Lecture one-Dr. Houston Flashcards
What is the neurocranium?
(cranial vault)
* Bony case of the brain and cranial meninges. Dome-like roof, the calvaria (skullcap), and floor or cranial base (basicranium).
What is part of the calvaria? What is part of the cranium base?
- Calvaria (skullcup): frotnal, part, occipital and temp bone (6-paired bones occurring bilaterally form the calvaria)
- Cranial base: Ethmoid, sphenoid and occipital…15 irregular bones form the cranial base
What is the pterion?
The pterion is the area of junction of four bones within the temporal fossa.
* temp, sphenoid, frontal and part
What is deep to the pterion?
middle mengingal artery
What is the viscerocranium?
Facial skeleton (facial bones)
What are the important sutures we should know of the skull?
Coronal suture: between frontal and parietal
Sagittal suture: between the two parietal
Lambdoid suture: between occipital and parietal bones
For the mouth, what bones is it made up of?
- Ant: maxilla bone
- Post: palatine
What goes through the external opening of the carotid canal?
Internal caratid artery comes through for circle of willis
What goes through the foremen magnum?
Spinal cord
What is located on the frontal bone?
Ethmoid bone which has the cribiform plate (CN1)
What is located with the sphenoid bone?
- Superior orbital fissure
- Greater wind of sphenoid
- Foramen ovale
- Foramen spinosum
What is located on the parietal bone? What goes through here?
Internal acoustic meatus -> 2 cranial nerves (vestibular-cochular and facial nerve)
* The foramen lacerum is between the parietal bone and sphenoid bone
What is located on the occipital bone?
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
- Fracture of the pterion can be what?
- What is the result?
- can be life-threatening because it overlies the frontal (anterior) branches of the middle meningeal vessels, which lie in grooves on the internal aspect of the lateral wall of the calvaria
- The resulting epidural hematoma (normally no epidural space)exerts pressure on the underlying cerebral cortex.
Untreated middle meningeal artery hemorrhage may cause what?
death in a few hours
What are the different head fractures a person can get?
What is a blowout fracture?
Indirect traumatic injury that displaces the orbital walls is called a “blowout” fracture.
- Fractures of medial wall may involve what?
- Fractures in inferior wall may involve what?
*
- Fractures of medial wall may involve ethmoidal and sphenoidal sinuses
- Fractures in inferior wall may involve maxillary sinus; may entrap the inferior rectus muscle, limiting upward gaze
Superior wall of orbit is stronger but what can happen?
Superior wall is stronger but thin enough to be penetrated
– a sharp object may pass into frontal lobe of brain.
Orbital fractures often result in what?
in intra-orbital bleeding, which exerts pressure on the eyeball, causing exophthalmos (protrusion of the eyeball). D/t increase pressure
List the sinuses
label them
What is the purpose of the TMJ?
Open and close mouth
What makes up the TMJ and gives the joint strength
- Fibrous capsule and lateral ligament
- Sphenomandibular and stylomandibular ligaments also support the jaw
What is made up of the lateral pterygoid?
superior and inferior head
How can one dislocate TMJ?
Yawning or taking a large bite
* excessive contraction of lateral pterygoids
* heads of mandibles to dislocate anteriorly
* mandible remains depressed and the person may not be able to close the mouth.
Sideways blow to the chin when the mouth is open
* dislocates the TMJ on the side that received the blow.
* traumatic dislocation and rupture of the joint capsule and lateral ligament can injury
to auriculotemporal nerve supplying the TMJ
* leads to laxity and instability of the TMJ.
What are the layers of the scalp?
- Skin
- CT (dense)
- Aponeurosis
- Loose CT
- Pericranium
What is a danger area of the layers of the scalp?
Loose connective layer
* Danger area - pus or blood spreads easily through emissary veins/calvaria (deep down into dipole veins then dura matter-> dura venous sinus)
* can reach intracranial structures e.g. meninges
Where can infection not pass in scalp injuries?
- into the neck (occipital belly of the occipitofrontalis muscle attaches to the occipital bone and mastoid parts of the temporal bones)
- laterally beyond the zygomatic arches (epicranial aponeurosis continuous with the temporal fascia that attaches to these arches)
Where can infection go to in scalp injuries?
- enter eyelids and root of nose (frontal belly of the occipitofrontalis muscle inserts into the skin and subcutaneous tissue, not bone)
- ecchymoses (purple patches) develop as a result of blood in subcutaneous tissue and skin of eyelids and surrounding regions.
- “black eyes” can result from injury to scalp or forehead.
List out the meninges (+ sublayers)
What is the flooe of the cranium (base)
cavernous sinus
How do the sinuses flow and where is common point where they all meet?
arachnoid granulation goes into what?
Superior sagittal sinus (venous blood) so CSF can be reabsorbed
- Basilar and occipital sinuses communicate through what?
- Because these venous channels are valveless, what can be an issue?
- Thus, pus in abscesses and tumor cells in these regions may what?
- Basilar and occipital sinuses communicate through foramen magnum via internal vertebral venous plexuses
- Because these venous channels are valveless, compression of the thorax, abdomen, or pelvis (e.g. heavy coughing and straining) may force venous blood into dural venous sinuses.
- Thus, pus in abscesses and tumor cells in these regions may metastasize to the vertebrae and brain.
What allows the spreading of infection from inferior to superior head?
Internal vertebral venous-plexus since they are valveless
where are the dural venous sinuses? (AND LABEL)
Dural venous sinuses of internal surface of cranial base
What is the membrane that is inferior below cerebrum?
tentorium cerebelli
Why is the cavernous sinus important?
Label
Label
What is the ventricular system of the brain?
Epidural hematoma:
* What is the origin?
* Torn branches of what?
* What is the result ?
* What does it look like under x ray?
- arterial in origin
- torn branches of middle meningeal artery
- brain compressed as blood mass increases
Subdural hematoma:
* What is the origin? Results in what?
* What can happens with the leaked blood?
* May develop when?
* What does it look like under x-ray?
- typically venous in origin and commonly results from tearing of a superior cerebral vein bridging in as it enters the superior sagittal sinus.
- escaped blood splits open dural border cell layer, creates a space at the dura–arachnoid junction
- usually follows a blow to the head that jerks and injures brain inside cranium
- hematoma may develop over many weeks from venous bleeding.
Subarachnoid hemorrhage:
* What is the origin?
* Results from what?
* Some associated with what?
* What does it look like under x ray?
- extravasation of blood, usually arterial, into subarachnoid space
- often result from rupture of a saccular aneurysm (sac-like dilation on an artery).
- some associated with head trauma involving cranial fractures and cerebral lacerations, or meningeal irritation
What are the number of different sets of vertebrae and what is their structure?
Excessive thoracic kyphosis:
* What is it ?
* What can it result from?
* What is the result?
* What is shown in older women with osteoporosis?
- abnormal increase in the thoracic curvature
- can result from erosion of anterior part of one or more vertebrae.
- progressive erosion and collapse of vertebrae results in an overall loss of height.
- widows hump colloquial kyphosis in older women from osteoporosis
- however, occurs in geriatric people of both sexes
Scoliosis:
* What is it?
* How is the spinous processes?
* Common in who?
* Causes what?
- abnormal lateral curvature accompanied by rotation of the vertebrae
- spinous processes turn toward the cavity of the abnormal curvature.
- common deformity of the vertebral column in pubertal girls
- causes include asymmetric weakness of the intrinsic back muscles (myopathic scoliosis), failure of half of a vertebra to develop (hemivertebra), and a difference in the length of the lower limbs are causes of scoliosis
What is the structures of vertebra?
Spinal Stenosis:
* What is it?
* May cause what?
* Txt?
- Stenotic(narrow) vertebral foramen in one or more lumbar vertebrae
- May cause compression of one or more spinal nerve roots occupying the vertebral canal.
- Surgical treatment may consist of decompressive laminectomy-> remove lamina for more space
Laminectomy:
* What is it?
* Term also commonly used to denote what?
* Provides what?
- Surgical excision of one or more spinous processes and their supporting laminae (#1)
- Term also commonly used to denote removal of most of the vertebral arch by transecting the pedicles (pediculectomy) (#2)
- Provides access to vertebral canal to relieve pressure on spinal cord or nerve roots, commonly caused by a tumor, herniated IV disc, spinal stenosis, or bony hypertrophy
What happens when there is a fracture of the atlas?
- Vertical forces (e.g. striking bottom of pool in diving accident) compresses the lateral masses between the occipital condyles and the axis drive them apart, fracturing one or both of the anterior or posterior arches
- If the force is sufficient, rupture of the transverse ligament that links them will also occur
- The resulting Jefferson or burst fracture in itself does not necessarily result in what?
- What is more likely in this case?
- The resulting Jefferson or burst fracture in itself does not necessarily result in spinal cord injury because the dimensions of the bony ring actually increase.
- Spinal cord injury is more likely, however, if the transverse ligament has also been ruptured
Vertebral body osteoporosis:
* What is demineralization?
* What does it especially affect?
* What do later stages show?
- Demineralization - diminished radiodensity of the trabecular (spongy) bone of the vertebral bodies, causing the thinned cortical bone to appear relatively prominent (Fig. B2.7A,B).
- Especially affects trabecular bone of the vertebral body (see Fig. B2.9A). Loss of the horizontal supporting trabeculae results in thickening of the vertical struts (Fig. B2.7A).
- Later stages x-rays reveal vertebral collapse
(compression fractures) and increased thoracic kyphosis
Ankylosing spndylitis:
* What is it?
* Over time causes what?
* If ribs are affected, what can happen?
* What is it called when found on and off x-ray?
- Inflammatory disease
- Over time can cause vertebrae to fuse, makes the spine less flexible and can result in a hunched posture.
- If ribs are affected, it can be difficult to breathe deeply.
- When condition is found on X-ray, it is called ankylosing spondylitis
- When condition can’t be seen on X-ray but is found based on symptoms, blood tests and other imaging tests, it is called nonradiographic axial spondyloarthritis.
Spina bifida occulta:
* Common or uncommon?
* What happens?
* Present in what? How?
* Most people dont have what?
- Most common congenital anomaly of the vertebral column
- Laminae (embryonic neural arches) of L5 and/or S1 fail to develop normally and fuse.
- Present in up to 24% of people, is concealed by skin, but its location is often indicated by a tuft of hair.
- Most people with spina bifida occulta have no back problems
Spina bifida cystica:
* What happened?
* What are the different types?
* What is usually present?
- One or more vertebral arches may almost completely fail to develop
- Herniation of the meninges (meningocele) and/or the spinal cord (meningomyelocele).
- Usually, neurological symptoms are present in severe cases of meningomyelocele (e.g. paralysis of limbs and disturbances in bladder and bowel control).
What is spondylolysis and spndylolisthesis?
Sacral vertebral:
* What is basiclaly the spinous process?
* What is the posterior sacral foramina?
* What is the sacral hiatus?
- Median crest
- Holes for nerve endings to travel through
- inferior aspect to allow us to access epidural space
What is the vertebra prominens?
- In the intervertebral disc, what is composed of?
- What is on the front and back of it? why?
Herniation of nucleus pulposus:
* Casues what?
* If degeneration of the posterior longitudinal ligament and wearing of the anulus fibrosus has occurred, what may happen?
* Herniations usually occur how?
- Herniation or protrusion of the gelatinous nucleus pulposus into or through the anulus fibrosus is a well-recognized cause of low back and lower limb pain.
- If degeneration of the posterior longitudinal ligament and wearing of the anulus fibrosus has occurred, the nucleus pulposus may herniate into the vertebral canal and compress the spinal cord or nerve roots of spinal nerves in the cauda equina (Fig. B2.8).
- Herniations usually occur posterolaterally,where the anulus is relatively thin and does not receive support from the posterior or anterior longitudinal ligaments.
Herniation of nucleus pulposus:
* Posterolateral herniation is most common where?
* Chronic pain resulting from what?
* Sciatica?
- Posterolateral herniation is most common in the lumbar region; approximately 95% of protrusions occur at the L4–L5 or L5–S1 levels.
- Chronic pain resulting from the spinal nerve roots being compressed by the herniated disc is referred to the area (dermatome) supplied by that nerve.
- Sciatica, pain in the lower back and hip and radiating down the back of the thigh into the leg, is often caused by a herniated lumbar IV disc or osteophytes that compress the L5 or S1 component of the sciatic nerve.
Relationship of vertebral column, spinal cord, and spinal nerves.
- Which has the epidural space in spinal cord?
- Where does the SC end?
- What is the cauda epuina?
Where does more or less gray matter present in the SC?
- Where is the spinal nerve located?
- What is teh epidural space occupied by?
What are the major blood supplies of the spinal cord?
Epidural Anesthesia (Blocks):
* An anesthetic agent can be injected into where?
* he anesthetic has a direct effect on what?
* The patient loses what?
* An anesthetic agent can also be injected into where?
* The distance the agent ascends (and hence the number of nerves affected) depends on what?
