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Anatomy (Jasmine) > Bones and Joints > Flashcards

Flashcards in Bones and Joints Deck (75):
1

Overview of the Back: Things to Know :( 

  • Posterior aspect of the body 
  • Muscoskeletal axis of support for trunk 
  • vertebrae are primary bony elements 
  • Interconnection of vertebrae to other skeletal elements by muscles 
  • Support of upper body weight 
  • Transmission of upper body weight through pelvis to lower limbs 
  • Protection of spinal cord 
  • Postural maintenance and movement of spinal column 
  • Formation of skeletal framework of neck and trunk 
  • Attachment sites for upper limb muscles 

2

What vertebrae are indicated and how many are found at each letter? 

At A? 

AT B? 

At C? 

At D? 

At E? 

A: Cervical Vertebrae (7) 

B: Thoracic Vertebrae (12)

C: Lumbar Vertebrae (5) 

D: Sacrum (5 fused) 

E: Coocyx (4 fused)

3

How is vertebrae developed in embryos? 

  1. Intersegmental formation of vertebrae from sclerotomes
  2. Origin of sclerotomes in adjacent somites
  3. Development of each vertebra from cranial parts of two somites below and caudal parts of two somites above
  4. Segmental development of spinal nerves 

4

What is the function of #1? 

Weight bearing part 

  • connection to adjacent vertebral bodies by intervertebral discs and ligaments
  • increase in size inferiorly

5

What is# 8 called? What is it? 

Vertebral Arch

formation of lateral and posterior parts of vertebral foramen

6

What is the vertebral canal? 

  • series of vertebral foramina
  • transmission of spinal cord and associated structures
  • continuous with cranial cavity through foramen magnum

7

What is #2? What are the two ligaments found in conjuction to #2? 

Spinous Process 

1. Supraspinous ligament 

2. Interspinous ligament 

8

What is #4? What goes through this structure of C7? 

Vertebral Foramen

Spinal Cord passes through 

9

What are the twp types of articular processes? Which is indicated by #3? 

Inferior Articular Process  (InferiorZygapophysis) and Superior Articular Process (Superior Zygapophysis) 

Superior Articular Process 

10

What is the intervertebral foramen? What does it allow passage of? 

Space between inferior and superior vertebral notches on pedicles of adjacent vertebrae. 

Passage of spinal nerves and blood vessels 

 

*** The vertebral notch is the formation of the intervertebral foramen****

11

What goes through the transverse foramen of C7? C5? 

C7- Nothing goes through there 

C5- Vertebral arteries 

12

Characteristics of ATLAS (C1- Cervical Vertebrae) 

  1. Absence of vertebral body 
  2. Two lateral masses interconnected by a ventral arch and a dorsal arch 
  3. Atlanto-occipital joint between occipital condyle and C1
    1. Allows flexion-extension (up/down motion) of neck to occur 
  4. Atlanto-axial joint between C1 and C2 
    1. Allows rotation of the head 

13

Characteristics of C2: AXIS 

  1. Facet for articulation with ventral arch of C1 on anterior surface of dens 
  2. Articulation between C1 and C2 ( atlanto-axial join) allows rotation of head 
  3. Alar ligament prevents excessive rotation of head

14

Characteristics: Thoracic Vertebrae 

  1. 12 thoracic vertebrae (T1-T12) 
  2. <3 shaped vertebral body 
  3. Circular vertebral foramen
  4. Superior articular facets point posteriorly 
  5. Inferior articular facets point anteriorly 

15

T1 vertebra articulates with the head of which rib? 

Rib 1 

16

What is a defining characteristic of T10 vertebra? T10 vertebra articulates with which which rib? 

No inferior articular facets on the body 

Rib 10 

17

 Characteristics of T11-T12 vertebrae:

 

  ▪  articulations with heads of ribs 11 and 12,   respectively

  ▪  only a single facet on each side of body

  ▪  no transverse costal facet

18

Characteristics of Lumbar Vertebra 

 

  1. Triangular shaped vertebral foramen 
  2. Thin and long transverse process 
    1. Massive and cone shaped TP on L5 vertebra for the illolumbar ligament 
  3. absense of costal facets 

19

Which 5 vertebrae fused to form the sacrum? Around what age is the sacrum fully fused? 

S1-S5 

23-24 

20

Foramen form on both the ventral and dorsal sides of the sacrum. What are they called? These foramen allow for passage of what? 

Dorsal sacral foramina and Ventral sacral foramina 

Allow for the passage of the ventral and dorsal rami of S1-S4 spinal nerves

21

The sacral groove is ___________ ( what position) to the sacral crest? The medial sacral crest is ( what position to the sacral groove? The lateral sacral crest is (what position) to the dorsal sacral foramina? 

Lateral 

22

Coccyx is formed by 4 individual elements. Which numbers fuse together in most individuals? 

 

Co2-Co4

23

Coccyx is recognizable due to the absense of these two vertebral structures. What are they? 

Vertebral arch and canal 

24

Articulation for the coccyx occurs with which strucure? What is the name of the articular process of Co1? 

Inferior end of the sacrum 

Coccygeal cornua 

25

What is kyphosis? Where can it be found? 

  1. Primary Curvature of the spinal column 
  2. anteriorly concave curvature in thoracic and sacral regions

  3. It can be found on the thoracic vertebrae and sacral vertebrae

 

26

What is lordosis? Where can it be found? 

  • posteriorly concave curvature in cervical and   lumbar regions
  • secondary curvature of vertebral column
  • balance of body weight and maintenance of upright bipedal posture with the least amount of muscular energy expenditure 
  • Found when infants start to sit upright ( when the lumbar lordosis starts to develop) 
  • Found in cervical and lumbar regions 

27

Dorsal Spaces are overlapping of laminae and spinous processes of adjacent vertebrae. These continue to get larger in the lumbar region. Why? 

In the lumbar regions there are large gaps that continue to get wider but are useful for flexion and extension of the lumbar vertebrae.

If the gaps were small then you would not have adequate movement of the lumbar vertebrate 

28

Invertebral disc are found between adjacent vertebrae with a layer of hyaline cartilage on each vertebral body. What is the IV disc composed of? (2) 

  • anulus fibrosus:
    •   —  collagenous ring around a wider zone of   fibrocartilage 
    •   —  prevention of excessive rotation between vertebrae
  •  nucleus pulposus:
    •   —  center of intervertebral disc
    •   —  gelatinous in nature
    •   —  absorption of compressive forces between vertebrae 

29

Intervertebral Joints are found in the cervical, lumbar, and thoracic regions. What motion do these joints allow in the cervical region? Thoracic region? Lumbar region? 

  • Cervical region- flexion and extension of the neck 
  • Thoracic region- rotation of the trunk 
  • Lumbar region- flexion/extension of the back 

30

What are unicate processes? What is the joint found between unicate processes? 

  1. Uncinate process = elevated lateral margins of superior surface of cervical vertebral body
  2. Uncoverterbral joints 
    1. Ex: C4 and C5 
       

31

Where is the anterior longitudinal ligament found? What is the function of this ligament? What is whiplash? 

  • Found: base of skull ↔ anterior surface of sacrum
    • attachment to anterior surfaces of vertebral   bodies and intervertebral discs along its length
  • Function: resistance to hyper-extension of spine
  • Injury: “whiplash” injury due to damage to anterior   longitudinal ligament during severe hyper-  extension of neck

32

Where is the posterior longitudinal ligament? What is the function of the ligament? 

  • Found at base of skull ↔ sacrum
    • lines anterior surface of vertebral canal
    • attachment to posterior surfaces of vertebral   bodies and intervertebral discs along its length
  • Function: resistance to hyper-flexion of spine

33

What are the ligamenta Flava? Where is it found? What is the function? 

  • location between laminae of adjacent vertebrae
    • posterior surface of lamina of vertebra below ↔ anterior surface of lamina of vertebra above
  • Function: prevention of hyper-flexion of spine
    • extension of spine to anatomical position from previous state of flexion
    • When you bend forward the ligamenta flava helps you come back to upright position 

  

34

Where is the supraspinous ligament found? What is the purpose? 

  • Attachment of tips of vertebral spinous processes from C7 to sacrum 
  • Purpose: prevention of hyper flexion of the spine 

35

What is the ligamentum nuchae? What is it an extension of? Where is it found? What is the function? 

  • Extension: cranial part of supraspinous ligament
  • Location: attachments to cranial base + posterior   tubercle of C1 + spinous processes of cervical   vertebrae + tip of C7 spinous process 
    • attachment sites for neck muscles
  • Function: prevention of hyper-flexion of neck 
    • bringing head to anatomical position
    • support of skull

36

What is the interspinous ligament? Where is it found? 

  • location between adjacent vertebral spinous processes
  • base of spinous process ↔ apex of spinous process
  • fusion with supraspinous ligament and ligamenta flava

37

What are the 3 clinical columns for vertebral stabilization? What is found in each column? 

  • anterior = vertebral body + anterior longitudinal ligament
  •  
  • middle = vertebral body + posterior longitudinal ligament
  •  
  • posterior = ligamenta flava + interspinous ligament + supraspinous ligament (+ ligamentum   nuchae in cervical region) 

38

What is found at 1? 

 

C1: Atlas

39

What is found at 2? 

C2: Axis 

40

What is found at 3? 

C6 Spinous Process 

41

What is found at 4? What vertebrae articulates with the structure found at 4? 

Rib 1

Articulates with T1 ( thoracic vertebrae) 

42

What is found at 1? What is found at 2? 

1. Inverterebral disc 

2. C7 Spinous process 

43

What is found at C? What is found at D? 

C. Transverse Process 

D. Spinous Process 

44

What is found at A? What is found at B? What is found at E? 

A. Vertebral body 

B. Rib 

E. Pedicle 

45

What is hemivertebra? What is Klippel- Fell Syndrome? What is it possibly associated with? 

  • development of vertebra on only one side
  • abnormal fusion of C1 and C2 OR C5 and C6 
  • possible association with high-riding scapula (Sprengel’s shoulder) and cardiac abnormalities

46

What is sacralization of lumbar vertebra? What is lumbarization of 1st sacral vertebrae? 

  • Fusion of L5 and S1 
  • Partial separation of S1 from sacrum

47

What is spina bifida? 

  •   incomplete fusion of vertebral arches in the midline
  •   w  “open” vertebral canal
  •   w  typically happens in lower part of spinal column
  •   w  complete failure of fusion of vertebral arch at lumbosacral junction with a meningeal outpouching (MOST severe type)

 

48

What are the two types of spina bifida? What is the most common variant of spina bifida? 

  • Meningocele → cerebrospinal fluid in outpouched meninges
  • Myelomeningocele → part of spinal cord in outpouched meninges

 

  • Spina bifida occulta:
    •   —  most common variant of spina bifida
    •   —  defect/incomplete fusion of vertebral arch of L5 or S1
    •   —  present in 10% of individuals
    •   —  clinically asymptomatic
    •   —  possible presence of tuft of hair over spinous processes

49

What is scoliosis? What are the 4 types of scoliosis? What is the most common type? 

  1. Abnormal lateral curvature of vertebral column
  • Possible involvement of rotational element of one vertebra upon   another
  1. Idiopathic scoliosis (most common type):
  •   —  may occur in infantile/juvenile/adolescent age-groups
  •     —  NOT congenital
  •     —  normal vertebral bodies + pedicles + laminae

2. Congenital scoliosis:

  • present from birth
  • associated with abnormalities of chest wall, genito-urinary   tract, and heart disease

3. Neuropathic scoliosis:

  • manifestation of abnormalities in CNS/PNS
  • more common in children with cerebral palsy or polio

4. Scoliosis with muscular abnormalities:

  •     —  rare occurrence
  •     —  manifestation through muscular dystrophy
  •     —  mal-alignment of spinal column

50

What is abnormal kyphosis? What are the two types of hyper kyphosis? 

 

  •  Partial of total loss of lordotic curvature of the spine
    • Normal range 20-45 degrees

      Hyper Kyphosis >45

  • Two Types 
  1. Schuermann's disease 
  • typical mid-thoracic region 
  • common in teenagers 
  • can't consciously correct posture 
  • irregular shaped vertebral bodies and herniated discs 

 2. Postural kyphosis 

  • most common form of hyper kyphosis 
  • common in young and old 
  • slouching is an example 

 

51

What is abnormal lordosis? What are the 4 common causes? 

  • Increased extension of lumbar vertebrae 
  • Flexion or anterior inferior rotation of the upper sacrum 
  • Common causes 
    • Pregnancy 
    • Visceral fat 
    • Weak trunk 
    • Weak hamstrings or tight hip flexors 

52

What is a herniated disc? 

Nucleus pulposus herniates out through annulus fibrosus and it presses on the spinal nerve 

53

What does a fracture of the cranio-cervical region look like? What is affected? What are possible consequences of this fracture?  

  • extremely high probability of significant spinal cord   injury
  • quadriplegia/temporary disruption of respiratory   function/hypotension (low blood pressure) are   possible consequences
  • disruption of normal limb functions (upper + lower)

54

What is pars interarticularis fracture? This is a common fracture among who? What are the common fracture sites? 

  •   fracture in region between superior and inferior   zygapophyseal joints (= pars interarticularis)
  •  possible compression of vertebral canal by   vertebral body
  •    L4 and L5 levels are common fracture sites
  •   —  common trauma in athletes

55

What is spondylitis? What are the three types of spondylitis? 

Ø  Inflammation of vertebral joints

Ø  Cervical spondylitis:

  • inflammation of cervical vertebrae

Ø  Lumbar spondylitis:

  • inflammation of lumbar vertebrae

Ø  Ankylosing spondylitis:

  • primarily affects sacroiliac joint

56

What is spondylodiscitis? 

Combination of spondylitis and inflammation of adjacent intervertebral disc space. 

57

What is spondylosis? 

  • Degenerative osteoarthritis of intervertebral joint

Ø  Narrowing of space between adjacent vertebrae

  • caused by disc degeneration

58

What is spondylolysis? Typically caused by what kind of fracture? It is most common among? 

  • Defect in pars interarticularis of vertebral arch
  • detachment of pars interarticularis and   separation of joints
  • more common in lumbar region

ØTraumatic spondylolysis of C2 caused by

  • hyper-extension of head on neck 

Ø  Typically caused by stress fracture of bone

Ø  Higher occurrence in adolescents engaging in tennis, diving, cheerleading, gymnastics, etc.

Ø  More common in males

59

What is spondolisthesis? Who is it most common among? What vertebra is it most commonly found affecting? 

Forward displacement of vertebra (especially L4/L5)

Ø  Commonly caused by spondylolysis

Ø  Degenerative spondylolisthesis:

  • vertebral displacement through joint arthritis,   joint remodeling, and/or weakness in ligamenta flava
  • more common in females, individuals over 50,   and African-  Americans

  

60

What is spinal stenosis? What are two types of spinal stenosis? Which is more damaging and why? 

Abnormal narrowing of vertebral canal

Ø  Compression of spinal cord and/or nerve roots

Ø  Possible causes include age, heredity, arthritis, spinal   instability, trauma, and tumor

Ø  Lumbar spinal stenosis:

  —  compression of nerve roots/cauda equina in lower back

  —  possible cause of sciatica

Ø  Cervical spinal stenosis:

  w  compression of spinal cord in neck

  w  more dangerous than lumbar spinal stenosis

  w  symptoms include major body weakness and paralysis

Cervical is more damaging because it affects all those around it rather than lumbar which affects just the things below. 

61

A young toddler presents to her pediatrician with rather new onset of bowel and bladder dysfunction and loss of the lower limb function. Her mother had not taken enough folic acid ( to the point of a deficiency) during her pregnancy. On examination, the child has protusion of the spinal cord and meniges and is diagnosed with which of the following conditions? 

A. Spinda bifida occulta

B. Meningocele 

C. Meningomyelocele

D. Myeloshchisis 

E. Syringomyelocele

 C. Meningomyelocele

Meningomyelocele is protrusion of the meninges and spinal cord through the unfused arch of the vertebra. A sufficient amount of folic acid during preg- nancy is shown to prevent these kinds of neural tube defects. Spina bifida occulta is failure of the vertebral arch to fuse (bony defect only). Meningocele is protrusion of the meninges through the defective vertebral arch. Syringomyelocele is protrusion of the meninges and a pathologic tubular cavity in the spinal cord or brain. 

62

A25-year-oldsoldiersuffersagunshot wound on the lower part of his back and is unable to move his legs. A neurologic exami- nation and magnetic resonance imaging (MRI) scan reveal injury of the cauda equina. Which of the following is most likely damaged?

(A)  Dorsal primary rami

(B)  Ventral primary rami

(C)  Dorsalrootsofthethoracicspinal nerves

(D)  Ventral roots of the sacral spinal nerves

(E)  Lumbarspinalnerves 

(D)  Ventral roots of the sacral spinal nerves

The cauda equina is the collection of dorsal and ventral roots of the lower lumbar and sacral spinal nerves below the spinal cord. Dorsal and ventral primary rami and dorsal roots of the thoracic spinal nerves and lumbar spinal nerves do not par- ticipate in the formation of the cauda equina. 

63

A 69-year-old man has an abnormally increased curvature of the thoracic vertebral column. Which of the following conditions is the most likely diagnosis?

(A) Lordosis
(B) Spina bifida occulta

(C) Meningocele
(D) Meningomyelocele

(E) Kyphosis 

E. Kyphosis 

Kyphosis (hunchback or humpback) is an abnormally increased tho- racic curvature, usually resulting from osteoporosis. Lordosis is an abnormal accentua- tion of the lumbar curvature. Spina bifida occulta is failure of the vertebral arch to fuse (bony defect only). Meningocele is a protrusion of the meninges through the unfused arch of the vertebra, whereas meningomyelocele is a protrusion of the spinal cord and the meninges. 

64

A 24-year-old woman comes to a hospi- tal to deliver her baby. Her obstetrician uses a caudal anesthesia during labor and child- birth to block the spinal nerves in the epi- dural space. Local anesthetic agents are most likely injected via which of the following openings?

(A) Intervertebral foramen

(B) Sacral hiatus
(C) Vertebralcanal
(D) Dorsal sacral foramen

(E) Ventral sacral foramen 

B. Sacral Hiatus 

Caudal (epidural) anesthesia is used to block the spinal nerves in the epidural space by injecting local anesthetic agents via the sacral hiatus located between the sacral cornua. An intervertebral foramen transmits the dorsal and ventral primary rami of the spinal nerves. The vertebral canal accommodates the spinal cord. Dorsal and ventral sacral foramina transmit the dorsal and ventral primary rami of the sacral nerves. 

65

A crush injury of the vertebral column can cause the spinal cord to swell. Which structure would be trapped between the dura and the vertebral body by the swelling spinal cord?

(A) Anterior longitudinal ligament

(B) Alar ligament
(C) Posterior longitudinal ligament

(D) Cruciform ligament

(E) Ligamentum nuchae 

C. Posterior Longitudinal Ligament 

The posterior longitudinal ligament interconnects the vertebral bodies and intervertebral disks posteriorly and runs anterior to the spinal cord within the verte- bral canal. The ligamentum nuchae is formed by supraspinous ligaments that extend from the seventh cervical vertebra to the external occipital protuberance and crest. The anterior longitudinal ligament runs anterior to the vertebral bodies. The alar and cruciform liga- ments also lie anterior to the spinal cord. 

66

A 26-year-old heavyweight boxer was punched on his mandible, resulting in a slight subluxation (dislocation) of the atlantoaxial

joint. The consequence of the injury was decreased range of motion at that joint. What movement would be most affected?

(A) Extension (B) Flexion (C) Abduction (D) Adduction (E) Rotation 

E. Rotation 

The atlantoaxial joints are synovial joints that consist of two plane joints and one pivot joint and are involved primarily in rotation of the head. Other movements do not occur at this joint. 

67

A 42-year-old woman with metastatic breast cancer is known to have tumors in the intervertebral foramina between the fourth and fifth cervical vertebrae and between the fourth and fifth thoracic verte- brae. Which of the following spinal nerves may be damaged? 

(A)  Fourth cervical and fourth thoracic nerves

(B)  Fifth cervical and fifth thoracic nerves

(C)  Fourth cervical and fifth thoracic nerves

(D)  Fifth cervical and fourth thoracic nerves

(E)  Third cervical and fourth thoracic nerves 

The Answer is D.

All cervical spinal nerves exit through the intervertebral foramina above the corresponding vertebrae, except the eighth cervical nerves, which run inferior to the seventh cervical vertebra. All other spinal nerves exit the intervertebral foramina below the corresponding vertebrae. Therefore, the fifth cervical nerve passes between the fourth and fifth cervical vertebrae, and the fourth thoracic nerve runs between the fourth and fifth thoracic vertebrae. 

68

During an outbreak of meningitis at a local college, a 20-year-old student presents to a hospital emergency department com- plaining of headache, fever, chills, and stiff neck. On examination, it appears that he may have meningitis and needs a lumbar puncture or a spinal tap. Cerebrospinal fluid (CSF) is normally withdrawn from which of the following spaces?

(A)  Epidural space

(B)  Subdural space

(C)  Space between the spinal cord and the pia mater

(D)  Subarachnoid space

(E)  Spacebetweenthearachnoidanddura

maters 

The Answer is D.

Cerebrospinal fluid (CSF) is found in the subarachnoid space, which is a wide interval between the arachnoid layer and the pia mater. The epidural space contains the internal vertebral venous plexus and epidural fat. The subdural space between the arachnoid and the dura contains a little fluid to moisten the meningeal surface. The pia mater closely covers the spinal cord and enmeshes blood vessels on the surfaces of the spinal cord. Thus, the space between the spinal cord and the pia is a potential space. 

69

A 23-year-old jockey falls from her horse and complains of headache, backache, and weakness. Radiologic examination would reveal blood in which of the following spaces if the internal vertebral venous plexus was ruptured?

(A)  Space deep to the pia mater

(B)  Space between the arachnoid and dura maters

(C)  Subduralspace

(D)  Epidural space

(E)  Subarachnoidspace 

TheAnswer is D. Thespacebetweenthevertebralcanalandtheduramateristheepidural space, which contains the internal vertebral venous plexus. The spinal cord and blood vessels lie deep to the pia mater. The space between the arachnoid and dura maters is the subdural space, which contains a film of fluid. The subarachnoid space contains cerebrospinal fluid (CSF). 

70

A middle-aged coal miner injures his back after an accidental explosion. His mag- netic resonance imaging (MRI) scan reveals that his spinal cord has shifted to the right because the lateral extensions of the pia mater were torn. Function of which of the following structures is most likely impaired?

(A) Filum terminale internum

(B) Coccygeal ligament
(C) Denticulateligament
(D) Choroid plexus

(E) Tectorialmembrane 

The Answer is C.

The denticulate ligament is a lateral extension of the pia mater. The filum terminale (internum) is an inferior extension of the pia mater from the tip of the conus medullaris. The coccygeal ligament, which is also called the filum terminale externum or the filum of the dura, extends from the tip of the dural sac to the coccyx. The vascular choroid plexuses produce the cerebrospinal fluid (CSF) in the ventricles of the brain. The tectorial membrane is an upward extension of the posterior longitudinal ligaments from the body of the axis to the basilar part of the occipital bone. 

71

Dorsal and ventral roots of the lower lumbar and sacral nerves are lacerated. Which structure is most likely damaged? 

The Answer is C. The cauda equina is formed by a great lash of the dorsal and ventral roots of the lumbar and sacral nerves. 

72

The spinal cord is crushed at the level of the upper part of the first lumbar vertebra. Which structure is most likely damaged? 

The Answer is B. The conus medullaris is a conical end of the spinal cord and terminates at the level of the L2 vertebra or the intervertebral disk between L1 and L2 vertebrae. A spinal cord injury at the level of the upper part of the first lumbar vertebra damages the conus medullaris. 

73

When the internal vertebral venous plexusisruptured,venousbloodmayspread into which tissue and space? 

The Answer is E. Epidural fat is shown in the magnetic resonance imaging (MRI) scan. In addition, the internal vertebral venous plexus lies in the epidural space; thus, venous blood from the plexus may spread into epidural fat. 

74

Which structure may herniate through the annulus fibrosus, thereby impinging on the roots of the spinal nerve? 

The Answer is A. The intervertebral disk lies between the bodies of two vertebrae and con- sists of a central mucoid substance, the nucleus pulposus, and a surrounding fibrous tis- sue and fibrocartilage, the annulus fibrosus. The nucleus pulposus may herniate through the annulus fibrosus, thereby impinging on the roots of the spinal nerves. 

75

Cerebrospinal fluid (CSF) is produced by vascular choroid plexuses in the ventricles of the brain and accumulated in which space? 

The Answer is D. The cerebrospinal fluid (CSF) is found in the lumbar cistern, which is a subarachnoid space in the lumbar area. CSF is produced by vascular choroid plexuses in the ventricles of the brain, circulated in the subarachnoid space, and filtered into the venous system through the arachnoid villi and arachnoid granulations.