Anatomy Flashcards
What are intrinsic muscles?
Have origin and insertion inside the limb.
Discuss the brachial plexus.
Nerves branch from ventral portion of spinal cord.
Thoracic intumescence - widening due to nerves branching from it.
C6-T1
Involves muscles and skin of thoracic limb except for the brachiocephalicus, omotransversarius, trapezius, and upper shoulder skin.
Which nerves are invovled in the brachial plexus?
ALL THESE NERVES ORIGINATE ON MEDIAL SIDE OF LIMB.
Lateral thoracic - ‘long nerve’, C8-T1, motor to deep pectorial and cutaneous trunci, sensory to skin on lateral thorax and skin over triceps. Most caudal.
Subscapular - C6-7, single or double, motor to subscapularis, long-5cm. Most cranial.
Suprascapular - C6-7, motor nerve to supraspinatus, infraspinatus, shoulder joint. Injury to neck of scapula can damage (weight bearing and forward/backward movements affected).
Axillary - C7-8, motor to flexors of shoulder joint, sensory to dorsal area, injury is rare due to its short length and protection by limb externally; if it does occur may be from wrenching.
Radial - C7-T1, supplies all extensor muscles of elbow, carpal and digital joints plus some muscles. Injury can occur easily over supracondylar crest of humerus (kiss hand reflex).
Musculocutaneous - C7-8, branches to coracobrachialis, biceps brachii, brachialis. Sensory to medial skin of antebrachium, lesions are uncommon.
Median - C8-T1, communicating branch to musculocutaneous, supplies some flexors and pronator teres, sensory skin on palmar surface of metacarpus and digits. In cats injuries are more common due to supracondraforamen (nerve runs through here).
Ulnar - C8-T1, close association with radial and medial nerves, motor supply to some flexors, sensory to skin caudal to antebrachium, dorsolateral on metacarpus and digit.
What is the cutaneous (panniculus) reflex?
Muscle shiver.
Think horse with fly.
C6 is the origin of which nerves?
Subscapular
Suprascapular
C7 is the origin of which nerves?
Suprascapular/subscapular
Axillary/Musculocutaneous
Radial
C8 is the origin of which nerves?
Axillary/Musculocutaneous
Radial
Median/Ulnar/Lateral thoracic
T1 is the origin of which nerves?
Radial
Median/Ulnar/Lateral thoracic
What are some of the test that can be used for examination of some nerves?
Withdrawal reflex - used during anaesthetics. Works for median, axillary, musculocutaneous, etc. C6-T1.
Triceps tendon reflex
Biceps tendon reflex
Cutaneous (panniculus) muscle reflex
Describe the components of the shoulder joint.
Spheroidal/simple joint - glenoid cavity of scapula and head of humerus.
Flexion and extension.
Part of joint capsule surrounds the tendon of origin of m. biceps brachii (held by transverse humeral ligament/transverse retinaculum).
Medial and lateral glenohumeral ligaments.
Muscular collateral ligaments (span from one bone to another, limiting movement); subscapularis, infraspinatus, supraspinatus.
Describe the components of the elbow (cubital) joint.
Composite joint, 3 bones;
Humero-radial joint - humeral condyle and head of radius, ginglymus (hinged joint, limited medial and lateral movement).
Humero-ulnar joint - humeral condyle, trochlear notch of the ulna, ginglymus, snapping hinge joint.
Proximal radio-ulnar joint - articular circumference of radius and radial notch of ulna, trochoid joint, rotation of radius on its long axis.
All 3 joints are within single articular capsule and articular cavity. All ligaments are extracapsular.
Thickenings of the fibrous membrane of the articular capsule gives more stability .
Lateral and medial collateral ligaments - attach lateral and medial epicondyles of humerus to radius and ulna.
Annular (ring) ligament of the radius - deep to collateral ligaments, partially encircles the head of radius, allows radial rotation.
Oblique ligament - crosses flexor angle of cubital articulation, humerus to ulna, prevents overextension.
Olecranon ligament - anconeal process of ulna to caudal surface of medial epicondylar crest.
Luxations of this joint are infrequent due to shape, condyle is prone to fracture.
Distal radioulnar joint - ulnar notch of radius and radial circumference of ulna, trochoid/simple, rotation of radius on long axis.
What are the 3 major joint areas of the carpal joint?
Antebrachiocarpal joint - trochlea of radius, ulna, radial carpal bone, ulnar carpal bone. Ellipsoid, compound joint, predominantly a hinge joint with slight abduction/adduction.
Middle carpal joint - proximal and distal rows of the carpal bone, condylar/compound joint.
Carpometacarpal joint - carpal bones I-IV and metacarpal I-IV. Plane/compound joint.
What is the intercarpal joint?
Joints between the carpal bones in a row, plane/compound joint.
What is the accessory carpal bone?
Bone that sticks out.
Part of plane/compound joint.
Amphiarthrosis (little movement).
Discuss the carpal joint as a whole.
Joint cavity has 2 main parts; antebrachium and proximal row or carpal bones, and proximal and distal rows of carpal bones and between the distal carpal and metacarpal bones.
Extensor retinaculum supplies dorsal fascial reinforcement and keeps extensor tendons in position. Stabilises.
Flexor retinaculum is present on palmar aspect and bridges the carpal canal. Stabilises.
Lateral and medial collateral ligaments are relatively short and only bridge the antebrachiocarpal joint.
Discuss the metacarpophalangeal joints.
Proximal phalanges, proximal sesamoids (paired except P1), dorsal sesamoid (single) and metacarpal bones.
Compound joint.
Multiple joint capsules that have dorsal and palmar outpouchings - attach to margin of articular surface of participating sesamoids.
Collateral ligaments.
Mainly hinge joint with slight abduction and adduction as well as axial rotation.
Discuss the proximal and distal interphalangeal joints.
Between respective phalanges; proximal and middle, middle and distal.
Saddle/simple joint.
Collateral ligaments.
Digital pads located on palmar surface of distal interphalangeal articulations.
What are the 2 sets of veins on the thoracic limb?
Superficial
Deep
What are the superficial veins present on the thoracic limb?
Cephalic
Accessory cephalic
Axillobrachial
Omobrachial
Discuss the cephalic vein.
Collects blood from palmar surface of manus.
Passes dorsoproximally across medial surface of distal antebrachium to cranial surface.
Close proximity to branches of radial nerve (clinical significance).
Proximal brachial region from a superficial position over triceps to deep under brachiocephalicus to external jugular.
Discuss the accessory cephalic vein.
Collects blood from dorsal area of manus.
Arises in dorsal metacarpal region from digital veins.
Joins cephalic vein on distal cranial surface of the antebrachium.
Discuss the axillobrachial vein.
Large vessel, proximal to cephalic vein.
Lateral proximal surface of brachium.
Passes deep into muscle mass caudal to scapulo-humeral articulation.
Joins axillary vein in the axilla.
Discuss the omobrachial vein.
Branch from axillobrachial.
Crosses superficial to deltoid and brachiocephalicus.
Has no muscular tributaries, only small vessels from skin and fascia.
Ends at external jugular.
What are the deep veins of the thoracic limb?
Radial Ulnar Median Brachial Axillary
Discuss the radial vein.
Small vessel, arises from deep palmar venous arch.
Follows mediocaudal border of radius.
Joins small ulnar vein at top third of radius.
Discuss the ulnar vein.
Same diameter as accompanying artery.
From supracarpal venous arch, runs proximal to deep digital flexor.
Receives tributaries from most of the flexor muscles in antebrachium.
Joins small radial vein at junction of proximal and middle third of the antebrachium to form median vein.
Discuss the median vein.
Continuation of junction of radial and ulnar veins.
Branches from palmar antebrachial vein and common interosseous.
Communicates with the cephalic vein via the median cubital vein.
Crosses biceps in a sigmoid flexure, before becoming the brachial vein.
Discuss the brachial vein.
From junction of collateral ulnar and median veins.
Receives bicipital and deep brachial veins.
Continued by axillary vein.
Discuss the axillary vein.
Continuation of brachial vein in axilla (armpit).
Receives axillobrachial, cranial circumflex humeral, lateral thoracic and subscapular veins.
Terminates at the subclavian vein.
What are the major arteries of the thoracic limb?
Axillary
Brachial
Median
Radial
Discuss the axillary artery.
Continuation of subclavian artery.
Passes cranial surface of first rib.
Two proximal branches - external thoracic artery to superficial pectoral muscles cranially, and lateral thoracic artery caudally supplies axillary lymph nodes, lat dorsi, deep pecs as well as cutaneous trunci of lateral thoracic region.
Give off subscapular artery before becoming brachial artery.
Discuss the brachial artery.
Courses through brachium on the medial surface of the medial head of triceps brachii.
Between musculocutaneous nerve and median and ulnar nerves.
Deep brachial artery from caudal surface to triceps brachii muscle.
Small bicipital artery craniodorsally.
Distal brachium supplies biceps brachii muscle.
Continued by median artery after common interosseous artery branches.
Discuss the median artery.
Largest artery on the antebrachium.
Begins after brachial artery gives off common interosseous branch.
Main branches; deep antebrachial, radial, superficial palmar arch.
First branches supply caudal side of antebrachium.
Terminal branches supply the digits.
Discuss the radial artery.
Origin just proximal to middle of the antebrachium.
Runs distally under origin of flexor carpi radialis.
Closely follows caudomedial border of the radius.
At carpus, divides into palmar and dorsal branches.
What are some skin modifications present in response to environment and eating habits in the hindlimb?
Claws in carnivores
Nails in primates
Hooves in ungulates
These are tools, sensory organs, and weapons.
Discuss foot pads.
Modification to the distal limb in carnivores.
Three groups; carpal/tarsal pads (1-not a lot of function), metacarpal/metatarsal pads (1), digital pads (4).
Made of fat and large portion of fibrous tissue.
What are the 5 segments of the distal phalanx?
Think layers of the claw.
Distinguished by location, structure, and horn production.
Perioplic - proximal part, near unguicular crest (proximal end of third phalanx), soft horn (wear).
Coronary - occupies floor of claw fold, tubular horn, middle layer of wall.
Wall - direct contact with unguicular process of distal phalanx.
Sole - ground surface, non-tubular soft, crumbly horn (soft cornification).
Footpads - digital, bulb in primates.
How many vessels are there on each digit?
4; 2 axial, and 2 abaxial.
Why is retractability an important modification in cat claws? How does it occur?
Prevents wear.
Retracts via medial dorsal elastic ligament and lateral dorsal elastic ligament. When both are tense, the claw is extended.
3rd digit is also slightly off centre to allow retraction.
What are the nerves to the Hindlimb?
Lumbosacral plexus (L4-7, S1-3) Obturator Nerve Femoral nerve Sciatic (Ischiatic) nerve Fibular (Peroneal) nerve Tibial branch of sciatic nerve
Discuss the obturator nerve.
Adductor of thigh, no cutaneous sensory field, section has little observable effect on gait.
May show partial paralysis or slight weakness in large animals when pressure applied.
Discuss the femoral nerve.
Extensors of stifle, sensory to medial thigh, section results in lack of stifle fixation or weight bearing.
Discuss the sciatic nerve.
Largest nerve in the body.
Extensors of hip and flexors of stifle.
Sensory to lateral leg and everything below stifle.
Section causes over-extension of the paw and paralysis of all muscles of leg except stifle extensors (femoral).
Animal can bear weight.
2 branches; fibular, tibial.
Clinical significance; femoral head and injections.
Discuss the fibular branch of the sciatic nerve.
Peroneal nerve, smaller branch of two.
Flexor of hock and extensors of digits.
Sensory to dorsal leg, hock and paw.
Section causes hock to straighten and paw to knuckle over.
Discuss the tibial branch of the sciatic nerve.
Extensors of hock and digital flexors.
Sensory to caudal hind paw.
Similar path to radial nerve - same clinical signs.
What are the ligaments involved in the sacroiliac joint?
Dorsal ligament - stronger, on dorsal surface between sacrum and ilium.
Ventral ligaments - two groups, ventral surface between sacrum and ilium.
Discuss the sacrotuberous ligament.
Fattened at both ends, runs from caudolateral apex of sacrum and first caudal vertebra transverse process, to the ischiatic tuberosity.
Provides support and structure, important for females during childbirth.
What are the 7 bones of the stifle?
Femur, tibia, fibula, sesamoids, fabella (lateral/medial), popliteal, patella.
What are the external ligaments of the stifle?
Lateral femoropatellar ligament - fabella lateral head of gastrocnemius.
Medial femoropatellar ligament - smaller, blends with periosteum of medial epicondyle of femur.
Patella ligament - main stabiliser
Lateral collateral ligament
Meniscofemoral ligament
Caudal cruciate ligament
Discuss the patella ligament?
Fat pad that is separate from the joint capsule.
Synovial bursa.
Inserts on tibial tuberosity.
Discuss the internal structures of the stifle.
Cruciate ligaments - cranial and caudal.
Cranial is more likely to be damaged, if it breaks you get a draw forward motion of the tibia against the femur. Opposite occurs if caudal breaks.
Cranial and caudal ligaments runs from femur to tibia, creates an x.
Menisci - semilunar, fibrocartilagenous, concave axial borders and conves abaxial borders. Lateral is thicker than medial.
What are the different types of skull in dogs?
Dolichocephalic - long (greyhound)
Mesaticephalic - middle (lab)
Brachycephalic - short (boxer)
What is the oral vestibule?
The area bounded by the teeth and lips.
Labial vestibule and buccal vestibule are both sections of this.
What are the sections of the oral cavity?
Oral vestibule Oral cavity proper - bordered by teeth. Hard palate Soft palate Teeth Tongue
Describe the different tooth (dens) types.
Brachyodont - cease to grow after eruption is complete, short crown exposed within oral cavity once eruption is complete, neck is embraced by gingiva, one or more relatively long roots are embedded in the jaw, all carnivore teeth, all pig teeth except canine, incisors of ruminants.
Hypsodont - present in areas where wear and tear is high, longer and continue to grow following eruption, short roots that form when growth ceases.
Discuss the tooth crown.
Encased in enamel, clinically it is the section exposed above the gingival margin.
Brachyodont teeth crown is primarily exposed above the gingival margin.
Hypsodont teeth the crown is part concealed below the surface.
What is the neck of a tooth?
Constricted portion of tooth located at the gum margin.
Not present on all teeth.
What is the root portion of a tooth?
Embedded in the alveolus (bony socket), covered by cementum.
What is the dentition in a dog?
Deciduous Di 3/3, Dc 1/1., Dp 3/3 (total 28)
Permanent I3/3, C1/1, P4/4, M2/3 (total 42)
FIRST NUMBER IS UPPER JAW, SECOND IS LOWER.
Only account for one side of mouth.
When does eruption of deciduous teeth occur? What is different between them and permanent teeth?
Commences postnatally 3 weeks, complete at 6 weeks.
Smaller than permanent, have sharp, pointed crowns and slender roots.
What is diphyodonty?
When an animal only has 2 sets of teeth over entire life, compared to multiple.
What are the replacement times of teeth?
Substantial variation between breeds, some variation between individuals. Incisors - 3-5months Canines - 5-7months Premolars (2nd to 4th) - 2-5months 1st premolars erupt at 4-5 months.
What do incisors look like?
Distinct crown and neck and single long root.
Crowns of upper are trilobed and lower are bilobed.
Increase in size from medial to lateral.
Upper incisors normally overhang lower.
Nibbling and grooming.
Enamel is densely calcified tissue of ectodermal origin, acellular.
What do canines look like?
Very large, crowns are curved slightly caudally and are conical in shape.
Root is longer than the crown, curves caudally within the alveolus.
How are the teeth supplied with their blood supply?
Teeth are supplied by superior and inferior alveolar veins, arteries and nerves.
Describe premolars?
Shearing function, laterally compressed and form a discontinuous serrated cutting edge.
1st premolar teeth have single roots, upper 4th premolars have 3 roots, remaining premolars have 2 roots.
