Vet anatomy

Stifle joint

...

Accessory carpal bone

.The accessory carpal bone is found on the distal thoracic limb, at the caudal of the carpus. The prominent bony projection is felt just proximal to the level of the carpal pad. The carpal pad is a vestigial pad that rarely makes contact with the ground. It is a short, rod like bone which articulates with the distal ulna and the intermedioradial and ulnar carpal bones, with these two it forms the intercarpal joint (which allows some movement). It provides the site of attachment to the extensor carpi ulnaris (which acts to flex the flexed carpus) and the flexor carpi ulnaris which extends the carpus. The cephalic vein crosses to the medial surface of the antebrachium at about the level of the accessory carpal bone.

Lateral saphanous vein

Vein lying superficially in the fascia of the lateral crural region of the pelvic limb. Arises from an anastomosus with the medial saphanous on the dorsal aspect of the tarsus. Runs proximo caudally across the lateral surface of the leg before following the gastrocnemius on the caudal border. Vein joins the femoral vein within the popliteal fossa. Its proximal aspect is better suited for venepuncture as it is more stable here than distally where it dips between the common calcanean and the flexor tendons. Site commonly used more proximal of the vein, just distal to the level of the stifle. Vein can be raised by applying pressure to the caudal aspect of the stifle.

Locate and name all joints

1. Intermandibular joint 2. gomophoses between teeth and jaws 3. temporomandibular joint 4. ossicular joints between the auditory ossicles in the ear 5. atlantooccipital joint 6. atlantoaxial joint 7. intervertebral joints 8. glenohumeral (shoulder) joint 9. elbow joint 10. accessory carpal joint 11. antebrachiocarpal joint 12. middle carpal joint 13. carpometacarpal joint 14. metacarpophalangeal joint 15. proximal interphalangeal joint 16. distal interphalangeal joint 17. costovertebral joint 18. sternochondral joint 19. costochondral joint 20. sternal joints 21. sacroilliac joint 22. hip joint 23. femoropatella joint 24. femorotibial joint 25. stifle joint 26. tarsal joint 27. middle tarsal joint 28. tarsometatarsal joint 29. metatarsophalangeal joint 30. proximal interphalangeal joint 31. distal interphalangeal joint

Autonomous skin zone tibial nerve

Autonomous skin zones are areas of skin innervated by a single named nerve. The named nerves of the pelvic limb arise from a network of spinal nerves called the lumbosacral plexus. The tibial nerve is a branch of the sciatic nerve, which arises from L6-S1. The tibial nerve innervates the caudal flexors of the digits and extensors of the hock. Its autonomous skin zone extends along the plantar surface of the pes. The integrity of this nerve may be tested in clinical examination by stimulation of the plantar aspects of digits 3 and 4. The withdrawal reflex should be stimulated and cause retraction of the limb. Paralysis causes the hock to be flexed and lowered closer to the ground during weight bearing.

Autonomous skin zone - radial nerve

Autonomous skin zones are areas of skin supplied by just one named nerve. The named nerves of the forelimb arise from the brachial plexus, which is the complex network of fibres arising from C6-T2. The radial nerve arises from spinal nerve C7-T2. It is the major nerve innervating the forelimb extensors - including the triceps and the craniolateral antebrachial group. its cutaneous branch supplies the skin of the dorsal antebrachium and paw. The integrity of this nerve can be tested in a neurological examination by means of stimulation of the dorsal aspect of digits 2,3 or 4 and will result in the withdrawal reflex of the limb. This means contraction of the elbow flexors as well as contralateral extension of the triceps muscle to affect balance. Damage to the radial nerve results in the loss of weight bearing ability and collapse of the limb. No compensation is available.

Autonomous skin zone peroneal nerve

Autonomous skin zones are areas of the skin innervated by a single named nerve. Named nerves of the pelvic limb arise from a network of spinal nerves known as the lumbosacral plexus. The peroneal nerve is a branch of the sciatic nerve which arises from L6 - S1 from the lumbo sacral plexus. The peroneal nerve innervates the craniolateral digital extensors and flexors of the tarsus. Its autonomous skin zone is along the dorsal aspect of the pes and the lateral crural region. The integrity of the nerve can be tested by stimulation of digits 2,3,4 which result in the withdrawal reflex. damage to the nerve results in slight over extension of the hock and an inability to extend the digits, which may be rested on their dorsal surfaces. The dog will flick its paw forward before bearing weight. The dorsal surface without sensation.

Autonomous skin zone ulnar nerve

Autonomous skin zones are areas of the skin supplied by just one named nerve. The named nerves of the forelimb arise from a network at the axillary region known as the brachial plexus, which arises from the spinal nerves C6-T2. The ulnar nerve arises from C8-T2 and innervates some of the muscles of the caudal antebrachial group, along with the median nerve. The flexor carpi ulnaris alone is innervated by the ulnar nerve. The autonomous zone of the ulnar nerve is the lateral aspect of the antebrachium and the lateral aspect of digit 5. It is here where the integrity of this nerve may be tested in a neurological examination by pinching the skin at this area. It should result in the withdrawal reflex and the flexion of the elbow joint and compensatory extension of the contralateral limb. paralysis causes no obvious change in gait or posture.

Digits

Dogs hold digitigrade stance, which means they walk on the joints of their digits. The digits are the toes of the animal and are present on the distal most aspect of both the fore and hind limb. In the manus or forepaw there are 5 digits, named 1-5 from medial to lateral. The digits are comprised of 2 (in the case of digit 1) or 3 (all other digits) long, slender bones called phalanges. The distal phalanx in each case ends in the ungula process or the claw. The proximal phalanx attaches proximally at the distal end of the metacarpal bones. The arrangement is very similiar in the pelvic limb, with the only difference being that digit 1 is not largely persistent and is so called a dew claw and commonly needs removal. It will have varying degrees of bony structures.

Aortic Valve puncta maxima

Puncta maxima means the point of maximum audibility. The heart in the dog is oval in shape and its long axis forms an angle of about 45 degrees with the sternum. Its base points craniodorsally and its apex lies near the junction of the sternum and the diaphragm, a little to the left of the midline. The puncta maxima for the aortic valve is just below the plane of the shoulder in the left 4th space. The aortic valve is located between the ascending aorta and the left ventricle, it closes at the end of systole and is heart as the second heart sound, dub. It is a semilunar tricuspid valve, which is opened when the pressures inside the heart exceed those in the aorta, and so blood is able to flow out of the heart. However, at the end of systole and start of diastole when the ventricles are relaxing and the pressure rapidly falling within them, this causes the backflow of blood down the aorta toward the ventricles. This causes the opening of the aortic valve and the prevention of blood to fall back down into the ventricles.

Pulmonic valve puncta maxima

Puncta maxima means the point of maximum audibility. The heart in the dog is oval in shape and its long axis forms an angle of about 45 degrees with the sternum. Its base points craniodorsally and its apex lies near the junction of the sternum and the diaphragm, a little to the left of the midline. The puncta maxima for the pulmonic valve is low in the left third intercostal space. The pulmonic valve is located between the pulmonary trunk and the right ventricle, it closes at the end of systole and is heart as the second heart sound, dub. It is a semilunar tricuspid valve, which is opened when the pressures inside the heart exceed those in the pulmonary trunk, and so blood is able to flow out of the heart. However, at the end of systole and start of diastole when the ventricles are relaxing and the pressure rapidly falling within them, this causes the backflow of blood down the trunk toward the ventricle. This causes the opening of the pulmonic valve and the prevention of blood to fall back down into the ventricles.

The right atrioventricular valve puncta maxima

Puncta maxima means the point of maximum audibility. The heart in the dog is oval in shape and its long axis forms an angle of about 45 degrees with the sternum. Its base points craniodorsally and its apex lies near the junction of the sternum and the diaphragm, a little to the left of the midline. The puncta maxima, correlating quite well to the position of the valve in life, is high, about the level of the olcecranon in the 4th space on the right side. The atrioventricular valve is the valve present between the right atria and the right ventricle and its closure is heard as the first heart sound, lub. The closure of the valve occurs during systole when the pressures in the ventricle exceed that in the atria and so the valves prevent the back flow of blood into the atria as the heart contracts. The valves have their their flaps maintained by slight contraction of the papillary muscles on the chordae tendinae. As the pressure falls in diastole, the pressure in the ventricle drops below that in the atria and the flaps open again, quietly, to allow filling.

Left atrioventricular valve puncta maxima

Puncta maxima means the point of maximum audibility. The heart in the dog is oval in shape and its long axis forms an angle of about 45 degrees with the sternum. Its base points craniodorsally and its apex lies near the junction of the sternum and the diaphragm, a little to the left of the midline. The puncta maxima, correlating quite well to the position of the valve in life, is low - at the level of the costochondral junction in the 5th intercostal space at the level of the olecranon. The atrioventricular valve is the valve present between the left atria and the left ventricle and its closure is heard as the first heart sound, lub. The closure of the valve occurs during systole when the pressures in the ventricle exceed that in the atria and so the valves prevent the back flow of blood into the atria as the heart contracts. The valves have their their flaps maintained by slight contraction of the papillary muscles on the chordae tendinae. As the pressure falls in diastole, the pressure in the ventricle drops below that in the atria and the flaps open again, quietly, to allow filling.

Acromion

The acromion process of the scapula, the scapula is present at the proximal most thoracic limb, it articulates with the humerus to form the glenohumeral joint or the SHOULDER joint. The acromion of the scapula is the bony protuberance at the distal aspect of the spine of the scapula. It is slightly dorsal and lateral to the articulation of the glenoid cavity of the scapula with the head of the humerus. The deltoideus muscle arises from the acromion and the spine of scapula to insert on the deltoid tuberosity of the lateral humerus innervated by the axillary nerve. The suprascapular nerve arises around the scapular notch and supplies a branch to the supraspinatus muscle. The nerve crosses the neck of the scapula - distal to the spine and deep to the acrominon to supply the infraspinatus muscle

Craniolateral and caudomedial antebrachial groups

The antebrachial muscles are located at the antebrachial region of the thoracic limb, which is distal to the shoulder joint - most having attachments around the level of the elbow joint. The caudomedial FLEXOR group originate around the viscinity of the medial epicondyle of the humerus. There are 4 muscles in this group, the flexor carpi radialis (palmar metacarpals) and the flexor carpi ulnaris (onto access carpal - innervated by ulnar nerve only) there are two flexors of the digits, the superficial digital flexor and the deep digital flexor which insert on the middle and distal phalanges respectively. The superficial DF is innervated by the median nerve only. The other muscles are innervated by the median and/ or ulnar nerve. The craniolateral EXTENSOR group originate around the area of the lateral epicondyle of the humerus. They serve to extend the digits and the carpus.They are all innervated by the radial nerve. There are 4 muscles again in this group - the extensor carpi radialis, the ulnaris lateralis which inserts far enough laterally to act as a both an extensor of the carpus and a flexor of the flexed carpus. There are two digital extensors - called common and lateral. These insert, via common tendons onto the distal phalanges.

Atlantooccipital joint

The atlantooccipital joint is the joint at the caudoventral aspect of the skull where it meets with the first cervical vertebrae, the atlas. The joint can be found ventral to the external occipital protuberance and craniomedial to the wings of the atlas which can be palpated laterally to the base of the skull. The joint is formed between the condyles of the occipital bone which articulate with the cranial articular fovea of the atlas. The joint formed allows flexion and extension and is so known as a 'yes/no' joint. The joint is stabilised by dorsal and ventral atlantooccipital membranes. Flexion of the neck at this joint allows for the collection of CSF from the cerebellomedullary cistern by means of entry into the foramen magnum.

Wing of the atlas

The atlas is the first cervical vertebrae and found directly caudal to the skull, articulated by the occipital condyles onto the articular fovea of the bone. The wings are large and prominent of this bone, they may be palpated in some dogs - but are largely covered by the musculature of the neck. The wings provide the site of attachment for many muscles include the omotransversarisus. It is used as a bony landmark for location of the foramen magnum to collect CSF from the cerebellomedullary cistern.

Dorsal spinous process of the axis

The axis is cervical vertebrae 2, so is located in the neck region - caudal to the skull. It may be palpated in the neck as it spans the dorsal surface of the atlas and the dorsal of C3. It is covered in the musculature of the neck and so may not always be so easily palpated.

Dorsal spinous process of the axis

The axis is the second cervical vertebrae found in the neck region. It is an elongated, ridgelike spinous process. it extends cranially, dorsal to the body of the atlas. It also extends caudally, dorsal to the lamina of C3. It provides an attachment for the nuchal ligament - which is a more prominent structure in ruminents who have to support a far larger head with less muscular effort. Caudal to the external occipital protuberance and dorsomedial to the wings of the axis.

Biceps brachii muscle

The biceps brachii is one of the major muscles of the brachium. The brachium being the 'arm' region of the thoracic limb, distal to the shoulder joint, but proximal to the elbow joint. The muscle is on the medial surface of the forelimb and is covered superfically by the pectoral muscles. It arises from the supraglenoid tubercle of the scapula, runs through the intertubercular groove of the humerus before inserting by means of its two heads onto the radial and ulna tuberosities at the proximal regions of these bones. Along with being a flexor of the elbow joint, it is also a potential extensor of the shoulder joint due to its attachment at the scapula. It is an antagonist to the triceps muscle which is the extensor muscle acting over the same joints. It is innervated by the musculocutaneous nerve. This nerve arises via the brachial plexus from C7 and C8 spinal nerves. This nerve also supplies the corcaobrachialis and the brachialis muscle. Dysfunction of the nerve causes little change in gait, but the animal is unable to elevate the paw.

Brachialis muscle

The brachialis muscle is a muscle of the brachium, the brachium is located distal of the shoulder joint but proximal to the elbow joint. The muscle is a flexor of the elbow, along with the biceps brachii and shares its innervation - the musculocutaneous nerve which arises from C7-C8 from the brachial plexus. The muscle, which lies largely deep to the long head of the triceps and so is not readily palpated, arises from the brachialis groove of the humerus, which is present at the proximal third of this bone. It curves laterally and cranially as it courses distally across the elbow joint to its tendinous insertion on the medial aspect of the proximal ulnar alongside the insertion of one of the heads of the biceps brachii.

Canthi of the eyes

The canthi of the eyes are the points where the superior and inferior palpebrae meet. The lateral canthus is more acute in angle than the medial in either case. The medial canthus is associated with the nictitating membrane and its associated gland of the third eyelid. Also the puncta for the removal of tear fluid to the nasolacrimal duct. They are anchored by medial and lateral palpebral ligaments to prevent collapse into the eyes when closed. Sensation to each canthus can be tested as they are supplied by the trigeminal nerve, which is cranial nerve 5 - but two different branches. The medial canthus is supplied by the opthalmic branch and the lateral by the maxillary. The orbicularis occuli, innervated byt the facial nerve causes closure of the eye.

Cardiac notch

The cardiac notch is located in the thoracic region. It is essentially the triangular opening between the cranial and middle lobes of the right lung which lead to a greater amount of exposure of the heart on the right side. It gives the site for puncta maxima of the right atrioventricular valve, cardiac puncture of the right ventricle and ultrasound imaging, being the ventral aspect of the 4th intercostal space. The notch is continuous at its apex with the fissure between the cranial and middle lobes.

carpus

The carpus is the equivalent of our wrist, it is found at the distal aspect of the thoracic limb, distal to the antebrachium (the radius and ulnar) but proximal to the digits. The carpus has three levels of articulation due to its association with various bones. The antebrachiocarpal joint is an ellipsoid joint which allows flexion, extension, abduction and adduction. this joint is formed between the distal radius and ulna and the proximal row of carpal bones - the accessory carpal bone, the intermedioradial carpal and the ulnar carpal. it allows the greatest amount of movement and is commonly entered for aspiration of synovial fluid to test for inflammation. Entry occurs through the flexed joint - best to enter just medial or lateral to the midsagittal plane of the joint to avoid vessels. The middle carpal joint is formed between the proximal carpal bones (intermedioradial medially, the ulnar carpal laterally and the accessory carpal bone) with the distal carpal bones, numbered I to 4 medially to laterally. This joint has some movement, not as much as the antebrachiocarpal but more than the carpometacarpal joint. The carppmetacarpal joint is formed between the carpal bones 1 to 4 and the bases of the metacarpal bones, which are numbered alike. It is a relatively immovable joint.

Hamstring muscle group

The caudal thigh muscles are known as the hamstrings. So present on the pelvic limb in the femoral region. They make up the muscle bulk of the caudal aspect of the thigh and are all innervated by sciatic nerve which arises from the lumbosacral plexus at l6-s1. As a group they function to extend the hip and flex the stifle. They consist of the biceps femoris laterally, the semitendinosus caudally and the semimembranosus medially. The biceps femoris is the longest and widest muscle of the thigh and sits laterally on the caudal aspect. It originates from the sacrotuberous ligament and the ischiatic tuberosty and insert onto the patella by the fascia lata and crural fascia. It acts over the hip joint to extend the stifle and the hock. The semitendinosus also arises from the ischiatic tuberosity and shares its insertion by means of the crural fasica. it extends the hip and the hock and flexes the stifle. The semimembranosus is wedged between the semitendinosus and the biceps femoris and arises from the ischiatic tuberosity and inserts to the distal medial lip of the caudal rough surface of the femur and proximal end of the tibia. It extends the hip and flexes or extends the stifle depending on the position of the limb.

Cephalic vein

The cephalic vein is the principle vein of the thoracic limb. It is a commonly used vein for venepuncture. It arises from the digital veins on the palmar surface of the manus. It extends proximally on the medial aspect of the manus and then crosses to reach the cranial aspect at about the level of the proximal carpus. It is joined by the accesory carpal vein here and then continues proximally toward the elbow joint. Running medially over the radius, it is lateral at the elbow joint. Continuing laterally it joins the external jugular near the thoracic inlet. It runs with the sensory branches of the radial nerve - which must be beared in mind while attempting to catherterise the vein.

Craniolateral crural muscle group

The crural region is the leg region of the pelvic limb. It is the area distal to the stifle joint and proximal to the hock joint. Comprises the bones of the tibia and fibula. The craniolateral crural muscles form the muscle bulk seen cranially, note that the medial aspect of the tibia is not covered with muscles. The craniolateral group comprise the large cranialis tibialis, the extensor digitorum longus, which arises from the extensor fossa of the femur and so acts over the stifle and acts in extension of the joint. The extensor digitorum lateralis, the extensor digitorium brevis and the fibularis longus. As a group they act to extend the digits and flex the hock. They are innervated by the peroneal branch of the sciatic nerve which arises from the lumbosacral plexus at L6 - S1.

Caudal crural muscles

The crural region is the leg region of the pelvic limb. It is the area distal to the stifle joint and proximal to the hock joint. Comprising the bones of the tibia and fibula. The caudal crural muscles act to flex the digits and extend the hock. (contrast to the caudomedial in the antebrachial region which flex the digits and the carpus. this is because the angle of the joint is cranial at the hock). The muscles in this region include the large and most obvious gastrocnemius muscle which arises from the the supracondylar tuberosities of the femur - with the fabellae seasomoids at its insertion. The superficial digital flexor, the deep digital flexor and the popliteus muscle. All muscles are innervated by the tibial branch of the sciatic nerve. The sciatic nerve arises from the lumbosacral plexus at L6- S1

Deltoid tuberosity

The deltoid tuberosity is a bony ridge present on the lateral aspect of the humerus. The humerus is present at the proximal thoracic limb, distal to the shoulder joint. The ridge from the greater trochanter extends distally and cranially and ends in a prominent ridge where the deltoideus muscle attaches. This rough, bony protuberance is known as the deltoid tuberosity. The deltoideus muscle arises from the spine and acromion process of the scapula (innervated by the axillary nerve) palpate the greater trochanter of the humerus cranioventral to the acromion of the scapula and feel down the tricipital line to the pbony prominence of the deltoid tuberosity on the lateral side.

Collateral ligaments of the elbow

The elbow joint is found in the thoracic limb - distal to the shoulder joint and proximal to the antebrachial bones (the radius and ulna). The medial and lateral collateral ligaments are pronounced thickenings of the joint capsule of the elbow. They act to prevent adduction and abduction of the elbow joint. The lateral collateral is attached proximally to the lateral epicondyle of the humerus and distally to the head of the radius. The medial collateral ligament is attached proximally to the medial epicondyle and distally to the region of the ulna. The medial collateral is covered by the biceps and brachialis tendons, but is still palpable

Elbow joint and ligaments

The elbow joint is one of the joints in the thoracic limb, along with the proximal shoulder joint and the distal carpal joints. It is easily identified by means of the caudolateral bony protuberance, the olecranon process of the ulna. The medial and lateral epicondyles of the humerus may also be palpated. The elbow joint is a hinge joint, but some rotational movement is allowed at the radioulnar joint. The joint comprises the condyles of the humerus, the head of the radius and the trochlear notch of the ulnar all encased by a joint capsule. The lateral and medial collateral ligaments are felt as pronounced thickenings of the capsule and act to prevent adduction and abduction of the joint. The joint is extended by the triceps and flexed by the biceps and brachialis muscles. The triceps tendon can be palpated on the olceranon process.

Medial and lateral epicondyles of the femur

The epicondyles of the femur are located at the distal aspect of the bone, hence distal to the hip joint but proximal to the crural bones - the tibia and fibula. About the level of the stifle joint. They are the proximal sites of attachment of the lateral and medial collateral ligaments of the stifle. These are strong ligaments which prevent abduction and adduction of the joint. The patella can be felt craniomedially and the cranial border of the tibia distally and medially. The sartorius medially, the quadriceps cranially and the hamstrings caudally.

External jugular vein

The external jugular vein is the largest vein in the neck. It is superficial in position and sub cutaneous along the greatest part of the neck, covered only by a layer of fascia. It forms cranially at the confluence of the maxillary and linguofacial veins near the angle of the mandible. It then courses caudally along the lateral surface of the sternocephalicus muscle and recieves the omobrachial and cephalic veins just cranial to the shoulder before passing into the thoracic inlet. It is laterally bordered by the brachiocephalicus. It is easily raised for intravenous injection or blood sampling. To raise the vein, pressure is applied ventral to the site of venepuncture- at the level dorsal to the thoracic inlet.

Facial nerve 7

The facial nerve is one of the major nerves of the facial region. It arises from the stylomastoid foramen just caudal to the external acoustic meatus. (hence middle ear infections can present with facial paralysis). It supplies the muscles of facial expression - so muscles like the cutaneous platysma muscle, the orbicularis occuli which closes the eye and orbicularis oris which closes the mouth. It also supplies the motor innervation to the ear by means of the auricopalpebral branch. The dorsal and ventral buccal branches run over the masseter muscle - but do not provide innervation to this muscle - or any other other muscles of mastication except the caudal belly of the digastricus muscle. The facial nerve does supply the buccinator muscle which forms the internal walls of the cheeks and works to oppose the tongue by pushing food from the oral vestibules. It provides taste sensation to the rostral 2/3 of the tongue.

Medial and lateral epicondyles of the femur

The femur is in the proximal pelvic limb, in the femoral region. The medial and lateral epicondyles of the femur are found at the distal aspect of the femur, at the proximal stifle joint. The epicondyles are the proximal attachment for the lateral collateral ligaments of the stifle which act to stablisie the joint and prevent abduction and adduction. The lateral epicondyle is also the site of origin of the popliteus muscle which acts to rotate the leg medially. The extensor fossa is also found at the lateral epicondyle which is the origin of the extensor digitorus longus. The semimembranosus is inserted just proximal to the medial epicondyle.

Frontal bone

The frontal bone is the most rostral bone of the cranium, or brain case. It articulates with the facial bones rostrally - specifically the facial bones medially and the maxilla laterally. The lacrimal and palatine bones ventrally. Caudally it articulates with the parietal bones, in particular the temporal line of the frontal bones which extends from the zygomatic process and proceeds caudally to meet the median saggittal crest in the dorsal midline. It overlies the frontal lobe of the cerebral hemisphere and gives site of attachment of the falx cerebri which is the meningeal fold separating the two hemispheres laterally. Contains within it the frontal sinuses at the rostral portion, medial to the orbits.

Greater trochanter of the femur

The greater trochanter of the femur is the largest eminence of the proximal extremity of the bone. it is located in the proximal region of the pelvic limb, lateral to the head of the femur, which articulates with a high degree of congruence with the acetabulum. It provides a site of attachment of the middle and deep gluteal muscles (which are innervated by the cranial gluteal nerves) Caudoventrally is the ischiatic tuberosity and dorsomedially you can feel the spines of the fused sacral vertebrae. The ischiatic nerve runs directly caudal to the greater trochanter

Greater tubercle of the humerus

The greater tubercle of the humerus is found at the proximal aspect of the bone - around the level of the shoulder joint in the forelimb. It is more dorsal than the head of the bone. it recieves the insertions of the supraspinatus, the infraspinatus and a part of the deep pectoral muscles. Felt ventral to the acrominon of the spine of the scapula.

Hip joint

The hip joint is found at the proximal pelvic limb.It is a typical ball and socket joint with a beautiful congruence between the ball shaped head of the femur and the acetebullar fossa of the pelvic bone. it allows for flexion and extension - as well as some abduction and adduction, which can be see in a dog as they cock their leg to urinate. The head of the femur is a near perfect hemisphere with just a fovea for the attachment of the ligament of the femoral head to connect with the acetabullar fossa. The transverse acetabullar ligament extends across the acetebular notch at the caudoventral of this structure - it is continuous with the labrum and acts to deepen the joint. The greater trochanter may be felt dorsolateral to the head of the femur and the ischiatic tuberosity caudally. Ventrally the brim of the pubis may be palpated.

Larynx and hyoid appt

The hyoid apparatus is a set of slender bones which form a sling to support the tongue and the larynx. It comprises the paired stylohoid bones, the epihyoid bones, the ceratohyoid bones, the singular - horizontal basihyoid, and the thyrohyoid bones. The thyrohyoid bones articulate with the thyroid cartilage of the larynx. The larynx is the entrance to the trachea and is comprised of the rostral most epiglottis, which is a shovel shaped cartilage that flops back to cover the trachea during swallowing. The paired thyroid cartillages which are thickened ventrally and do not quite meet dorsally. The irregularly shaped artytenoid cartilages which have the process which can dilate and constrict the rima glottidis during inhalation and exhalation and the cricohyoid cartilage which is the most caudal and is a ring shape which articulates with the trachea.

Infraorbital foramen and nerve

The infraorbital foramen is the opening in the rostral maxilla, cranial to the level of the 3rd premolar. It originates at the maxillary foramen and the canal runs rostrally to the infraorbital foramen. Lateral aspect of the maxilla Through this runs the maxillary nerve which branches as the superior alveolar nerve to supply the teeth of the upper arcade with sensation. The infraorbital nerve emerges and provides sensory innervation to the nose and rostral lips via many fasiculi. The nerve also runs with the infraorbital vein and artery.

Infraspinatus and supraspinatus

The infraspinatus muscle is an intrinsic muscle of the forelimb found at the proximal region, it acts over the shoulder joint. It is found in the infraspinous fossa of the scapula, caudal to the spine. It is deep to the deltoideus muscle.it attaches to the greater tubercle of the humerus and has an associated bursa at the tendon to reduce friction. A bursa is a connective tissue sac which contains synovial fluid. It acts to extend or flex the shoulder joint - depending on its position and is innervated by the suprascapular nerve. The suprascapular nerve also innervates the more cranial supraspinatus muscle, which lies in the supraspinous fossa of the scapula cranial to the spine of scapula. It is covered largely by omotransversarius and the cervical part of the trapezius muscle. It inserts, as well, onto the greater tubercle of the humerus and acts to extend and stabilise the joint.

Ischiatic tuberosity

The ischiatic tuberosity is a bony protuberance of the pelvis, so found on the caudolateral aspect of the pelvic region - at the most proximal pelvic limb. It is more caudal than the hip joint. It is a part of the ischium, which connects with the illeum cranially and the pubis craniomedially. it provides the site of attachment to the sacrotuberous ligament, the ligament spans from the last sacral segment and the first caudal to the lateral angle of the tuberosity. It provides the site of attachment to the muscles of the hamstrings, biceps femoris, semitendinosus and semimembranosus (which attach to the ventral surface)

Tarsus

The joint of the tarsus is also called the hock and is located at the distal pelvic limb, distal to the crural bones. It is located between the tibia and fibula and the metatarsals. It is composed of 7 bones arranged in 3 irregular rows. The proximal row is composed of the long, laterally located calcaneus. Its tuber extends further proximally that the crurotarsal joint itself. And to this attaches the stout tendons of the gastrocnemius and SDF. The calcaneus articulates with the talus medially and the 4th tarsal distally. The medially located talus has a trochea articular surface to articulate with the cochlea of the tibia. It articulates with the central tarsal bone. The distal row of tarsals consists of 4 bones, the first, second and third are located medially to laterally, separated from the proximal row by the central tarsal. The 4th is the most lateral and completes the distal row, articulating with the calcaneus proximally. The major joint through which practically all movement occurs is the crurotarsal joint. It is a strick hinge joint. The joints distal of this show very limited movement - especially the tarsometatarsal joint

Lacrimal gland

The lacrimal gland is a small, flat, lobular structure on the dorsolateral surface of the orbit, within the periorbita. It lies deep to the orbital ligament which forms the lateral border of the orbit and spans between the zygomatic process of the frontal bone dorsally and the frontal process of the zygomatic bone ventrally. It secretes a serous tear fluid which is secreted to the dorsal fornix of the eye via many openings in the dorsal palpebrae or eyelid. The fluid is spread across the eye by blinking and serves to moisten the eye and remove debris and irritants. It is mixed with secretions from the tarsal gland - which are oily and help to keep the aqueous secretion in place. The fluid is passed across the eye and collects in the lacrimal lake which is the depression around the lacrimal caruncle in the medial canthus of the eye.

Lateral and medial epicondyles of the humerus

The lateral and medial epicondyles are located at the distal aspect of the humerus, distal to the shoulder joint and proximal to the antebrachium. They are about the level of the elbow joints and provide sites of attachment for the medial and lateral collateral ligaments of the elbow which prevent adduction and abduction of the joint. The medial epicondyle is the region where the flexor group of antebrachial muscles arises - innervated by the median and ulnar nerve. The lateral epicondyle is the region for origin of the extensor muscles of the carpus and digits which are innervated by the radial nerve.

Line of pleural reflection

The line of pleural reflection is the line demarcating the junction between the costal and diaphragmatic pleura. The costal pleura is reflected acutely onto the phrenicopleural fascia covering the diaphragm and becomse the diaphragmatic pleura. The line where this reflection takes palce is known as the line of pleural reflection. It therefore defines the extent of the pleural cavity. It is located slightly more cranial than the costal arch. It runs from the sternum along the 8th costal cartilage, crosses the 9th cartilage and then proceeds in a curve that intersects the 11th costochondral junction to reach the dorsal end of the last rib where it passes caudomedially to the second lumbra transverse process. The lungs rarely expand to these recesses.

Parotid gland and duct

The lobular parotid gland embraces the ventral ear. It is a v or u shaped gland, which is relatively thin. Located within the depression between the masseter muscle and the wing of the atlas. Its duct leaves the cranial aspect of the gland and continues over the lateral aspect of the masseter muscle - in between the dorsal and ventral buccal branches of the facial nerve. the duct opens into the vestibule at a small parotid papilla opposite the caudal part of the carnissal tooth P4. The gland produces largely serous secretions which is more important in species which spend time chewing their food as it serves to soften the bolus for swallowing. It is innervated by the glossopharyngeal nerve. Ventral to the parotid gland lies the fibrous capsule of the mandibular salivary gland.

Medial and lateral malleoli

The malleoli are present at the distal crural region - the medial malleoli is on the medial aspect of the distal tibia and the lateral malleoli on the lateral aspect of the fibula. The lateral malleolus forms an interlocking joint with the tibia and completes the articular surface for the tarlus.The lateral malleolus has two grooves that contain the tendons of the peroneus longus, peroneus brevis and lateral digital extensor. The grooves redirect the force of contraction. They are the origins of the collateral ligaments which support the hock joint and prevent abduction and adduction of the joint.

Symphysis of the mandible

The mandible is the lower jaw which houses the lower arcade, it is composed of two side which are joined rostrally at the symphysis. And felt as somewhat of an indentation at the rostral most point of the mandible, ventral to the space between the first left and first right incisor. The joint allows for more precise positioning of the jaws during activities such as gnawing on bones. The joint may be a weak spot on the skull such as that blunt trauma may separate the mandibles are require them to be put back together by surgical means.

Mandibular lymph nodes

The mandibular lymph nodes are superficial lymph nodes which are clumped around the lingofacial vein ventral to the mandibular salivary glands. There may be two or 3 nodes on either side, and they are small pea sized glands which slip through your fingers upon palpation. They drain the superficial structures of thef ace and intermandibular space. They are a site commonly used to assess for inflammation which may be associated with a local or systemic infection or the possibilitty of a disease such as lymphoma. They are a part of the immune system and act to filter the blood for debris and bacteria. Drain the structures of the muzzle, the salivary glands, the intermandibular space and some of the masticatory muscles. Its efferent goes to the retropharyngeal lymph centre (between the wing of the atlas and the corotid artery.

Mandibular salivary gland and duct

The mandibular salivary gland is a large salivary gland present on the lateral surface of the head, caudal to the angle of the mandible. It is in close proximity to the mandibular lymph nodes and this can cause a source of confusion in obtaining samples of lymph for testing. The gland is covered in a tough capsule which also contains the caudal end of the monostomatic salivary gland. The mandibular lymph nodes are small, pea shaped glands which are softer to palapate and clustered around the lingofacial vein, they slip through your fingers as you palpate them. The mandibular salivary gland secretes a mixture of serous and mucous which passes along the duct in the sublingual folds, ventral to the mucous membranes to open at the sublingual caruncles either side of the frenulum of the tongue.

Manubrium

The manubrium is the most cranial of the sternebrae, there are 8 sternebrae in the dog. The manubrium ends in a club like projection and can be palpated in the ventral midline of the neck. It forms the ventral border of the thoracic inlet. The manubrium articulates with the costal cartilage of the first rib. It provides attachment for some of the muscles of the neck such as the sternocephalicus, sternohyoideus and sternothyroideus.

Olecranon process of the ulna

The olceranon process of the ulna is readily palpated. it is present at the distal end of the humerus of the thoracic limb, on the caudal aspect - it is well known as being within the region of the elbow joint. It provides the site of attachment for the extensors of the elbow joint, the triceps brachii, anconeus and tensor fascia antebrachii. Also feel the epicondyles of the humerus in this region.

Masseter muscle

The masseter muscle is one of the muscles of mastication which functions to close the jaw, along with the temporalis muscle and the medial and lateral pterygoids. It is innervated by the maxillary branch of the trigeminal nerve. The dorsal and ventral buccal branches of the facial nerve run across its surface, but do not serve to innervate the muscle. It originates from the ventral surface of the zygomatic arch to the masseteric fossa of the ramus, the angular process and the ventrolateral surface of the mandible. The duct of the parotid salivary gland also runs over its surface. It is a pectinate muscle, with fibres that run in all directions to allow for complexity of movement of the muscle

Median saggital crest

The median saggital crest is the prominent bony feature on the dorsal midline of the cranium. It is formed from the paired parietal bones, which are met rostrally by the frontal bones - including the temporal line which runs from the zygomatic process of the frontal bones and meets the crest. Caudally it meets the external occipital protuberance. It forms the temporal fossa, along with the caudal part of the frontal bones which is the site of attachment for the temporalis muscle.

Mental foramen/ nerve

The mental foramina are found on the rostral aspect of the mandible, which is the lowered jaw. There are typically 3 mental foramina, so named rostral, middle and caudal. The foramina originate caudally from the mandibular canal, which has its entrance at the mandibular foramen at the medial aspect of the ramus. Through which is transmitted the inferior alveolar branch of the mandibular branch of the trigeminal nerve. This gives sensory innervation to the teeth of the lower arcade before emerging as the mental nerve to supply the lower lip and chin with sensation. It is accompanied by the inferior alveolar artery which branches into the mental artery and inferior labial veins.

Metacarpal bones

The metacarpal bones are the bones of the distal forelimb, distal to the antebrachium in the region of the manus. There are 5 metacarpal bones, numbered 1-5 medially to laterally. They all articulate proximally with their corresponding carpal bone, except for the 5th metacarpal which also articulates with the 4th metacarpal. Distally they all articulate with their corresponding phalanges. There are 2 seasamoids associated with palmar aspect of the metacarpophalangeal joint for redirection of force of the flexor tendons. This joint is also associated with the metacarpal pad, which is the large pad on the palmar surface.

Metatarsal bones

The metatarsals are located at the distal end of the pelvic limb, at the region of the hock. There are 4 metatarsals in the hock, so named 2-5 medially to laterally. Metatarsal 4 is often absent in dogs, if it is present it may be greatly reduced in size. The metatarsals articulate proximally with the 4 tarsal bones, the 4th tarsal bone is far larger than the rest and so both metatarsals 4 and 5 articulate with it. The metatarsals articulate distally with the corresponding proximal phalanx. There are proximal seasamoids at this joint, the metatarsophalangeal joint - for the passage of the tendons of the flexors of the digits.

Nasolacrimal duct

The nasolacrimal duct is the duct which drains the old tear fluid from the eye to the opening of the nose to be evaporated. The duct is formed at the medial aspect of each eye, just in from the medial canthus. The fluid collects in the lacrimal lac, which surrounds the fleshy caruncle in this region. It is then taken up, by means of syphon action to the lacrimal puncta present in the superior and inferior palpebrae at this region. The puncta then join the lacrimal canaliculi before running as the common duct rostrally through the maxilla for a ways before emerging and running on the internal surface of the bone covered in mucosa. The duct opens at the external nares for evaporation. Blockage of the duct at any level, due to infection or forgein bodies will cause the inability of the tear fluid to drain from the eyes and so will stream down the face instead - this can be seen in spring when there are an abundance of seed heads and allergens present in the air.

Nictitating membrane

The nictitating membrane is also called the third membrane and is visible in healthy animals by applying gentle pressure to the globe and everting the lower eyelid. It is present in the medial canthus. The third eyelid is covered in conjunctiva on both sides and invisible when the eye is closed. It is supported by a T shaped cartilage, which is orientated so the bar lies in the free edge of the fold and the stem points back into the orbit medial to the eyeball. It has an associated gland, called the gland of the third eyelid which adds to the serous tear film secretion. The third eyelid is of immunologic nature, with nodules of lymphoid tissue present on its medial surface, which is able to be everted over the eye. The membrane is maintained in the medial canthus by means of sympathetic stimulation to smooth muscle. However, cats are often seen to have their everted over their eyes when content. Damage to sympathetic stimulation, such as occurs in horners syndrome, may be seen as the passive slipping of the eyelid from its position in the canthus - across the eye.

External occipital protuberance

The occipital bone is the caudal most bone of the cranium. It overlies the occipital lobe of the brain. The protuberance is a bony extension which is palpataed caudally of the external sagittal crest (dorsal midline of the head). It may be used as a bony landmark for the positioning of the needle for collection of CSF from the cerebellomedullary cistern, along with the wing of the atlas C1.

Orbit and orbital ligament

The orbit is the casing which encloses the eye. In the dog this is an incomplete bony rim, formed by the frontal bone dorsally (the zygomatic process), ventrally by the zygomatic bone (frontal process) and medially by aspects of the frontal, lacrimal, presphenoid and palatine bones. The lateral border of the orbit is completed by the orbital ligament, which is a tough, thick ligament and palpable due to the difference in feel from the surrounding bone. The orbit is related dorsomedially to the frontal sinus and rostromedially to the maxillary recess. The lacrimal gland may be palpated at the dorsolateral aspect of the orbit.

Pad names and joints

The pads of the paws are present on the palmar surface of the forepaw and the plantar surface of the hind paw. The dog is digitigrade, which means it walks on its digits. The pads act to support the joints they overlie and are named as such. The digital pads lie over the distal phalangeal joint nearest to the paw and supports the weight placed on the phalanges. There are 5 digital pads in the forelimb and 4 in the hindlimb. The central pad is called the metacarpal pad in the forelimb and the metatarsal pad in the hind limb and it supports the weight of the animal that comes down through the metacarpal or metatarsal bones. The accessory carpal bone has an associated carpal pad which lies just distal to the bone and does not commonly make contact with the ground. It is a vestigial pad. The pads contain adipose tissue and collagen to act as shock absorbers during locomotion

Maxilla

The paired maxilla are the principle facial bones and meet in the ventral midline to form part of the roof of the mouth. They form the lateral aspects of the nasal cavity and give rise to the dorsal and ventral nasal conchae, which is a thin scroll like bones in the nasal cavity which are covered by epithelium and serve to increase the surface area for air entering the nose. The maxilla houses the cheek teeth of the upper arcade including the canines, the 4 premolars and the 2 molars. The maxillary foramen passes through the bone and opens at the infraorbital foramen about the level of the 3rd tooth. The maxillary branch of the trigeminal nerve passes through this, giving off superior alveolar branches to supply the teeth as it goes and emerging as the infraorbital nerve which supplies the nose and upper lip. Articulates with the nasal and incisive bones rostrally and the frontal and zygomatic bones caudally.

Parietal bone

The parietal bones are found on the dorsal cranium. Most notably marked by the median sagittal crest which is the bony ridge between these two bones. It articulates with the frontal bones cranially and the occipital bone caudally. It forms the temporal fossa along with the temporal line of the frontal bone. Medially with the zygomatic and temporal bones. The temporalis muscle sits within this site and is involved in closing the mouth. It overlies the parietal lobes of the brain.

Patella and patella ligament

The patella is the largest seasamoid bone in the body. The bone is embedded within the tendon of insertion of the quadriceps femoris, and acts in facilitating the redirection of the force of the muscle to allow flexion of the stifle. The patella sits in the trochlear groove of the femur, which is at the distal aspect of the bone. If the groove is too shallow, or the ridges not well extended then this may result in luxation of the patella, where it rides out of the groove. This is painful and increases the chance of arthritis. It is particularly common in smaller breeds of dog. The patella ligament is formed from the distal extension of the quadriceps tendon as it passes through the patella. It attaches to the tibial tuberosity of the tibia. It forms the cranial aspect of the stifle and is separated from the joint cavity by the infrapatella fat pad.

Wing of the Illeum

The pelvis is the most proximal aspect of the pelvic limb. The illeum being the most cranial of the pelvic bones, articulating with the ischium caudally and the pubis ventromedially. The wing of the illeum is the wide cranial part of the bone, which is concave laterally and provides the site of attachment of the gluteus medialis muscle. The crest of the illium is cranial and may be palpated. Caudally to the wing is the hip joint and sacrotuberous ligaments.

Phalanges

The phalanges, or the bones which comprise the digits, are found at the distal most aspect of each limb. The number of phalanges per digit may vary depending on the toe in question. In the forepaw there are 3 phalanges for each of the 4 main digits, digit 1 has just 2 phalanges. In the hind paw there are 3 phalanges in each of the 4 persistant digits. Digit 1 can have a variable number of phalanges - though commonly just the distal phalanx is present, having the ungual process or claw attached. This is called a dew claw and is commonly surgically removed. Each phalange is a long, slender bone with a base, body and head from proximal to distal. movement of the joints between the bones is by flexion and extension and is controlled by the digital flexors and extensors, as well as intrinsic muscles of the fore or hind paw.

Pinna and the external ear canal

The pinna is the sheet of cartilage, which is rolled ventromedially to form the external ear. The external ear has many superficial vessels which can be susceptible to damage and form large collections of blood known as haematomas. These can be drained and heal well. The pinna may be errect in some breeds, or more pendular in others - depending on the rigidity of the cartilage. The muscles of the ear are supported at the base of the ear by plates of cartillage. Their motor innervation is supplied by the auricopalpebral branch of the facial nerve (CN 7). The tragus is present at the entrance to the external ear canal, and provides a landmark for surgeries such as the lateral ear canal resection. the intertragic incisure is lateral - as demarcated by the cutaneous marginal pouch. The pretragic incisure is present medially. The external ear canal is roughly L shaped and as a result of this it is prone to infection due to the difficulty to drain. The ear canal is lined with hair and wax. It ends at the external acoustic meatus - marked by the tympanic membrane.

Pleura cupulae

The pleura cupulae is the reflection of the parietal pluera at the level of the thoracic inlet. It is where the cranial portions of the costal and mediastinal pleura come together to form a dome. The dome extends a bit beyond the level of the first rib and so it is unprotected by the bony structures and vulnerable to injury. The lungs rarely extend into this space. Puncture in this region during surgery or trauma can lead to pneumothorax, collapse of the lung due to the loss of pressure differences between the inside and outside of the thoracic cavity. Obstructions by the oesophagus can lead to puncture of the cupulae without the presence of an external puncture site and can be more difficult to detect.

Popliteal lymph node

The popliteal lymph node is the lymph node draining the distal aspect of the pelvic limb. It is found caudal to the stifle, in a region known as the popliteal region. It is a small node, which lies in the fat at the caudal border of the biceps femoris muscle. Its efferent flow is directed to the medial illiac centre. lymph nodes are part of the bodys immune system and act to filter potential pathogens and debris from the blood. They can often be hard to palpate, but become harder and enflammed during infection or disease state such as lymphoma.

Trachea/ oesophagus in the neck

The position of the trachea and oesophagus in the neck is rather awkward considering. The nasocavity is dorsal to the oral cavity, however the trachea for passage of air to the lungs is VENTRAL to the oesophagus which transports a bolus of food to the stomach. This requires the need for a pharynx - the point where the two passages must cross. The closure of the epigolttic cartilage over the entrance to the larynx, along with the lifting of the soft palate temporarily ceases breathing to allow swallowing to occur. The bolus passes from the oral cavity to the oral pharynx and then through the laryngopharynx dorsal to the larynx before entering the oesophagus. The oesophagus travels DORSAL to the trachea until about mid way down the neck, where it slips to the left to maintain this position as it enters the thoracic inlet. The trachea is palapable in the neck region by means of the c shaped cartilagenous rings. The oesophagus is a muscular tube and is not able to be palapated.

Quadriceps muscle group

The quadriceps femoris is a large muscle comprising of 4 heads, which is the cranial muscle of the thigh. Despite this grouping, it manages to cover most of the lateral, medial and cranial surface of the femur. The 4 heads of the muscle fuse distally at the stifle, by means of the patella ligament which encompasses the patella, before inserting onto the tibial tuberosity at the proximal aspect of this bone. It is the most power extensor of the stifle and necessary for weight bearing in the animal. It is supplied by the femoral nerve, damage to which causes collapse of the stifle and in ability to bear weight. The rectus femoris arises from the illium and so acts over the hip joint and aids in hip flexion as well as extending the stifle

Costochondral junctions

The rib cage is the thoracic region of the dog, the thoracic vertebrae T1- T13 each give rise to a rib. The ribs articulate with the sternebrae by means of the costal cartilage. That is to say each rib consists of a dorsal rib proper, which is bony and a cartillagenous ventral part - the costal cartilage. Where these two parts meet is the costochondral junction. The first 8 ribs articulate directly with the sternebrae through their costal cartilages. ribs 9-12 articulate with the cartilage of the rib infront and give rise to the costal arch.

Sacrotuberous ligament

The sacrotuberous ligament is a strong ligament which spans from the last sacral segement and first caudal vertebrae to the ischiatic tuberosity of the ischium. It is in the gluteal region of the pelvic limb. it is found between the levator ani and the superficial gluteal muscles. It aids in stabilising the sacroilliac joint and provides a site for muscle attachment including the biceps femoris and superficial gluteal muscles. The ligament and the hip bone form two formina corresponding to the greater and lesser ischiatic notches, which are separated by the ischiatic spine. The ischiatic nerve and the cranial gluteal nerve adn vessel emerge through the greater ischiatic foramen.

Shoulder joint and landmarks

The shoulder joint is the most proximal joint of the thoracic limb. It is formed between the glenoid cavity of the scapula and the ball head of the humerus. Hence it is a ball and socket joint. Movement is free in the sagittal plane, allowing flexion and extension - but also significant rotation, abduction and adduction can occur. There are medial and lateral glenohumeral ligaments to strenghten the joint, but strength is also derived from the presence of local muscles including the supraspinatus and infraspinatus

spine of the scapula

The spine of the scapula is a bony ridge which is readily felt at the proximal most aspect of the thoracic limb. It is just distal to the cranial angle of the bone, and if followed ventrally ends in the bony protuberance the acromion. The acromion and spine serves as a site of origin of the deltoideus muscle. It is also the insertion point for the trapezius and omotransversarisu muscles.The spine divides the scapula into two fossa, the cranial supraspinous for the supraspinatus which extends the shoulder joint, and the caudal infraspinous fossa where the infraspinatus arises, which acts to either flex or extend the shoulder depending on the position of the joint.

Medial and lateral styloid processes of the radius and ulna

The styloid process are present at the distal aspect of the antebrachial bones, so in the forelimb, distal to the elbow joint. The medial styloid is present at the medial aspect of the distal radius and the lateral styloid at the distal aspect of the lateral ulna bone. The lateral styloid process articulates with the ulnar carpal bone and the accessory carpal bone. The styloid processes provide attachment for the collateral ligaments of the carpal joint which act in stabilising the joint.

Superficial cervical/ prescapular lymph node

The superficial cervical lymph nodes or 'lymph centres' are also known as the prescapular lymph nodes. They are areas of lymphoid tissue which house lymphocytes and filter the blood for debris and pathogens. The superficial cervical nodes lie cranial to the supraspinatus within the suprapsinous fossa of the scapula, and are covered by the omotransversarius and brachiocephalicus. They recieve lymph from the superficial part of the lateral surface of the neck, the caudal surface of the head (including the ear and the pharynx) and the lateral surface of the thoracic limb/ proximal of the forelimb. it flows to the lymphatics at the thoracic inlet.

Tuber calcanei

The tarsus, or hock region of the pelvic limb consists of 7 bones in 3 irregular rows, one of those bones is the lateral calcaneus bone which has a bony protuberance which spans more proximal than the crurotarsal joint itself. It is a prominent bony protuberance which provides the site of attachment of the common calcaneal tendon, which is largely contributed to by the SDF and gastrocnemius muscles and the crural fascia. It acts like a lever for extension of the hock

Teeth

The teeth are found in the mouth, there are two arcades of teeth, the upper - found in the incisive and maxilla bones and the lower, all of which are in the mandible. Dogs are heterodonts, with different types of teeth to serve for different purposes. As such they have 6 upper and 6 lower incisors which are used for nibbling and grooming, they have 2 upper and 2 lower canines which are used for tearing. They have a single root which is larger than the crown itself, and curves to lie dorsal to the first premolar - making its extraction very difficult. There are 8 premolars on both the upper and lower arcade, with the 4th premolar on the upper jaw being the carnissal tooth which is scissor like and involved in slicing. It acts against the first molar on the lower jaw- which is the large carnissal for the lower jaw. There are 4 molars on the upper jaw and 6 on the lower. These are used for crushing and grinding - as seen with a dog chewing a bone. Dogs are dyphodont - having 2 waves of teeth in their lives, with the puppy teeth being replaced at about 6 - 12 months

Temporal line

The temporal line is the bony ridge which spans from the lateral aspect of the frontal bone of the skull (being the zygomatic processes) and runs caudomedially on an oblique angle to meet the median sagittal crest at the dorsal midline. The bony ridge then continues caudally as the external occipital protuberance. In brachyocephalic breeds where the external sagittal crest is less prominent, the temporal line becomes the more palpable bony ridge of the dorsum of the cranium. The temporal fossa for the origin of the large temporalis muscle, is bordered medially at its cranial aspect by the temporal line, and caudomedially by the external sagittal crest.

Temporalis muscle

The temporalis muscle is one of the muscles of mastication which is involved in the closure of the mandibles. It is innervated, along with the other muscles of mastication by the mandibular branch of the trigeminal nerve (CN 5). The temporalis muscle originates at the temporal fossa - which is bordered craniomedially by the temporal line and caudomedially by the external sagittal crest. Its fibres blend with the masseter muscle, which originates from the ventral aspect of the zygomatic arch. The temporalis muscle inserts on the cornoid process of the mandible. The masseter muscle inserts onto the masserteric fossa, the ventrolateral surface of the mandible and the angular process of the mandible. The temporalis muscle is important in dogs, who move their jaws in a scissor like fashion in order to eat prey. A paralysis of the nerve causing loss of LMN supply will lead to severe atrophy and show the great space uptaken by the mascle on the face - as shown by the prominence of the zygomatic arch.

Temporomandibular joint

The temporomandibular joint is a complex joint formed between the mandibles and the skull. There are technically two TMJs on the skull, a left and a right and while movements at one must naturally cause movements at the other - the extent and exact type of movements may not neccessarily be identical. The joint is able to move, largely in flexion extension but to some extent translation is permitted as well - although is a function more pronounced in ruminents and is seen with them chewing their cud. The joint is formed between the elongated condyles of the ramus of the mandible and the mandibular fossa of the squamous temporal bones. There are thin cartillagenous articular disks which separate the articular surfaces of the bones and divides the joint cavity into two compartments. The joint capsule is strengthened by lateral and caudal ligaments and bony support is given caudally by the retroarticular process of the squamous temporal

Thoracic inlet

The thoracic inlet is the entrance to the chest. Can be thought of as the entrance point of the trachea and oesophagus into the thorax. it is bordered ventrally by the manubrium (the first sternebrae) The first rib on either side laterally and the first thoracic vertebrae dorsally. It is a relatively small opening and covered extensively by the musculature of the thoracic limb and expaxial muscles. It allows access to the thorax of the o. t as mentioned before as vell as the large external jugular veins and the common carotid arteries. The plueral cupula it the reflection the mediastinal and costal pleura at a cup shaped dome that extends beyond the first rib. Here it is susceptible to damage due to trauma and surgery and so can cause pneumothorax

Shaft of the tibia

The tibia is one of the bones of the crus found in the middle of the pelvic limb. It is distal to the femur and stifle joint and proximal to the hock joint. Laterally to the tibia is the fibula. The shaft of the tibia is not covered by muscles medially, and so it able to be felt superficially. The craniolateral crural muscles which act to extend the digits and flex the hock can be felt laterally and the caudal muscles, largely the two heads of the gastrocnemius can be felt caudally to the shaft.

Tibial tuberosity

The tibial tuberosity is present on the proxmial aspect of the bone, it is in the pelvic limb, just distal to the stifle joint. The bony tuberance serves as the site of attachment of the quadriceps femoris muscle which extends the stifle, by means of the patella ligament which runs through the patella. The tuberosity is continued distally as the cranial border of the tibia.

Triceps brachii

The triceps brachii is the major muscle which fills the space caudal to the shoulder joint. It has 4 heads in the dog, 3 arising from the proximal humerus and the long head arising from the caudal border of the scapula. All the heads insert via the tricipital tendon onto the olecranon tuberosity of the ulna. The heads are named long, lateral, accessory and medial. It functions to extend the elbow. It is a major antigravitational muscle for posture in the forelimb. The long head also acts over the shoudler joint, so is able to cause flexion of this joint. It is innervated by the radial nerve. Damage to the nerve results in the loss of weight bearing ability.

Trochlear groove and ridges

The trochlear of the femur is the distal aspect of the bone, so is found in the pelvic limb at the level of the stifle joint. The patella sits in the trochlear groove and the patella tendon passes over the groove to insert on the tibial tuberosity. The surface of the trochlea is very smooth to allow free movement of the patella during flexion and extension of the stifle. If the groove is too shallow, or the ridges not well formed then the patella may ride out of the groove - known as a luxating patella and cause pain and arthritis. this is more common in smaller dogs. The ridges prevent the transverse sliding of the joint, so aid in its stabilisation.

Xiphoid cartilage

The xiphoid cartilage is a flat cartilage that projects caudally from the last sternebrae between the costal arch. It provides support to the cranial aspect of the abdomen, gives for the origin of the rectus abdominus muscle and also the linea alba which is the white line seen at the ventral midline, running from the xiphoid to the pelvic symphsis. The xiphoid may be palpated by feeling down the sternebrae to the caudal aspect

Zygomatic arch

The zygomatic arch is the cheek bone! It is a prominent bony structure on the lateral aspect of the skull. It is composite of the zygomatic bone rostrally and the zygomatic process of the squamous temporal bone caudally. It provides the site of attachment of the masseter muscle, one of the muscles of mastication which inserts on the masseteric fossa of the mandible (and the angular process and the ventrolateral region). It forms the ventral aspect of the bony orbit and provides attachment for the the orbital ligament - the lateral aspect in dogs and cats. deep to the bone is the zygomatic salivary gland.

Regions of the vertebral column

There are 5 regions of the vertebral column, within each region the characteristics of the bones may vary. There are 7 cervical vertebrae, which extend from the base of the skull to about the level of the shoulder. There are 13 thoracic vertebrae, each with an associated rib, which span from the level of the shoulder/ thoracic inlet to the end of the rib cage. The ribs are articulated by means of cranial and caudal costal fovea of the first through 10th vertebrae. The spine of the 11th thoracic vertebrae is almost perpendicular and is known as the anticlinal vertebrae and demarks the change in orientation of the dorsal spinous process from caudal to cranial in correspondance to the direction of the force applied by the muscles. There are 7 lumbar vertebrae which span the abdominal region of the animal. There are 3 fused sacral vertebrae which make up the pelvic region and articulate with the pelvic bones. There are a variable number of caudal vertebrae in the dog, the average is about 20. From cervical to sacral there is passage of 2 spinal nerves from each vertebral foramen, however in the atlas, first cervical vertebrae- there is passage of 2 pairs of spinal nerves.

Common calcanean tendon

This is the archilles tendon in humans. The tendon is found on the distal end of the caudal aspect of the pelvic limb, around the region of the hock. It is the combined tendon of insertion of a few different muscles, but largely comprised of the gastrocnemius tendon which inserts onto the calcaneal tuber. The tendon is surpassed about midway, when it is overcome from the medial aspect by means of the superficial digital flexor tendon. This tendon caps the calcaneal tuber and then runs further distally to insert onto the proximal phalanges. The tendon also has contribution by the hamstrings (biceps, semitendinosus etc) by means of the crural fascia. Rupture of the tendon causes a plantigrade stance with slight curling of the toes due to intact flexor tendons.

Femoral pulse

This is the most commonly used site for obtaining the pulse of an animal. It is located on the medial thigh, close to the abdomen. It is bordered by the pectineus and adductor CAUDALLY, the sartorius CRANIALLY and the abdominal wall medially. It lies along the superficial surface of the vastus medialis... It is a branch of the external illiac artery, the femoral artery is accompanied by the femoral vein and the saphenous nerve (branch of the femoral nerve)