Anatomy Flashcards
What is a collection of nerve cell bodies called when found in the CNS and when found in the PNS?
CNS = nucleus PNS = ganglion
Dendrites conduct information in which direction?
Axons conduct information in which direction?
Dendrites conduct information TOWARDS the cell body
Axons conduct information AWAY from the cell body
Which cell type produces myelin for the myelin sheath in the CNS and PNS?
CNS = Oligodendrocytes PNS = Schwann cells
Where are the cell bodies of multipolar and unipolar neurones located?
Multipolar - cell body in the CNS
Unipolar - cell body in the PNS
Which cranial nerve is the only one to arise from the pons?
CN V (Trigeminal)
How many pairs of spinal nerves are there?
31 pairs (8C, 12T, 5L, 5S, 1C)
Describe the route of motor axons from the spinal cord to the spinal nerve
All motor axons pass from the ANTERIOR horn of the spinal cord into the anterior rootlets then into the anterior root and into the spinal nerve
Describe the modalities of roots, spinal nerve and rami
Roots have single modalities (anterior roots are MOTOR, posterior roots are SENSORY)
Spinal nerves and rami have mixed modalities
Describe the route of sensory axons from the spinal nerve into the spinal cord
all sensory axons pass from the spinal nerve to the POSTERIOR roots then into the posterior rootlets and then posterior horn of the spinal cord
Spinal nerves only contain sympathetic fibres, no parasympathetics T/F
TRUE
What is a dermatome?
An area of skin supplied with sensory innervation from a single spinal nerve
What is a myotome?
The skeletal muscles supplied with motor innervation from a single spinal nerve
Considering dermatomes, what is the landmark of the male nipple and umbilicus?
Male nipple - T4
Umbilicus - T10
The anterior rami of which spinal nerves form the cervical plexus?
C1-C4
Posterior scalp, neck and diaphragm
The anterior rami of which spinal nerves form the brachial plexus?
C5-T1
Upper limb
The anterior rami of which spinal nerves form the lumbar plexus?
L1-L4
Lower limb
The anterior rami of which spinal nerves form the sacral plexus?
S1-S4
Lower limb, gluteal region and perineum
How many bilateral plexuses of nerves are there in the body?
4; cervical, brachial, lumbar, sacral
Describe sympathetic outflow form the spinal cord
Exits via T1-L2 (thoracolumbar outflow)
Which part of the spinal cord (anterior or posterior roots) do sympathetic axons pass through?
Anterior - MOTOR
They then pass into all spinal nerves and into both anterior and posterior rami
(remember it is just the roots which are single modalities)
Describe the location of paravertebral and pre vertebral ganglia
Paravertebral ganglia are associated with the sympathetic chain
Prevertebral ganglia are associated with the abdominal aorta
Parasympathetic outflow leaves the CNS via which cranial nerves?
CN III, VII, IX and X
*Also leave via sacral spinal nerves
What are some of the causes of Horner’s syndrome (impaired sympathetic innervation to the head and neck)
Root of the neck trauma, carotid dissection, pancoast tumour
What do the skin dimples in the back indicate the positions of?
The posterior superior iliac spines (PSIS)
Lower back pain may be due to strain of which muscle?
Erector spinae
What are the extrinsic back muscles?
NB these attach the back to the pectoral girdle and move the upper limb (they are not actually for back functions (e.g maintenance of posture))
Levator spinae
Rhomboids
Trapezius
Latissmus dorsi
Which extrinsic back muscle attached superiorly to the occipital bone?
Trapezius
What are the intrinsic back muscles?
NB these are entirely within the back and maintain back posture and move the spine
Erector spinae (superficial) Transversospinalis (deep)
Describe the attachments of the 3 vertical muscle groups which make up the erector spinae
Inferiorly a common tendon attaches to the sacrum and iliac crest
Superiorly the muscle fibres attach via a tendon to; ribs (between rib angles and tubercles), transverse process of vertebra and spinous process of vertebra
Describe the location of transverspospinalis
Located within the grooves between transverse and spinous processes
What are the muscles of the anterolateral abdominal wall from superficial to deep?
External oblique
Internal oblique
Transversus abdominus
Which muscle is involved in extension of the spine?
Erector spinae (if it contracts unilaterally then lateral flexion occurs)
Which muscles are involved in flexion of the spine?
Psoas major and rectus abdomoinus
What happens to the size of vertebrae from superior to inferior?
Vertebrae become larger as they bear more weight and become smaller again as weight is transferred to the hip bones
What are the curvatures of the spine?
Cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral kyphosis
What are the primary and secondary curvatures of the spine?
Primary - thoracic and sacral kyphosis
Secondary - cervical and lumbar lordosis
Which joints in the back are affected by arthritis?
Facet joints
Where are the spinal nerves found in the vertebral column?
Intervertebral foramen
Which parts of the spine don’t have intervertebral discs?
None between C1 and C2 and none at the fused sacrum/ coccyx
Intervertebral discs contribute to how much length of the spine?
20-25%
Describe the composition of an intervertebral disc
Outer fibrous ring (annulus fibrosus)
NB this is FIBROCARTILAGE
Inner soft pulp (nucleus pulposus)
Describe the location of the ligamentum flavum ligaments
Connect to adjacent laminae of vertebrae
What are the functions of the anterior and posterior longitudinal ligaments of the spine?
Anterior LL - prevents over-extension of the spine
Posterior LL - prevents over-flexion of the spine
NB these attach to the anterior/ posterior aspects of vertebral bodies and to intervertebral discs
Describe the location of the supraspinous ligaments
Connects the tips of spinous processes
NB strong and fibrous
Describe the location of interspinous ligaments
Connect superior and inferior surfaces of adjacent spinous processes
NB weak and membranous
Which vertebrae doesn’t have a body or spinous process?
Which vertebrae has an odontoid process?
Which is the first palpable spinous process?
C1 (atlas)
C2 (axis)
C7 (vertebrae prominens)
What are the main movements of the atlanto-occipital joint?
Flexion and extension of the neck
What is the main movement of the atlanto-axial joint?
Rotation
What types of joints are the atlanto-occipital and the atlanto-axial joints?
Synovial
What is contained within the sacral canal of the sacrum?
Cauda equina and meninges
In caudal anaesthesia, where is the local anaesthetic injected into?
The sacral hiatus
this anaesthetises the sacral spinal nerve roots of the caudal equina
Where does the spinal cord begin and end?
Begins at the foramen magnum (continuous with the medulla oblongata where the brainstem ends)
Ends at L1/L2 (caudal equina begins)
How many cervical spinal nerves are there?
8
What is the function of epidural fat?
Shock absorber (protects the spinal cord)
What is a laminectomy?
Removal of 1+ spinous processes and the adjacent lamina to allow the spinal cord to be visualised
When is laminectomy used?
To relieve pressure on the spinal cord
What are some somatic general sensory symptoms a patient may complain of?
( if there is a pathology of somatic sensory nerves)
Pain (neuralgia)
Pins and needles
Numbness (anaesthesia)
Sensitivity (hyperaesthesia)
Hot or cold
Loss of co-ordination/ balance/ clumsiness (ataxia)
What are some somatic motor symptoms a patient may complain of?
( if there is a pathology of motor nerves)
Muscle stiffness, tightness or spasm (cramp)
Muscle loosness (reduced tone/ hypotonia)
Muscular weakness (reduced power)
Loss of co-ordination/ balance/ clumsiness (ataxia)
Sensory pathology can be due to a CVA. Where is a common location for this to occur?
Internal capsule in the brain
Which dermatome has no sensory component?
C1
What is the difference between a spinal nerve and a named nerve?
A spinal nerve contains axons from one spinal cord level only e.g C5
A named nerve contains axons originating from 1 or more spinal cord levels e.g musculocutaneous nerve C5,6,7
Which is worse; injury to a spinal nerve or injury to a named nerve?
Injury to a spinal nerve
This may impact many structures supplied by its branches whereas a named nerve will just affect the couple of structures it supplies
T1 and T2 are important sites for what?
Referred pain from the myocardium
The anatomical snuff box is supplied by the cutaneous branches of which nerve?
Radial nerve
What do cervical plexus (C1-C4) motor axons supply?
Neck postural and strap muscles
Diaphragm
What do the brachial plexus (C5-T1) motor axons supply?
Muscles of the upper limb
Extrinsic back muscles
What do T2-L3 motor axons supply?
Postural back muscles
Intercostal muscles
Anterolateral abdominal wall muscles
What do the lumbosacral plexus L1-L4 motor axons supply?
Muscles of the lower limb
Perineal skeletal muscles
Describe the patellar tendon reflex
Patellar tendon tapped
Quadriceps contract
Knee joint extends
Describe a monosynaptic reflex arc
Normal muscle tone - monosynaptic reflex arc occurs each time skeletal muscle is stretched
What do UMN and LMN lesions cause?
UMN - Spasticity
LMN - flaccidity
Why might athletes present with anaesthesia (loss of sensation) in parts of a limb?
They have big muscles which can compress nerves on movement
What is a space occupying lesion and give some examples
Abnormal tissue taking up space in the brain
E.g tumours, bleeds
What is the Monro-Kellie hypothesis?
The relationship between pressure and volume in the brain
SOL can cause increased ICP which can result in herniation of brain contents though foramina in the skull
What are the 5 layers of the scalp?
SCALP;
Skin
Connective tissue (rich blood supply here- contains the named arteries of the scalp)
Aponeurosis (tendinous layer)
Loose connective tissue (thinnest layer)
Pericranium (periosteal layer - membranous layer on the surface of bone)
DO YOU NEED TO REVISE THE BONES OF THE SKULL
YES
What type of joints are the sutures of the skull?
Fibrous joints
What is the thinnest part of the skull?
What structure can be damaged if this part of the skull is damaged?
Pterion (H suture)
Middle meningeal artery can haemorrhage
From superficial to deep what are the 3 layers of the meninges?
Dura, arachnoid mater, pia mater
What is the sensory nerve supply to the dura matter?
CN V
What are the 3 folds of dura to be aware of?
Diaphragm sellae
(forms a roof over the pituitary fossa)
Tentorium cerebelli
(forms a tent over the cerebellum)
Falx cerebri
(sits between the R&L cerebral hemispheres)
Describe the location of the falx cerebri
Sits between the R&L cerebral hemispheres
Extends between the crista galli of the ethmoid bone anteriorly and the internal occipital protuberance of the occipital bone posteriorly
Where do the superior and inferior sagittal sinuses meet?
The confluence of the sinuses
Where does the sigmoid sinus drain into?
Internal jugular vein
Why are the facial veins a bad site for infection to start (danger triangle of the face)?
They have no valves
They are thick so don’t heal well if they get a laceration
Wha is the function of the arachnoid granulations?
Reabsorption of CSF into the dural venous sinuses
What level of the spine is used for lumbar punctures?
L3-L5 (within the caudal equina - the nerves are much more mobile so less likely to pierce a nerve)
The cerebral aqueduct connects which two structures?
The third and fourth ventricles of the brain
The central canal passes all the way down the spinal cord, it is continuous with the 4th ventricle of the brain and contains CSF. T/F
True
What is the difference between the following;
Extradural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Extradural haemorrhage - bleed between bone and dura
Subdural haemorrhage -
Bleed between the dura and arachnoid
Subarachnoid haemorrhage - bleed into the CSF of the subarachnoid space
Trauma to the pterion, rupturing the middle meningeal artery would cause what kind of bleed?
Extradural haemorrhage
Falls in the elderly and those with drinking problems may tear cerebral veins, causing what kind of bleed?
Subdural haemorrhage
Ruptured circle of willis (‘berry aneurysm) causes what kind of bleed?
Subarachnoid haemorrhage
The circle of willis sits in the subarachnoid space
How does a ventricular peritoneal shunt for hydrocephalus work?
Hydrocephalus means water on the brain. A ventricular peritoneal shunt connects the ventricles with the peritoneal cavity where CSF can be absorbed.
Describe the passage of the needle during lumbar puncture?
Supraspinous, intraspinous and ligamentum flavum ligaments
Epidural fat
Dura mater, arachnoid mater
SUBARACHNOID SPACE
What is meant by the ‘nerve point’ of the neck?
Where the sensory nerves of the cervical plexus converge
This is at the midpoint of the posterior border of the SCM
