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Liv vet med yr1 > Forelimb > Flashcards

Forelimb Flashcards

1
Q

Locomotor system

A

Musculoskeletal system that allows wide range of animal movement

Components
- Bones - act as rigid support
- Joints - allow movement between bones
- Muscles - produce movement between bones

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2
Q

Cursorial adaptation of locomotor system

A

1) Reduced pectoral skeleton
- Allows more cranial/caudal movement

2) Elongation at proximal end of limb - scapular lies laterally

3) Elongation at distal end of limb - long metacarpals, walk on toes or hooves

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3
Q

Reduced pectoral skeleton

A

In cursors clavicle is usually absent or vestigial
- No skeletal component attaching forelimb to trunk
- This type of joint is purely muscular - SYNOSARCOSIS
- This particular joint is the OMOTHORACIC JUNCTION

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4
Q

Elongation at proximal end of limb

A

Scapula lies laterally

Stride length is increased by increasing the leg length.
- At proximal end of forelimb, the scapula moves from lying flat against the back of a broad chest, to lying flat against the sides of a deep narrow chest

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5
Q

Elongation at distal end of limb

A

Long metacarpals, walk on toes/hooves

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6
Q

Interaction between limbs and trunk

A

Folding limb = flexion

Moving limb forwards = protraction

Stretching limb = extension

Moving limb backwards = retraction

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7
Q

Link between locomotion and diet

A

Locomotion and diet are linked in evolution

Herbivores with roughage diets and bulky abdominal viscera have less flexible trunks and rely more on limbs elongation

Horse:
- Relatively rigid vertebral column
- Most of propulsion/stride length results from limbs
- Fixed suspension phase

Carnivores with small volume, consuming meat diet
- Run fast
- Flexible trunks, multipurpose limbs

Cat:
- Flexible vertebral column, allowing limbs to swing more
- Acts like bow to increase propulsion/stride length from limbs
- Flexed + extended suspension phases

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8
Q

Axial skeleton

A

Bones of vertebral column, skull and ribcage

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9
Q

Appendicular skeleton

A

All bones of fore and hindlimbs

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10
Q

Bone types

A

1) Flat (scapula/pelvis)
- Large SA for muscle attachment
- Protection of underlying structures

2) Long (humerus/femur)
- Support + leverage in limbs

3) Short (carpus/tarsus)
- Large range of movement
- Anti-concussive

4) Sesamoid bones
- Embedded in tendons
- Change in angle over bony surface
- Redirect forces
- Reduce friction to prevent damage

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11
Q

General features of bones

A

1) Smooth surface area
- Passage of structures/tendons
- Articular surfaces

2) Specific bony contours
- Tuberosities/tubers/tubercles
- Provide site for attachment of structures

3) Rough surface areas
- General muscle attachment

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12
Q

Visible features of long bones on radiographs

A

Diaphysis = shaft

Cortex = wall

Medullary cavity = hollow centre

Epiphysis = end

Metaphysis = transition zone

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13
Q

Bone growth

A

Short/sesamoid bones:
- Usually 1 centre of ossification per bone

Flat/long bones:
- Usually more than one centre per bone

Attachment sites for important structures may have a separate centre

Cartilage between centres appears black on radiographs = physis/growth plate

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14
Q

Clinical significance of growth plates

A

Young animal:
- Open phases/growth plates
- Produce increase in bone length

Mature animal:
- Closed growth plates = physeal scars
- Time of closure depends on contribution of specific physis to limb length
- Can estimate age from growth plate closure times

Adult dogs:
- Shaft is weakest point = fractures

Young dogs:
- Growth plate weakest = damage/separation
- Can cause premature closure of growth plate

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15
Q

Skeletal muscle

A

Individual muscle fibres

Arranged in parallel lines

Collected into bundles

Covered by fibrous tissue
- Deep fascia

Attached to rigid structures
- Usually bone

Origin - usually proximal
Insertion - usually distal

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16
Q

Skeletal muscle classification

A

Intrinsic muscles
- Origin + insertion within appendicular skeleton
- Movement of limb joints
- Flexion and extension

Extrinsic muscles
- Origin on axial skeleton
- Insertion in appendicular skeleton
- Movement of limb relative to trunk
- Protraction + retraction of limb

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17
Q

Regions of the forelimb

A

Omo - shoulder

Brachium - arm
- Region from shoulder to elbow

Antebrachium - forearm
- Region from elbow to carpus

Carpus - wrist

Manus - hand
- Region distal to carpus

Digit - toe

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18
Q

Scapula

A

Type of flat bone

Body
Neck
Glenoid cavity
- Articular surface (shoulder joint)
- Concave
- Smooth surface

Supraglenoid tubercle
- Attachment of biceps brachii m.

Lateral surface:
- Spine
- Supraspinous fossa
- Infraspinous fossa
- Acromion process

Medial/costal surface:
- Serrated
- Rough bone
- Attachment of:
- Serratus ventralis m. (D)
- Subscapularis m. (V)

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19
Q

Scapula of cat

A

More rounded cranial angle than dog

Suprhamate process
- Proximal to acromion process

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20
Q

Scapula development

A

Centres of ossification - 2
- Body
- Supraglenoid tubercle

Potential problem
- Tendon of origin of biceps brachii m.
- Physis weak point = avulsion fracture

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21
Q

Scapula palpation

A

Can palpate:
- Dorsal border
- Cranial border
- Cranial angle
- Spine
- Acromion
- Guide for locating shoulder joint
- Caudal border (beneath muscle)

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22
Q

Brachiocephalic muscle

A

Extrinsic muscle

Origin = cervico-thoracic fascia
Insertion = humerus (aponeurosis)

Function - protractor

Parts of m.
- Cleidocervicalis
- Cleidomastoideus
- Cleidobrachialis

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23
Q

Omotransversarius m.

A

Extrinsic muscle

Origin = transverse wing of atlas (C1)
Insertion = acromion process

Function - protracts the limb

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24
Q

Latissimus dorsi m.

A

Extrinsic muscle

“broadest muscle of the back”

Origin = thoracolumbar fascia
Insertion = humerus (aponeurosis)

Function - retractor

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25
Q

Serratus ventralis m.

A

Located between forelimb and trunk

Origins:
- Thoracic wall (ribs)
- Cervical vertebrae
Insertions:
- Proximal scapula (medial)
- Proximal to pivotal point

Functions:
- Cranial portion - retractor
- Caudal portion - protractor
(no effect on shoulder)

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26
Q

Abductor muscles

A

Extrinsic

Move limb away from midline
- Muscles located proximal to pivotal point and limb

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27
Q

Adductor muscles

A

Extrinsic

Move limb towards midline
- Located distal to pivotal point and medial to limb
- Limited movement

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28
Q

Trapezius m.

A

Extrinsic

Origin = cervicothoracic fascia
Insertion = proximal scapular spine

Cranial + caudal part

No effect on shoulder

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29
Q

Rhomboideus m.

A

Extrinsic

Lies deep to trapezius

Origin = cervicothoracic fascia
Insertion = dorsal border of scapula

Abductors of limb

No effect on shoulder

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30
Q

Pectoral muscles

A

Extrinsic

Origin = sternum
Insertion = humerus

2 heads: deep + superficial

Adductor of limb

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31
Q

Intrinsic muscles

A

Both origin + insertion within appendicular skeleton

No effect on limb relative to trunk

Move joints within limb
- Flexion
- Extension

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32
Q

Humerus

A

S shaped long bone

Proximal end:
- Head (articulates with glenoid cavity @ shoulder joint)
- Greater tubercle - lateral aspect
- Lesser tubercle - medial aspect
- Intertubercular groove
- Smooth bone surface
- Tendon of origin of biceps brachii m. passes through this structure

Distal end:
- Olecranon/ulnar fossa (caudal)
- Radial fossa (cranial)
- proximal to articular surfaces
- Supratroclear foramen:
- nothing passes through
- may not be present in short legged dogs

Centres of ossification: 5
- Proximal epiphyses = 1
- Body - 1
Condyle:
- Medial epicondyle
- Medial half of the condyle
- Lateral half of the condyle

Palpation landmarks
- Greater tubercle (guide for locating shoulder joint)
- Lateral epicondyle
- Medial epicondyle

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33
Q

Humerus of cat

A

Proximal end same as dog

Distal end:
- Olecranon fossa
- Radial fossa
- No supratrochlear foramen
- Suprachondyloid foramen
- Brachial artery
- Median nerve
- Vulnerable in fractures

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34
Q

Peripheral nervous system (forelimb)

A
  • Cranial nerves
  • Spinal nerves
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35
Q

Spinal nerves

A

Leave spinal cord

Intervertebral foramen

Paired left and right

Branches
- Dorsal branches supply dorsal structures

C6, C7, C8, T1, T2
Ventral branches of these nerves form brachial plexus located in axillary region
- Emerging nerves supply forelimb
- some extrinsic + all intrinsic
- Motor = efferent fibres
- Sensory = afferent fibres
- Spinal reflexes

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36
Q

Nervous system in forelimb

A

Efferent supply:
- Carry impulses from brain to structure
- Motor nerve fibres

Afferent supply:
- Carry impulses from structure to brain
- Sensory nerve fibres
- Proprioception - location of limb in space

Mixed nerves:
- Consist of both motor and sensory fibres and transmit messages in both directions at once
- Spinal reflexes

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37
Q

Brachial plexus

A

Suplies all intrinsic muscles

Supplies some extrinsic muscles

Latissiumus dorsi (retractor)

Serratus ventralis (protractor + retractor)

Pectorals (adductor)

Does not supply:
- Brachiocephalicus (protractor)
- Trapezius + rhomboideus (abductors)

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38
Q

Joints

A

Between every bone in skeleton

Fibrous:
- Little movement
- e.g skull sutures

Cartilaginous:
- Little movement

Synovial

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39
Q

Synovial joint

A

Allows large range of motion between bones

Most limb joints

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40
Q

Features of synovial joints

A

Hyaline cartilage
- Covers articular surfaces
- Reduce friction, flexible joint
- Avascular (no vessels)
- No nerve endings

Synovial fluid
- Viscous/sticky
- Nourishes cartilage
- Lubricates

Synovial membrane
- Produces synovial fluid
- Physical barrier to contain fluid

Joint capsule
- Fibrous layer
- Incorporates synovial membrane
- Attaches around osterochondrial junction

Ligament

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41
Q

Ligaments

A

Dense, fibrous connective tissue

Run from bone - bone

Collateral ligaments support joint (medial + lateral)

Function:
- Support joint, hold bones together
- Restrict movements b/w bones

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42
Q

Shoulder joint

A

Scapula - glenoid cavity

Humerus - head

Palpable landmarks:
- Acromion process (scapula)
- Greater tubercle (humerus)

All synovial joint features
- BUT poorly developed collateral ligaments at the lateral aspect

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43
Q

Bicipital bursa (shoulder joint)

A

Joint capsule extends into inter-tubercular groove
- Between greater + lesser tubercles

Wraps around tendon of origin of Biceps brachii (originates on supraglenoid tubercle of scapula)

Held in place by transverse ligament

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44
Q

Shoulder joint support

A

Lateral support:
- Supraspinatus m.
- O = supraspinus fossa
- I = greater tubercle
- Also extend shoulder joint
- Infraspinatus m.
- O = infraspinous fossa
- I = distal to greater tubercle
- Also abducts the shoulder
- N = suprascapular nerve - motor fibres only

Medial support
- Supscapularis m.
- O = sub scapular fossa
- I = lesser tubercle
- Also adducts the shoulder joint
- N = subscapular nerve - motor fibres only

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45
Q

Shoulder joint extensors

A

Cross cranial to shoulder joint

Brachiocephalicus
- Extrinsic muscle
- Also limb protraction
N = not from brachial plexus

Biceps brachii m. (1 head in dog)
- O = supraglenoid tubercle
- I = ulnar + radial tuberosities
- Intrinsic muscle
- Also allow elbow flexor/shoulder extensor
- Motor nerve supply: Musculocutaneous nerve
- Bicipital bursa
- Protects tendon of origin
- Intertubercular groove
- Transverse ligament

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46
Q

Shoulder joint flexors

A

Cross caudal to shoulder joint

Latissimus dorsi
- Extrinsic muscle
- Also limb retraction
- Nerve supply from brachial plexus

Teres Major
- O = caudal border of scapula
- I = medial humerus
- Nerve supply:
- Axillary nerve
- Motor + sensory fibres

Teres Minor
- Overlies lateral aspect joint space

Deltoids muscle
- 2 heads
- O = scapular spine + acromion process
- I = lateral aspect of humerus
- Intrinsic muscle
- Nerve supply:
- Axillary nerve
- Mixed type (M+S fibres)

Triceps muscle
- 4 heads
- Long head
- O = caudal border scapula
- 2 parts
- I = olecranon of ulna
- Also elbow extensor
- Nerve supply:
- Radial nerve
- Motor + sensory fibres

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47
Q

Shoulder extensors

A

Cranial to shoulder

Brachiocephalicus

Biceps brachii

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48
Q

Shoulder flexors

A

Caudal to shoulder

  • Latisimus dorsi
  • Deltoeus
  • Teres major
  • Triceps - long head
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49
Q

Radius + ulna

A

Long bones

Paired + crosses each other obliquely

Ulna - longer and leverage

Radius - shorter and main weight bearing

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50
Q

Radius

A

Proximal end:
- Head - fovea captitis (articular surface/elbow joint)
- Neck

Body

Distal end
- Trochlea - articular surface (carpus)
- Styloid process
- Medial
- Attachment medial collateral ligament of carpus
- Ulnar notch

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51
Q

Ulna

A

Proximal end:
- Olecranon process
- Anconeal process
- Beak shaped
- Fits into olecranon/ulna fossa of humerus
- Troclear notch
- Articular surface (elbow joint)
- Lateral coronoid process
- Medial coronoid process
- Radial notch
- Articulates with radius

Body

Distal end:
- Styloid process
- Attachment lateral collateral ligament of carpus

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52
Q

Proximal articulation of radius + ulna

A

Radius (head)

Radial notch of ulna

Held by annular ligament
- Runs lateral to medial coronoid process
- Rotation possible

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53
Q

Distal articulation of radius + ulna

A
  • Fibrous joint
  • Some rotation possible
  • Interosseous space:
    • Between bodies
    • Interosseous ligament
    • Fibrous joint
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54
Q

Evolution of radius + ulna

A

Toes rotated cranially

Elbows rotated caudally

Radius + ulna then rotate around eachother

Proximal:
- Ulna most medial projection

Distal:
- Ulna most lateral projection

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55
Q

Palpation of radius + ulna

A

Ulna:
- Olecranon process
- Lateral styloid process

Radius:
- Medial styloid process

Cat:
- Square olecranon
- Radius + ulna similar diameter

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56
Q

Development of radius + ulna

A

Radius (growth plates):
- Proximal epiphyses
- Body
- Distal epiphyses
- Total = 3

Ulna:
- Olecranon process
- Anconeal process
- Body
- Distal epiphyses - conical shape
- Total = 4

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57
Q

Elbow joint

A

Humerus - radius + ulna
- Complex joint

Humerus:
- Trochlea
- Articulates with trochlea notch of ulna + fovea capitis of radius
- Capitulum:
- Articulates only with fovea capitis of radius

Extensive joint capsule
- Osteochondral junction
- Incorporates proximal radio-ulnar articulation

Stability:
- Collateral ligaments
- Humerus - radius + ulna
- Bony structures:
- Anconeal process (ulna)
- Olecranon/ulna fossa (humerus)

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58
Q

Elbow joint - movement

A

Limited to flexion + extension

Ulna acts as lever

Elbow extensors insert onto olecranon
- Avulsion possible

Joint between radius + ulna:
- Rotation possible
- Annular ligament
- Interosseous ligament
- Fibrous joint distally
- Supination
- Pronation
- Dogs - rotation limited
- Cats - large amount of rotation

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59
Q

Elbow extensors

A

Caudal to elbow joint, insert onto olecranon process

Triceps muscle (4 heads)
i) Long head
- O = caudal border of scapula (also shoulder flexor)
ii) Lateral head
- O = lateral aspect humerus
iv) Accessory head
(ii, iii, iv - no effect on shoulder)
Motor nerve supply - radial nerve

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60
Q

Elbow flexors

A

Cranial to elbow joint

Biceps brachii muscle
- O = supraglenoid tubercle
- I = proximal radius
(also shoulder extensor)

Brachial muscle
- O = caudal aspect humerus
- I = proximal radius
- Follows musculospiral/brachial groove
- Motor nerve supply: musculocutaneous nerve

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61
Q

Elbow rotators

A

Supinator muscle
- O = lateral epicondyle
- Radial nerve

Pronator teres muscle
- O = medial epicondyle
- I = proximal radius
- Median nerve

62
Q

Forelimb supply

A

Limb naturally in extended position

Blood vessels cross flexor aspect of joints

Avoids stretching of vessels

Vein, arteries, nerves

Arterial supply:
- Oxygenated blood from heart to peripheral tissues
- Major vessel runs down limb
- Changes name according to region

63
Q

Forelimb arterial supply

A

Subclavian artery
- Runs around 1st rib - axilla

Axillary artery
- Runs through axilla

Brachial artery
- Runs down brachium
- Branches

Median artery
- Runs down medial aspect antebrachium
- Branches - radial artery
- Terminates in superficial palmar arch

Superficial brachial artery
- Runs down cranial aspect antebrachium

64
Q

Palmar blood supply

A

Median artery
- Superficial palmar arch
- Palmar common digital arteries

Caudal interosseous artery
- Deep palmar arch
- Palmar common/digital/metacarpal arteries
- Digital arteries

Palmar supplies fuse then branch resulting in arterial supply to each digit
- 4 vessels per digit
- Palmar supply most important
- Axial palmar proper digital A largest
- Implications when amputating toes

65
Q

Dorsal blood supply

A

Superficial brachial artery
- Superficial dorsal supply to forepaw
- Dorsal common digital arteries
- Dorsal digital artery

66
Q

Forelimb venous blood drainage

A

Veins

Deep system:
- Follows arterial supply

Superficial system:
- Cephalic vein
- Drains into jugular vein/vena cava

67
Q

Carpus

A

Composed of carpal bones
- Short bones

Proximal row:
- Radial/intermediate carpal bone (fused)
- Ulnar carpal bone
- Accessory carpal bone

Distal row:
- 1st, 2nd, 3rd and 4th carpal bones

Carpus - development
- Single centre of ossification
- Except accessory carpal bone = 2
- Fused radial/intermediate carpal bone =2

68
Q

Carpal joints

A

Antebrachio-carpal joint:
- Between antebrachium + carpus
- Between antebrachium + carpus
- Radius - RCB + UCB
- Ulna - UCB + ACB

Midle carpal joint:
- Proximal + distal rows

Carpo-metacarpal jont:
- Distal row + metacarpal bones
- Intercarpal joints

69
Q

Carpal joints - movements

A

Standing position = extension

Large range of flexion
- Most movement antebrachio-carpal joint
- Least movement carpo-metacarpal joint
- Some movement between carpal bones
- ACB acts as level for distal limb
- Insertion of major carpal flexor muscle
- Counteraction by palmar ligament

70
Q

Carpal joint - support

A

Typical synovial joint:
- Single joint capsule extending
- Proximally between metacarpal bones
- Distally between metacarpal bones
- Poor communications between compartments

Collateral ligaments:
- Lateral:
- Ulna to 5th metacarpal bone
- Medial:
- Radius to 2nd metacarpal bone
- Styloid processes vulnerable intracarpal ligaments

Palmar aspect:
- Fibrocartilagenous reinforcement of the joint capsule
Functions:
- Friction free surface for passage of tendons
- Passive maintenance of joint extension/prevention of collapse into hyperextension

Retinaculum
- Sleeve of deep fascia, encloses the carpal region both at palmar + dorsal surface:
- Attaches to lateral aspect of the Accessory carpal bone
- Crosses from ACB to medial aspect carpus
- From carpal canal

71
Q

Carpal canal

A

Dorsal boundary:
- Fibrocartilagenous reinforcement of palmar aspect of carpal joint capsule

Lateral boundary:
- ACB

Palmar boundary:
- Palmar/flexor retinaculum

Dog:
- Deep digital flexor tendon through the tunnel/canal
- Blood vessels + nerves
- Superficial digital flexor tendon outside

72
Q

Carpal joint palpation

A
  • Accessory carpal bone
  • Joint spaces (flexion)
  • Medial styloid process (radius)
  • Lateral styloid process (ulna)
73
Q

Manus

A

Metacarpal bone

Digit
- Proximal phalanx
- Middle phalanx
- Distal phalanx
- Long bones
- Sesamoids

Dog + cat = digitigrade
- 4 weight bearing + 1 vestigial
- Numbered medial to lateral

1st digit = dew claw
- Vestigial
- Medial aspect
- Non-weight bearing
- Has 3 elements
- Commonly removed in puppies

74
Q

Manus development

A

Centres of ossification
- MC (2): Body + proximal end
- PP (2): Body + proximal end
- MP (2): Body + proximal end
- DP (1)

75
Q

Digit

A

Distal Phalanx (DP):
- Long bone - debate
- Ungual process
- Ungual crest
- Round root of claw
- Very vascular
- Extensor process
- Extensor tendons
- Palmar process
- Flexor tendons

76
Q

Joints of manus

A

Metacarpo-phalangeal joint

Promimal interphalangeal joint (PIP)

Distal interphalangeal joint

  • All typical synovial joints
  • Flexion + extension

Stability:
- Collateral ligaments
- Sagittal ridge/groove

77
Q

Metacarpo-phalangeal joint

A

2x proximal sesamoids
- Palmar aspect
- Either side of sagittal ridge
- Protect flexor tendons
1x dorsal sesamoid
- Protect extensor tendons

Resting position extended

Interosseous muscle + proximal sesamoids

Sling configuration - suspends MCP joint

Supported by metacarpal foot pad

78
Q

Distal inter-phalangeal joint

A

Deep digital flexor tendon

Common digital extensor tendon

Dorsal elastic ligament:
- Proximal end (MP)
- Extensor process DP

Dog:
- Forces balanced to maintain tip of claw above horizontal
- Problem if DDFT severed

79
Q

Manus - cat

A

Claws not visible:
- Very strong dorsal elastic ligament
- DIP joint hyperextended
- Claw rests in skin fold/sheath so not visible
- Remain sharp for hunting/climbing

Exposure of claws:
- DDFT flexes joint
- Manual pressure to digital pad

80
Q

Muscles of antebrachium

A

Affects joints of carpus + digits

Muscle belly - antebrachium

Tendon of insertion - distal to carpus

Extensors of distal limb:
- O = lateral epicondyle of humerus
- Run over dorsal aspect carpus
- Radial nerve

Flexors of distal limb:
- O = medial epicondyle
- Run over palmar aspect carpus
- Median + ulnar nerves

81
Q

Extension of carpus

A

O = lateral epicondyle
Innervation = radial nerve

Extensor carpi radialis m.
- I = metacarpal bones

Abductor pollicus longus/extensor carpi obliquus m.
- Crosses at level of carpus
- Sesamoid in tendon of insertion
- I = proximal end of metacarpal II

Extensor carpi ulnaris/ulnaris lateralis m.
- I = 5th metacarpal bone + ACB
- Flexion or extension depending on position of limb

82
Q

Extension of carpus + digitalis

A

O = lateral epicondyle
I = radial nerve

Common digital extension m
- I = all digits
- Distal phalanx - extensor process
- Extends carpus and digits II to V

Lateral digital extensor m.
- I = 4th + 5th digits
- Distal phalanx - extensor process
- Extension of digit II, IV and V

83
Q

Flexion of carpus

A

O = medial epicondyle
I = median + ulnar nerves

Flexor carpi ulnaris m.
- O = olecranon/epicondyle of humerus
- I = accessory carpal bone

Flexor carpi radialis m.
- I = metacarpal bones

84
Q

Flexion of carpus + digits

A

O = medial epicondyle
I = median + ulnar nerves

Superficial digital flexor m.
- I = middle phalanx of all digit (II, III, IV, V)
- Runs out with carpal canal

Deep digital flexor muscle
- O - also radial + ulnar heads
- I - 3rd/distal phalanx of all digits
- Distal phalanx - palmar process
- Tendon runs through carpal canal
- Passes through SDFT

85
Q

Footpads

A

Carpal/stopper pad:
- Protects accessory carpal bone

Metacarpal pad x1 (heart shaped):
- Overlies MCP joints

Functions:
- Resistance to trauma
- Traction - prevent slipping
- Anti-concussive
- Protect deep structures
- Support digit
- Allow weight bearing over DP, MP, PP + MCP joints

86
Q

Organisation of skin

A

Epidermis + dermis

Epidermis:
- Cells constantly produced by germinative layer
- Cells age as move outwards
- Dead at surface + slough
- Constant replacement
- No blood supply
- No nerve supply
- Active production of skin cells

87
Q

Footpad modifications

A

Trauma resistance:
- Increased skin thickness
- Increased turnover of cells
- Active germination layer
- Deposition of keratin
- Hard proteinaceous material
- Keratinised stratified squamous epithelium
- Rough surface (conical papillae)
- Grip
- Sweat glands
- Heat loss
- Hairless, thick skin

88
Q

Footpad components

A

Skin
- Epidermis
- Contains the germinative layer
- Dermis

Superficial fascia

Digital cushion
- Rich in fibroelastic tissue
- Fat
- Vascular supply
Function = shock absorption

Clinical considerations
- Wounds
- Elastic tissue
- Contains excessive vascular channels
- Sweat
- Bandaging
- Damage to DDFT
- stubbed toe

89
Q

Claw

A

No superficial fascia

Dermis
- Fused directly to periosteum of ungual process of DP

Germinative layer
- Active in n2 areas only

Stratum tectorum
- Waterproof surface layer
- Produced by skin in ungual recesses

Tip touches ground
Position maintained by:
- Extensor tendons
- Dorsal elastic ligament
- Balanced by DDFT
Continuous growth
- Tip wears naturally
- Reduced wear
- Not walking
- Walking on soft ground
- Dew claw
- DDFT damage
Claw grows in circular fashion
- Can eventually grow into pan

90
Q

Germinative areas (claw)

A

Germinative area 1:
- Recess between claw + skin
- Horn grows over dorsal + lateral surfaces of ungual process
- Horse shoe shaped in transverse section/short axis

Germinative area 2:
- Palmar surface of ungual process
- Horn covers palmar surface

91
Q

Lymphatic system (paw)

A

Cardiovascular system
- Continuous system
- Leaky capillary bed
- Exchange of material
- Net loss
- Fluid accumulation
- Oedema/swelling in peripheral tissues

Lymphatic vessels
- Recovery/scavenging system
- Series of individual vessels
- Thin walled
- Run from periphery to thoracic duct
- Thoracic duct empties into caudal vena cava
- Transports lost material back into systemic circulation

Lymph nodes
- Filters
- Located where lymph vessels converge
- Prevent contaminants reaching systemic circulation
- Remove invading organisms
- Contain defence cells

92
Q

Forelimb lymph nodes

A

Prescapular lymph node

Axillary lymph node

Enlarged in response to infection.

Can use to differentiate between localised/generalised disease

Important in large animals for meat inspection

93
Q

Nerve supply (paw)

A

Brachial plexus supplies:
Selected extrinsic muscles:
- Pectoral muscles
- Latissimus dorsi
- Serratus ventralis
All intrinsic muscles:
- Subscapular nerve
- Suprascapular nerve
- Musculocutnaeous nerve
- Axillary nerve
- Radial nerve
- Median + ulnar nerve

94
Q

Subscapular nerve

A

Motor nerve - no cutaneous sensation

Medial shoulder support
- Subscapularis m.

95
Q

Suprascapular nerve

A

Motor nerve - no cutaneous sensation

Lateral shoulder support
- Supraspinatous m.
- Infraspinatous m.

96
Q

Musculocutaneous nerve

A

Mixed nerve

Sensory:
- Cutaneous sensation to:
- Cranial + medial aspect of elbow
- Medial aspect of antebrachium

Motor:
- Elbow flexors
- Brachialis m.
- Biceps brachii m.
- Coracobrachialis m.

If damaged:
- No compensation
- Loss of elbow flexion

97
Q

Axillary nerve

A

Mixed nerve

Motor supply:
- Dedicated shoulder flexors
- Deltoideus m.
- Teres major m.

Sensory fibres:
- Cutaneous sensation to:
- Lateral aspect shoulder + brachium

Damage - compensation by:
- Latissimus dorsi
- Long head of triceps

98
Q

Median + ulnar nerve

A

Mixed nerve

Sensory fibres
- Cutaneous sensation to:
- Caudal + palmar aspect limb
- Dorsal aspect 5th digit

Motor supply:
- Carpal + digital flexors
- Flexor carpi ulnaris m.
- Flexor carpi radialis m.
- Superficial digital flexor m
- Deep digital flexor m.

Damage - no compensation
- Loss of distal limb flexion

99
Q

Radial nerve

A

Mixed nerve

Sensory fibres:
- Cutaneous sensation to:
- Dorsal + cranial aspect limb
- Except dorsal aspect 5th digit

Motor supply
- Extensors of elbow
- Triceps m.
- Extensors of carpus + digits
- Extensor carpi radialis m.
- Extensor carpi ulnaris/ulnaris lateralis m.
- Common digital extensor m.
- Lateral digital extensor m.

100
Q

Radial nerve - route

A
  • Starts medial
  • Passes caudal to shoulder
  • Passes through triceps
    • Supplies triceps
  • Follows musculospiral groove
  • Branch - lateral epicondyle
    • Supplies distal limb extensors
  • Branch - cranial/dorsal aspect of limb
    • Runs alongside cephalic vein
    • Supplies cutaneous sensation
  • Humeral fracture most common cause of damage
  • deficits depend on level of damage
101
Q

Radial nerve damage

A

Motor losses

Proximal level:
- All extensor m. affected
- Can’t extend elbow, carpus or digits
- Limb appears longer than opposite one

Distal level:
- Extensors of carpus + digits affected
- Can’t extend carpus/digits

Triceps intact
- Can’t extend elbow
- Can weight bear if limb extended
- Can learn to swing leg to compensate

102
Q

Brachial plexus damage

A

Tear/avulsion = stretching

  • High impact collision
  • Head + neck one direction
    • Limb the other direction
  • Regeneration possible with time
  • Mismatching may result in aberrant sensation

Tumour
- Effects depend on which nerves affected

Effect on limb:
- CAN protract/abduct limb
- Can’t retract/adduct limb
- Can’t extend/flex limb
- Can’t weight bear

No cutaneous sensation on limb or lateral thorax to level of 3rd intercostal space

103
Q

Equine forelimb

A

Unguligrade

Perissodactyla

Weight bearing distal phalanx of 3rd digit

Same bones

Same joints

Same muscles as dog

Manus expanded
- Don’t confuse with antebrachium

104
Q

Superficial structures of equine forelimb

A

Chestnut:
- Vestigial horn pad
- 1st metacarpal bone

Ergot:
- Horny lump in skin
- Palmar aspect MCP joint
- Hidden by hairs
- Remnant of metacarpal pad

105
Q

Biceps brachii m. (equine)

A

Function = extends shoulder/flexes elbow
Origin = supraglenoid tubercle
- Separated from glenoid cavity
Insertion = proximal radius

Double tendon of origin
- Humerus
- Intermediate tubercle
- 2 inter-tubercular grooves

Bicipital bursa
- Separate from shoulder joint capsule

Lacerates fibrosis:
- Fibrous extension
- Joins extensor carpi radialis
- Inserts proximal MC3
- Maintains shoulder + carpus in extension
- Part of stay apparatus

106
Q

Elbow joint (equine)

A

Radius + ulna fused
- No rotation
- No annular ligament
- Collateral ligaments present

Triceps only 3 heads

Bursa:
- Fluid filled cushion
- Protection of tendons
- Tricipital bursa
- Between tendon + olecranon process
- Subcutaneous bursa
- Between skin + tendon of insertion of triceps

Clinical significance:
- Capped elbow - poor bedding
- Deeper swelling - true bursitis

107
Q

Carpus (equine)

A

Carpal bones:
- All present except 1st
- 3rd CP largest

Movement:
- Most at antebrachio carpal joint
- Lease carpometacarpal joint
- Collecting joint fluid samples

108
Q

Carpus joint (equine)

A

Synovial joint
- Separates compartments

Support:
- Collateral ligaments
- Palmar ligament
- Palmar fibrocartilagenous plate:
- Origin of check ligament for DDFT
- Flexor reticulum

Carpal canal:
- Palmar fibrocartilagenous plate
- Palmar/flexor retinaculum
- Accessory carpal bone
(Dog: DDFT only)
Horse: both DDFT + SDFT

109
Q

Tendon sheath (equine)

A

Protects tendon in confined spaces

Dorsal aspect:
- Surrounds extensor tendons

Carpal canal:
- 1 sheath for DDFT + SDFT
- Inflammation - increased pressure
- Throroughpin bulges proximally + distally

110
Q

Metacarpal bones (equine)

A

3rd MC = cannon bone

Weight bearing

Distal articular surface
- Sagittal ridge

2nd + 4th metacarpal bones:
- Splint bones
- Vestigial - non-weight bearing
- Button at distal end - palpable

Joints between MCs:
- Fibrous joints (syndesmosis)
- Mineralise with age
- Splints

111
Q

Phalanges (equine)

A

Proximal phalanx (P1)
- Long pastern bone
- Raised V on palmar surface
- Attachment oblique distal sesamoidean ligament

Middle phalanx (P2)
- Short pastern bone

Bony contours
- Attachement collateral ligaments - ringbone

112
Q

Distal phalanx (P3) (equine)

A

Pedal/coffin bone
- Complex shape
- Extensor process
- Attachment common digital extensor tendon
- Palmar processes
- Support lateral cartilages
- Solar surface
- Attachment deep digital flexor tendon

Dorsal surface:
- Striations:
- Hoof attachment
- Blood vessels
- Vascular channel
(vs nutrient foramen)

113
Q

Manus bone development (equine)

A

Centres of ossification:
MC 3:
- Body + distal epiphyses (2)
MC 2 + 4:
- Proximal epiphyses + body (2)
PP:
- Proximal epiphyses + body (2)
DP:
- Body (1)

114
Q

Proximal sesamoids (equine)

A

No dorsal sesamoid

Proximal sesamoid bones:
- Triangular shaped
- Distal end MC3
- Either side of sagittal ridge
- Embedded in suspensory ligament (interosseous L)

Functions
- Protect SDFT and DDFT

115
Q

Distal sesamoid (equine)

A

Navicular bone
- 2 flat articular surfaces
- Covered with hyaline cartilage
- Vascular channels
- Located palmar aspect DIP joint
- Dorsal surface
- Articulates with MP + DP
- Palmar surface
- Guides DDFT over DIP joint
- Under large amount of pressure

116
Q

Metacarpo-phalangeal joint (MCP) (equine)

A

Fetlock
- MC3 and PP
- Synovial joint
- Extensive joint capsule
- Large dorsal pouch
- Protects extensor tendons
- Large palmar pouch
- Incorporates proximal sesamoids
- No dorsal sesamoid (c.f dog)

Natural position = extension
Limited to flexion + extension
- Sagittal ridge distal MC3
- Sagittal groove proximal PP
- Collateral ligaments
- MC - PP

Tendency to collapse into hyperextension
- Suspensory ligament
- Sesamoidean ligaments

117
Q

Suspensory ligaments (equine)

A

Entirely ligamentous

Origin:
- Proximal palmar MC3
- Fills area between splint bones
Branches:
- Abaxial aspect proximal sesamoids
- Passes to dorsal aspect
- Fuses with common digital extensor tendon

Function:
- Prevent collapse of MCP joint during weight bearing
- Return MCP from hyperextension to normal extended position
- Relies on stability of proximal sesamoid bones

118
Q

Carpal joints - support (equine)

A

Inter-sesamoidean ligament
- Reinforced fibrocartilage
- Proximal scutum (shield)
- Passage of DDFT + SDFT over sesamoids

Collateral sesamoidean ligaments:
- Proximal sesamoids - MC + PP

119
Q

Sesamoiden ligaments 2 (equine)

A

1) Cruciate
2) Short
- Proximal sesamoids - PP
3) Oblique:
- Proximal sesamoids - PP
- V-shaped through on PP
4) Straight ligament:
- Proximal sesamoids - MP
- Inserts with SDFT

120
Q

MCP Joint (equine)

A

Function relies on interaction between
- Suspensory ligament
- Proximal sesamoids
- Sesamoidean ligaments
- Common digital extensor tendon

121
Q

Proximal Interphalangeal joint (PIP) (equine)

A

“Pastern” joint
Limited to flexion + extension
- Distal PP - sagittal groove
- Proximal MP - sagittal groove
- Collateral ligaments:
- Run from PP - MP
- Extension runs to navicular bone

122
Q

Distal interphalangeal joint (DIP) (equine)

A

Coffin joint - buried in hoof

Components:
- Middle P + distal P
- Distal sesamoid + DP
- Distal sesamoid MP

Extensive joint capsule
- Forms bursa
- Protects extensor tendon
- Accessible for injection

Flexion + extension
- Sagittal ridge + groove
- Broad so some rotation possible to accommodate uneven ground
- Collateral ligaments (CL)
- MP - DP
- Movement
- Common digital extensor tendon
- Deep digital flexor tendon
- No dorsal elastic ligament in horse

123
Q

Digital sesamoid (equine)

A

Ligaments of distal sesamoid:
- Collateral ligament:
- PP - distal sesamoid
- Impar ligament:
- DP - distal sesamoid

Navicular/podotrochlear bursa:
- Fluid filled pocket
- Located between sesamoid + DDFT
- Separated from DIP joint by impar ligament
- Protects deep Digital flexor tendon (DDFT)

124
Q

Lateral/ungual cartilages (equine)

A
  • Cartilage plates
  • Palmar processes DP
  • Medial + lateral
  • Project above level of hoof
  • Shock absorption
  • Palpable feature in liver animal (proximal part)

Radiography:
- Cartilage not visible
- Mineralise as age
- “sidebone”

125
Q

Extensor tendons (equine)

A

Below carpus = fibrous tissue only
(tendons/ligaments)
Muscle bellies in antebrachium

Common digital extensor (CDE):
- Crosses dorsal aspect carpus
- Joined by 2 branches of suspensory ligament
- Insert PP, MP + DP

Latera digital extensor (LDE):
- Inserts PP
- Separates from CDE

126
Q

Flexor tendons (equine)

A

Superficial digital flexor tendon:
- Accessory check ligament
- O = proximal to carpal canal
- Passes through carpal canal
- Splits to allow DDFT pass through it
- Inserts MP

Deep digital flexor tendon:
- Passes through carpal canal
- Accessory check ligament
- Originates from fibrocartilage plate on palmar aspect of carpus
- Fuses with DDFT
- Passes through split in SDFT
- Runs over navicular bursa/navicular bone
- Inserts DP

127
Q

Metacarpal region palpation (equine)

A

Dorsal aspect = extensor tendons

Palmar aspect =
- Skin
- SDFT
- DDFT
- Check ligament (fuses with DDFT)
- Suspensory ligament (splits into 2 branches)

Clinical relevance:
- Tendon trauma in common
- Ultrasound examination is ideal for soft tissue damage

128
Q

Metacarpal region - ultrasound (equine)

A

Most lesions appear as hypoechoic (grey) from inflammation + necrosis; white lines are normal appearance of collagen

Utility severity = how much of tendon is involved

Convince owner and trainer to rest patient if lesions appear.

129
Q

Digital region (equine)

A

Scutum = cartilage shield/plate
- Palmar aspect joints
- MCP = intersesamoidean ligament
- Smooth passage for tendons

Annular ligaments:
- Hold DDFT + SDFT against bones

Tendon sheath:
- Shared by SDFT + DDFT
- Extends from annular ligament distally
- Inflammation - increased pressure

Clinical considerations:
- Palpation of swellings
- Bony swellings: splints
- Soft swellings
- Articular joint
- Between suspensory ligament + MC3
- Tendon sheath
- Palmar to suspensory ligament + proximal to annular ligament

130
Q

Stay apparatus

A

Most of weight borne on forelimb

Mechanism for passive weight bearing

Serratus ventralis
- Suspends weight of body between forelimbs

Maintenance of extension:
- Shoulder:
- Biceps brachii
- Elbow:
- Collateral ligaments
- Alignment of bones
- Carpus:
- Lacertus fibrosis

Prevention of hyperextension of the:
- Carpus:
- Palmar fibrocartilage joint reinforcement
- SDFT and check ligament
- Retinaculum
- MCP joint:
- Suspensory ligament
- Common digital extensor
- Proximal sesamoids
- Distal sesamoidean ligaments
- MCP, PIP + DIP joints:
- Prevention of hyperextension = DDFT + SDFT - check ligaments
- Annular ligaments
- Bind them to palmar aspect of digit

131
Q

Blood supply (equine)

A

Arterial supply similar to dog

Brachial artery
- Medial aspect elbow
- Palpable pulse

Medial + lateral digital arteries
- Abaxial aspects proximal sesamoids (behind fetlock joint)
- Palpable pulse

Venous drainage
- Similar to dog
- No clinical relevance

132
Q

Nerve supply (equine)

A

Brachial plexus:
- Same branches as dog
- Same motor function as dog

Nerve damage uncommon

Suprascapular nerve (motor)
- Runs round neck of scapula
- Supplies:
- Supraspinatous
- Infraspinatous
- No cutaneous sensation
- Damage causes joint instability

Different sensory areas:
- Distal to carpus
- Median + ulna nerves combine
- Supply pastern + foot
- Combined with musculocutanous nerve
- Medial aspect metacarpal area

133
Q

Median + ulnar nerves (equine)

A

Combine distal to carpus

2 major branches:
1) Palmar metacarpal nerves
- Paired (medial + lateral)
- Run between MC3 + splint bones
- Emerge at distal end of splint bones
- Supply dorsal aspect of digit

2) Palmar nerves
- Paired (medial + lateral)
- Between suspensory ligament + SDFT
- Cross abaxial aspect proximal sesamoids
Become:
- Palmar digital nerve
- Dorsal and palmar branches
- Supplies hoof contents

134
Q

Hoof

A

Divided into 4 parts
- Wall (toe/quarters/heel/bar)
- Periople
- Sole
- Frog

135
Q

Solar surface of hoof

A

Frog - rubbery wedge shaped structure between the bars

Bars of heel - 2 bars on each hoof, on either side of frog

Sole - covers the bottom of foot

White line - interconnected lamina

Walls - weight bearing (nails)

Bulbs of heel

Central sulcus

Collateral sulci

Coronary band:
- Transition between skin + hoof wall
- Produces hoof wall
- Marks boundary between skin + hoof

Periople:
- Round coronary region
- Produces waterproof later
- Extends 2/3 way down hoof
- Prevents evaporation, wear + tear

136
Q

Hoof contents

A
  • Middle phalanx (distal end/P2)
  • Distal phalanx (P3)
  • DIP joint
  • Navicular bone
  • DDFT
  • Navicular bursa

Clinical significance:
- Penetration injuries:
- Significance depends on:
- Location
- Depth
- Abscess formation/pododermatitis
- Significant pain
- Palpable digital pulses

Lateral/ungual cartilages:
- Cartilage plates
- Palmar processes DP
- Medial (inner) + lateral (outer)
- Shock absorption
- Mineralise as age (sidebone)

137
Q

Hoof production

A

Dermis (corium)
- Covers DP + digital cushion
- Blood + nerve supply
- Sensitive
- Supplies germinative layer

Germinative layer:
- Produces epidermis
- Active in 2 areas only
- Coronary band
- Solar suface

Dermis fused to DP
- Surface of dermis forms vertical ridges = laminae
- Primary = macroscopic
- Secondary = microscopic
- Secondary (contains blood + nerves)

Hoof wall:
- Epidermal horn tubes glide distally
- Internal surface interdigitates with dermal laminae
- Forms corresponding primary + secondary laminae known as epidermal/insensitive laminae

Interdigitation = white line
- Prevents separation of epidermis from DP
- Transfers weight from hoof wall to DP

Solar surface - active germinative layer
- Sole:
- Keratinised flakes
- No tubular horns
- Frog:
- Incomplete keratinisation
- Soft + elastic

138
Q

Coronary band

A

Dermis formed into conical shaped papillae

Produce epidermis in the form of tubes of keratin

Extend distally towards ground

Grow 5-6mm / 1/4 inch per month

Gaps filled by intertubular horn

Form hoof wall

Weight bearing surface

139
Q

Weight bearing in hooves

A

Frog contacts ground first

Forces passed to:
- Digital cushion (blood forced back up leg)
- Lateral cartilages

Hoof wall contacts ground
- Weight transferred to distal phalanx then via laminae to hoof wall

140
Q

Farrier

A

Foot trimming
- Horn grows continuously

Shoeing:
- Protect weight bearing wall
- Shape doesn’t restrict heel
- Therapeutic shoes

Nails:
- Insensitive laminae
- Outwith white line
- Sledge tipped nails
- Tips clipped + flattened = clenches
- Must raise clenches before one can remove shoe

141
Q

Ruminant hoof

A
  • Cloven hoof
  • Medial + lateral claws
  • Interdigital cleft
  • Sole
  • Heel
  • No frog
  • No angles and the bars
  • Wall
    • Lateral - convex
      • Continuous with heel
    • Medial - vertical
      • Stops at paralegal groove
      • Transition hard - soft horn
      • Prone to damage

Shock absorption:
- Bulbous heels
- Digital cushion
- Digits splay
- Supported by interdigital ligaments
- No lateral cartilages
- No frog

142
Q

Ruminant hoof growth

A
  • Coronary band
  • Only part of dermis covered by laminae
  • Sensitive laminae
  • Insensitive laminae
  • Primary only
  • No secondary
143
Q

Sheep + goat hooves

A

Goat hooves are well adapted for climbing hard walls, softer soles for traction on steep inclines

Same as cattle

Skin gland proximal to inter-digital cleft
- Waxy substance produced by sebaceous + serous gland
- Also seen in ungulates

Overgrowth a problem
- Need to be trimmed

144
Q

Pig hoof

A
  • Similar to ruminants
  • No frog
  • No lateral cartilages
145
Q

Comparative anatomy of scapula

A

Dog:
- Acromion process
- Tuber spine is absent
- Supraglenoid tubercle part of glenoid cavity
Horse:
- Narrow supraspinous fossa
- Acromion process is absent
- Prominent tuber spine
- Supraglenoid tubercle separate from glenoid cavity
- Glenoid notch is present
Cow:
- Broad dorsal border + larger infraspinous fossa
- Acromion process is blunt + doesn’t reach to the level of glenoid cavity
- Tuber spine is less prominent/absent
- Indistinct glenoid notch
Pig:
- Round cranial margin
- Poorly defined acromion
- Prominent tuber

146
Q

Comparative anatomy of the humerus

A

Horse:
- Greater tubercle
- Cranial + caudal parts
- Level with humeral head
- Lesser tubercle
- Similar size
- Intermediate tubercle
- Double intertubercular groove
- Supratrochlear foramen absent
- Very prominent deltoid tuberosity
Dog:
- Single greater tubercle
- Supratrochlear foramen
Cow:
1) greater tubercle
- Cranial + caudal parts
- Much higher level than humeral head
- Pointed shape
- Cranial part of greater tubercle is massive and overhangs inter tubercular groove medially
2) Single inter tubercular groove
3) Circular area for insertion of infraspinatus m.
- Lateral aspect of greater tubercle
4) Relatively to horse deltoid tuberosity is small
5) No supratrochlear foramen
Pig:
- Greater tubercle
- Cranial + caudal parts
- Also higher than humeral head
- Rounded shape
- Almost enclose inter tubercular groove
- Single interbucular groove
- No supratrochlear foramen
- No flattened thumb print

147
Q

Comparative anatomy of radius + ulna

A

Dog + cat:
- 2 separate complete bones
- Rotation possible
Horse:
- Proximal ulna present + fused to radius
- Body of ulna absent
- Distal ulna present + fused with radius
- Lateral styloid process
- Radius - medial styloid process
- No rotation possible
Ruminant:
- 2 complete bones
- Fuse as animal ages
- No rotation
Pig:
- 2 complete separate bones
- Ulna same diameter as radius
- No interosseous space
- No rotation

148
Q

Comparative anatomy of carpus

A

Dog + cat:
- Radial + intermediate fused
- Distal row all present
Horse:
- All present (except variable 1st CB)
Pig:
- All present
Ruminant:
- Proximal row all present
- Distal row:
- 1st CB absent
- 2nd + 3rd CB fused

149
Q

Comparative anatomy of carpal canal

A

Dog + cat:
- Only DDFT passes through
Horse:
- Both DDFT + SDFT
Ruminant + pig
- DDFT + half SDFT (SDFT splits)

150
Q

Comparative anatomy of the manus

A

Dog:
- Digitigrade
- Weight bears on digit 3rd phalanges)
- 2nd-5th weight bearing
- 1st digit vestigial
Horse:
- Unguligrade
- Perissodactlya
- Weightbears on distal phalanx
- 3rd MC and digit only
- Rest absent
Ruminants:
- Unguligrade
- Artiodactyla
- 3rd + 4th digits are present
- Weight bears on distal phalanx

151
Q

Comparative anatomy of metacarpal bones

A

Ruminants:
- MC1 + 2 absent
- MC 3 + 4:
- Separate in foetal life
- Fuses in uterus
- 2 medullary cavities
- Axial bony septum
- Proximal end - 1 articular surface
- Distal end - 2 articular sufaces
- 4 Centres of ossification
- MC 5 - vestigial spur

152
Q
A

Liv vet med yr1 (18 decks)

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