Chapter 13 Flashcards
Vertebral column
Provide a sturdy shelter for the enclosed spinal cord. The vertebral ligaments, meninges, and cerebrospinal fluid provide additional protection.
Meninges
Singular is meninx; are three protective, connective tissue coverings that encircle the spinal cord and brain.
From superficial to deep, what are the three meninges?
- Dura mater
- Arachnoid mater
- Pia mater
Dura mater
Most superficial meninx. Is a thick, strong layer composed of dense irregular connective tissue.
Arachnoid mater
The middle meninx. Is a thin, avascular covering made of cells and thin, loosely arranged collagen and elastic fibers.
Subdural space
A thin space between the dura mater and the arachnoid mater which contains interstitial fluid.
Pia mater
Innermost meninx. Is a thin, transparent connective tissue layer that adheres to the surface of the spinal cord and brain. Consists of thin squamous to cuboidal cells within interlacing bundles of collagen fibers and some fine elastic fibers. Contains many blood vessels that supply oxygen and nutrients to the spinal cord.
Denticulate ligaments
Triangular-shaped membranous extensions of the pia mater that suspend the spinal cord in the middle of its dural sheath. Extend along the entire length of the spinal cord and protect it against sudden displacement that could result in shock.
Subarachnoid space
Space between the arachnoid mater and the pia mater which contains shock-absorbing cerebrospinal fluid.
Spinal meninges
Surround the spinal cord. Are continuous with the cranial meninges. Cover the spinal nerves up to the point where they exit the spinal column through the intervertebral foramina.
Cranial meninges
Encircle the brain. Are continuous with the spinal meninges.
Epidural space
Space between the dura mater and the wall of the vertebral canal.
Spinal cord
Roughly oval in shape and is flattened slightly anteriorly and posteriorly.
In adults, the spinal cord extends from the ______ to ______. In newborn infants, it extends to ______. Length ranges from ______, with a maximum diameter of approximately ______ in the lower cervical region and is smaller in the thoracic region and at its inferior tip.
Medulla oblongata; L2; L3 or L4; 42 to 45 cm (16-18 in.); 1.5 cm (0.6 in.)
When viewed externally, what two conspicuous enlargements can be seen on the spinal cord?
- Cervical enlargement
- Lumbar enlargement
Cervical enlargement
The superior enlargement. Extends from C4-T1. Nerves to and from the upper limbs arise from here.
Lumbar enlargement
The inferior enlargement. Extends from T9-T12. Nerves to and from the lower limbs arise from here.
Conus medullaris
Tapering, conical structure where the spinal cord terminates.
Filum terminale
An extension of the pia mater that extends inferiorly, fuses with the arachnoid mater, and dura mater, and anchors the spinal cord to the coccyx. Arises from the conus medullaris.
Spinal nerves
Paths of communication between the spinal cord and specific regions of the body. There are 31 pairs of spinal nerves total.
Of the spinal nerves, there are __ pair(s) of cervical nerves, __ pair(s) of thoracic nerves, __ pair(s) of lumbar nerves, __ pair(s) of sacral nerves, and __ pair(s) of coccygeal nerves.
8; 12; 5; 5; 1
Roots
Two bundles of axons that connect each spinal nerve to a segment of the cord using rootlets.
Posterior (dorsal) root/rootlets
Contain only sensory axons, which conduct nerve impulses from sensory receptors in the skin, muscles, and internal organs into the CNS.
Posterior (dorsal) root ganglion
A swelling which contains the cell bodies of sensory neurons.