The anterior and posterior radicular arteries are 32 pairs of small/ [1] variously sized arteries that enter an intervertebral foramen, [2] bifurcating within it to form an anterior and a posterior radicular artery which accompany the anterior root and posterior root of a spinal nerve, respectively. They supply the corresponding spinal cord segment as well as the anterior and posterior root of the spinal nerve and its sensory ganglion (dorsal root ganglion). [1]
At the level of the lumbosacral enlargement, a relatively large radicular artery (the great radicular artery) that reaches the spinal cord is often present. [2]
The radicular arteries are crucial for adequate arterial supply of most of the spinal cord as the anterior and posterior spinal artery do not provide sufficient arterial supply to the spinal cord by themselves - with the exception of the cervical portion of the spinal cord. An injury to a spinal nerve may thus also entail an injury to the corresponding radicular artery with consequent ischaemic damage to the corresponding spinal cord segment. [1]
The radicular arteries additionally provide arterial supply to the posterior and anterior roots of a spinal nerve as well as the sensory ganglion. [2]
In the thoracolumbar region, most segmental medullary arteries regress during early development to form radicular arteries; those that persist give off radicular arteries as branches. [2] Radicular arteries can sometimes be functionally replaced by segmental medullary arteries. However, unlike those arteries, radicular arteries do not form anastamoses with the anterior or posterior spinal arteries. Radicular arteries are also generally smaller. The so-called great radicular artery it is in fact a segmental medullary artery. [3] [ verification needed ]
The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions, ranging from vomiting to sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers, and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep–wake cycle. "Medulla" is from Latin, ‘pith or marrow’. And "oblongata" is from Latin, ‘lengthened or longish or elongated'.
The brainstem is the stalk-like part of the brain that connects the forebrain with the spinal cord. In the human brain, the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch.
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.
In neuroanatomy, the trigeminal nerve (lit. triplet nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (trigeminal, from Latin tri- 'three' and -geminus 'twin') derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that autonomic nerve fibers as well as special sensory fibers (taste) are contained within it.
The phrenic nerve is a mixed motor/sensory nerve that originates from the C3-C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. In humans, the right and left phrenic nerves are primarily supplied by the C4 spinal nerve, but there is also a contribution from the C3 and C5 spinal nerves. From its origin in the neck, the nerve travels downward into the chest to pass between the heart and lungs towards the diaphragm.
The internal carotid artery is an artery in the neck which supplies the anterior and middle cerebral circulation.
In human anatomy, the spinal canal, vertebral canal or spinal cavity is an elongated body cavity enclosed within the dorsal bony arches of the vertebral column, which contains the spinal cord, spinal roots and dorsal root ganglia. It is a process of the dorsal body cavity formed by alignment of the vertebral foramina. Under the vertebral arches, the spinal canal is also covered anteriorly by the posterior longitudinal ligament and posteriorly by the ligamentum flavum. The potential space between these ligaments and the dura mater covering the spinal cord is known as the epidural space. Spinal nerves exit the spinal canal via the intervertebral foramina under the corresponding vertebral pedicles.
In human anatomy, the artery of Adamkiewicz is the largest anterior segmental medullary artery. It typically arises from a 9th to 12th left posterior intercostal artery, enters through the L2-L3 intervertebral foramen to join the anterior spinal artery and supply much of the inferior half of the spinal cord.
A dorsal root ganglion is a cluster of neurons in a dorsal root of a spinal nerve. The cell bodies of sensory neurons known as first-order neurons are located in the dorsal root ganglia.
The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, midline basilar artery. As the supplying component of the vertebrobasilar vascular system, the vertebral arteries supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain.
The dorsal root of spinal nerve is one of two "roots" which emerge from the spinal cord. It emerges directly from the spinal cord, and travels to the dorsal root ganglion. Nerve fibres with the ventral root then combine to form a spinal nerve. The dorsal root transmits sensory information, forming the afferent sensory root of a spinal nerve.
The conus medullaris or conus terminalis is the tapered, lower end of the spinal cord. It occurs near lumbar vertebral levels 1 (L1) and 2 (L2), occasionally lower. The upper end of the conus medullaris is usually not well defined, however, its corresponding spinal cord segments are usually S1–S5.
The inferior thyroid artery is an artery in the neck. It arises from the thyrocervical trunk and passes upward, in front of the vertebral artery and longus colli muscle. It then turns medially behind the carotid sheath and its contents, and also behind the sympathetic trunk, the middle cervical ganglion resting upon the vessel.
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 spinal artery arises from the vertebral artery in 25% of humans or the posterior inferior cerebellar artery in 75% of humans, adjacent to the medulla oblongata. It is usually double, and spans the length of the spinal cord. It supplies the grey and white posterior columns of the spinal cord.
The anterolateral central arteries or lenticulostriate arteries are a group of small arteries mostly arising from the middle cerebral artery that enter the brain through the anterior perforated substance to provide arterial supply to parts of the basal ganglia. They are end arteries.
Segmental medullary arteries are arteries of varying size in the thoracolumbar region that arise from segmental arteries of this region and pass through intervertebral foramina to supply the spinal cord. They may join the anterior spinal artery.
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 the 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.
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots of the ciliary ganglion, which join enter the posterior surface of the ganglion.
Radicular veins are segmental veins providing venous drainage of the spinal cord and canal. They communicate with anterior and posterior spinal veins as well as epidural venous plexus. They exit the spinal canal through the intervertebral foramina, accompanying the corresponding of radicular arteries.