Flashcards in USMLE Road Map - Back Deck (128):
Vertebral column - Components:
Spina bifida results when the ...?
Laminae fail to fuse to form a spinous process and is MC seen at lower lumbar or sacral vertebral levels.
2 types of spina bifida:
Spina bifida occulta:
One or more spinous processes fail to form at lumbar or sacral levels.
--> Asymptomatic - may be marked by a tuft of hair in skin over the defect.
Spina bifida cystica:
A cysts protrudes through the defect in the vertebral arch.
--> May result in hydrocephalus and neurological deficits.
In spina bifida cystica with meningocele:
The cyst is lined by the dura and arachnoid and contains CSF.
In spina bifida with meningomyelocele:
The lumbosacral spinal cord is displaced into the cyst.
--> Stretches the lumbosacral spinal nerves and may result in bladder, bowel, or lower limb weakness.
Spina bifida with myeloschisis or rachischisis:
The caudal end of the neural tube fails to close in the dorsal midline and is exposed on the surface of the back.
Abnormal increase in the POSTERIOR curvature of the spine.
Kyphosis may also be caused by ...?
1. Anterior wedge-shaped thoracic vertebrae.
2. Resorption of the anterior parts of the thoracic vertebral bodies from osteopororsis.
Abnormal increase in the ANTERIOR curvature of the spine.
Lordosis - May be caused by ...?
A weakening of the anterior abdominal wall musculature as a result of weight gain.
Abnormal lateral curvature.
Scoliosis - May be caused by:
1. An absent half of a vertebra.
2. Wedge-shaped vertebra.
3. Asymmetric weakness of back musculature.
Zygoapophyseal, or facet, joints are formed:
Between the facets of superior and inferior processes at the junction of each pedicle and lamina.
--> Facet joints permit gliding motions. Intrinsic or deep muscles act at these joints.
Nucleus pulposus is the ...?
Postnatal remnant of the fetal notochord.
Role of intervertebral disks:
Function to absorb shock and distribute weight over the entire surface of the vertebral disks.
Anterior longitudinal ligament:
Covers the anterolateral parts of the vertebral bodies and the disks and functions to limit vertebral EXTENSION.
Posterior longitudinal ligament:
Cover the posterior parts of the vertebral bodies and the disks and functions to limit vertebral FLEXION.
The posterior longitudinal ligament is ... than the anterior longitudinal ligament.
Narrower and weaker.
Elastic ligamentum flavum extends:
Between the laminae of adjacent vertebrae. These ligaments also function to limit vertebral FLEXION and help maintain normal vertebral curvatures.
Intervertebral foramina are bounded by the ...?
1. Pedicles of adjacent vertebrae.
2. Posteriorly by the facet joints.
3. Anteriorly by the bodies and the intervertebral disks.
The vertebral canal is formed by ...?
All of the individual vertebral foramina and the ligaments and disks that interconnect them.
The vertebral canal contains:
2. Spinal cord.
3. Roots of spinal nerves.
The epidural space:
Outside the dural layer of the meninges.
The epidural space contains:
2. Internal vertebral venous plexus.
The internal venous plexus connects:
Veins that drain:
with dural venous sinuses of the cranial cavity.
The internal venous plexus also provides a route for ...?
Metastasis of neoplasms of:
to the cranial cavity.
The dura mater of the spinal cord is continuous with the meningeal dura of the cranial cavity and ends at the ...?
The arachnoid mater also extends to the ...?
S2 and is pressed against the dura by the pressure of CSF.
Subarachnoid space contains:
CSF secreted into ventricles of the brain --> Circulates through the subarachnoid space, and is returned to the venous system.
CSF - Role:
1. Normal pressure of 100cm H2O.
2. Cushions the brain and spinal cord.
3. Absorbs waste products.
4. Transports hormones.
Pia mater covers:
The spinal cord and the roots of spinal nerves.
Denticulate ligaments are ...?
Lateral extensions of the pia that anchor the spinal cord to the dura.
The filum terminale consists of ...?
Pia that extends from the inferior end of the cord at the level of the L2 vertebra and joins the dura and arachnoid to end in the sacral canal at the S2.
The spinal cord occupies ...?
The superior 2/3 of the vertebral canal and ends approx. at the level of L2.
The conus medullaris is the ...?
Tapered inferior end of the spinal cord that contains the sacral and coccygeal cord segments and is located at the level of the L2 vertebra.
The spinal nerves exit the vertebral canal through:
1. Intervertebral foramina.
2. Sacral foramina.
3. Sacral hiatus.
The first 7 cervical nerves exit ...?
SUPERIOR to the cervical vertebra for which they named (eg, the C4 nerve exits between C3-C4).
Beginning with the T1 spinal nerve, ...?
All other spinal nerves exit inferior to the vertebra for which they are named (eg, the L4 nerve exits between L4-L5).
The 8 cervical nerve exits through ...?
The intervertebral foramen between the C7-T1, because there are 8 cervical nerves but only 7 cervical vertebrae.
The cauda equina is formed by ...?
Dorsal and ventral roots of lumbar and sacral spinal nerves that extend inferior to the end of the spinal cord at the L2.
LP - What is used for:
1. Sample CSF.
2. Introduce anesthetic agents into the subarachnoid space.
LP is typically performed between the ...?
L4-L5 vertebrae well below the inferior end of the spinal cord.
In a midline LP a needle will traverse:
2. Superficial and deep fascia.
3. Supraspinous and interspinous ligaments.
4. Intralaminar space.
5. Epidural space.
In a LP OFF THE MIDLINE the needle will traverse ...?
A ligamentum flavum instead of the supraspinous and interspinous ligaments and the intralaminar space.
Role of the vertebral column:
1. Contains and protects the spinal cord.
2. Supports the skull and the upper limb.
3. Transmits weight to the lower limb through the pelvis.
Radiculopathies result from ...?
COMPRESSION of the roots of spinal nerves in the intervertebral foramina or in the vertebral canal.
Radiculopathies - Typical symptoms are:
Pain and paresthesia (altered sensations usually in the form of numbness or tingling) in the dermatomes supplied by the compressed sensory roots.
--> May ALSO have muscle weakness in myotomes supplied by the compressed motor roots.
Radiculopathies may be caused by:
4. Herniated disk.
Additional bone growth by osteophytes at the facet joints.
Inflammation that results in additional bone growth by osteophytes at the margins of the vertebral BODIES.
Spondylitis - The anterior longitudinal ligament and the sacroiliac joints may undergo ...?
Patients exhibit ankylosis + bamboo spine - Marie-Strumpell disease.
Degenerative changes in intervertebral disks, and is usually combined with OA at the margins of the vertebral bodies.
1. Small bodies.
2. Short spinous processes with bifid tips.
3. Traverse processes that transmit the vertebral arteries.
Cervical vertebrae have facet joints ...?
From C3 to C7 that are oriented at a 45-degree angle relative to the transverse plane.
This alignment permits:
Flexion/extension + Lateral bending + Rotation.
Cause the cervical vertebrae to be strongly extended and then strongly flexed and may result in an anterior dislocation of the facet joints.
Cervical vertebrae have ... processes on the bodies of C3-C7.
The uncinate processes form ...?
Uncovertebral synovial joints with the vertebral bodies SUPERIOR to them.
--> OA changes in these joints --> Compression of the roots of C3-C7 cervical spinal nerves.
Atlas (C1) has ...?
Posterior arch and anterior arch and NO BODY or SPINOUS PROCESS.
The is NO ... between the C1 and the C2 vertebrae.
The superior articular process of the atlas articulate with the ...?
Occipital CONDYLES of the skull, forming the "yes" joints - These facet joints permit mainly FLEXION/EXTENSION.
The dens of the axis (C2) articulates with the ...?
Anterior arch of the atlas, and forms the "no" or pivot joint --> Rotation of the atlas and the skull.
The dens is held in place by the ... ligament.
Transverse ligament of the atlas.
Rupture of the transverse ligament of the atlas causes ...?
Dislocation of the atlantoaxial joint and displacement of the dens POSTERIORLY into the cervical spinal cord.
Compression of the ventrolateral part of the cervical spinal cord by the dens may result in ...?
The dens is attached to the margins of the foramen magnum by ... ligaments.
Rupture of the alar ligaments causes ...?
Excessive rotation of the skull.
The C7 vertebra (vertebra prominens) has a ...?
Long spinous process and small transverse foramina that do NOT transmit the vertebral arteries.
A herniated disk occurs when ...?
A nucleus pulposus protrudes at the POSTEROLATERAL part of the annulus fibrosus resulting in COMPRESSION of nerve roots of lower cervical or lower lumbar spinal nerves.
Herniated disk - The compressed roots are MC those of the more ... spinal nerve.
INFERIOR (eg, herniation at the C5-C6 --> Compress the C6 roots).
Herniated nucleus pulposus at cervical levels occur MC at the disk between ...?
C6-C7 and C7-T1.
Compression of the C7 spinal nerve:
1. Referred pain in the neck and shoulder.
2. Pain + Paresthesia in the INDEX/MIDDLE finger.
3. Diminished triceps reflex and weakness in extension of the forearm at the elbow (triceps) or weakness in extension of the wrist and fingers (posterior forearm muscles).
Compression of the C8 spinal nerve:
1. Pain in the neck and shoulder.
2. Pain + Paresthesias in the RING/LITTLE fingers.
3. Weakness in the hypothenar and interosseous muscles of the hand.
A cervical rib may arise from ...?
Costal process of C7.
Cervical rib - What may be compressed?
The T1 spinal nerve + The subclavian artery --> As they course superiro to the cervical rib instead of superior to the 1st thoracic rib.
Cervical rib - A patient may present with a ...?
Diminished radial pulse + pain + paresthesias in the medial forearm.
Signs of HORNER syndrome may also be seen.
1. Heart-shaped bodies.
2. Long, obliquely, oriented, spinous processes.
3. Costal facets on the bodies and on the transverse processes for articulation with ribs.
Thoracic vertebrae - Facet joints are oriented ...?
At a 60-degree angle relative to the transverse plane --> Permits mainly LATERAL BENDING/ROTATION.
--> Flexion/extension limited by the fixation provided by the ribs.
1. Kidney-shaped bodies.
2. Short, horizontally oriented spinous processes.
3. Long transverse processes.
Lumbar vertebrae - Their facet joints are oriented ...?
Perpendicular to the transverse plane --> Permits mainly FLEXION/EXTENSION and lateral bending.
--> Rotation is limited.
Lumbar vertebrae - The superior and inferior processes are interconnected by ...?
An isthmus or pars interarticularis --> These structures combined with the spinous process and a transverse process, are in the shape of a "Scottie dog".
There is a defect or fracture of the isthmus, with NO ANTERIOR DISPLACEMENT of the vertebral body.
Spondylolysis - Radiographs show ...?
That the Scottish terrier appears to be wearing a collar at the site of the fracture.
Unilateral or bilateral defect or fracture of the isthmus is accompanied by AN ANTERIOR DISPLACEMENT of the vertebral body.
Spondylolisthesis - Radiographs show ...?
That the head of the "Scottie dog" (the transverse process) appears to be separated from the body.
Spondylolisthesis - MC between ...?
L5 and the sacrum --> May stretch roots of lumbosacral spinal nerves in the cauda equina.
Spondylolisthesis - Presentation:
Patients have BILATERAL low back pain that radiates into BOTH lower limbs and weakness in muscles of the leg.
Narrowing of the vertebral canal, can be caused by spondylosis, in which degenerative changes occur in the L4 or the L5 intervertebral disks OR by OA at the facet joints at these levels.
A herniated nucleus pulposus at lumbar levels occurs MC in disks ...?
Between L4-L5 vertebrae or L5-S1.
Compression of the L5 or the S1 spinal nerve roots may result in ...?
Sciatica --> Characterized by pain that radiates from the back into the thigh, leg, and foot.
Compression of the L5 may result in ...?
Pain and paresthesias in the posterior thigh, the anterolateral leg, and dorsum of the foot.
--> May be weakness in extension of the great toe (extensor hallucis longus) and weakness in dorsiflexion (tibialis anterior).
Compression of the S1 spinal nerve roots may result in ...?
Pain and paresthesias in the POSTEROLATERAL leg, heel, and lateral side of the foot.
--> May be weakness in flexion of the leg at the knee (hamstrings), weakness in plantar flexion (gastrocnemius and soleus), and a diminished Achilles tendon reflex.
Sacrum - It contains a median crest:
Which represents the fused sacral spinous processes.
Sacrum - It contains the intermediate crests ...?
Which represent the fused articular processes.
The promontory forms ...?
The VENTRAL surface of the S1 vertebra --> Boundary of the pelvic inlet important in obstetrics.
Sacrum - Foramina:
4 pairs of dorsal sacral foramina and 4 pairs of ventral sacral foramina that transmits the dorsal rami and the ventral rami of the S1 through the S4 sacral spinal nerves, respectively.
Sacrum - Contains the sacral canal, ...?
Ends at the sacral hiatus in the DORSAL MIDLINE --> Contains the roots of the S1-coccygeal spinal nerves, and the sacral hiatus transmits the S5 and coccygeal spinal nerves.
Epidural or caudal block:
Performed by administering anesthetic through the sacral HIATUS, which diffuses through the meninges and anesthetizes the roots of the sacral and coccygeal spinal nerves in the cauda equina.
The coccyx is formed by ...?
3-5 fused coccygeal vertebrae.
The coccyx is an attachment for ...?
The gluteus maximus and for the anococcygeal ligament, which is an attachment site for muscles of the pelvic diaphragm.
Muscles of the back - Divided into 3 groups based on their function/innervation/attachments to bony structures.
1. Superficial muscles of the back.
2. Intermediate muscles of the back.
3. Deep/intrinsic muscles of the back.
Superficial muscles of the back - Attached to ...?
Pectoral girdle and act on upper extremity.
Superficial muscles of the back - Include:
2. Latissimus dorsi.
3. Rhomboid major.
4. Rhomboid minor.
5. Levator scapulae.
Superficial muscles of the back - Innervation:
Ventral rami of spinal nerves through branches of the branchial plexus, except for the trapezius, which is supplied by CN XI (accessory nerve).
Intermediate muscles of the back - Attach to ...?
The ribs and act as accessory muscles of respiration.
Intermediate muscles of the back include:
1. Serratus posterior superior.
2. Serratus posterior inferior.
3. 12 pair of levator costarum muscles.
Deep or intrinsic muscles of the back - Attach mainly to ...?
Transverse and spinous processes of vertebrae and act on the vertebral column at the intervertebral joints.
Deep or intrinsic muscles of the back - Include:
Erector spinae, which includes 3 parallel muscles groups:
From lateral to medial -->
Acting bilaterally, the components of the erector spinae ...?
Extend the vertebral column at intervertebral joints.
Acting unilaterally, the components of the erector spinae ...?
Produce lateral bending of the vertebral column at intervertebral joints.
Splenius capitis and splenius cervicis, 2 of the deep muscles of the back, lie ...?
Superficial to components of the erector spinae in the neck.
The splenius capitis acts to ...?
EXTEND the head.
The splenius cervicis acts to ...?
Rotate the head.
Acting unilaterally, both splenius capitis and splenius cervicis produce ...?
Lateral bending of the cervical vertebrae.
The deep muscles of the back also consists of ...?
Transversospinalis muscles - Include:
3 muscles groups that lie deep to the erector spinae - From superficial to deep:
Transversospinalis muscles - Acting bilaterally:
EXTEND the vertebral column.
Transversospinalis muscles - Acting unilaterally:
ROTATE the vertebral column.
The muscles of the suboccipital triangle ...?
Contribute to extension at the atlantooccipital joints + rotation at the atlantoaxial joints.
The deep muscles of the back are innervated by ...?
Dorsal rami of spinal nerves.
Trapezius - Innervation:
Lat dorsi - Innervation:
C6-C7-C8 - Thoracodorsal.
Levator scapulae - Innervation:
Dorsal scapulae C5.
Rhomboideus major/minor - Innervation:
Dorsal scapular C5 - Same as levator scapulae.
Suboccipital - Act on atlas and axis - Muscles involved:
1. Rectus capitis posterior minor.
2. Rectus capitis posterior major.
3. Inferior oblique (capitis).
4. Superior oblique (capitis).