Lecture 17 Flashcards
Somatic Innervation
Arise segmentally along the developing CNS in association with somites; part of each somite (dermomyotome) gives rise to skeletal muscle and the dermis of the skin
Hypaxial Muscles
Cells that migrate anteriorly give rise to muscles of the limbs and trunk and to the associated dermis
Epaxial Muscles
Cells that migrate posteriorly give rise to the intrinsic muscles of the back and the associated dermis
Dermatome
Area of skin supplied with afferent nerve fibers by a single posterior spinal root
Myotome
All the muscles that are innervated by a single efferent anterior root; most muscles are composed of more than one myotome
Spinal Cord
Approx. 1/2 meter in length and maybe 1-1.5 cm in diameter; enlarged in cervical C3-T1 and lumbar L1-S2; contains “conus medullaris”, “cauda equina”, and “filum terminale”
Filum Terminale
Thin filament of meningeal tissue extending from conus medullaris to the coccyx
Number of spinal nerves in each section of spinal cord
8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal
Plexuses and which nerves they contain
Cervical (C1-C4), Brachial (C5-T1), Lumbosacral (L1-S4)
Gray Matter (Horns)
Equivalent of CNS nuclei; posterior (dorsal) horns receive incoming sensory fibers, anterior (ventral) horns are site of cell bodies of alpha motor neurons to skeletal muscle fibers; lateral horns are located only in thoracic and upper lumbar region and are the site of cell bodies of autonomic neurons
White Matter (Columns/Funiculi)
Consist of myelinated tracts; divided into posterior/dorsal columns, anterior/ventral columns, and lateral columns
Commisures
Can be either white or gray and divided into anterior or posterior
Dorsal Rootlets and Root
Carries afferent fibers and contains dorsal root ganglion, which are the location of cell bodies of afferent neurons
Ventral Rootlets and Root
Carries efferent fibers and have NO associated ganglion
Spinal Nerve
Carries a mixture of fibers; afferent/efferent, visceral/somatic, and proprioceptive
Primary Dorsal Rami
To epaxial musculature (deep back muscles) and skin on either side of dorsum of back
Primary Ventral Rami
To hypaxial musculature (rest of skeletal musculature including muscles of limbs) and rest of skin
Autonomic White Ramus Communicans
Carries pre-ganglionic sympathetic fibers from lateral horns of central gray of spinal cord (thoracolumbar regions)
Autonomic Gray Ramus Communicans
Carries post-ganglionic sympathetic fibers from paravertebral ganglia back to spinal nerve
Dura Mater
Tough outer layer of meninges of spinal cord
Subarachnoid Space
Contains cerebrospinal fluid
Pia Mater
Delicate innermost layer of meninges of spinal cord
Coverings and Spaces of Spinal Cord
Epidural space, dura mater, subdural space, arachnoid, subarachnoid space, pia mater, denticulate ligaments
