Anatomy Flashcards
What is a collection of nerve cell bodies called?
CNS- nucleus
PNS- ganglion
What is the myelin sheath made by/of?
PNS- Schwann cells
CNS- oligodendrocytes
What are the features of multipolar neurons?
- MOTOR
- 2+ dendrites
- motor neurons of skeletal muscle and autonomic NS
- cell bodies in CNS but axons in PNS
What are the features of unipolar neurons?
- SENSORY
- double process
- cell body in PNS
What are tracts in the CNS?
collections of axons surrounded by connective tissue and blood vessels (nerves in PNS)
What part of the brain does each cranial nerve come off?
- CNI+II = forebrain
- CNIII+IV = midbrain
- CN V = pons
- CN VI+VII+VIII = junction
- CN IX+X+XII = medulla
- CN XI = spinal cord
What are the components of the autonomic nervous system?
- sensory = visceral afferents
- motor = sympathetic and parasympathetic
What are the main facts about sympathetic nervous system?
- thoracolumbar outflow
- cell bodies are in the T1-L2 lateral horns
What is the path of the sympathetic nerves?
anterior root –> anterior rami of spinal nerve –> white rami –> sympathetic trunk –> can ascend, descend, synapse at same level or can pass through to abdominopelvic splanchnic nerves
What is the sympathetic supply to the heart?
synapse at cervical paravertebral ganglia and then move in cardiopulmonary splanchnic nerves
What is the sympathetic supply to the lungs?
synapses in upper thoracic paravertebral ganglia and then to cardiopulmonary splanchnic nerves
What is the sympathetic supply to the abdomen and pelvis?
goes to prevertebral ganglia where they synapse then move in periarterial plexuses on arteries to organs
What is the main exception to the synapsing of the sympathetic nervous fibres?
the adrenal gland has nerves that synapse directly onto the suprarenal medullary cells
What is the outflow for parasympathetic?
craniosacral outflow (CN III, IX and X and sacral nerves)
What do the parasympathetic fibres travel via?
- ciliary ganglion (eye)
- parasympathetic ganglia of the head (lacrimal gland and salivary gland)
- vagus nerve
- sacral spinal nerves
What are the skin dimples in the back?
posterior superior iliac spines
Where is the only place that the spinal nerves are found?
the intervertebral foramina
What joins the articular processes of adjacent vertebrae?
facet joints
What are the three midline ligaments of the spine?
- ligamentum flavum: posteriorly connects adjacent laminae
- anterior longitudinal: strong and prevents over-extension
- posterior longitudinal: weaker and prevents over-flexion
What are the two spinous ligaments of the spine?
- supraspinatous: connects the tips of the spinous processes
- interspinatous: connects in-between the spinous processes
What are the spinal nerve divisions?
8c 12t 5l 5s 1c
Where do the spinal nerves run?
C1-C7 emerge above their vertebrae but the rest emerge below
What do the spinal nerves come from and go to?
- from spinal cord segment of the same number via anterior and posterior roots which combine
- to structures via rami
Which of the anterior and posterior rami are bigger?
anterior is bigger as it supplies everything but the back which is supplied by the posterior rami
What runs through each of the spinal roots?
- motor runs through anterior to join spinal nerve
- sensory runs into posterior roots after spinal nerve
What is included within the spinal nerve?
both motor and sensory innervation
What does the spinal nerve supply within its segment?
- general sensory
- somatic motor to skeletal muscles
- sympathetics to the skin and smooth muscle of arterioles
What is a dermatome?
area of skin that is supplied by sensory innervation from a single spinal nerve (overlaps)
What is a myotome?
skeletal muscles supplied with motor innervation from a single spinal nerve
What is the nipple and umbilicus area supplied by?
Nipple = T4 Umbilicus = T10
What are the upper and lower limb nerve divisions?
Upper limb = C5-T1
Lower limb = L2-Co1
What are nerve plexuses?
intertwining of anterior rami and the fibres can be shared
What are the main nerve plexuses?
- cervical C1-4
- brachial C5-T1
- lumbar L1-4/sacral L5-S4
What is Horner’s syndrome?
- miosis, ptosis, reduced sweating and increased warmth/redness
- impaired sympathetic innervation to head and neck
- compression of the sympathetic ganglia
What is the type of fibres in each of the CNV divisions?
- CNV1 and CNV2 are sensory
- CNV3 is sensory and motor
Where is the sensory division in the face of CNV?
- CNV1 runs between eyelids and down ridge of nose
- CNV2 divides at lips
What are the muscles that CNV3 supplies?
- muscles of mastication
- tensor veli palatini
- tensor tympani
What is the path of the facial nerve out of the cranium?
out of internal acoustic meatus until geniculate ganglion and then into facial canal and out of stylomastoid foramen
What are the 5 branches of facial expression of the facial nerve?
Temporal Zygomatic Buccal Mandibular Cervical
to zanzibar by motor car
What are the main roles of glossopharyngeal?
- general sensation (eg tonsils, oropharynx, nasopharynx, middle ear etc)
- special sensory for taste
- visceral afferent to carotid sinus/ carotid body chemoreceptors
- somatic motor
- parasympathetic to parotid
What layer are the arteries to the scalp in?
sCalp
connective tissue layer
What is the pterion and what does it cover?
- convergence of the frontal, parietal, temporal and sphenoid bones
- H shaped suture
- thinnest part of the skull
- covers the middle meningeal artery
What are the three parts of the erector spinae muscles?
- sacrum iliocostalis
- longissimus
- spinalis
What muscles move the spine and assist in posture?
Transversospinalis
Erector spinae
Where do the vertebral arteries pass through in the cervical vertebrae?
C1-6 in the transverse foramen but not C7
What are the two main movements at the neck?
- 2 atlanto-occipital joint = flexion/extension
- atlanto-axial joint = lateral/medial rotation
Why does the spinal cord not always get damaged if there is a vertebral dislocation?
the vertebral canal is bigger than the spinal cord
Where do the arteries run through the sacrum?
anterior and posterior sacral foramen
Where are epidural injections given?
L3/4 interspace where cauda equina is so less chance of damage
When should a lumbar puncture never be performed?
when there is raised ICP as it can cause brain herniation due to the pressure
What layers does the needle for a spinal anaesthetic go?
supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater to the subarachnoid space
How is caudal anaesthetic given?
through the sacral hiatus into the epidural space
What is a laminectomy?
removal of the laminae which form the arch that makes the spinous process
Where is the best place to test a dermatome?
in the middle of it as far away from the edge as possible to avoid overlap
What are the dermatomes for the badge patch area, groin, medial malleolus and heel?
C5= badge patch area L1= groin L4= medial malleolus S1= heel
Is peripheral nerve cutaneous innervation different to dermatomes?
peripheral nerves have more than one spinal nerve root and have names eg femoral nerve L2-4
What is the nerve point of the neck?
above the midpoint of the posterior border of SCM where sensory nerves meet in cervical plexus
What is the subcostal nerve?
T12
What is the lower anterolateral trunk wall supplied by?
iliohypogastric and ilioinguinal nerves which are both L1
How does referred pain in a heart attack work?
T1 and T2 anterior rami sensory axons connect to the heart and to the upper limb
How do you clinically test myotomes?
there is one movement that is most strongly associated with each myotome
What myotomes do shoulder abduction and adduction test?
Shoulder abduction= C5
Adduction= C7
What myotomes do finger flexion, extension, abduction and adduction test?
Finger flexion= C8
Extension= C7
Abduction and adduction= T1
What myotomes do elbow flexion and extension test?
Elbow flexion= C5 and C6
Extension= C7 (and C8)
What myotomes do wrist flexion and extension test?
Wrist flexion= C7 (C6)
Extension= C6 (C7)
What myotomes do hip flexion and extension test?
Hip flexion= L2 and L3
Extension= L5 and S1
What myotomes do knee flexion and extension test?
Knee flexion= L5 and S1
Extension= L3 and L4
What myotomes do ankle dorsiflexion, plantar flexion, inversion and eversion test?
Ankle dorsiflexion= L4 and L5
Plantar flexion= S1 and S2
Inversion= L4
Eversion= L5 and S1
What is a monosynaptic reflex arc?
in a spinal cord reflex, the impulses pass through posterior rami, synapse in the spinal cord and then the motor impulses at the anterior rami go straight to cause a reaction
What do upper and lower motor neuron lesions cause?
UMN lesions = spasticity (descending controls from the brain are not working to continual over contraction)
LMN lesions = flaccidity
What are the main reflexes to test?
- knee (L4) (34 kick the door)
- ankle (S1) (12 tie my shoe)
- supinator (C6)
- biceps (C5) (56 pick up sticks)
- triceps (C7) (78 lay them straight)
Where do the first 6 CN leave the cranial cavity?
- CNI- cribriform plate of ethmoid bone
- CNII- optic canal
- CNIII, IV, V1 and VI- superior orbital fissure
- CN V2- foramen rotundum
- CN V3- foramen ovale
Where do the last 5 CN leave the cranial cavity?
- CNVII and VIII- internal acoustic meatus
- CNIX, X and XI- jugular foramen
- CNXII- hypoglossal canal
What is involved in the clinical testing of the trigeminal?
- close eyes and use cotton wool to test sensory areas of the face (S)
- palpate the temporalis and masseter with teeth clenched
- patient open jaw against resistance (M)
What is involved in the clinical testing of the facial nerve?
- frown, close eyes tight, smile and puff out cheeks to check muscles of facial expression
- ask about taste
What is involved in the clinical testing of the vagus nerve?
- say ‘ah’ to test palate (also tests CNV3 due to tensor veli palantini) and make sure uvula goes straight up
- swallow
- listen to speech
- cough
What does CNXI supply?
sternocleidomastoid and trapezius
What is odd about the spinal accessory nerve?
it ascends through the foramen magnum and exits through jugular foramen
What is involved in the clinical testing of the spinal accessory nerve?
shrug shoulders (trap) and turn head up to opposite side (stern)
What is involved in the clinical testing of the hypoglossal nerve?
stick tongue out (points towards the side of the injury if there is one)
What does the hypoglossal nerve supply?
all tongue muscles but not the palatoglossus
What nerve is the dura mater innervated by?
CNV
What are the two layers of the dura mater?
periosteal and meningeal
What is the diaphragm sellae?
sheet that lies over the pituitary fossa
What is the sheet that lies over the cerebellum?
tentorium cerebelli
What is the falx cerebri?
- midline structure
- separates the cerebral hemispheres
- attaches to crista galli of the ethmoid bone
What drains the venous blood from the cranial cavity?
- cerebral veins drain the brain then into
- dural venous sinuses
- drain into internal jugular vein
eg superior and inferior sagittal sinuses and sigmoid sinus
What is the arterial supply to the brain?
from the vertebral arteries through C6 to 1 (from RSA) and internal carotid artery
What makes up the circle of Willis?
- two vertebral arteries become one basilar artery
- into posterior cerebral arteries
- joins with posterior communicating to the internal carotid (gives off two terminal - middle cerebral and anterior cerebral arteries)
- anterior communicating arteries join the cerebral arteries at the front laterally
Where does the circle of Willis sit?
in the CSF in the subarachnoid space
What is hydrocephalus?
excessive production or obstruction to the flow of CSF
What is the treatment for hydrocephalus?
a shunt can carry excess fluid into peritoneal cavity where it is reabsorbed
What are the three types of brain bleed?
- Epidural: eg trauma to pterion
- Subdural: eg cerebral veins from falls in the elderly
- Subarachnoid: eg aneurysms so ruptured Circle of Willis
What can raised ICP cause?
herniations which can be both supratentorial and infratentorial
