Medical School Back Anatomy
A comprehensive set of anatomy flashcards based primarily on Gray's Anatomy for Students.
Terms in this set (85)
Primary curvatures of the vertebral column
Concave anteriorly, reflecting the original shape of the embryo, and retained in the thoracic and sacral regions.
Secondary curvatures of the vertebral column
Concave posteriorly, bringing the center of gravity into a vertical line, and retained in the cervical and lumbar regions.
Bones of the back
32-33 total vertebrae. 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 3-4 fused coccygeal.
Anterior, major weight-bearing component of the bone. Increases in size from C1 to L5.
Forms the lateral and posterior walls of the vertebral canal, which extends from C1 to S5. Contains the spinal cord. The roof of the arch is formed by right and left laminae, which fuse at the midline. Projections serve as attachments for muscles and ligaments, levers for the action of muscles, and sites of articulation with adjacent vertebrae.
Anterior wall of the vertebral arch
Formed by the vertebral bodies of the vertebrae, intervertebral discs, and associated ligaments.
Superior and inferior vertebral notch
Located between the vertebral body and the origin of the articular processes. They participate in the formation of the intervertebral foramina.
Projections of the vertebral arch
Spinous process projects posteriorly and inferiorly from the roof of the arch. Transverse processes extend laterally from the region where the lamina meets the pedicle. Superior and inferior articular processes also project from the same region, and articulate with the inferior and superior articular processes of adjacent vertebrae.
The end of the vertebral arch that attaches to the vertebral body.
Involved with the movement of the upper limbs (superficial group) and thoracic wall (intermediate group). Innervated by anterior rami of spinal nerves.
Involved with the movement of the vertebral column, head and ribs. "True back muscles" which are innervated by posterior rami of spinal nerves.
Meninges of the spinal cord
Three connective tissue membranes that surround the spinal cord within the vertebral column. Pia mater - innermost, associated with the surface of the spinal cord. Arachnoid mater - separated from pia mater by the subarachnoid space, which contains the cerebrospinal fluid. Dura mater - thickest and most external, lies directly against the arachnoid mater, but is not attached to it.
Extradural (epidural) space
Separates the dura mater from the surrounding bones of the vertebral canal. Contains loose connective tissue, fat, and a venous plexus.
Posterior rami of the spinal nerves
Small, innervate the back.
Anterior rami of the spinal nerves
Large, innervate most regions of the body except for the back and head.
Length of the spinal cord
Typically ends between L1 and L2. Does not extend the entire length of the vertebral canal since, during development, the vertebral column grows much faster than the spinal cord.
Formed between adjacent vertebral arches. Superior and inferior margins are formed by notches of the adjacent pedicles. Posterior margin is formed by the zygapophysial joint between the articular processes of the vertebral arches. Anterior border is formed by the intervertebral disc between the vertebral bodies of the adjacent vertebrae. Each spinal nerve exits the vertebral column laterally through an intervertebral foramen.
Morphology of cervical vertebrae
Characterized by their small size. Foramen transversarium present in each transverse process. First and second vertebrae are specialized to accommodate the movement of the head (Atlas and axis).
Vertebra C1, articulates with the head. Lacks a vertebral body and intervertebral disc. Ring-shaped and composed of two lateral masses interconnected by an anterior arch and a posterior arch. Contains large protruding transverse processes that act as levers for muscle action, particularly for the muscles that move the head at the atlanto-axial joints ("No" movement).
Vertebra C2. Contains a large tooth-like dens, which extends superiorly from the vertebral body. The anterior surface of the dens has an oval facet for articulation with the anterior arch of the atlas.
Allows the head to nod up and down on the vertebral column ("Yes" movement).
Attach to the two superolateral surfaces of the dens and the medial surfaces of the occipital condyles. Serve to prevent excessive rotation of the head and atlas relative to the axis.
Morphology of thoracic vertebrae
Characterized by their articulated ribs. Ribs are separate bones and articulate via synovial joints with the superior and inferior costal facets (one facet for the head of its own rib and another for the head of the rib below) on the sides of the vertebral bodies and the transverse costal facets of the transverse processes (tubercle of the rib contacts the facet).
Morphology of lumbar vertebrae
Characterized by their large size and lack of facets for articulation with the ribs. Transverse facets are long and thin with the exception of L5, which has very large facets which serve as an attachment site for the iliolumbar ligaments, which connect to the pelvic bones.
Morphology of the sacrum
Triangular in shape with an apex pointed inferiorly. Has two large lateral facets for articulation with the pelvic bones. Posterior surface has four pairs of posterior sacral foramina for the passage of the posterior rami (S1-4). The anterior surface has four pairs of anterior sacral foramina for the passage for the passage of the anterior rami(S1-4).
A typical vertebra has a total of six joints - four synovial joints (two above and two below) and two symphyses (one above and below). Each symphysis includes an intervertebral disc.
Found between adjacent vertebral bodies and consists of an outer anulus fibrosus (limits vertebral rotation) and a central nucleus pulposus (absorbs compression forces between vertebrae).
Exist between the superior and inferior articular processes on adjacent vertebrae. In cervical regions they slope inferiorly from anterior to posterior, facilitating flexion and extension. In thoracic regions they are oriented vertically, facilitating rotation. In lumbar regions they are curved and adjacent processes interlock, limiting range of movement.
Anterior longitudinal ligament
Extends from the base of the skull to the anterior surface of the sacrum. Along its length it attaches to the vertebral bodies and intervertebral discs.
Posterior longitudinal ligament
Is on the posterior surface of the vertebral bodies and lines the anterior surface of the vertebral canal. It is attached along its length to the vertebral bodies and intervertebral discs, and the upper part of the ligament, which connects C2 to the intracranial aspect of the base of the skull, is termed the tectorial membrane.
Pass between the laminae of adjacent vertebrae and form part of the posterior surface of the vertebral canal. These ligaments serve to resist separation of the laminae in flexion and assist in extension back to the anatomical position.
Connects and passes along the tips of the vertebral spinous processes from C7 to the sacrum.
A triangular, sheet-like structure that connects and passes along the tips of the vertebral spinous processes from C7 to the skull. Supports the head, resists flexion, facilitates returning the head to the anatomical position, and provides attachment sites for adjacent.
Pass between adjacent vertebral spinous processes. Attach from the base to the apex of each spinous process.
Superficial (appendicular) group of back muscles
Trapezius, latissimus dorsi, levator scapulae, rhomboid major, rhomboid minor.
Originates at the superior nuchal line and spinous processes of C7 to T12. Inserts at the lateral one-third of the clavicle, acromion and spine of the scapula. Motor innervation from the accessory nerve [XI], proprioception from C3 and C4. Rotates the scapula during abduction of the humerus above horizontal;upper fibers elevate, middle fibers adduct, and lower fibers depress scapula.
Originates at the spinous processes of T7 to L5 and the sacrum, iliac crest, and ribs 10 to 12. Inserts at the floor of the intertubercular sulcus of the humerus. Innervated by the thoracodorsal nerve (C6 to C8). Extends, adducts, and medially rotates the humerus.
Originates at the transverse processes of C1 to C4. Inserts at the upper portion of the medial border of the scapula. Receives innervation from C3, C4, and the dorsal scapular nerve (C4, C5). Elevates the scapula.
Originates at the spinous processes of T2 to T5. Inserts at the medial border of the scapula between the spine and inferior angle. Innervated by the dorsal scapular nerve (C4 and C5). Retracts (adducts) and elevates the scapula.
Originates at the lower portion of the ligamentum nuchae and the spinous processes of C7 and T1. Inserts at the medial border of the scapula at the spine of the scapula. Innervated by the dorsal scapular nerve (C4 and C5). Retracts (adducts) and elevates the scapula.
Intermediate (respiratory) group of back muscles
Serratus posterior superior, serratus posterior inferior
Serratus posterior superior
Originates at the lower portion of the ligamentum nuchae, the spinous processes of C7 to T3, and the supraspinous ligaments. Inserts at the upper border of ribs 2 to 5 just lateral to their angles. Innervated by the anterior rami of upper thoracic nerves (T2 to T5). Elevates ribs 2 to 5.
Serratus posterior inferior
Originates at the spinous processes of T11 to L3 and the supraspinous ligaments. Inserts at the lower border of ribs 9 to 12 just lateral to their angles. Innervated by the anterior rami of the lower thoracic nerves (T9 to T12). Depresses ribs 9 to 12 and may prevent lower ribs from being elevated when the diaphragm contracts.
Deep group of back muscles
Splenius capitis, splenius cervicis
Originates at the lower half of the ligamentum nuchae and the spinous processes of C7 to T4. Inserts at the mastoid process and the skull below the lateral one-third of the superior nuchal line. Innervated by the posterior rami middle cervical nerves. Individually turns face to the same side; together draws the head backward, extending the neck.
Originates at the spinous processes of T3 to T6. Inserts at the transverse processes of C1 to C3. Innervated by the posterior rami of the lower cervical nerves. Individually turns face to the same side; together extends neck.
Organization of the thoracolumbar fascia
Superiorly passes anteriorly to the serratus posterior muscle and is continuous with the deep fascia of the neck. In the thoracic region it covers the deep muscles and separates them from the superficial and intermediate muscle groups. Medially, it attaches to the spinous processes of the throacic vertebrae and, laterally, to the angles of the ribs. In the lumbar region it consists of three layers: posterior, middle and anterior.
Erector spinae muscles
Largest group of intrinsic back muscles. Primary extensors of the vertebral column and head (Straighten the back and pull head posteriorly). Divides in the upper lumbar region into three vertical columns of muscle. The outer column is the iliocostalis, the middle column is the longissimus, and the inner column is the spinalis.
Most lateral of the erector spinae muscles. Associated with the costal elements and passes from the common tendon of origin to multiple insertions into the angles of the ribs and the transverse processes of the lower cervical vertebrae.
The middle and intermediate column of erector spinae muscles. Extends from the common tendon of origin to the base of the skull, laterally positioned in the area of the transverse processes of the various vertebrae.
The most medial of the erector spinae muscles. Interconnects the spinous processes of adjacent vertebrae. Most constant in the thoracic region and generally absent in the cervical region. Is associated with the semispinalis capitis as it approaches the skull.
Run obliquely upward and medially from transverse processes to spinous processes, filling the groove between these two vertebral projections. They are deep to the erector spinae and consist of three major subgroups - semispinalis (most superficial), multifidus, rotatores (deepest). Bilateral contraction extends the vertebral column, unilateral contraction rotates the trunk.
Two groups of muscles deeply placed in the back and innervated by posterior rami of spinal nerves, consisting of levatores costarum, interspinales and intertransversarii muscles.
First group of segmental muscles. Arise from transverse processes of vertebra C7 and T1 to T9 and insert into the tubercle of the rib below the vertebra of origin. Contraction elevates the ribs.
Interspinales and intertransversarii
Second group of segmental muscles which pass between adjacent spinous and transverse processes, respectively. Postural muscles which stabilize adjoining vertebrae during movements of the vertebral column.
Small group of deep muscles the connect C1 to C2 and connect both vertebrae to the base of the skull. Include the rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis inferior, and the obliquus capitis superior. Contraction of these muscles extends the head at the atlanto-axial joint.
Rectus capitis posterior major
Suboccipital muscle that originates at the spinous process of C2 and inserts at the lateral portion of the occipital bone below the inferior nuchal line. Innervated by the posterior ramus of C1 and functions to extend the head and rotate the face to the same side as the muscle.
Rectus capitis posterior minor
Suboccipital muscle the originates at the posterior tubercle of C1 and inserts at the medial portion of the occipital bone below the inferior nuchal line. Innervated by the posterior ramus of C1 and functions to extend the head.
Obliquus capitis superior
Suboccipital muscle that originates at the transverse process of C1 and inserts at the occipital bone between the superior and inferior nuchal lines. Innervated by the posterior ramus of C1 and functions to extend and bend the head to the same side.
Obliquus capitis inferior
Suboccipital muscle that originates at the spinous process of C2 and inserts at the transverse process of C1. Innervated by the posterior ramus of C1 and functions to rotate the face to the same side.
Formed by suboccipital muscles and contains the posterior ramus of C1, the vertebral artery, and associated veins. The medial border is formed by the rectus capitis posterior major, the lateral border is formed by the obliquus capitis superior, and the inferior border is formed by the obliquus capitis inferior.
Occurs in the region associated with the origins of spinal nerves C5 to T1, which innervate the upper limbs.
Occurs in the region associated with the origins of spinal nerves L1 to S3, which innervate the lower limbs.
Anterior median fissure
Extends the length of the anterior surface of the spinal cord.
Posterior median sulcus
Extends the length of the posterior surface of the spinal cord.
Extends along each side of the posterior surface of the spinal cord, marking where the posterior rootlets of the spinal nerves enter the cord.
Rich in nerve cell bodies, which form longitudinal columns along the cord, and in cross-section form the characteristic H-shaped appearance in the central regions of the cord.
Surrounds the gray matter and is rich in nerve cell processes, which form large bundles or tracts that ascend and descend in the cord to other spinal cord levels or carry information to and from the brain.
Segmental spinal arteries
Feeder arteries that enter the vertebral canal through the intervertebral foramina at every level. Arise from the vertebral and deep cervical arteries in the neck, the posterior intercostal arteries in the thorax, and the lumbar arteries in the abdomen.
Anterior and posterior radicular arteries
Arteries that follow and supply the anterior and posterior roots. Arise from the segmental spinal arteries.
Segmental medullary arteries
Arteries that pass directly to and reinforce the longitudinally oriented vessels. Arise from the segmental spinal arteries.
Anterior spinal artery
A single artery that originates within the cranial cavity as the union of two vessels that arise from the vertebral arteries. Passes inferiorly and parallel to the anterior median fissure along the surface of the spinal cord.
Posterior spinal arteries
Two arteries that originate in the cranial cavity, usually arising from a terminal branch of each vertebral artery. The right and left arteries descend along the spinal cord, bracketing the posterolateral sulcus and the connection of posterior roots with the spinal cord.
Arteria radicularis magna or the artery of Adamkiewicz
The largest of the segmental medullary arteries. Arises in the lower thoracic or upper lumbar region, usually on the left side, and reinforces the arterial supply to the lower portion of the spinal cord, including the lumbar enlargement.
Spinal dura mater
The outermost meningeal membrane, separated from the bones forming the vertebral canal by an extradural space.
A thin delicate membrane against, but not adherent to, the deep surface of the dura mater. Separated from the pia mater by the subarachnoid space. Ends at the level of vertebra S2.
The space between the arachnoid and pia mater containing CSF. Continuous at the foramen magnum and surrounds the brain. Inferiorly, it terminates at approximately the lower border of S2.
Delicate strands of tissue that are continuous with the arachnoid mater on one side and the pia mater on the other, spanning the subarachnoid space and interconnecting the two adjacent membranes.
A vascular membrane that firmly adheres to the surface of the spinal cord. Extends into the anterior median fissure and reflects as sleeve-like coatings onto posterior and anterior rootlets and roots as they cross the subarachnoid space. As the roots exit the space, the coatings reflect onto the arachnoid mater.
A longitudinally oriented sheet of pia mater that extends laterally from the cord toward the arachnoid and dura mater.
Posterior roots of spinal nerves
Contain processes of sensory neurons carrying information to the CNS, with the cell bodies clustered in spinal ganglia at the distal ends of the posterior roots.
Anterior roots of spinal nerves
Contain motor nerve fibers, which carry signals away from the CNS, with the cell bodies located in the anterior regions of the spinal cord.
An area of the spinal cord that gives rise to the posterior and anterior rootlets, which will form a single pair of spinal nerves.
Approximately 31 pairs. 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
Spinal nerves in relation to the vertebral canal
C1 to C7 emerge above their respective vertebrae, C8 emerges between C7 and T1, and all remaining spinal nerves, beginning with T1, emerge from the vertebral canal below their respective vertebrae.