Spine Anatomy | Mayfield Brain & Spine, Cincinnati
The Peripheral Nervous System provides communication between the brain and spinal cord and the Relation of Spinal Nerves to Vertebrae. J Clin Neurosci. Feb;15(2) Epub Nov 7. The relation between the lumbar vertebrae and the spinal nerves for far lateral lumbar spinal. Spinal nerve, in vertebrates, any one of many paired peripheral nerves that arise from the spinal cord. In humans there are 31 pairs: 8 cervical, 12 thoracic.
Excessive "hollowing" of the back is termed lordosis. Five sometimes six vertebrae are fused in the adult to form the sacrum, which can be felt below the "small of the back. It has a roughly triangular appearance with a pelvic and dorsal surface, a lateral mass on each side, and a base and apex.
The pelvic surface, concave and facing antero-inferiorly, presents four paired sacral foramina for the ventral primary rami of sacral nerves 1 to 4. The dorsal surface, convex and facing posterosuperiorly, presents a modified series of spinous processes termed the median sacral crest and four paired sacral foramina for the dorsal primary rami of sacral nerves 1 to 4. Below, the sacrum shows right and left sacral cornua, which bound a variable gap termed the sacral hiatus.
An anesthetic for the spinal nerves may be injected extradurally through the sacral hiatus caudal analgesia. The cornua articulate with corresponding horns on the coccyx. The lateral part or mass of the sacrum, lateral to the sacral foramina, consists of the fused transverse processes including their costal elements. Its superior surface is frequently termed the ala. The superolateral part of the lateral mass presents the auricular ear-shaped surface for articulation with the hip bone sacro-iliac joint.
The surface is limited behind by an area sacral tuberosity for interosseous ligaments. The base, formed by the suprior part of the first sacral vertebra, presents a prominent anterior margin termed the promontory fig. Superior articular processes articulate with the fifth lumbar vertebra.
The sacral canal which contains the dura, cauda equina, and filum terminale extends from the base to the sacral hiatus. The apex of the sacrum may be fused with the coccyx. The vertebrae usually four below the sacrum are variably fused in the adult to form the coccyx, which resembles a miniature sacrum in shape.
Development of vertebrae figs. Typically, a vertebra at birth shows three ossific areas, one for the centrum defined in fig. At about puberty, ossific centers appear in the margins of the upper and lower surfaces of the body ring epiphyses and at the tips of the various processes. Developmental failure of half a vertebra hemivertebra is one cause of lateral curvature scoliosis. Failure of fusion of the halves of one or more neural future vertebral arches is termed spina bifida.
The meninges alone meningoceleor the spinal cord and meninges meningomyelocelemay protrude through the defect spina bifida cystica. When the defect is skeletal rather than neural, it may be concealed by the skin although sometimes marked by a tuft of hair and is termed spina bifida occulta. In the sacrum, this is quite common.
Spinal Nerves: Cervical, Thoracic, Lumbar, Sacral, Coccyxgeal
Surface anatomy The spinous processes of the vertebrae are palpable in the median furrow of the back. The external occipital protuberance is palpable in adults.
The spines of vertebrae C6, C7, and T1 are usually prominent and palpable, and they are made more conspicuous by flexion of the neck and trunk. In the thoracic region, the spinous process of each vertebra extends to the level of at least the body of the vertebra below. The inferior angle of the scapula is frequently at the level of the spinous process of T7.
A horizontal plane between the highest points of the iliac crests supracristal plane is usually at the level of the spinous process of L4, and this is used as a landmark for lumbar puncture. A needle introduced here should enter the subarachnoid space after 4 to 6 cm.
Spinal nerve - Wikipedia
The posterior superior iliac spine is commonly marked by a skin dimple fig. Additional reading Kohler, A. This classic study of the entire skeleton is available in a more recent edition in German. This well known work is an important account of the normal and abnormal vertebral column.
Questions How many vertebrae are movable? Eighty-nine per cent of people have 24 presacral vertebrae, 6 per cent have 23, and 5 per cent have 25 P.
The cervical and lumbar curvatures are secondary appearing during fetal life and accentuated during infancy. Lumbar vertebrae have small, additional mamillary and accessory processes.
Chapter 39: The vertebral column
The axis has an odontoid process the dens but no superior articular processes merely facets. The atlas has only transverse processes.
Hence the remaining spinal nerves below leave inferior to the correspondingly numbered vertebrae. The slipping forward of a vertebral body e. A year-old nurse complained of numbness of the right big toe, a burning pain down the lateral side of the right leg and foot, bowel and bladder problems, and weakness of the lower limbs.
She developed a marked depression over the spinous process of L5. Bowel and bladder difficulties were produced by compression of the cauda equina from gross distortion of the vertebral canal.
Decompression by removal of some bone near the pedicles relieved the symptoms G. Numerous case studies on anatomy have been described by E. Lachman Case Studies in Anatomy, 3rd ed. Above S2, a subarachnoid space is also present see fig. The centrum does not correspond to the whole of the body: The three primary areas become united by bone in early childhood 3 to 6 years.
A number of secondary centers the ring epiphyses and centers for the tips of the transverse and spinous processes appear at about puberty. The spinal cord and meninges myelomeningoceleor the meninges alone meningocelemay protrude through the defect spina bifida cystica.
When the defect is skeletal rather than neural, it is termed spina bifida occulta; this defect is found in the sacrum in approximately one fifth of the general population A. Greek roots with a similar significance are spondyl- and rhachi- e.
Figure legends Figure The primary 1, thoracic; 2, sacral and secondary 3, cervical; 4, lumbar curvatures of the vertebral column. Figure The parts of a vertebra T. Adjacent intervertebral notches form intervertebral foramina for the transmission of nerves.
Figure The atlas from above. Muscle origins and the superior vertebral artery are shown on the right side.
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Figure lateral and posterosuperior views of the axis. Figure Various vertebrae from lateral, superior, and posterior aspects. Figure The positions, lengths, and directions of A the spinous processes and B the transverse processes.
The vertebrae in black mark the levels at which a change in direction of curvature occurs. Figure Thoracic vertebrae and C7 and L1. Note the bodies, pedicles, transverse and spinous processes, and costrotransverse joints. Figure Lumbar vertebrae and female pelvis.Spinal cord Segmentation
Figure Oblique view of the lumbar vertebrae. Note the very small twelfth rib, the joints between the articular processes ofthe lumbar vertebrae the arrow indicates the joint between L1 and L2and the sacrum.
In this view the outline of a Scotch terrier is formed by the transverse process snout, overlapping the vertebral bodythe superior articular process earand the inferior articular process forepaw. The neck of the dog corresponds to the important pars interarticularis, injury to which may result in spondylolisthesis.
Figure Female sacrum and coccyx. A, Pelvic and, B, dorsal aspects showing muscular and ligamentous attachments. C, Right lateral aspect in the anatomical position. Figure Female and male sacra from above. The superior aspect of the lateral part is the ala. Although there are seven cervical vertebrae C1-C7there are eight cervical nerves C1 — C8.
All cervical nerves except C8 emerge above their corresponding vertebrae, while the C8 nerve emerges below the C7 vertebra. Elsewhere in the spine, the nerve emerges below the vertebra with the same name. The cervical nerves innervate the sternohyoidsternothyroid and omohyoid muscles. A loop of nerves called ansa cervicalis is part of the cervical plexus. Thoracic nerves[ edit ] The thoracic nerves are the twelve spinal nerves emerging from the thoracic vertebrae.
Each thoracic nerve T1 -T12 originates from below each corresponding thoracic vertebra. Branches also exit the spine and go directly to the paravertebral ganglia of the autonomic nervous system where they are involved in the functions of organs and glands in the head, neck, thorax and abdomen.
The intercostal nerves come from thoracic nerves T1-T11, and run between the ribs. At T2 and T3, further branches form the intercostobrachial nerve. The subcostal nerve comes from nerve T12, and runs below the twelfth rib. The medial branches ramus medialis of the posterior branches of the upper six thoracic nerves run between the semispinalis dorsi and multifiduswhich they supply; they then pierce the rhomboid and trapezius musclesand reach the skin by the sides of the spinous processes.
This sensitive branch is called the medial cutaneous ramus. The medial branches of the lower six are distributed chiefly to the multifidus and longissimus dorsioccasionally they give off filaments to the skin near the middle line. This sensitive branch is called the posterior cutaneous ramus. List of lumbar nerves Lumbar plexus and branches The lumbar nerves are the five spinal nerves emerging from the lumbar vertebrae.
They are divided into posterior and anterior divisions. The medial branches of the posterior divisions of the lumbar nerves run close to the articular processes of the vertebrae and end in the multifidus muscle. The laterals supply the erector spinae muscles. The upper three give off cutaneous nerves which pierce the aponeurosis of the latissimus dorsi at the lateral border of the erector spinae muscles, and descend across the posterior part of the iliac crest to the skin of the buttocksome of their twigs running as far as the level of the greater trochanter.
The anterior divisions of the lumbar nerves rami anteriores increase in size from above downward.