locomotion anatomy

VET30370

intrinsic muscles

originate and insert on the bones of the thoracic limb

have no direct association with the neck or trunk

lateral shoulder muscles

supraspinatus

infraspinatus

deltoid

supraspinatus

action- extend shoulder

origin- scapular supraspinous fossa

insertion- greater tubercle of humerus

innervation- suprascapular n.

infraspinatus

action- abduct shoulder, rotate shoulder laterally, extend or flex the joint

origin- scapular infraspinous fossa

insertion- greater tubercle of humerus

innervation- suprascapular n.

deltoid

action- flex shoulder

origin- scapular spine & acromion process

insertion- deltoid tuberosity of humerus

innervation- axillary n.

medial shoulder muscles

subscapular

teres major

subscapular

action- extend the shoulder, adduct the shoulder, rotate shoulder medially

origin- subscapular fossa

insertion-lesser tubercle of humerus

innervation- subscapular n.

teres major

action- flex shoulder, rotate shoulder medially

origin- scapular caudal border

insertion- teres major tuberosity of the humerus

innervation- axillary nerve

shoulder extensors

• supraspinatous

• subscapular

• biceps

shoulder flexors

• deltoid

• teres major

• triceps

thoracic limb nerves

• axillary

• musculocutaneous

• radial

• ulnar

• median

axillary nerve

originates from C7-C8

innervates:

• shoulder flexors

  • deltoid

  • teres major

  • subscapularis

• skin of dorsolateral brachium

musculocutaneous nerve

originates from C6-C7

innervates:

• biceps (elbow flexor)

• brachialis (distal branch)

• skin of medial antebrachium (medial branch)

radial nerve

originates from C7-T1

innervates:

• tricep (elbow extensor)

• carpus & digit extensors (deep branch)

  • extensor carpi radialis

  • common digital extensor

  • lateral digital extensor

  • ulnaris lateralis

• skin of the cranial & lateral antebrachium & dorsal paw (superficial branch)

ulnar nerve

originates from C8-T2

gives off caudal antebrachial cutaneous branch above the elbow

innervates:

• carpus & digit flexors

  • flexor carpi ulnaris

  • deep digital flexors

• skin of caudal antebrachium, palmar paw, & 5 metacarpal

median nerve

originates from C8-T1

innervates:

• carpus & digit flexors

  • pronator teres

  • flexor carpi radialis

  • superficial digital flexor

  • deep digital flexor

• skin caudal antebrachium & palmar manus

caudal brachium muscles

tensor fasciae antebrachii

triceps

triceps

action- extend elbow, flex shoulder

origin- scapular caudal border, humerus tricipital line & lesser tubercle

insertion- olecranon tuber of ulna

innervation- radial n.

cranial brachium muscles

• biceps

• brachialis

biceps

action- flex elbow, extend shoulder

origin- scapular supraglenoid tubercle

insertion- ulnar & radial tuberosities

innervation- musculocutaneous n.

brachialis

action- flex elbow

origin- proximal humerus

insertion- ulnar & radial tuberosities

innervation- musculocutaneous n.

cranial & lateral antebrachium muscles

• extensor carpi radialis

• common digital extensor

• lateral digital extensor

• ulnaris lateralis

extensor carpi radialis

action- extend carpus

origin- lateral supracondylar crest of humerus

insertion- base of metacarpals 2 & 3

innervation- radial n.

common digital extensor

action- extend digits 2-5, extend carpus

origin- lateral epicondyle of humerus

insertion- distal end of phalanges of digits 2-5

innervation- radial n.

lateral digital extensor

action- extend digits 3-5, extend carpus

origin- lateral epicondyle of humerus

insertion- proximal end of phalanges of digits 3-5

innervation- radial n.

ulnaris lateralis

action- abduct carpal joint

origin- lateral epicondyle of humerus

insertion- metacarpal 5 & accessory carpal bone

innervation- radial n.

caudal & medial antebrachium muscles

pronator teres

flexor carpi radialis

superficial digital flexor

flexor carpi ulnaris

deep digital flexor

pronator teres

action- flex elbow, rotate forearm medially (pronation)

origin- medial epicondyle of humerus

insertion- medial border of radius

innervation- median n.

flexor carpi radialis

action- flex carpus

origin- medial epicondyle of humerus & medial radius

insertion- bases of metacarpals 2 & 3

innervation- median n.

superficial digital flexor

action- flex digits 2-5

origin- medial epicondyle of humerus (distal)

insertion- base of phalanges of digits 2-5

innervation- median n.

flexor carpi ulnaris

action- flex carpus

origin- medial epicondyle of humerus (distal)

insertion- accessory carpal bone

innervation- ulnar n.

deep digital flexor

action- flex carpus, flex digits

origin- humerus, ulnar, & radial heads

insertion- distal phalanx of each digit

innervation- median & ulnar n.

carpal & thoracic limb digital extensors

• extensor carpi radialis

• common digital extensor

• lateral digital extensor

carpal & thoracic limb digital flexors

• ulnaris lateralis

• flexor carpi radialis

• superficial digital flexor

• flexor carpi ulnaris

• deep digital flexor

thoracic limb blood flow

• aorta

• subclavian

• axillary

  • gives off 4 branches (don’t need to know)

• brachial

• median

  • ulnar

  • radial

superficial hip & thigh musles

• tensor fascia latae

• superficial gluteal

• middle gluteal

• deep gluteal

tensor fascia latae

action- flex hip, extend stifle

origin- tuber coxae & ilium

insertion- lateral femoral fascia

innervation- cranial gluteal n

superficial gluteal

action- extend hip, abduct limb

origin- sacrum & 1st caudal vertebrae

insertion- third trochanter of femur (proximal)

innervation- caudal gluteal n

middle gluteal

action- extend hip, abduct hip, rotate limb medially (main propulsive muscle)

origin- ilium

insertion- greater trochanter of femur (proximal)

innervation- cranial gluteal n

deep gluteal

action- extend hip, abduct hip, rotate limb medially

origin- ilium body & ischiatic spine

insertion- greater trochanter of femur (proximal)

innervation- cranial gluteal n

caudal thigh muscles

• biceps femoris

• semitendinosus

• semimembranosus

biceps femoris

action- extend hip, stifle, hock

origin- sacrotuberous ligament & ischiatic tuberosity

insertion- patella, cranial tibia, & tuber calcanei

innervation- sciatic n

semitendinosus

action- extend hip & hock, flex stifle

origin- ischiatic tuberosity

insertion- cranial tibia & tuber calcanei

innervation- sciatic n

semimembranosus

action- extend hip & stifle

origin- ischiatic tuberosity

insertion- distal femur & medial condyle of the tibia (distal)

innervation- sciatic n

medial thigh muscles

• sartorius

• pectineus

• adductor

• gracilis

sartorius

action- flex the hip & stifle, extend stifle

origin- crest of ileum & ventral iliac spine

insertion- patella & cranial tibia

innervation- femoral n

pectineus

action- adduct limb

origin- pubic tubercle

insertion- distal femur

innervation- obturator n

adductor

action- adduct limb, extend hip

origin- pelvic symphysis, ischiatic arch, ventral pubis & ischium

insertion- middle femur

innervation- obturator n

gracilis

action- adduct limb, flex stifle, extend hip & hock

origin- pelvic symphysis

insertion- cranial tibia & tuber calcanei

innervation- obturator n

deep hip muscles

• external obturator

• gemelli

• quadratus femoris

external obturator

action- rotate pelvis laterally

origin- pubis & ischium

insertion- trochanteric fossa of femur (proximal)

innervation- obturator n

gemelli

action- rotate limb laterally

origin- ischium & acetabulum

insertion- trochanteric fossa of femur (proximal)

innervation- sciatic n

quadratus femoris

action- extend hip, rotate limb laterally

origin- ischium

insertion- intertrochanteric crest of femur (proximal)

innervation- sciatic n

tarsus extensors

• gastrocnemius

• superficial digital flexor

• deep digital flexor

gastrocnemius

action- extend tarsus, flex stifle

origin- medial & lateral supracondylar tuberosties of the femur (distal)

insertion- tuber calcanei

innervation- tibial n

superficial digital flexor

action- flex 1-4 principal digits, flex stifle, extend tarsus

origin- lateral supracondylar tuberosity of the femur (distal)

insertion- tuber calcanei & middle phalanges of digits 2-5

innervation- tibial n

deep digital flexor

action- flex digits, extend tarsus

origin- caudal tibia & proximal fibula

insertion- distal phalanges

innervation- tibial n

tarsus flexors

• tibialis cranialis

• peroneus (fibularis) longus

• long digital extensor

• lateral digital extensor

tibialis cranialis

action- flex tarsus, rotate paw laterally

origin- cranial tibia

insertion- base of metatarsals 1 & 2

innervation- fibular n

peroneus (fibularis) longus

action- flex tarsus, rotate paw medially

origin- lateral condyle of the tibia & femur (distal), proximal fibula,

insertion- 4th tarsal bone & basses of metatarsals

innervation- fibular n

long digital extensor

action- flex tarsus, extend digits

origin- extensor fossa of femur (distal)

insertion- distal phalanges of digits 2-5

innervation- fibular n

lateral digital extensor

action- extend digits

origin- proximal fibula

insertion- phalange of digit 5

innervation- fibular n

hing limb digital extensors

• long digital extensor

• lateral digital extensor

hind limb digital flexors

• superficial digital flexor

• deep digital flexor

achilles tendon

• superficial digital flexor

• gastrocnemius

hindlimb nerves

• cranial gluteal

• caudal gluteal

• femoral

  • saphenous

• obturator

• sciatic

  • fibular

  • tibial

femoral nerve

originates from L4-5/6

gives of saphenous branch

responsible for stifle extension to support weight of the pelvic limb

innervates:

• sartorius

• skin on medial side of thigh, stifle, leg, tarsus, paw

obturator nerve

originates from L4-6

innervates:

• adductor muscles

  • external obturator

  • pectineus

  • gracilis

  • adductor

sciatic nerve

originates from L6-7 & S1-2

innervates

• biceps femoris

• semitendinosus

• semimembranosus

• gemelli

• quadratus femoris

fibular nerve

originates from L6-7

branches into superficial & deep fibular branches

innervates:

• tarsus flexors & digital extensors

  • tibialis cranialis

  • peroneus (fibularis) longus

  • long digital extensor

  • lateral digital extensor

tibial nerve

originates from L7 & S1

caudal portion of the sciatic

innervates:

• tarsus extensors & digital flexors

  • gastrocnemius

  • superficial digital flexor

  • deep digital flexor

cranial gluteal nerve

originates from L6-7 & S1

innervates:

• middle gluteal

• deep gluteal

• tensor fascia latae

caudal gluteal nerve

originates from L1 & S1-2

innervates:

• superficial gluteal

hind limb blood flow

• aorta

• external iliac

  • deep femoral

• femoral

• saphenous

• cranial & tibial

hip extensors

• superficial gluteal

• middle gluteal

• biceps femoris

• semitendinosus

• semimembranosus

hip flexors

• tensor fascia latae

• sartorius

• pectineus

stifle

knee joint

hock

tarsal joint (ankle)

fetlock

metacarpophalangeal joint (knuckle)

horse & ruminant distal limb

• reduced number of digits

• highly modified phalanges

• dorsal aspect- extensor tendons

• palmar/plantar aspect- flexor tendons

bovine limb features

• 2 weight bearing digits

• metacarpal 3 & 4 fused

• interdigital ligaments present

equine distal limb

• 1 weight bearing digital

• 3rd metacarpal (cannon bone) flanked by 2 splint bones (metacarpal 2 & 4)

stay apparatus

specialized system of collagenous structures that enable the horse to bear weight with minimal energy expenditure

• patellar locking mechanism

• reciprocal apparatus

• suspensory ligament

epidermis histology

• stratum corneum

• stratum granulosum

• stratum spinosum

• stratum basale

stratum basale

basement membrane of singular columnar basal cells

contains melanocytes

undergoes mitosiss

stratum spinosum

multiple layers of polygonal cells

stratum granulosum

multiple layers of cells with basophilic granules

stratum corneum

multiple layers of flattened cells with no nuclei

equine foot

• epidermal component (modified skin)

  • outer insensitive part

  • dead & non-vascular

• dermal component

  • inner sensitive part

  • living & vascular

equine hoof segments

• laminar

• coronary

• periople

• sole

• frog

hoof function

• protect underlying structures

• dissipate concussion on foot impact

• suspend distal phalanx within it

equine hoof dermal components

• dermis of skin

• perioplic corium

• coronary corium

  • overlying dermis synthesizes hoof wall

• lamellar corium

equine hoof epidermal components

• stratum externum

  • periople

• straum medium

  • horn tubules

• stratum lamellatum

  • epidermal lamellae

periople

• thin, soft, outermost hoof layer

• varnish-like → acts as waterproof barrier

tubular horn

• thickest layer

• main structural component → provides strength & stability

• keratinized tubes surrounded by intertubular horn

epidermal lamellae

• make up inner layer of the hoof wall

• create a massive surface area for attachment

  • suspends & anchors distal phalanx within the hoof

• 600 parallel lamellae that interdigitate with dermal lamellae of the corium

  • each primary laminae give rise to 100 secondary epidermal lamellae

laminitis

occurs when the lamina tears away from the hoof wall

• secondary epidermal lamellae elongate to a point (normally rounded)

• pointed tip and basement membrane separate from basal cells of the primary dermal lamellae

• leukocytes infiltrate dermis and empty basement membrane of the secondary epidermal lamellae