Normal Anatomy Flashcards
Which gauss line (isomagnetic contour) must be contained within the controlled area of a high field magnet?
5 gauss line
How does gadolinium contrast media work?
It shortens T1 (spin-lattice) relaxation time making tissues brighter on T1w images.
The Impar ligament and DDFT distal to the navicular bone are susceptible to magic angle on high or low field systems?
High field
What is represented by the letter C and what four structures does it attach to (4)?
C = chondocoronal ligament
Attaches to the colateral cartialge, middle phalanx, common digital extensor tendon and chondrosesamoidean ligament.
Dorsal to the stright sesamoidean ligament what is the circular area of low signal intensity
The accessory ligament of the SSL
The impar ligament may appear heterogenous because?
It is filled with fluid fill pockets of synovium from the DIPj
In images obtainted with B0 perpendicualr to the limb which collateral ligament of the DIPj is suseptible to magic angle
Lateral
What shape is the SSL in cross section?
Triangular proximally, oval in the body and round distally.
How does the insertion of the SSL appear?
It can have a bulbous appearance and may have a focal central triangular area of higher signal intensity close to the insertion
Identify structures B, C, D, F, H
B - Sublamellar dermis and vascualr plexus
C - Solar dermis and vascular plexus
D - Circumflex vessels
F - Lamellar interface (formed by the interdigitating permal and epidermal lamellae)
H - Hoof wall
Using a magnet with B0 perpendicualr to the limb (e.g. low feild standing) are the OSLs suseptibel to magic angle?
Proximal aspect of the medial (related to the variabel fibre pattern in this region.
What is the signal intensoty of the SDFT in the pastern region.
Superficial digital flexor tendon (SDFT) has a uniformly low signal intensity until close to its insertion, where it becomes more heterogeneous.
Which aspect of the manica flexoria is thicker?
Proximal aspect
What is indicated by the black arrow in these images?
A Gibb’s or truncation artefact
In sound horses what regions of the sagittal ridge of MC3 and MT3 are has thicker subchondral bone?
Dorsal third
What is represent by the white arrows?
Either side of the sagittal ridge of MC/T3 a small number of vascualr channels may be present wthin the condyles.
What type of bone is cortical bone?
Woven bone
The magic angle effect is most obvious when a structure is?
is at 55 degrees to the static magnetic field.
Is the appearance of the SL branch normal?
In a sagittal plane, at the palmar/plantar aspect of the branches of the SL, level with the MCP/MTP joint, there is often a region of diffuse, high SI, which continues distally to the insertion onto the proximal sesamoid bone
Should the superficial collateral ligaments of the fetlock appear symetrical in size?
Some mild asym- metry in thickness between lateral and medial superficial collateral liga- ments is a normal variation. The superficial components are thicker and longer than the deeper oblique components. The deep and superficial com- ponents of the collateral ligaments may be separated by synovial fluid
Why is there often a linera intermediate SI band within the dorsal aspect of the DDFT at the level of the fetlock joint?
This is attributed to structural change within the DDFT secondary to compression against the palmar/plantar aspect of the MCP/MTP joint.
At the level of the fetlock what is present between the SDFT and DDFT?
On transverse images, the palmar/plantar surface of the DDFT is con- nected at midline by fascia to the dorsal border of the SDFT, and these surfaces of the tendons may have a thicker paratenon compared with the dorsal surface of the DDFT and the palmar/plantar surface of the SDFT.
Why do the OSLs have a heterogenous appearacne comapred to the DDFt and SDFT?
Due to the fascicular nature of these ligaments
What is the normal signal intensity of the intersesamoidean ligament
heterogeneous, intermediate SI, with small, focal areas of intermediate to high SI on T2*-weighted images
How thick is the normal PAL
<2mm
Do the OSLs have symetrical size.
There is often some asymetry of size, no spesific side.
Flow artefact is most apparent on which sequence
Transverse, fat surpressed images
Within the non collagenous portion of the SL origin what is the predominant tissue?
There are nerves, vessels, and adipose tissue within the bundles, but their composition is considered insignificant compared to the content of muscle.
In the forelimb the which lobe of the SL origin is more round and which is more oval?
The medial portion of the proximal suspensory is mostly oval in appearance, whereas the lateral portion is more circular
The lateral aspect of the ALDDFT extends more palmarly than then medial aspect. Why is this?
There laterally located accessoriosuperficial fibers which attach to the SDFT.
What are the signal charicteristics of the ALDDFT
Distally it is homogenous low SI. More proximally it increases to intermediate. This change occurs at the level of C3
The subchondral bone within the small carpal bones is usually thicker at which aspect (2)?
Dorsal and medial aspects
What is the normal signal intensity of the ECR at the level of the carpus
low signal intensity, interrupted by variable numbers of oblique bands of intermediate signal intensity (on both T1- and T2-weighted images). Due to these bands the tendon has a ‘stripy’ appear- ance on sagittal and dorsal high-field images
What is the course of the extensor carpi obliquus
It runs across from the lateral distal aspect of the radius to the medial aspect of the third metacarpal bone.
Which extensor tendon runs under the lateral collateral ligament of the carpus
Lateral digital extenson tendon.
Where does the ulnaris lateralis attach?
It has two branches. The short branch runs on the distal caudolateral aspect of the radius and inserts on the accessory carpal bone. The long, smaller branch runs dorsal to the short branch and inserts on the base of the fourth metatacarpal bone.
Where does the flexor carpi ulnaris attach?
ACB
Where does the flexor carpi radialis attach?
Axial aspect of the second metacarpal bone.
What is the level of the musculitendinous junction of the SDFT and DDFT?
At the lvel of the proximal row of carpal bones. However the most dorsal radial head of the DDFT is tendinous throughout the carpal region.
The palmar part of the carpal flexor retinaculum extends from where to where?
It extends from the accessory carpal bone to the medial collateral ligament of the carpus and to the proximal palmar aspects of the second and fourth metacarpal bones.
What is structure 30?
Palmar carpal ligament
What are structures 27, 28, 29
27 - Radiocarpal ligament
28 - Medial palmar intercarpal ligament
29 - Lateral palmar intercarpal ligament
What is the normal signal intensity of the palmar intercarpal ligaments?
Intermediate to high signal intensity
Where does the accessory ligament of the SL origionate in the forelimb?
The palmar cortex of the third carpal bone and the axial aspect of the fourth metacarpal bone.
What normal variant can be seen at the distal medial aspect of the unlar carpal bone?
Variability in shape of the distal medial aspect of the ulnar carpal bone and discrete osseous fragment(s) seen in 5/30 horses.
Name structures I, N, O
I - Talocalcaneal ligament
N - Plantar tarsometatarsal ligament
O - Deep branch of the plantat tarsometatarsal ligament
Name structures J, K, L
J - Talocalcaneal- centroquartal ligament
K - Centrodistal ligament
L - Tarsometatarsal ligament
Name structures S and N
S - Medial head of the DDFT
N - Lateral head of the DDFT
What is the normal appearance of the intertarsal ligaments?
There are small focal areas of high signal intensity within the centrodistal intertarsal ligament. The focal areas of high signal intensity within each of the intertarsal ligaments, reflecting synovial fluid between fascicles of the ligament.
What structures are indicated by the arrow and the arrow head in this tarsus?
Arrow - Accessory ligament of the SL
Arrow head - Accessory ligament of the DDFT
Where does the accessory ligament of the SL origionate from in the hindlimb?
The plantar aspect of the 4th tarsal bone.
Where does the ALDDFT origionate from in the hindlimb?
It extends distally from the plantar ligament between the calcaneus and the fourth tarsal bone
Where is the subchondral bone of the small tarsal bones thickest?
Generally the subchondal bone paltes are thicker laterally.
From where does the CCL origionate and insert?
Origin medial aspect of the lateral femoral condyle, Insertion craniomedial aspect of the incercondylar eminence of the tibia.
To perform a parasagital MRI of the stifle and see the entire CCL what angle should the slices be orientated?
CdLCrMO
Which collateral ligament of the stifle is generally larger in cross sectional area in normal horses?
Medial
What structure is indicated by the large arrow?
The meniscofemoral ligament of the lateral meniscus.
What is represented by O?
Origin of the SDFT in the supracondylar femoral fossa
On what sequences are the cruciate ligaments suseptible to magic angle artefact?
These are most likely to occur on short TE (echo time) sequences therefore affecting T1-weighted and PD images in particular.
What artefact is demonstraighted in this image?
Motion artefact,
Name as many structures as possible?
Labelled structures: 1, frontal lobe; 2, parietal lobe; 3, occipital lobe;
4, cerebellum; 5, corpus callosum; 6, lateral ventricle (rostral); 7, interthalamic adhesion; 8, optic chiasm; 9, pituitary gland; 10, pons; 11, medulla oblongata; 12, fourth ventricle; 13, obex; 14, cervical spinal cord; 15, pineal gland; 16, colliculus; 17, hypothalamus;
18, olfactory lobe and recess; 19, hippocampus; 20, rostal colliculus; 21, caudal colliculus; 22, cerebellar peduncle; 23, coronal radiation; 24, lateral ventricle (caudal); 25, internal jugular vein; 26, temporal lobe; 27, facial nerve; 28, medial guttural pouch;
29, trigeminal nerve; 30, lateral pterygoid muscle.
Is the nasal septum always completely straight?
The nasal septum is often slightly deviated as a normal anatomic variant and not considered clinically significant
A small T1w hyperintensity is noted in the centre of the pituitary gland, what could this represent?
Thought to represent normal paramagnetic neurotransmitters and/or cho- lesterol byproducts
Is contrast enhancement of the choroid plexus of the lateral ventricles normal?
The choroid plexus of the lateral ventricles have increased signal intensity on the post-contrast image due to these structures being highly vascular.
What happens to the normal pituitary glad following contrat administration?
Homogenous enhancement
The ALDDFT is significant smaller in the hindlimb but its larges portion is medial or lateral?
Medial
