The MSK anatomy of trunk & hindlimb - XERTE Flashcards
what is the vertebral formula for dogs?
C7, T13, L7 S3
Cd5-23 (no. of caudals are breed variable)
How can you tell thoracic and lumbar vertebrae apart?
the thoracic vertebrae articulate with ribs and possess tall spinous processes
You can also appreciate the sudden alteration from caudodorsal to craniodorsal orientation of spinous processes
what are the two most cranial cervical vertebrae also called and why?
they are called the atlas and axis due to their specialised morphology which gives them different mobility to the rest of the spine
how do the ribs articulate with the vertebrae?
most ribs make two separate articulations with the vertebral column, there are several joint types involved
where are the cartilaginous parts of the axial skeleton?
the junction between the ribs and sternal elements - though these may ossify/fuse w/ some species and/or in older animals
what happens if the annulus fibrosus degenerates?
fragmentation of the annulus (ring) may allow the nucleus to escape, usually in the direction of the vertebral canal - in/directly may press on the cord
degenerative changes to the annulus fibrosus may affect what?
may affect any disk but the effects are naturally likely to be most severe when they involve the disks at the most mobile regions
which regions are the most mobile regions that are likely to be affected most severely due to the annulus fibrosus degenerating?
those of the neck, thoracolumbar junction and, in large animals especially - the lumbosacral junction are susceptible
in what region does degeneration of the annulus fibrosus rarely happen and why?
in the thoracic region
because the intercapital ligaments reinforce the disc dorsally
how many cervical vertebrae do mammals have?
7 cervical (neck) vertebrae
How do giraffes follow the rule of only having 7 neck vertebrae?
their extreme neck length is only achieved by elongation of the vertebrae
which two mammals break the rule of having seven cervical (neck) vertebrae?
three-toed sloths (8) and manatees (6)
where do epaxial muscles lie?
lie dorsal to the transverse processes of the vertebrae
where do hypaxial muscles lie?
lie ventral to the transverse processes of the vertebrae
what groups can the epaxial muscles be further grouped into?
a lateral column
a middle/intermediate column
a medial column
what system is the lateral column of epaxial muscles?
the ilicostalis system
what system is the intermediate/middle column of epaxial muscles?
the longissimus system
what system is the medial column of epaxial muscles?
the transversospinalis system
what do the hypaxial muscles technically include?
the muscles of the thoracic and abdominal walls
why is a good understanding of the muscles of the vertebral column important?
for specific surgeries e.g. dorsal laminectomy
which vertebral column muscles flex the spine (along with the rectus abdominis)?
HYPAXIAL
major psoas
minor psoas
iliacus
which vertebral column muscles extend the spine?
EPAXIAL
iliocostalis
longissimus
semispinalis
multifidi
rotatores
spinalis
spinialis capitus
intertransversarii
which epaxial muscles are found in the medial column?
semispinalis
multifidi
rotatores
which epaxial muscle is found in the most lateral column of the epaxial muscles?
iliocostalis
what does the iliocostalis do?
it is found alone and it moves the spine laterally and can also aid inspiration
which muscle is found in the intermediate column of the epaxial muscles?
longissimus
what does the longissimus muscle do?
it is alone, and it moves the back, neck and head laterally
what are all the muscles of the thorax?
external intercostal
internal intercostal
levatores costarum
subcostal
rectus thoracis
retractor costae
transversus thoracis
serratus dorsalis
scalenus
diaphragm
where do the fibres of the internal and external intercostal muscles run?
the fibres run:
caudoventrally between ribs - EXTERNAL
cranioventrally between ribs - INTERNAL
what nerve is the diaphragm innervated by?
the phrenic n.
what do the primary muscles of inspiration include?
the diaphragm, internal and external intercostal muscles and levator costae
what do the primary muscles of expiration include?
the diaphragm, internal intercostals and serratus dorsalis
what are accessory muscle of respiration?
those that do not normally participate in breathing unless called upon during periods of high demand
what muscles can be included in the accessory muscles of inspiration?
the scalenus and the sternomastoid
what muscles do the accessory muscles of exhalation include?
the four abdominal muscle groups: rectus abdominis, external oblique, internal oblique and transverse abdominis.
contraction of the abdominal muscles increases what?
increases intra-abdominal pressure and forces the diaphragm to a more cranial position within the rib cage
what can abdominal muscles only assist with in terms of breathing?
they can only assist with exhalation - the term abdominal breathing indicates vigorous exhalation
what is aponeurosis?
a thin sheath of connective tissue that helps connect muscle to bone
what are all the abdominal muscles innervated by?
by the ventral branch of caudal intercostal & lumbar nerves
br.?
branch
nn.?
nerve (plural)
why is it important to know the four abdominal muscles forming the ventrolateral abdominal wall?
as these muscles are incised during abdominal surgical approaches
what are the four main abdominal muscles?
external abdominal oblique
internal abdominal oblique
transversus abdominus
rectus abdominis
describe the external abdominal oblique muscle?
flat muscle, superficial, caudo-ventral fibre direction
describe the internal abdominal oblique muscle?
flat muscle, beneath the above, cranio-ventral fibre direction
describe the transversus abdominus muscle?
flat muscle
describe the rectus abdominis muscle?
strap-like muscle
intercostal - meaning?
between ribs
Describe how the Serratus dorsalis caudalis muscle looks?
look a bit serrated (bread knife) because of how they insert on individual ribs
What is the Serratus dorsalis caudalis muscle?
it is one of the primary muscles of expiration - particularly the caudal part
the cranial part aids inspiration more
what is the serratus ventralis muscle composed of?
cervical and thoracic portions that originate from the cervical vertebrae and ribs
where is the serratus ventralis muscle found?
the muscle converges to insert on the medial surface of the scapula to form the sling support that suspends the thorax between the forelimbs
the serratus ventralis is not a muscle of?
it is not a muscle of respiration
what is recurrent airway obstruction also known as?
chronic obstructive pulmonary disease
what is recurrent airway obstruction in horses?
it is a respiratory disease syndrome that affects horses and ponies - it is similar to asthma in humans
what happens when a horse has recurrent airway obstruction?
the animals experience expiratory difficulty caused by obstruction of airflow in large and small airways
what is one sign that a horse has recurrent airway obstruction - linked to muscles?
the abdominal muscles may become overdeveloped and a ‘heave line’ may be seen
what does a heave line mark?
marks the musculo-aponeurotic junction of the external abdominal oblique
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