Nervous System Flashcards
Describe the peripheral nervous system.
Made up of paired cranial and paired spinal nerves. Dorsal sensory roots of spinal cord have ganglia and ventral motor roots have rootlets. Spinal nerves are where sensory and motor nerves meet. Cranial nerves can be either or both cranial and spinal nerves.
Define dermatome.
Regions of skin supplied by all the afferent nerve fibres of a single spinal nerves.
Define plexus.
Somatic plexus - a network of nerves formed from ventral rami of spinal nerves.
Peripheral plexus - different spinal nerves cross and form new peripheral nerves, such as brachial and lumbar plexuses.
Describe the gross structure of the spinal cord.
Cervical and lumbar regions are thicker than the thoracic and coccygeal regions. There are a greater number of neurones in the cervical and lumbar regions as gives large spinal nerves. Cervical plexus supplies forelimb and lumbar plexus supplies hindlimbs.
Conus medullaris is where the spinal cord tapers. Cauda equina is a branching of nerves to the lower body.
Describe the histological structure of the spinal cord.
White matter - myelinated fibres. Is around grey matter and split into funiculi - dorsal, lateral and ventral.
Grey matter - unmyelinated fibres and nerve cell bodies. Split into horns, ventral and dorsal on each side.
Middle is where cerebrospinal fluid is.
How do spinal nerves emerge from the spinal cord?
8 cervical nerves and 7 cervical vertebrae. C1 nerve root emerges cranial to corresponding vertebrae. Continues to C8 nerve, which emerges caudal to the C7 vertebrae. All spinal nerves onwards emerge caudal to corresponding vertebrae. Nerves then travel in intervertebral foramina.
Name and describe the meninges, the 3 layers of connective tissues around brain and spinal cord.
Dura mater - thickest, is durable, offers structural protection and support.
Arachnoid mater - finer than dura mater with a web-like structure.
Pia mater - thinnest layer and is not visible to the eye but is tightly adhered to the brain and spinal cord.
What is the periosteum?
A layer that covers bone to allow for muscular attachments and penetration of lymphatic and blood vessels.
What are the 3 spaces around the central nervous system?
Epidural space - lies outside the dura mater, a true space embedded with fat and blood vessels.
Subdural space - between dura and arachnoid maters, thin as layers are pushed together due to fluid pressure below.
Subarachnoid space - filled with cerebrospinal fluid, the pressure of which pushes arachnoid to dura.
What is a cisternal tap?
Needle between skull and atlas/C1 in order to sample CSF. But is lumbar cisterna for large animals: S4 for horse and ox, as subarachnoid space is relatively large at the end of the spinal cord.
