Blood Supply to the Forelimb PDF

Blood Supply to the Forelimb  Subclavian Artery Supplies blood to the forelimb To structures of the neck and cervicothoracic junction Winds around the cranial border of the first rib to enter the limb through axilla ; it changes the name as axillary...

Blood Supply to the Forelimb  Subclavian Artery Supplies blood to the forelimb To structures of the neck and cervicothoracic junction Winds around the cranial border of the first rib to enter the limb through axilla ; it changes the name as axillary artery at this point Subclavian artery detaches four branches in its intra thoracic course Left subclavian artery remains distinct and takes separate ,more distal origin Right branches from brachiocephalic trunk  Axillary Artery Crosses the axilla to continue distally over the medial surface of the arm, caudal to the humerus Supplies structures of the shoulder It changes its name again when level with teres tubercle and branching off subscapular artery and called as brachial artery  Branches of Axillary Artery External thoracic artery – Short artery that supplies the superficial pectoral muscles Lateral thoracic artery – Accompanies the lateral thoracic nerve to the ventrolateral abdominal wall as far back as the flank – Supply parts of latissmus dorsi, deep pectoral, cutaneous trunci and thoracic mammary glands Suprascapular artery – Accompanies the suprascapular nerve to supply the Supraspinatus and infraspinatus muscles in horse and ox – is a branch of the superficial cervical artery in dog Cranial circumflex humeral artery Cranial circumflex humeral artery is the most distal branch of the axillary artery It may also arise from the subscapular artery It sends branches to the joint capsule of the shoulder joint and biceps brachii It anastomoses with the caudal circumflex humeral artery  Branches of Axillary Artery Subscapular Artery Largest branch of the axillary artery and divided into three branches: Thoracodorsal artery – Arises from the subscapular artery and runs caudally with the thoracodorsal nerve to supply the latissimus dorsi Caudal circumflex humeral artery – Accompanies the axillary nerve and passes between the teres major and the head of the humerus – Supplies the four heads of triceps in the dog – A small branch , the collateral radial artery, supplies the nutrient artery of the humerus – Anastomoses with the cranial humeral circumflex artery Circumflex scapular artery ( in horses) – It is the continuation of the subscapular artery – Anastomoses with the suprascapular artery  Brachial Artery Continuation of the axillary artery on the medial aspect of the arm and supplies it Passes distally in the company of the median nerve and brachial vein caudal to the biceps brachii muscle Descends over the medial head of the triceps brachii, crosses obliquely the distal half of the humerus near the elbow joint It passes under the pronator teres muscle, gives off its most distal branch, the common interosseous artery Continues as median artery in the forearm after branching common interosseous artery  Brachial Artery It gives off the following branches: Deep brachial artery Bicipital artery Collateral ulnar artery Superficial brachial artery Transverse cubital artery Common interosseous artery Used to palpate the pulse in horses – Palpate on the medial side of the horse limb through the superficial pectoral muscle just cranial to the medial collateral ligamant  Branches of brachial artery Deep brachial artery – It is a large branch – May be double – Passes caudally into the triceps brachii muscle to supply it – In horses, it has an ascending branch which anastomoses with the caudal circumflex humeral artery descending branch which anastomoses with the collateral ulnar artery Bicipital artery – Supplies biceps  Branches of Brachial artery Collateral Ulnar Artery Caudal branch in the distal third of the forearm Passes caudally along the ventral border of the medial head of the triceps brachii Gives branches to the triceps brachii, tensor fasciae antebrachii, pectoralis transversus, cutaneous trunci and skin It is related to the ulnar nerve Passes distally between the ulnar and humeral heads of the deep digital flexor, later between the flexor carpi ulnaris and ulnaris lateralis It unites with the lateral palmer artery to form the supracarpal arch in horses  Branches of Brachial artery Superficial brachial artery – Passes to the cranial aspects of the forearm – Continues in the forearm as cranial superficial antebrachial artery – Divided into a medial and lateral branches and supply the blood to the dorsum of the paw via dorsal common digital arteries Transverse cubital artery – Detached just proximal to the elbow joint – Supplies the elbow and adjacent muscles  Branches of Brachial artery Common Interosseous Artery Last and short branch passes to the proximal part of the interosseous space between radius and ulna before dividing into three branches Ulnar artery Course caudally and continues distally to supply deep digital flexor, ulnaris lateralis Caudal interosseous artery Lie between apposed surfaces of radius and ulna, passes distally through lateral side of the carpal canal In the carpometacarpal region it joins with radial and median arteries to form arches that supply the palmar surface of the forepaw Caudal interosseous cannot occluded with tourniquet in the mid forearm because it is protected between the radius and ulna Common interosseous artery continues as the cranial interosseous artery  Braches of Brachial artery Cranial Interosseous Artery Palmar branch divides into Passes through the proximal – Superficial Palmar branch interosseous space of the forearm anastomoses with collateral ulnar and descends in the groove artery between the radius and ulnar – Deep palmar branch In the distal half of the forearm it ramifies in the palmar aspect of the divides into carpus Dorsal branch also contributes to the formation of the proximal deep palmar arch – contributes to the formation of the dorsal carpal rete and sends a Cranial interosseous artery gives palmar ( interosseous) branch muscular branches to abductor through the distal interosseous space digit 1 longus, Lateral digital extensor and communis and sometimes the flexors of the carpus  Median Artery Direct continuation of the brachial artery past the common interosseous artery Supplies forearm by Deep antebrachial artery to caudomedial muscles Radial artery of the forearm Divides into palmar and dorsal carpal branches that supply deep vessels of the digits Continues through carpal canal to join branches of common interosseous arteries to form palmar arterial arches Palmar arches Supply palmar aspect of the forearm and manus Gives off Palmar metacarpal arteries ( deep palmar arch) Palmar common digital arteries (superficial palmar arch)  Digital arteries Blood vessels of the Dorsal and Palmar metacarpal metacarpus and digits digital arteries – Deep arteries travelling next to Distribution varies with the the metacarpal bones species – Parallel the larger common digital arteries Number of digital arteries – Usually contribute to the arise from, medial to lateral formation of proper digital Palmar common digital arteries arteries Proper digital arteries – Distal branches of common – Superficial arteries locate on digital arteries past the proximal the palmar side of the end of the digits metacarpus – Extend down the sides of the – Carnivores also have dorsal digits as axial and abaxial proper common digital arteries digital arteries Species difference:Horse Arteries to manus Medial palmar artery ( 2nd palmar Medial and lateral digital ( common digital) proper common digital) – Large distal continuation of median artery arteries – The main supply to the digits – Passes on the abaxial surface – Proximal to the meta of the proximal sesamoid carpophalangeal joint it divides bones and flexor tendons in to medial and lateral digital Terminal arch arteries – The distal continuation of the Lateral palmar ( third palmar digital arteries after they common digital) artery enter the solar canal through – much smaller than the medial solar foramina palmar artery – Travels on the lateral side of the flexors Species difference :Horse Digital Arteries Medial and lateral digital arteries – Common name for proper digital arteries – Passes on the abaxial surface of the proximal sesamoid bones and distally on the lateral side of the digital flexors – Numerus dorsal and palmar branch and end as terminal arch Terminal arch – The distal continuation of the digital arteries after they enter the solar canal through solar foramina  Species differences : OX Median artery – continues to the distal metacarpus where it becomes third palmar common digital artery divide in to axial digital arteries on the axial sides of the third and fourth digits Abaxial digital arteries on the abaxial sides of the digits Dorsal metacarpal artery III – Only significant artery on the dorsal side of the manus – Travels in the dorsal longitudinal groove  Clinical: In digit amputation in ruminants : - Cut through the proximal phalanx at an angle due to: 1. Branches of axial digital arteries are going in that bone from that axial surface, so to preserve that blood supply to the bone 1. Cutting at an angle it avoids having a stump that will hang up on things - The palmar common digital III should be ligated in digital amputation (the large source of blood coursing distally in the interosseous space). Veins of the forelimb  Veins of the forelimb Two divisions of venous drainage – Deep division basically travel with like named arteries The palmar and digital veins drain into the radial and median veins, which join to continue as the median vein – Superficial division Travel alone just beneath the skin Superficial division Accessory Cephalic Vein – Arise from dorsal digital arteries – Travels proximally to empty in to the cephalic vein on the cranial surface of the forearm above the carpus in carnivores and ox – empty in to cephalic vein near elbow in horses  Cephalic Vein Arises from the palmar surface of the manus, passes proximally up the forearm and arm Under brachiocephalic muscle to empty into the external jugular vein Its branches omobrachial and axillo brachial veins provide other drainage routes – most accessible for venipuncture – most commonly used site in the dog for intravenous injections or for obtaining blood samples  Median Cubital vein Connected the superficially located cephalic vein and deeply located median vein over the flexor surface of the elbow  Clinical Veins of the thoracic limb in the ox Injection of anesthetic in distal superficial veins in cattle is used as an alternative to the nerve block widely used in horses. It is also used for antibiotic injections for treatment of foot infections (foot rot). A tourniquet is usually applied to either the accessory cephalic vein or, most commonly, to the dorsal common digital vein III Blood Collection Sites in the dog (Veinpuncture) The most common sites to take blood samples from are the jugular vein, cephalic vein and saphenous vein. Lymph Nodes Part of the lymphatic system Filters lymph fluid Important part of the immune system Trapping bacteria, viruses, foreign bodies Gland  Lymph Nodes of the Forelimb One axillary center exists The center drains the deeper principal nodes are contained structures of the entire limb and within the axilla where they lie on the more superficial structures of the medial muscles of the the distal segments shoulder The efferent vessels pass directly, – Additional nodes may be found in or after serial passage through relation to the first rib or more several nodes, to one of the caudally on the chest wall major lymphatic or venous – In the horse alone, a more distal channels at the entrance to the group of cubital nodes is placed over the medial aspect of the elbow chest Lymph Nodes of the Forelimb  Clinical Knowledge of the location, the accessibility and the tributary territory is essential for any veterinarian, especially surgeons, pathologists and those engaged in meat inspection. Lymph nodes are also important for the assessment of meat. If the examination of the lymph nodes indicates a systemic infection, the slaughtered animal has to be declared unfit for consumption. Knowledge about location and dimensions of palpable lymph nodes is also relevant for clinical examination. Abnormalities of the lymph nodes reflect processes occurring in the area that they drain. The nodes generally become enlarged and may be inflamed and firm. Prophylactic removal of lymph nodes is often required in the treatment of neoplastic disease, as the nodes may harbor tumor cells which can become disseminated and cause metastases. Leukaemia and some types of lymphoma are associated with generalized enlargement of the lymph nodes.