Epidural space | |
---|---|
![]() The medulla spinalis and its membranes | |
Details | |
Identifiers | |
Latin | spatium epidurale, spatium extradurale, cavum epidurale |
MeSH | D004824 |
TA98 | A14.1.01.112 A14.1.01.110 |
TA2 | 5381, 5383 |
FMA | 71228 |
Anatomical terminology |
In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine). [1] [2]
The anatomy term "epidural space" has its origin in the Ancient Greek language; ἐπί, "on, upon" + dura mater also known as "epidural cavity", "extradural space" or "peridural space". In humans the epidural space contains lymphatics, spinal nerve roots, loose connective tissue, adipose tissue, small arteries, dural venous sinuses and a network of internal vertebral venous plexuses. [3]
In the skull, the periosteal layer of the dura mater adheres to the inner surface of the skull bones while the meningeal layer lays over the arachnoid mater. Between them is the epidural space. The two layers of the dura mater separate at several places, with the meningeal layer projecting deeper into the brain parenchyma forming fibrous septa that compartmentalize the brain tissue. At these sites, the epidural space is wide enough to house the epidural venous sinuses. [2] [4] [5]
There are four fibrous septa: [4]
In pathological conditions fluid such as blood can fill this space. For example a torn meningeal artery (often the middle meningeal artery) or dural venous sinus (rarely) may bleed into this potential space and result in an epidural hematoma. [5]
In the spinal canal, the periosteal layer adheres to the inner surface of the spinal canal which is formed by the bodies of vertebrae. The meningeal layer lays over the spinal arachnoid mater. [2] Between the vertebrae and the dural sheath is the spinal epidural space. Unlike the cranial epidural space, the spinal epidural space contains adipose tissue, the internal vertebral venous plexuses and the spinal nerve roots. [1] The spinal epidural space spans the length of the spinal cord, from the foramen magnum superiorly to the sacral hiatus inferiorly. [6]
Epidural space is the smallest at the cervical region, measuring 1 to 2 mm. At L2 to L3, enlarges until 5 to 6 mm. It then enlarges progressively until lower lumbar and sacral region. [7] However, some authors stated that it decreases in size after mid-lumbar region until 2 mm at S1 level. [8]
Articles related to anatomy include:
In anatomy, the meninges are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in the subarachnoid space between the arachnoid mater and the pia mater. The primary function of the meninges is to protect the central nervous system.
Pia mater, often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. Pia mater is medieval Latin meaning "tender mother". The other two meningeal membranes are the dura mater and the arachnoid mater. Both the pia and arachnoid mater are derivatives of the neural crest while the dura is derived from embryonic mesoderm. The pia mater is a thin fibrous tissue that is permeable to water and small solutes. The pia mater allows blood vessels to pass through and nourish the brain. The perivascular space between blood vessels and pia mater is proposed to be part of a pseudolymphatic system for the brain. When the pia mater becomes irritated and inflamed the result is meningitis.
Arachnoid granulations are small protrusions of the arachnoid mater into the outer membrane of the dura mater. They protrude into the dural venous sinuses of the brain, and allow cerebrospinal fluid (CSF) to exit the subarachnoid space and enter the blood stream.
In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. The other two meningeal layers are the arachnoid mater and the pia mater. It envelops the arachnoid mater, which is responsible for keeping in the cerebrospinal fluid. It is derived primarily from the neural crest cell population, with postnatal contributions of the paraxial mesoderm.
The great cerebral vein is one of the large blood vessels in the skull draining the cerebrum of the brain. It is also known as the vein of Galen, named for its discoverer, the Greek physician Galen.
A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrounding the brain. It usually results from tears in bridging veins that cross the subdural space.
Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds, subarachnoid bleeds, epidural bleeds, and subdural bleeds. More often than not it ends in death.
The falx cerebri is a large, crescent-shaped fold of dura mater that descends vertically into the longitudinal fissure between the cerebral hemispheres of the human brain, separating the two hemispheres and supporting dural sinuses that provide venous and CSF drainage to the brain. It is attached to the crista galli anteriorly, and blends with the tentorium cerebelli posteriorly.
The cerebellar tentorium or tentorium cerebelli is an extension of the dura mater between the inferior aspect of the occipital lobes and the superior aspect of the cerebellum. The free border of the tentorium gives passage to the midbrain.
The arachnoid mater is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural crest mesoectoderm in the embryo.
The dural venous sinuses are venous sinuses (channels) found between the endosteal and meningeal layers of dura mater in the brain. They receive blood from the cerebral veins, and cerebrospinal fluid (CSF) from the subarachnoid space via arachnoid granulations. They mainly empty into the internal jugular vein.
The straight sinus, also known as tentorial sinus or the sinus rectus, is an area within the skull beneath the brain. It receives blood from the inferior sagittal sinus and the great cerebral vein, and drains into the confluence of sinuses.
The superior sagittal sinus, within the human head, is an unpaired area along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses. Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to venous circulation.
The falx cerebelli is a small sickle-shaped fold of dura mater projecting forwards into the posterior cerebellar notch as well as projecting into the vallecula of the cerebellum between the two cerebellar hemispheres.
The transverse sinuses, within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove along the interior surface of the occipital bone. They drain from the confluence of sinuses to the sigmoid sinuses, which ultimately connect to the internal jugular vein. See diagram : labeled under the brain as "SIN. TRANS.".
The intervertebral foramen is an opening between two pedicles of adjacent vertebra in the articulated spine. Each intervertebral foramen gives passage to a spinal nerve and spinal blood vessels, and lodges a posterior (dorsal) root ganglion. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina.
The posterior atlantooccipital membrane is a broad but thin membrane extending between the to the posterior margin of the foramen magnum above, and posterior arch of atlas below. It forms the floor of the suboccipital triangle.
The calvaria is the top part of the skull. It is the superior part of the neurocranium and covers the cranial cavity containing the brain. It forms the main component of the skull roof.
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal cord is hollow and contains a structure called central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system (CNS).