk
- Normal walk
- Shortened walk
10
Q
Gait, walk, stride
Trot
A
- Diagonal
- 2 beat
- Opposite FL and HL hits the ground together
- RH + LH / RF + LH / RH + LF
- Types of trot:
- Slow/short trot
- Brisk/medium trot
- Quick/running trot
11
Q
Gait, walk, stride
Galoop
A
- 4 beat
- LF or RF leading
- Steps:
- RF (suspension)
- LH
- RH
- LF
- The vertebral column is held ridgid, the trunk is less actively involved
- Paried coordination between the HL and FL
- The direction of movement is determined by the diagonal from the driving HL to the FL along which the trunk is being propelled:
- Left gallop
- Right gallop (RF leads)
12
Q
Gait, walk, stride
Canter
A
- 3 beat
- 2 paired
- Collected gallop
- Non leading diagonal limbs land together
- Steps:
- RF (suspension)
- LH
- RF + LF
13
Q
Gait, walk, stride
Backwards
A
- 2 beat
- RF move more together, as do RH + LH
14
Q
Gait, walk, stride
Pass
A
- RH + RF / LH + LF