Thoracic limb anatomy.Part2.SVF120 - StudentCopy.pdf

Anatomy of the Thoracic Limb Chapter 6 Part 2 (p 6.8 – 6.14) Dr Christine Steyn Dep. Anatomy & Physiology Faculty Vet Science, UP 6.4 Muscles of the carpal and digital joints Situated on the antebrachium Function: Extension and...

Anatomy of the Thoracic Limb Chapter 6 Part 2 (p 6.8 – 6.14) Dr Christine Steyn Dep. Anatomy & Physiology Faculty Vet Science, UP 6.4 Muscles of the carpal and digital joints Situated on the antebrachium Function: Extension and Flexion Extensors – Craniolateral on antebrahium Flexors – Caudomedial on antebrachium  Muscles of the carpal and digital joints M. extensor carpi radialis – Cranial aspect of antebrahium – Origin: Lateral epicondyle – Insertion: Proximal part of MC II and III – Extension of the carpus – N. radialis  Muscles of the carpal and digital joints M. extensor digitorum communis – Lies lateral to M. ext. carpi radialis – Origin: Lateral epicondyle – Insertion: P3 of all the digits – Function: Extends all the digits – N. radialis  Muscles of the carpal and digital joints M. extensor digitorum lateralis – Lies lateral to M. ext. dig. communis – Origin: Lateral epicondyle – Insertion: P1 of digits IV and V – Function: Extends lateral digits – N. radialis  Muscles of the carpal and digital joints M. extensor carpi ulnaris – Lies caudal to M. ext. dig. lateralis – Origin: Lateral epicondyle – Insertion: Proximal end of MC V/ Acc. carpal bone in other species – Function: Flexion of the carpus! – N. radialis  Muscles of the carpal and digital joints M. flexor carpi radialis – Lies caudal to radius – Origin: Medial epicondyle – Insertion: Proximal part of MC II and III – Function: Flexion of the carpus – N. medianus  Muscles of the carpal and digital joints M. flexor digitorum superficialis – Lies caudal on antebrachium, covers flexor muscles – Origin: Medial epicondyle – Insertion: P2 of digits II - V – Function: Flexion of the digits – N. ulnaris  Muscles of the carpal and digital joints M. flexor digitorum profundus – Lies deep to M. flex. dig. superf. – Three parts – Origin: Medial epicondyle – Insertion: P3 of digits I - V – Function: Flexion of the digits – N. ulnaris  Muscles of the carpal and digital joints M. flexor carpi ulnaris – Origin: Medial epicondyle – Insertion: Accessory carpal bone – Function: Flexion of the carpus – N. ulnaris  Short muscles of the digital joints Lie in metacarpal region – activate individual digits Mm. interossei – Origin: Metacarpal bones – Insertion: Proximal sesamoid bones – N. ulnaris Passive stay apparatus of the horse Horse can fix its joints – stand for hours Front limb – carry 55 – 60% of body mass – mass of the head, neck and part of the trunk is carried via the extrinsic muscles. – M. serratus ventralis is fan-shaped, connective tissue fibres. Shoulder, elbow and carpus must be prevented from flexion Carpus and digits must be prevented from excessive extension Passive stay apparatus of the horse Flexion prevented: – Lacertus fibrosus – Insertion of collateral ligaments of elbow and – Powerful M. triceps brachii Overextension prevented: – Flexor tendons – accessory ligaments – Suspensory apparatus of the fetlock and pedal joints – M. interosseus medius & ligaments of proximal sesamoid bones Summary of muscles and nerves of the thoracic limb Shoulder joint – Infraspinous, supraspinous and subscapular muscles act as stabilisers; suprascapular & subscapular nerve – True flexors of the shoulder; axillary nerve Elbow joint – Extensors; radial nerve – Flexors; musculocutaneous nerve Carpus & digits – Extensors on craniolateral antebrachium; radial nerve – Flexors on caudomedial antebrachium; median & ulnar nerve  Foot pads Frequent contact with the ground – Devoid of hair; Epidermis is developed – densely cornified. – Concussive shock – subcutis is developed Plantigrade animals – carpal, metacarpal, digital pads Digitigrade animals – dogs and cats Unguligrade animals - horses  Hoof of the horse Wall Toe Quarters Bulb Heel Sole Frog Periople Coronet  Hoof of the horse Wall – Outer layer – Middle layer – Inner layer – lamellae Bearing surface – white line Sole Frog – digital pad The end