2 Anatomy: Equine

Front 1

Vertebral formula

Back 1

C7
T18
L6
S5
Ca 15-21
- bears weight of heavy abdominal organs

Front 2

movability of spinal regions

Back 2

- cervical and caudal: free and flexible movements
- thoracic and lumbar vertebrae: less movable than dogs and cats

Front 3

movements of vertebral segments

Back 3

- movements b/w vertebrae are limited but the cumulative movements in each region are appreciable
- column movements are mainly dorsal, ventral, and lateral flexion
- little rotation occurs

Front 4

least movable spinal region

Back 4

- least movable at thoracic and lumbar
due to:
1. interspinous ligaments
2. intertransverse ligaments
3. synovial lumbar joints

Front 5

interspinous ligaments

Back 5

white, fibrous
- between thoracic and lumbar vertebrae, making these regions stiff

Front 6

intertransverse ligaments

Back 6

- membranes which link the lumbar transverse process
- between thoracic and lumbar vertebrae, making these regions stiff

Front 7

lumbar synovial joints

Back 7

- some lumbar transverse processes are connected to one another by synovial joints in the horse only
- particularly between the L4 and L5, L6 and S1, but often involves other lumbar transverse processes
- makes the lumbar region stiff
- they are well formed and reinforced (ventral joint capsule)

Front 8

most mobile part of the vertebral column

Back 8

lumbosacral joint
- essential for transmission of propulsion from the PLs to the cr part of the body

Front 9

vertebral column vs carnivores

Back 9

-consider when casting that the fall should be gentle and violent movements in the thoracolumbar region should be avoided
- vs carnivores: flexible, can curl up and are able to propel themselves forward while running by placing their PLs a long way forwards, beyond the center of gravity

Front 10

lumbar area

Back 10

1. relatively short: only 10% if the vert column length vs 16% for carnivores and 25% in humans
2. relatively immobile: intervertebral discs are thin

Front 11

center of gravity

Back 11

- weight acts through it
- near TLs in most quadrupeds due to weight of head and neck, therefore TLs bear more weight that PLs:
55:45 horse vs 60:40 dog
- TLs: postural fx
- PLs: propulsion

Front 12

center of gravity and head

Back 12

- center of gravity may be shifted by movement of the head
- lame forefoot contacting the groun causes the horse to lift the head away from the offending side
- necessary to lift head away from the side of the forelimb to be raised for examination or hoof trimming

Front 13

dorsoscapular ligament gen

Back 13

- thoracolumbar fascia in the interscapular region (withers)
- fibroelastic CT extending from T2-5, attaching to the spinous processes, transverse processes, scapula and ribs in this region
- fuses with its fellow over the spinous processes of T2 and T3
- arises ventral to ligamentum nuchae and medial to the rhomboideus m
- absorbs concussion of TLs

Front 14

dorsoscapular ligament layers

Back 14

1. superficial
2. middle
3. deep

Front 15

dorsoscapular ligament: superficial layer

Back 15

- yellow elastic tissue
- medial part of serratus ventralis and rhomboideus thoracis m
- interdigitates with the fascicles of both mm
- fibers extend laterally beyond the serratus ventralis m
- attaches to ribs laterally

Front 16

dorsoscapular ligament: middle layer

Back 16

- below superficial
- runs over longissimus thoracis m and between it the iliocostalis m to attach to the ribs proximally
- lateral fascicle provides attachment for the serratus dorsalis m (cr part)

Front 17

dorsoscapular ligament: deep layer

Back 17

- lateral to splenius m and longisimus thoracis m
- medial to spinalis thoracis et cervicus and multifidi m
- ends by attaching to the transverse processes of thoracic vertebrae

Front 18

dorsoscapular ligament and infection

Back 18

-close to supraspinous bursa (lying between the ligamentum nuchae and the spinous processes of T3
1. inhibits spread of infection (eg fistulous withers) to underlying tissues
2. permits cranio-caudal spread of such infection along its fascicles

Front 19

dorsoscapular ligament and concussion

Back 19

- dorsoscapular ligaments attachment to the transverse processes in the region, medial aspect of the scapula and ribs
= part of the concussion absorption mechanism of the TL

Front 20

muscles of the neck

Back 20

1. brachiocephalicus
2. sternocephalicus
3. splenius
4. sternohyoid
5. sternothyroideus
6. longus capitis
7. longus colli

Front 21

brachiocephalicus

Back 21

only cleidomastoideus part
- fused with omotransversarius
= cleidocephalicus= cledimastoideus

Front 22

sternocephalicus

Back 22

only sternomandibularis part
-attaching to the angle of the mandible

Front 23

splenius

Back 23

two parts( dog only has one):
1. splenius cervicus
2. splenius capitis

Front 24

mm of occipito-atlanto-axial joints

Back 24

1. rectus capitis dorsalis major and minor
2. obliquus capitis cranialis and caudalis
3. rectus capitis lateralis and ventralis

Front 25

function of mm of occipito-atlanto-axial joints

Back 25

involved in activating:
1. atlanto-occipital joint: flexion and extension= yes
2. atlanto-axial joint: rotation around the dens= no

Front 26

atlanto occipital membrane

Back 26

atlanto occipital membrane, as well as the dura mater and arachnoid, have to be punctured in order to get into the subarachnoid space for collection of CSF

Front 27

occipito-atlanto-axial joints vs dog

Back 27

- atlanto- occipital joint and atlanto-axial joint do not differ significantly from the dog except...
- presence of the longitudinal ligament of the dens (ligamentum longitudinale dentis) and ligament of the apex of the dens ( ligamentum apicis dentis)

Front 28

ligamentum nuchae

Back 28

- very well developed
- median, elastic ligament
- support the head and neck
- provides attachment for soome neck mm
- two (paired) parts:
1. funiculus nuchae
2. lamina nuchae

Front 29

funiculus nuchae anatomy

Back 29

- paired, cordlike, continuous with the supraspinous ligament at T3 (both fuse at this level)
- originates at the external occipital protruberance, running caudally without attaching to C1 and C2
- significantly widened at the withers

Front 30

supraspinous ligament

Back 30

extends cranially from the summits of the spinous processes of caudal, sacral, lumbar and thoracic vertebrae

Front 31

funiculus nuchae vs ox

Back 31

- differs from ox in that it extends well into the thoracic region, slanting ventrolaterally over the summits of spinous processes
- therefore friction over spine summits not as great in ox

Front 32

ligamentum nuchae vs supraspinous ligament

Back 32

caudal to T3= supraspinous ligament

Front 33

lamina nuchae anatomy

Back 33

- paired, fenestrated ventrally
- extends from spinous processes of C2 to C7
- fuses with funicular part dorsally, but at about C3 caudally
- attaches to the spinous processes of T1 to T4
-

Front 34

ligamentum nuchae and infection

Back 34

with dorsoscapular ligament, impedes the spread of infection in the neck
- determines the route and spread of infection

Front 35

lamina nuchae vs ox

Back 35

- divided in cr and ca parts:
1. cr extends from the funicular part to the spines of C2 and C3
2. ca unpaired, extends from spinous processes of T1 to the spinous processes of C4-7

Front 36

cr nuchal bursa

Back 36

lies b/w the funicular part and the dorsal tubercle of the atlas
- acquired but relatively constant
- poll evil: inflammation causing necrosis of the funicular part of the ligaments

Front 37

ca nuchal bursa

Back 37

- lies between the funicular part of the spinous process of the axis
- acquired, less constant that the cr nuchal bursa

Front 38

bursa associated with the ligamentum nuchae

Back 38

1. cr nuchal bursa
2. ca nuchal bursa
3. supraspinous bursa

Front 39

supraspinous bursa

Back 39

- lies between the funicular part of the summit of the spinous process of T3
- genetically determined
- about 40 mm long
- clinically important: fistulous withers when inflammed and ruptures, requiring sx intervention at the level of a vertical line through the tuber spinae of the scapula

Front 40

external jugular v

Back 40

- lies in muscular jugular groove
- dorsal: cleidomastoideus
- ventral: sternocephalicus
- medial: omohyoideus
- caudoventrally: covered by cutaneous colli

Front 41

cutaneous colli horse vs donkey

Back 41

- donkey: cover ext jug for whole neck
- horse: cover ext jug in ca 1/2 therefore venipuncture at cr part of v

Front 42

visceral space boundaries

Back 42

1. ventral: strap mm: sternohyoideus and sternothyroideus
2. laterally: omohyoideus and sternocephalicus
3. dorsally: longus collis, longus capitis

Front 43

contents of visceral space

Back 43

1. cervical trachea
2. cervical esophagus
3. cervical thymus
4. carotid sheath

Front 44

cervical trachea

Back 44

- ventral aspect superficial, cr
- tracheotomy at the level of 4th or 5th tracheal cartilage

Front 45

esophagus

Back 45

dorsal, L, dorsal

Front 46

cervical thymus

Back 46

poorly developed in the horse

Front 47

carotid sheath

Back 47

1. common carotid a
2. vagosympathetic trunk
3. recurrent laryngeal n
4. tracheal duct/ trunk
NO internal jugular v in horse

Front 48

deep cervical lymph nodes

Back 48

drain neck, head, larynx, esophagus and thyroid
- efferents to the tracheal trunk or cr mediastinal lymph nodes