Exam 4 Review:  Chapter 12:  The Meninges

meninx / meninges - The first layers of protection over the brain, spinal cord, and cranial and spinal nerves are three layers of tough connective tissue; the dura mater, arachnoid membrane, and pia mater.

cranial meninges - The portion of the three meninges which cover the brain within the brain case of the skull; the first layers of protection over the brain and cranial nerves are three layers of tough connective tissue; the dura mater, arachnoid membrane, and pia mater.

spinal meninges - The portion of the three meninges which cover the spinal cord and spinal nerves within the spinal canal of the vertebral column; the first layers of protection over the spinal cord and spinal nerves are three layers of tough connective tissue; the dura mater, arachnoid membrane, and pia mater.

dura mater - The outermost and heaviest, most fibrous, layer of the meninges covering the brain and spinal cord, composed of dense irregular fibrous connective tissue, a structure which contain some of the larger blood vessels, particularly the venous sinuses; it forms a protective physical barrier for the CNS.

epidural space - The anatomical location external to the dura is merely a "potential" space in the cranium, since the dura is fused to the cranial periosteum, while, in contrast, in the vertebral canal, it generally contains adipose tissue.

subdural space - The anatomical location between the dura and the arachnoid is merely a "potential" space because under normal circumstances, the arachnoid is directly attached to the dura mater.

arachnoid - The middle layer of the meninges, a thin, spongy membraneous covering of the brain and spinal cord with a spider-web-like appearance which does not conform to the irregularities of the surfaces of the brain and spinal cord; it is composed of a delicate loose fibrous connective tissue; the space under the arachnoid and above the pia mater, the subarachnoid space, contains cerebrospinal fluid.

pia mater -The inner layer of the meninges, a thin, membraneous covering which adheres smoothly to the surface of the brain and spinal cord and conforms to all the irregularities of their surfaces; is is composed of a very thin layer of dense irregular fibrous connective tissue; the smaller surface blood vessels of the brain and spinal cord are contained within this layer; at spinal levels, the pia mater gathers laterally, pierces the arachnoid and attaches to the dura, forming the denticulate ligament -- this* stabilizes the spinal cord within the vertebral canal and decreases the likelihood of cord damage when physical trauma occurs.  (*The filum terminale has a similar function.)

subarachnoid space - The space under the arachnoid and above the pia mater which contains cerebrospinal fluid.

meningitis - Inflammation of the meninges of the brain and the spinal cord, most often caused by a bacterial or viral infection and characterized by fever, nausea and vomiting, intense headache, and stiff neck; bacterial forms tend to have more severe prognosis.

falx cerebri - The scythe-shaped mid-saggital fold of the dura mater occupying the longitudinal fissure between the two cerebral hemispheres and which contains the sagittal venous sinuses.

Sketch and label

1. The protective coverings of the brain as seen in frontal section. What, if any, differences are there to the same structures of the spinal cord.

The only significant difference observed in the spinal cord is the presence of an epidural space separating the periosteum of the surrounding vertebral bone; this space contains adipose tissue and blood vessels.  In the cranium, the dura matter is continuous with the periosteum of the skull bones.