A29 - The vertebral column, epaxial and hypaxial muscles, muscles moving the head Flashcards
1
Q
Give the general structures of a vertebrae
A
-
Corpus vertebrae
- Extremitas cranialis [=Caput vertebrae] (cranial covex)
- Extremitas caudalis [=Fossa vertebrae] (caudal concave)
- Crista ventralis
-
Arcus vertebrae
- Pediculus arcus vertebrae
- Lamina arcus vertebrae
- Foramen vertebrale
- Incisura vertebralis cranialis
- Incisura vertebralis caudalis
- Foramen intervertebrale
- Processus spinosus
- Processus transversus
- Processus articularis cranialis
- Processus articularis caudalis
- Processus mamillare (on the arch of Th and L vertebrae, between proc. articularis cranialis and proc. articularis caudalis)
-
Processus accessori
- Proc. articularis caudalis → proc. transversus
- Sus: caudal thoracic vertebrae
- Car: Thoracic and lumbar vertebrae
2
Q
Give the number of vertebrae in different species
A
3
Q
Curvatures in the vertebral column
A
- In domestic animals, the vertebrae form a chain arranged horizontally, along which three major curvatures are recognized:
- Dorsal convex curvature (head → neck)
- Dorsal concave curvature (neck → chest)
- Dorsal convex curvature (thorax → lumbar region)
4
Q
Definition of epaxial muscles
A
- Muscles of the axial zone, which elevate, laterally flex and rotate the cervical, thoracic and lumbar vertebrae
- Innervation: dorsal branches of the spinal nerves
5
Q
Definition of hypaxial muscles
A
- Mainly in the cervical region
- Muscles which depress the cervical vertebrae
- Number of muscles are small compared to epaxional musculature
6
Q
Give the epaxial muscles
A
Long muscles:
-
M. splenius (superficial layer)
- Pars capitis
- Pars cervicalis
-
M. iliocostalis (middle layer)
- Pars thoracica
- Pars lumborum (ca)
- M. longissimus (middle layer)
- Pars lumborum
- Pars thoracis
- Pars cervicalis
- Pars atlantis
- Pars capitis
-
M. spinalis et semispinalis (deep layer)
- Pars thoracis
- Pars cervicalis
-
M. semispinalis capitis (deep layer)
- M. biventer cervicis
- M. complexus
-
M. multifidi (deep layer)
- Pars lumborum
- Pars thoracis
- Pars cervicalis
Short muscles:
- M. intertransversarii
- Mm. interspinales
-
Mm. rotatores
- Pars brevis
- Pars longus
7
Q
M. splenius
A
- Divided into (ø ca):
- Pars capitis
- Pars cervicalis
-
Origin:
- Th1-3, processus spinosus
- Lig. nucahe, caudal end
-
Insertion:
- Crista nucha
- Mastoid part of os temporale
-
Action:
- Bilateral: Extend the neck, raises head
- Unilateral: Draw head laterally
- Eq: Movements of head when galopping, maintains balance when jumping
- Innervation: r. dorsalis ex nn. cervicalis et thoracis
Epaxial
8
Q
M. iliocostalis (lateral)
A
- Ca, divided into:
- Pars lumborum (ca)
- Pars thoracica
- Origin: Crista iliaca and fascial sheet
-
Insertion:
- Eq, sus: Fuse with m. longissimus
- Others:
- Ribs on a**ngulus costae
- C7 vertebra, processus transversus
-
Action:
- Fix/stabilize the vertebral column
- Lateral flexion and expiration
- Innervation: r. dorsalis ex nn. cervialis et thoracis spinalis
Epaxial
9
Q
M. longissimus (medial)
A
- Divided into:
- Pars lumborum
- Pars thoracis
- Pars cervicalis
- Pars atlantis
- Pars capitis
- Origin: Sacrum and ilium
-
Insertion:
- _Lumborum and thoraci_s:
- Processus transversus/mamillaris/spinosus of lumbar and thoracic vertebrae
- Angula costae
- Cervicis: Between processus transversus of thoracic vertebrae and cervical vertebrae
- Atlantis: Between thoracic/cervical vertebrae and ala atlantis
- Capitis: Processus mastoideus of temporal bone
- _Lumborum and thoraci_s:
-
Action:
- Bilateral: Stabilize and flex head, neck and back dorsally ! increase wightbearing capasity
- Unilateral: Flex the vertebral column laterally, rotate atlantoaxial joint
- Innervation: r. dorsalis ex nn. lumbales, throacis et cervicalis spinalis
Epaxial
10
Q
M. spinalis or M. spinalis et semispinalis
A
- M. spinalis (eq, sus)
- M. spinalis et semispinalis (ca, ru)
- Divided into:
- Pars thoracis
- Pars cervicalis
- Origin: Lumbar vertebrae, processus spinosus
- Insertion: C2-C3, processus spinosus
-
Action:
- Bilateral: Extend/stabilize the back, elevate the neck
- Unilateral: Flex nec/back laterally
- Innervation: r. dorsalis ex nn. lumbales, thoracis et cervicalis spinalis
Epaxial
11
Q
M. semispinalis capitis
A
- Divided into:
- M. biventer cervicis (dorsal)
- M. complexus (ventral)
-
Origin:
- M. biventer cervicis: Th2-4, processus transversus
- M. complexus: C3-Th1, processus articularis caudalis
- Insertion: Os occipitale (crista nuchae, protubiranta occipitalis externa)
-
Action:
- Bilateral: Extends neck
- Unilateral: Flexes head and neck laterally
- Innervaiton: rr. dorsalis ex nn. cranialis thoracis et cervialis spinalis
Epaxial
12
Q
Mm. multifidi
A
- Divided into:
- Pars lumborum
- Pars thoracis
- Pars cervicalis
- Origin: Processus transversus from sacrum → axis
- Insertion: 3 segments cranial to vertebrae of origin, processus spinosus or arcus dorsalis
-
Action: Stabilize the vertebral column in junction with other muscles
- Lumbar region: Flex the back ventrally
- Thoracic region: Rotate the vertebral column
- Cervical region: Elevate/flex the neck laterally
- Innervation: Dorsal branches of segmental spinal nerves
Epaxial
13
Q
Mm. intertransversarii
A
- Extend mainly between the processus transversus of adjacent vertebrae
- Action: Stabilize and flex cervical and lumbar vertebral column
- Innervation: Dorsal branches of segmental spinal nerves
Epaxial
14
Q
Mm. interspinales
A
- Runs between the adjacent processus spinosus of lumbar, thoracic and cervical vertebrae
-
Action:
- Stabilize the vertebral column
- Ca: flex the spine ventrally
- Innervation: Dorsal branches of segmental spinal nerves
Epaxial
15
Q
Mm. rotatores
A
- Divided into:
- Pars brevis
- Pars longus
- Cranial part of thoracic vertebrae, between processus spinosus/transversus
Epaxial
18
Q
M. scalenus
A
M. scalenus dorsalis: (ø eq)
- Origin: Processus transversus of C4-C6
-
Insertion:
- Dorsal muscular part: rib 1-4
- Ventral muscular part: rib 1-9
M. scalenus medialis
- Origin: Processus transversus of C6-C7
- Insertion: Rib 1
M. scalenus ventralis: (ø ca)
- Origin: Processus transversus of C4-6?
- Insertion: Rib 1
-
Action:
- Inspiration
- Unilateral contraction: flexes nack laterally
- Bilateral contraction: flexes neck ventrally
- Innervation: R. ventralis ex nn. spinalis cervicalis
19
Q
Statics of the trunk
A
- Statics: Maintains the equilibrium of the body in a state of rest or in motion
- Dynamics: Analyses the movement of the body during locomotion
- Eq: More weight (55%) is carried by the forelimbs
“Bow and string” theory:
-
Bow: The thoracolumbar vertebrae, their articulations and the ligaments and muscles provides a flexible structure
- Dorsally it has a convex arch which gets its elasticity and nuchael and supraspinous ligaments
- The two ends of the bow are fixed by:
- Sternum
- Linea alba
- Abdominal muscles
- String: Abdominal muscles, which reaches from the thorax to the plevis
- The bow is indirectly attached to the string by interosition of the:
- Cranially: Thoracic skeleton
- Caudally: Pelvic bones
- The string attaches all along the bow
-
Abdominal wall region it is formed by:
- Linea alba
- Abdominal muscles
- Aponeurosis
-
Thorax it is formed by:
- Sternum
- Ribs
- Intercostl muscles
-
Abdominal wall region it is formed by:
- Contraction of the abdominal muscle → flexion of bow
- Contraction of the epaxial muscles → straightens the bow
- Weight of the viscera attached to the vertebral column → straightens the bow
- Weight of the viscera on the abdominal muscles → bends the bow
- “Bow and string theory” can extend into the cervical region, but the curve is in the opposite direction to that of the thoracolumbar region
- Cervical vertebrae and their articulations consititue the bow
- Nuchal ligament acts as the string
- Role of the cantilevers (utstikker): equalize centrifugal push
- Division of the cantilevers:
- Front: head and neck
- Hind: sacrum and tail
- Role: pusch against the bow, allowing the limb to reach gallop
- Sacrum serve as base of attachment of muscle mass of hindlimb, for mobile connection with last lumbar vertebra but immobile with pelvis
- Speed increases → thrust increases → lowering of head & lens neck muscles → reastablish equilibrium of body as a whole
22
Q
M. sternocephalicus
A
- Origin: manubrium sterni
-
Insertion:
-
Divided into:
- M. sternomastoideus: mastoid part of os temporale
- M. sternooccipitalis: c**rista nucha of os occipitale
-
Divided into:
- Action: Draw the head and neck to the side
23
Q
M. brachiocephalicus
A
From humerus to head and neck
- Divided into:
-
M. cleidobrachialis
- Origin: Clavicle
- Insertion: Distal part of christa humeri
-
M. cleidocephalicus
-
M. cleidomastoideus
- Origin: Processus mastoideus of os temporale
- Insertion: Iscription clavicularis
-
M. cleidocervicalis
- Origin: The dorsal midline over the cranial half of the neck
- Insertion: Inscription clavicularis
-
M. cleidomastoideus
-
M. cleidobrachialis
-
Action:
- If forelimb is fixed: unilateral contraction of the muscle moves head into the lateral direction, bilateral contraction fixes head and neck (or bends downward)
- If limb is free (it’s in an elevated position), it will move forelimb cranially
- Innervation: N. accessorius (XI)
