Anatomy: Back and Spinal Cord Flashcards
Back components
Made up of the vertebral column, the spinal cord, spinal nerves, the overlaying muscles, skin
Vertebral column function
Encloses and supports spinal cord, supports head and trunk, an attachment for the limbs and transfers weight of the body to the lower limbs
Vertebral column components
33 vertebrae and their intervening intervertebral discs,
Regions of the vertebrae
7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 3-5 fused coccygeal
Curvatures of the vertebral column
Cervical curvature (lordotic), thoracic curvature (kyphotic), lumbar curvature (lordotic), sacral/coccygeal curvature (kyphotic)
Kyphotic curvatures
Concave anteriorly, thoracic and sacral, primary curvatures present in the fetus
Lordotic curvatures
Concave posteriorly, cervical and lumbar, secondary curvatures that develop postnatally
Kyphosis
AKA hunchback, excess forward thoracic curvature, congenital or posture related, due to collapse of vertebral bodies
Lordosis
AKA swayback, excess inward lumbar curvature, temporary during pregnancy or caused by pathology or excessive weight
Scoliosis
Lateral curvature of the spine, congenital or pathologic (from cerebral palsy and muscular dystrophy)
Four movements of the back
Extension, flexion, lateral flexion, rotation
Extrinsic muscles of the back
Move the upper limbs and ribs
Intrinsic muscles of the back
Maintain posture and move the vertebral column
Vertebral components
Vertebral body, vertebral arch, processes for muscle attachment and articulation with bones
Vertebral arch
Formed by paired pedicles attached to the vertebral body and paired laminae joined to form the spinous process
Transverse processes
Project laterally from the vertebral arch
Superior and inferior articular processes
Articulate with vertebrae above and below
Vertebral foramen
Encircled by the vertebral body and arch
Vertebral canal
Formed by the vertebral formina to protect the spinal cord
Where do spinal nerves exit?
From the intervertebral foramina between adjacent vertebral arches
Intervertebral joints
Between intervertebral disks and articular surfaces of vertebral bodies, symphyses, cartilaginous joints that are only slightly mobile
Zygapophyseal joints
AKA facet joints, between superior and inferior articular processes, synovial joints, contain fluid, allow for movement, prone to arthritis
Intervertebral discs
Have annulus fibrosis surrounding the nucleus pulposus
Herniated disc
Degeneration of the annulus fibrosis leads to herniation of the nucleus pulposus, can impinge on spinal cord or spinal nerves
Joints of the vertebral column
Intervertebral joints and zygapophyseal (facet) joints
Ligaments of the vertebral column
Supraspinous, interspinous, posterior longitudinal, anterior longitudinal, ligamentum flavum, nuchal
Supraspinous ligaments
Attach the spines of adjacent vertebrae to each other
Interspinous ligaments
Attach the spines of adjacent vertebrae to each other
Nuchal ligament
Continuation of supraspinous and interspinous ligaments, attach to the external occipital protuberance of the skull, limits cervical spine flexion
Ligamentum flavum
Present on the inner aspect of the vertebral arch
Posterior longitudinal ligament
On the posterior aspect of the vertebral bodies, limits vertebral column hyperflexion
Anterior longitudinal ligament
Runs along the anterior surface of the vertebral bodies, limits vertebral column hyperextension
Spinal stenosis
Zygapophysial joint hypertrophy, ligamentum flava hypertrophy, and mild disc protrusion that reduce the dimensions of the vertebral canal
Conus medullaris
Cone-shaped end of the spinal cord, at the intervertebral disc between L1 and L2
Filum terminale
Inferior continuation from the apex of the conus medullaris
Swellings of the spinal cord
Cervical enlargement and lumbosacral enlargement, associated with spinal nerves that innervate the upper and lower limbs
Cervical enlargement
C5-T1 spinal nerves, innervate the upper limbs
Lumbosacral enlargement
L1-S3 spinal nerves, innervate the lower limbs
How many spinal nerves are there?
31 total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
Cauda equina
Loose collection of ventral and dorsal roots located inferior to the conus medullaris, formed by the lumbar and sacral spinal nerves
Meninges of the spinal cord
Dura mater, arachnoid mater, pia mater
Pia mater
Lies directly on the spinal cord, forms strong pointed denticulate ligaments on either side of the spinal cord that work to secure the spinal cord to the dura mater
Epidural space
Superficial to the dura mater
Subdural space
Deep to the dura mater
Subarachnoid space
Deep to the arachnoid mater and contains cerebrospinal fluid
Lumbar puncture
CSF samples taken by putting a needle between L3/L4 or L4/L5 (has to be bellow the conus medullaris) and between the spinous processes. It then goes through the extradural space, the dura mater, the arachnoid mater into the subarachnoid space
Lumbar cistern
Subarachnoid space where CSF is often sampled from
Spinal block
Following lumbar puncture, anesthetic can be directly injected into the CSF
Epidural
Anesthesia from a catheter in the epidural space or a needle through the sacral hiatus
Spinal nerves
Associated with the 31 spinal cord segments, part of PNS, innervates specific areas of the skin (sensory) and muscles of the head, trunk and limbs (motor)
Mixed nerves
Contain both sensory and motor nerve fibers
Sensory nerve fibers
AKA afferent nerves, carry info towards the CNS
Motor nerve fibers
AKA efferent nerves, carry info away from CNS
Somatic nerves
Innervation of the muscles and overlying skin of the body
How spinal nerves attach to the spinal cord
Posterior and anterior roots
Posterior root
AKA dorsal root, contains the processes of sensory neurons carrying info to the CNS
Dorsal root ganglion
AKA spinal root ganglion, at the distal end of the posterior root, usually in the intervertebral foramen, contain cell bodies of sensory neurons
Posterior horn
AKA dorsal horn, in the posterior regions of the gray matter of the spinal cord, where sensory neurons synapse with DRG neurons
Anterior root
AKA ventral root, contains motor nerve fibers that carry signals away from CNS
Anterior horn
AKA ventral horn, in the anterior region of the gray matter of the spinal cord, contains cell bodies of primary motor neurons
Posterior ramus
Innervates only intrinsic muscles of the back and some skin on the back, contain mixed sensory and motor nerve fibers
Anterior ramus
Innervates most other skeletal muscles and most remaining areas of the skin, contain mixed sensory and motor nerve fibers
Spinal nerves that pass superior to their associated vertebrae
C1-C7
Spinal nerves that pass inferior to their associated vertebrae
C8 and below
Dermatone
Area of skin innervated by one spinal cord level, or on one side by a single spinal nerve
Myotome
Portion of skeletal muscle innervated by a single spinal cord level