Neck Flashcards
Cervical vertebrae
-7 cervical vertebrae
-almost all mammals
Atlas and axis of cervical vertebrae
-first two: atlas and axis
-have modified movement to allow free movement of head
Cervical vertebrae shape
-body flattened dorsally, and with arch forms vertebral foramen
-body has a median crest ventrally, with a cranial convex surface and a caudal concave surface
Transverse foramina
-actually short canals and transmit vertebral vessels
Vertebral foramina
-forms the vertebral canal for the spinal cord
Spinous process
-length and angles vary
Synovial joints of cervical vertebrae
-joints between caudal and cranial articular processes of neighbours
Transverse processes
-divided into dorsal and ventral
Intervertebral foramina
-bases of arch notched and with neighbour to form hole for the spinal nerves to pass through
Intervertebral disc
-a fibrocartilagous structure between neighbouring vertebral bodies
-made of a soft gel-like center called nucleus pulposus (pulpy nucleus) and surrounded by concentric layers of dense fibrous tissue called annulus fibrosus
Where are intervertebral discs absent?
-between C1 and C2
Disc hernias
-caused by the rupture of annulus fibrosis (fibrous layer surrounding intervertebral disc)
Intervertebral disc species differences
-Thick in dogs and cats (~15-20% of columnar length)
-Thin in ungulates (~10% of columnar length)
Atlas
-C1
-has no body, no spinous process but dorsal and ventral arches
-wings of atlas (transverse process) are often visible and palpable in live animals
-caudal aspect of ventral arch has wings with excavations (fovea) for condyles
-dorsal arch has transverse foramina (absent in ox)
-lateral vertebral foramen transmits 1st spinal nerve
-alar foramen (only a notch in dog) transmits ventral branch of 1st spinal nerve
Atlas ventral arch fovea
-articulates with axis forming fovea dentis
Axis
-C2
-spinous process is high (and long in dogs)
-has caudal articular facets for C3
Transverse foramen of axis
-has transverse processes with transverse foramen in its root to transmit vertebral vessels
Lateral vertebral foramen of axis
-transmits 2nd spinal nerve
Dens
-body of atlas fuses with axis to form dens in embryos
-fits into fovea dentis of atlas and serves as the pivot for rotation of atlas and head
Dens structure in different species
-rod-like in carnivores, and sproutlike in ox and horse
-roughened dorsally for ligaments
Atlanto-occipital joints
-for 2 condyles and 2 separate capsules
-no disk, and no articular process
-involved in flexion and extension (“yes” joint)
Atlanto-axial joint
-covered by a single capsule
-no disk, no articular process
-involved in rotation (“no” joint)
C3 to C5 vertebrae
-differ little
-except spinous process becomes increasingly taller
C6
-has a longer spinous process and expanded ventral lamina of transverse process
C7
-has the highest spinous process and lacks transverse foramina
Palpable bony processes in neck
-part of wings of atlas
-caudolateral parts of transverse processes of C2 to C5
Nuchal ligament
-ligament of neck
-elastic, unlike other long ligaments of column
-bursae reduce friction
- funicular part continues with supraspinous ligament
>funicular part attached to axis in dogs, and to occipital in large animals
-lamellar part attached to spinous processes of large animals
Muscles of neck
Muscles divided into groups, most individual muscles are not clinically significant
-epaxial
-hypaxial
-ventral muscles
-extrinsic limb muscles
Epaxial muscles
-muscles of column dorsal to line of transverse processes
-extensors
-includes transverso-spinalis system, longissimus system, splenius
**iliocostalis system of trunk does not extend well into neck
Hypaxial muscles
-muscles of column ventral to line of transverse processes
-flexors
Superficial muscles of the neck
-brachiocephalicus
-serratus
-splenius
-sternomandibularis
Vasculature of the neck
-common carotid artery
-vertebral artery and vein
-deep cervical artery and vein
-external jugular vein
Common carotid artery
-blood to head, face and brain
Vertebral artery and vein
-passes through transverse canals of cervical vertebrae
Deep cervical artery and vein
-supplies dorsal muscles of neck
-other smaller branches such as superficial cervical supply ventral muscles of neck
External jugular vein
-in domestic mammals, blood from head almost entirely drained via the external jug
