horse front limb anatomy Flashcards
how do horse limb muscles differ to dogs
- Similar to dog but simpler
- Rotators, adductors & abductors reduced or absent.
- Limbs fixed in pronation
- Muscles developed for movement in craniocaudal (sagittal) plane
supraspinatus
- Originates
supraspinous
fossa/cartilage/
spine - Inserts on cranial
parts both greater
& lesser tubercle
either side biceps
tendon - Stabilises &
extends shoulder
deltoideus
- Originates scapular
spine & caudal
scapula - Inserts on deltoid
tuberosity - Flexes shoulder
infraspinatus
- Originates infraspinous fossa/cartilage/
spine/cartilage - Inserts: deep & superficial insertions to
caudal part of greater tubercle - Synovial bursa under superficial tendon
- Flexes shoulder. Functions as
(contractile) lat. collateral ligament
teres minor
- Originates distal
half caudal border
of scapula - Inserts on deltoid
tuberosity - Flexes shoulder
subscapularis
- Origin: sub scapular
fossa - Insertion: lesser
tubercle of
humerus - Extendes &
stabilises shoulder
triceps brachii
- THREE heads - Long, lateral, medial
- From caudal scapula to the olecranon
- Extends elbow
- Radial n.
biceps brachii
- Origin: scapular tuberosity
- Insertion: radial tuberosity/medial elbow joint/ ECR tendon/forearm fascia
- Flexes elbow
- Tendon of origin is flat, broad & fibrocartilagenous
in type - Lacertus fibrosus (part of the stay apparatus of
the fore limb) connects to extensor carpi radialis
(ECR)
biceps brachii has a ___ associated with it
bursa
Large bicipital bursa as
passes over intermediate
tubercle of the humerus
shoulder joint; 3 synovial structures
- Shoulder joint
(scapulohumeral joint) - Bicipital bursa (no
communication with shoulder
joint) - Infraspinatus bursa
describe collateral ligaments of the shoulder
- There are no true collateral
ligaments - Muscles functions as (contractile)
collateral ligaments - SUBSCAPULARIS (medial)
- SUPRASPINATUS &
INFRASPINATUS (lateral)
nerve associated with supraspinatus and infraspinatus
suprascapular nerve
EXTENSOR CARPI RADIALIS
- Origin: lateral supracondylar
crest of the humerus & radial fossa - Insertion: metacarpal tuberosity
- Extends carpus
common digital extensor
- Origin: has 3 heads (radial, humeral & ulnar)
- Insertion: extensor process P3 (+P1 & P2)
- Connected to suspensory ligament (SL) via extensor branches
- Extends carpus & digit
lateral digital extensor
- Origin: proximal radius & ulna
- Insertion: on P1
extensor capri obliquus
- Origin: distolateral cranial radius
- Crosses carpus
- Insertion: dorsomedially on proximal MC2
which extensors have tendon sheaths
- Extensor Carpi Radialis (ECR)
- Common digital Extensor
- Lateral digital Extensor
ulnaris lateralis
- Origin: lateral epicondyle
humerus - Insertion: accessory carpal bone & proximal MC4
- Flexes carpus
FLEXOR CARPI RADIALIS
- Origin: medial humeral epicondyle
- Insertion: proximal MC2
flexor carpi ulnaris
- Origin: humeral head (medial epicondyle) &
ulnar head (medial olecranon) - Insertion: accessory carpal bone
superficial digital flexor
- Origin: medial epicondyle of humerus
- Insertion: distal P1 & proximal P2
- Accessory ligament of the SDFT or superior check ligament
(from radius) - Forms sleeve around DDFT at fetlock joint level (MANICA
FLEXORIA)
deep digital flexor
- Origin: THREE heads (humeral, ulnar & radial)
- Insertion: P3
- Accessory ligament of the DDFT or inferior check
ligament (from distal palmar carpal ligament) - Navicular bursa (between DDFT & navicular bone)
navicular bursa is between
DDFT & navicular bone
suspensory ligament
- Origin: Proximocaudal on MC3, and palmar carpal lig
- Insertion: Proximal sesamoid bones
- Extensor branches (from proximal sesamoid bones to join the common digital extensor
tendon, around proximal P1) - Contains little muscular tissue
- Counteracts overextension of the fetlock joint
- proximal part, body, branches, extensor branches
what is the tendon sheath called that encloses the SDFT and DDFT
digital flexor tendon sheath
what tendon sheath is associated with the palmar aspect of the carpus
carpal canal/ carpal sheath
what nerve innervates triceps and extensors
radial nerve
radial nerve
- Innervates:Triceps and Carpal & digital extensors
- Sensory to skin of lateral antebrachium (lateral
cutaneous ante brachial nerve) - If injured (dropped elbow, flexed carpus & digit, can’t bear weight below triceps - unable to voluntarily extend foot)
what nerve innervates the flexors of carpus and digits
median nerve and ulnar nerve
median nerve
- Innervates Flexors of carpus & digits
- Joined with musculocutaneous nerve part of
the way - Main sensory nerve to distal limb where it
divides into medial & lateral palmar nerve
ulnar nerve
- Innervates Flexors of carpus & digits
- Skin sensation of caudal fore arm & lateral
metacarpus (caudal cutaneous antebrachial nerve & dorsal branch respectively)
at the level of the carpus what nerves are associated
- All sensory - no motor as no muscles present
- Mainly from median nerve
describe the nerves of the front limb
- Median nerve branches to medial palmar nerve and lateral palmar nerve
- Medial palmar nerve turns into medial palmar digital nerve (by SDFT and DDFT)
- Lateral palmar nerve turns into lateral palmar digital nerve (by SDFT and DDFT)
- Lateral palmar nerve also branches into the medial and lateral palmar metacarpal nerves (by the splint bones)
- Ulnar n. Caudal aspect of limb above carpus, in between flexor carpi ulnaris and ulnaris lateralis
main trunk of arteries
axillary –> brachial–> median –> medial palmar artery (just proximal to carpus) –> medial and lateral palmar digital arteries
MEDIAL PALMAR ARTERY
- main supply lower limb & foot
- runs medially between SL & DDFT
- branches to medial & lateral
palmar digital arteries
veins
follow arteries except cephalic vein on medial side
