Canine forelimb 2 PDF

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1 Lecture 2 8.Canine forelimb 2Elbow joint Hinge joint so only allows for flexion and extension Most common joint to causes lameness in dogs and cats Elbow dysplasia, OCD, osteoarthritis and more 3 main articulations: Humeroradial = bears most of the weight Humeroulnar = resists lateral movement Pro...

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Lecture 2

Canine forelimb 2 Elbow joint • Hinge joint so only allows for flexion and extension • Most common joint to causes lameness in dogs and cats • Elbow dysplasia, OCD, osteoarthritis and more • 3 main articulations: 1. Humeroradial = bears most of the weight 2. Humeroulnar = resists lateral movement 3. Proximal radioulnar = allows rotational movement of antebranium • All one synovial space: - Can be divided to lateral and medial by the trochlear notch - The medial compartment is most problematic Medial coronoid process • Prone to problems as its likely due to an un-equal load sharing between radius and ulna due to joint incongruence • Most impact on the medial coronoid process Elbow dysplasia • Abnormal loading of joint surfaces: - Stress fractures of coronoid - OCD of humeral head - Lameness - Leading cause of elbow arthritis Elbow support structures • Collateral ligaments: 1. Lateral epicondyle to the lateral radical head and lateral ulna 2. Medial epicondyle to medial radial head • Annular ligament = encircles head of the radius and attaches it to the coronoid processes either side Muscles of the elbow • Elbow flexors: 1. Brachialis 2. Biceps brachii = wraps around the humerus • Innervated by the musculocutaneous nerve • Elbow extensors: 1. Triceps brachii = 4 heads, a) Long (caudal scapula) b) Lateral (Lateral humerous) c) Accessory (neck of humerous) d) Medial (medial humerous) 2. Anconeus = Olecranon to lateral condylar ridge Muscles of the antebrachium • Craniolateral muscles of the antebrachium: • Most originate on the lateral humeral epicondyle • All innervated by the radial nerve • Mostly extensors 1. Ulnaris lateralis = Flexors 2. Lateral digital extensor 3. Common digital extensor 4. Extensor carpi radialis

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Lecture 2

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• Caudomedial muscles: • All originate on the medial humeral epicondyle • All innervated by the median and ulnar nerve 1. Flexor carpi ulnaris = 2 heads 2. Superficial digital flexor 3. Deep digital flexor = 3 heads 4. Flexor carpi radialis • Rotational muscles: • Supinator = Lateral humeral epicondyle to radius, radial nerve • Pronator teres = Medial humeral epicondyle, median nerve • Abductor polices longus = Lateral ulna to medial digit Carpus • A complex joint with several levels of articulation • Each level has a different range of motion: 1. Antebrachiocarpal joint = Greatest and separate 2. Inter-carpal joint = Moderate 3. Carpometacarpal = Minimal Extensor tendons over the dorsal carpus • Common digital extensor tendon sits in extensor groove on lateral craniodistal radius Lateral digital extensor sits between radius and ulna • at level of radio-carpal joint • Extensor reticulum restrains tendons • Arthrocentesis between tendons • The tendons of common digital extensor and the lateral digital extensor fuse prior to insertion on the distal phalanges of their respective digit • There is an elastic ligament from P2 to P3 in each digit to partially retract the claw Flexor tendons in the foot • Flexor retinaculum • Superficial digital flexor tendon forms a tube around deep digital flexor tendon in digital synovial sheath • Deep digital flexor tendon then emerges palmar to insert on palmar aspect of P3 • Interosseous muscles = From proximal palmar metacarpal to proximal P1 of same digit Pads of the foot have specialised epidermal structures • Neurological input to the antebrachium • Median and ulnar nerve: - Carpal and digital flexor muscles - Run medially to humerous then caudomedial in antebrachium - Median nerve just cranial to elbow collateral ligament - Ulnar nerve is between olecranon and medial epicondyle • Radial nerve: - Important fro elbow extension - Carpal and digital extensors - Nerve runs caudomedial to humerus then wraps over brachialis to craniolateral in antebrachium - Important to weight bearing muscles

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Lecture 2

1. Median a) Flexors of carpus b) Sensory to palmaromedial paw 2. Ulnar a) Flexor carpi ulnaris, DDF and interosseous b) Sensory to caudal antebrachium, palmar paw and lateral digit 5 Both supply motor innervation to all carpal and digital flexors • 1. Radial a) Extensors of the elbow b) Extensors of carpus/digits c) Sensory to cranial/lateral antebrachium and dorsal paw Autonomous sensory zones 1. Radial = Craniolateral, antebrachium, dorsal paw 2. Ulnar = Caudal antebrachium, palmarolateral paw and lateral digit 3. Median = Palmaromedial paw Blood supply to the forelimb

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