Structural Modifications Of The Foot pad And Nerve Supply Flashcards
Describe where the carpal/ stopper pad is found hence its function
Protects accessory carpal bone
Describe the shape and location of the metacarpal pad
Heartshaped, overlies metacarpal phalangeal joint
Describe the number and location of the distal pads
Overlies distal interphalangeal joint, there are 4
What 2 layers does the skin consist of?
Epidermis and dermis
What does the integumentary system consist of?
Skin and appendages/ accessory structures
Describe the structure of the epidermis
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)
Describe the structure and function of the dermis
Blood supply
Nerve supply
Sensitive and bleeds
Supports germinative layer (active production of skin cells)
Describe footpad modifications to resist trauma resistance
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
Identify the components of the footpad and the function of the footpad
Skin (epidermis contains the germinative layer,dermis)
Superficial fascia
Digital cushion (rich in fibre-elastic tissue, fat, vascular tissue)
FUNCTION= SHOCK ABSORPTION
Identify the clinical considerations associated with the footpad
Wounds- elastic tissue, contains excessive vascular channels
Sweat- bandaging
Damage to Deep digital flexor tendon- stubbed toe
Describe the structure of the claw
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
How is the normal position of the claw maintained?
Normal claw touches the ground Position maintained by: -extensor tendons -dorsal elastic ligament -balanced by deep digital flexor tendon
How does the claw grow
In a circular fashion
Tip wears naturally
What factors may lead to reduced wear of the claw?
Not walking
Walking on soft ground
Dew caw
DDFT damage
What type of skin makes up the horn?
Epidermis
Identify the nerves of the brachial plexus which supply selected extrinsic muscles and all intrinsic muscles?
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
Describe the structure of the subscapular and suprascapular nerve and where do they supply
Both have motor nerves only (no cutaneous sensation)
Subscapular nerve- medial shoulder support (subscapularis muscle)
Suprascapular nerve- lateral shoulder support (supraspinatous muscle, infraspinatous muscle)
Describe the structure of the musculocutaneous nerve. What happens if its damaged?
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
Describe the structure of the axillary nerve, what it supplies and what happens if its damaged
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
Describe the structure of the median and ulnar nerve. Where does it supply and what happens if its damaged?
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
Describe the structure of the radial nerve and where it supplies.
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)
Describe the route of the radial nerve
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)
What motor loses can occur as a result of radial nerve damage?
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
What sensory losses can occur as a result of radial nerve damage?
Cranial and dorsal aspect of the limb
Trauma to dorsal aspect of the paw if drags
Self mutilation
CHECK SENSATION USING FORCEPS
What effect a brachial plexus damage have on the limb?
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
