Structural Modifications Of The Foot pad And Nerve Supply

Question 1

Describe where the carpal/ stopper pad is found hence its function

Answer 1

Protects accessory carpal bone

Question 2

Describe the shape and location of the metacarpal pad

Answer 2

Heartshaped, overlies metacarpal phalangeal joint

Question 3

Describe the number and location of the distal pads

Answer 3

Overlies distal interphalangeal joint, there are 4

Question 4

What 2 layers does the skin consist of?

Answer 4

Epidermis and dermis

Question 5

What does the integumentary system consist of?

Answer 5

Skin and appendages/ accessory structures

Question 6

Describe the structure of the epidermis

Answer 6

Cells constantly produced by Germative layer
Cells age as move outwards
Dead at the surface and slough
Constant replacement
No blood supply
No nerve supply (insensitive and no bleeding)

Question 7

Describe the structure and function of the dermis

Answer 7

Blood supply
Nerve supply
Sensitive and bleeds
Supports germinative layer (active production of skin cells)

Question 8

Describe footpad modifications to resist trauma resistance

Answer 8

Increased skin thickness
Increased turnover of cells- active germinative layer
Deposition of keratin- hard proteinaceous material, keratinised stratified squamous epithelium
Rough surface to grip
Sweat glands for heat loss
Hairless

Question 9

Identify the components of the footpad and the function of the footpad

Answer 9

Skin (epidermis contains the germinative layer,dermis)
Superficial fascia
Digital cushion (rich in fibre-elastic tissue, fat, vascular tissue)

FUNCTION= SHOCK ABSORPTION

Question 10

Identify the clinical considerations associated with the footpad

Answer 10

Wounds- elastic tissue, contains excessive vascular channels
Sweat- bandaging
Damage to Deep digital flexor tendon- stubbed toe

Question 11

Describe the structure of the claw

Answer 11

No superficial fascia
Dermis- fused directly to periosteum of ungual process of digital phalanx
Epidermis- heavily keratinised
Stratum tectorum (waterproof surface laye, produced by skin in the ungual recesses)

Germinative layer (only active in 2 layers)
GERMINATIVE LAYER 1:
-recess between claw and the skin
Horn grows over dorsal and lateral surfaces of ungual process
Horse shoe shaped in a transverse section

GERMINATIVE LAYER 2:
Palmar surface of the ungual process
Horn covers palmar surface

Question 12

How is the normal position of the claw maintained?

Answer 12

Normal claw touches the ground 
Position maintained by: 
-extensor tendons 
-dorsal elastic ligament 
-balanced by deep digital flexor tendon

Question 13

How does the claw grow

Answer 13

In a circular fashion

Tip wears naturally

Question 14

What factors may lead to reduced wear of the claw?

Answer 14

Not walking
Walking on soft ground
Dew caw
DDFT damage

Question 15

What type of skin makes up the horn?

Answer 15

Epidermis

Question 16

Identify the nerves of the brachial plexus which supply selected extrinsic muscles and all intrinsic muscles?

Answer 16

Selected extrinsic muscles:

• pectoral muscles
• latissimus dorsi
• serratus ventralis

All intrinsic muscles: 
-subscapular nerve 
-suprasacpular nerve 
Musculocutaneous nerve 
Axillary nerve 
Radial nerve 
Median and ulna nerve

Question 17

Describe the structure of the subscapular and suprascapular nerve and where do they supply

Answer 17

Both have motor nerves only (no cutaneous sensation)
Subscapular nerve- medial shoulder support (subscapularis muscle)

Suprascapular nerve- lateral shoulder support (supraspinatous muscle, infraspinatous muscle)

Question 18

Describe the structure of the musculocutaneous nerve. What happens if its damaged?

Answer 18

Mixed nerve:
SENSORY: Cutaneous sensation to cranial and medial aspect of the elbow and medial aspect of the antebrachium

MOTOR: elbow flexors (branchiis muscle,biceps branchii muscle and Coracobrachialis muscle)

If damaged, no compensation and loss of elbow motion

Question 19

Describe the structure of the axillary nerve, what it supplies and what happens if its damaged

Answer 19

Mixed nerve
MOTOR SUPPLY: dedicated shoulder flexors (deltoideus muscle, teres major muscle)
SENSORY FIBRES: cutaneous sensation to lateral aspect of shoulder and brachium

Damage- compromised by:
Latissimus dorsi
Log head triceps

Question 20

Describe the structure of the median and ulnar nerve. Where does it supply and what happens if its damaged?

Answer 20

Mixed fibre
SENSORY FIBRES: cutaneous sensation to caudal and palmar aspect of the limb and dorsal aspect of the 5th digit
MOTOR SUPPLY: carpal and digital flexors (flexor carpi ulnaris muscle flexor carpi radius muscle, superficial digital flexor muscle, deep digital flexor muscle)

Damage= no compensation and therefore loss of distal lib flexion

Question 21

Describe the structure of the radial nerve and where it supplies.

Answer 21

Mixed nerve
SENSORY SUPPLY: cutaneous sensation to dorsal and cranial aspect of the limb, except the dorsal aspect 5th digit
MOTOR SUPPLY: extensors of the elbow (triceps muscle), extensors of carpus and digits (extensor carpi radialis muscle, extensor carpi ulnaris/ ulnaris lateralis muscle, common digital extensor muscle, lateral digital extensor muscle)

Question 22

Describe the route of the radial nerve

Answer 22

Starts medially, passes audial to the shoulder, passes through triceps (supplies triceps), follows musculospinal groove and branchialis muscle.
Branch into the lateral epicondyle (supplies distal limb extensors) and branches into cranial dorsal aspect of the limb (runs alongside the cephalic vein and supplies cutaneous sensation)

Question 23

What motor loses can occur as a result of radial nerve damage?

Answer 23

Proximal level:

• all extensor muscles effected
• cannot extend elbow, carpus or digits
• cannot bear weight
• limb appears longer than opposite one

Distal level:
Extensors of carpus and digits affected (cannot extend carpus/ digits)

Triceps intact

• can extend elbow
• can bear weight if limb is extended
• can learn to swing leg to compensate

Question 24

What sensory losses can occur as a result of radial nerve damage?

Answer 24

Cranial and dorsal aspect of the limb
Trauma to dorsal aspect of the paw if drags
Self mutilation

CHECK SENSATION USING FORCEPS

Question 25

What effect a brachial plexus damage have on the limb?

Answer 25

Can protract/abduct limb
Cannot retract/ adduct lim
Cannot extend/ flex limb
Cannot bear weight

NO CUTANEOUS SENSATION ON LIMB OR LATERAL THORAX TO LEVEL OF 3RD INTERCOSTAL SPACE