Anatomy Flashcards
What is the function of the back
Maintaining posture
Movement of the limbs and trunk
What is indicated by the dimples on the lower back
Positions of the posterior superior iliac spine
What is the first palpable vertebral process - usually
C7
What are the extrinsic back muscles
Those with an attachment out with the back itself Trapezius Rhomboids Levator scapulae Latissimus dorsi
What innervates the extrinsic back muscles
Anterior rami of the spinal nerves
Exception is the trapezius (CNIX)
What are the intrinsic back muscles
Those whose attachments are entirely within the back
Erector spinae and transversospinalis
What are the functions of the intrinsic back muscles
Maintain posture and move the spine
Which of the intrinsic back muscles is superficial
Erector spinae
What are the attachments of the erector spinae muscles
Inferiorly attach to the sacrum and iliac crest via a common tendon
Superiorly attach via individual muscle fibres to either a rib, a transverse process or a spinous process
Are the erector spinae muscles horizontal or vertical
Vertical
3 sets that lie lateral to the spine itself
What are the attachments of the transversospinalis
Found between the transverse and spinous processes
Individual fibres attach to a vertebrae and either; the skull, a rib, another vertebrae or the sacrum
What is the nerve supply of the intrinsic back muscles
They have segmental nerve supplies - match the myotome distribution
Posterior rami from the cervical, thoracic and lumbar branches
What are the main causes of back pain
Majority is mechanical (e.g. muscle strain)
1% is from the cord itself
2% is visceral - GI, pelvic, renal or AAA
What movements occur if the erector spinae contacts
If bilaterally = extension
If unilaterally = lateral flexion
Which type of spinal curve is primary
Kyphosis - cervical and sacral still present in adults
Lordosis is secondary - develops as we do
What is the function of the transverse processes
ligament, muscle and rib articulations
What is the function of the articular processes
Form the facet joints and allow for mobility with adjacent vertebrae
What is found in the intervertebral foramen
spinal nerves
Describe the structure of the intervertebral discs
outer fibrous ring – annulus fibrosus
for strong bond
inner soft pulp – nucleus pulposus
for flexibility and protection
Which vertebral levels have no discs
None between C1 and 2 or the fused sacrum and coccyx
Describe the ligamentum flavum
Short ligaments
Connect adjacent laminae posterior to the cord
Describe the posterior longitudinal ligament
Narrow and weak ligament
Prevents over flexion of the spine
Less support for disc - more likely to prolapse posteriorly
Describe the anterior longitudinal ligament
Broad and strong
gives strong support to the disc
Prevents over flexion of the spine
Describe the supraspinous ligaments
Connect the tips of spinous processes
Strong and fibrous
Describe the interspinous ligament
Connect superior and inferior surfaces of adjacent spinous processes
weak, membranous
What are the common features of the cervical vertebrae
transverse foramen
bifid spinous process
triangular shaped vertebral foramen
Which vertebrae has an odontoid process
C2 - Axis
This projects superiorly
What forms the atlanto-occipital joints
The occipital condyles and the superior articular facets of the atlas
They are synovial
What movements occur at the atlanto-occipital joints
Flexion and extension of the neck
Small amounts of lateral flexion and rotation
What forms the atlanto-axial joints
3 synovial articulations
2 between the inferior articular facets of the atlas and superior articular facets of axis
1 between the anterior arch of the atlas and odontoid process of the axis
What is the main movement atlanto-axial joints
Rotation
Are cervical vertebrae more likely to dislocate or fracture
Dislocate
How do you administer caudal anaesthesia
Enter at L3/4
Inject the anaesthetic into the sacral hiatus
This will numb the sacral spinal nerve roots of the cauda equina
More commonly used in children
At what level is an epidural administered
L3/4
Below the end of the spinal cord so you do not hit it
Where does the spinal cord begin and end
Begins at the foramen magnum (continuation of medulla oblongata)
Ends around L1/L2 vertebral level
What is the cauda equina
The nerve roots from L2-to CO form this as they descend to the correct vertebral level to exit the spine
Below the end of the cord itself
What is a laminectomy
Removal of one or more spinous processes and the adjacent lamina
When is a laminectomy needed
Used to access spinal canal, posterior exposure of the spinal cord and/or spinal roots
Relieve pressure on spinal cord or nerve roots
What sensory symptoms may occur if the spinal nerves are damaged
Pain, pins and needles, numbness, hypersensitivity, loss of coordination and temperature changes
What motor symptoms may occur if the spinal nerves are damaged
Muscle stiffness, tightness or spasm
Floppiness or loss of tone
Weakness - reduced power
Loss of coordination or balance
What general somatic sensory functions does a spinal nerve supply its segment with
Receptors for touch, temperature, proprioception, vibration and pain
these are located in the body wall
What general somatic motor functions does a spinal nerve supply its segment with
Supply the skeletal muscles with motor fibres
Found in the body wall
used for locomotion
What sympathetic motor functions does a spinal nerve supply its segment with
Autonomic control of the smooth muscle in associated blood vessels and hair follicles
What are the spinal reflexes
circuits of sensory afferents and motor efferent nerve fibres
Have a protective function
List the dermatomes found in the hand
C6 = thumb
C7 = middle finger
C8- little finger
List the dermatomes found in the arms and forearms
C5 = regimental badge patch C6 = lateral forearm and thumb T1 = medial forearm to elbow T2 = medial arm, base of axilla and sternal angle
What are the dermatomal landmarks on the trunk
T4 = nipple T10 = umbilicus T12 = pubic symphysis
List the dermatomes found in the head and neck
C2 - back of scalp and Adam’s apple
C3 - back and side of neck and jugular notch
Where is the C4 dermatome
Clavicle and shoulder tip - acromion is the landmark
List the dermatomes found in the lower limb
L1 – Groin L2 – Anterior/inside thigh L3 – Anterior knee L4 – Inner calf to medial malleolus L5 – Outer calf and dorsum of foot S1 – Heel or pinky toe S2 – Posterior knee/thigh S3 – Buttock S4 – Perineum S5 – Perianal skin
Which nerve sections form plexuses
The anterior rami
T2-T12 don’t contribute
Which named nerves give cutaneous supply to the trunk
Intercostal nerves from T2-11 anterior rami supply upper anterolateral trunk
Subcostal nerve from T12 supplies the lower region
Lower anterolateral trunk wall is supplied by iliohypogastric & ilioinguinal nerves
What is the difference between a spinal nerve and a named nerve
Spinal nerves contain axons from only 1 spinal level
Named nerves contain axons from 1 or more levels
Which spinal nerve roots form the femoral nerve
L2,3,4
Therefore it supplies these 3 dermatomes
List the named cutaneous nerves of the neck
Lesser occipital (C2) - behind ear Greater auricular (C2,3) - angle of mandible and external ear Transverse cervical (C2,3) - anterior neck Supraclavicular (C3,4) = clavicle and shoulder tip
What is the nerve point of the neck
Point at which the sensory nerves from the cervical plexus converge
At the midpoint of the posterior border of the SCM
List the named cutaneous nerves of the upper limb
Supraclavicular Axillary Musculocutaneous nerve - cutaneous branch Radial nerve Ulnar nerve Median
Which spinal levels form the axillary nerve
C5 and C6
Which spinal levels form the radial nerve
C5,6,7,8 and T1
Which spinal levels form the ulnar nerve
C7,8 and T1
Which spinal levels form the median nerve
C5,6,7,8 and T1
Describe the sensory pathway
Stimulation in a specific area causes an AP to be generated by receptors in that area
Passes into the associated nerve plexus
Continues to the anterior rami and then the associated spinal nerve
Then AP travels along the posterior root and then rootlets
Finally enters the posterior horn of the spinal cord
What muscles are supplied by the motor axons of the cervical plexus
Postural neck muscles and the strap muscles
Diaphragm
What muscles are supplied by the motor axons of the brachial plexus
Muscles of the upper limb
Some of the extrinsic back muscles (those that move limb and scapula)
What muscles are supplied by the T2-L3 motor axons
Postural back muscles (via posterior rami) Intercostal muscles (via anterior rami) Anterolateral abdominal wall muscles
What muscles are supplied by the motor axons of the lumbosacral plexus
Muscles of the lower limb
Perineal skeletal muscles
How do you test the C5 myotome
Shoulder abduction - test the deltoid action
How do you test the C6 myotome
Elbow flexion
Testing biceps brachii
How do you test the C7 myotome
Elbow extension
Testing triceps brachii
How do you test the C8 myotome
Finger flexion
Testing FDS
How do you test the T1 myotome
Finger abduction
Testing the dorsal interossei
How do you test the L3 myotome
Knee extension
Testing quadriceps femoris
How do you test the L4 myotome
Ankle dorsiflexion
Testing tibialis anterior
How do you test the L5 myotome
Great toe extension
Testing EHL
Have to do this although it contributes to ankle dorsiflexion and plantaflexion as L4 and S1 respectively compensate
How do you test the S1 myotome
Ankle plantarflexion
Testing the gastrocnemius
How do you test the S2 myotome
Knee flexion
Testing biceps femoris
Describe the motor pathway
AP’s generated by intention in the primary somatomotor cortex
AP conducted via the UMN in the corticospinal tract
Continue along axons to anterior horn of relevant spinal level
They synapse with the LMN at that level and stimulate a further AP
Continues along spinal nerve and then either the A or P rami
May pass through a nerve plexus
Reach the NMJ and supply the muscle
What is a reflex
An involuntary response to a stimulus
List the main spinal reflexes and the level they test
Biceps - C5,6 Triceps - C7 Brachioradialis - C6 Knee Jerk - L3 Ankle jerk - S1
How can the olfactory nerves be damaged
Base of skull fracture
Will lead to anosmia
CSF can start dripping through the nose - clear fluid
Can olfactory nerves be repaired
YES
some of the only nerves that can
Possible to regain your sense of smell
Describe the path of the olfactory nerve
Lays within olfactory mucosa in the nasal cavity
Pass through the cribiform plate of the ethmoid bone
Synapses in the olfactory bulb
Passes back in the olfactory tract to the cortical areas
Describe the path of the optic nerve
Neurons from the retina travel posteriorly in the optic nerve
Passes through the optic canal in the middle cranial fossa
Meet at the optic chiasm to cross and become the optic tracts
Connect with CNS at the diencephalon
What passes through the optic canal
Optic nerve
Ophthalmic artery
How do you test the olfactory nerve
Not routinely done
Can ask if they’ve noticed a change
Or ask to smell a familiar smell (coffee, orange etc) while holding one nostril shut
How do you test the optic nerve
Acuity (Snellen charts) Colour (Ishihara plates – colour blindness) Fields (Four quadrants) Reflexes (Pupillary light reflexes) Fundoscopy
What are the functions of the oculomotor nerve
Eye movement - motor
Pupil construction - parasympathetic
Where do the parasympathetic fibres of the oculomotor nerve synapse
Ciliary ganglion
They then join the ciliary nerves
Describe the path of the oculomotor nerve
Leaves from the midbrain
Travels towards the orbit in the lateral wall of the cavernous sinus
Passes through the superior orbital fissure - through the common tendinous ring
Enters the orbit and supplies all muscles except 2
How do you test the oculomotor nerve
Part of the H test for eye movement
To test parasympathetics check for pupillary constriction
Describe the path of the trochlear nerve
Leaves from the midbrain
Travels towards the orbit in the lateral wall of the cavernous sinus
Passes through the superior orbital fissure - over common tendinous ring
Enters the orbit and supplies the superior rectus
Describe the path of the abducent nerve
Leaves brain at the pontomedullary junction
Travels towards the orbit within the cavernous sinus
Pass through the superior orbital fissure
Supplies the lateral rectus
What is the function of the trochlear nerve
Eye movement - motor
What is the function of the abducent nerve
Eye movement - motor
How do you test the trochlear and abducent nerves
Part of the H test for eye movement
What is the function of the vestibulocochlear nerve
Axons are in the vestibular and cochlear apparatus
Passes through the internal acoustic meatus in the posterior fossa
Travels posteriomedially to the pontomedullary junction
How do you test the vestibulocochlear nerve
Rinne and Weber tests
What passes through the IAM
Vestibulocochlear nerve and the labyrinthine artery
What is the function of the spinal accessory nerve
Motor supply to the SCM and the trapezius
Describe the path of the spinal accessory nerve
Arises from the cervical spinal cord (C1-4)
Ascends through foramen magnum then travels towards jugular foramen in posterior cranial fossa
Passes through jugular foramen
Axons supply SCM on deep surface, then continue across the posterior triangle to supply trapezius and SCM
How do you test the spinal accessory nerve
Ask patient to shrug shoulders
Ask them to turn head to flex neck and turn towards the opposite side
Look for symmetry and strength
What is the function of the hypoglossal nerve
Motor supply to the muscles of the tongue
Describe the path of the hypoglossal nerve
Leaves CNS at medulla oblongata (many rootlets)
Moves anteriorly then passes through the hypoglossal canal
Descends lateral to carotid sheath.
At the level of the hyoid turns anteriorly towards lateral aspect of tongue.
Supplies most muscles of the tongue.
How do you test the hypoglossal nerve
Ask patient to stick tongue straight out
If both CNXII’s are functioning normally the tongue tip remains in the midline on protrusion
If there is unilateral CN XII pathology the tongue tip will point towards the side of the injured nerve
What are the divisions of the trigeminal nerve
CNV1 - ophthalmic - sensory
CNV2 - maxillary - sensory
CNV3 - mandibular - sensory and motor
Describe the path of the trigeminal nerve
Leaves brain at the pons
Travels inferior to the edge of the tentorium cerebelli between the posterior and middle cranial fossae
CNV1 passes through superior orbital fissue
CNV2 passes through foramen rotundum
CNV3 passes through the foramen ovale
What does CNV1 supply
Sensory to the upper eyelid, cornea, conjunctiva and root/bridge/tip of nose
Bone and soft tissue of orbit, anterior nasal cavity, paranasal sinuses and the anterior + posterior cranial fossae
What does CNV2 supply
Sensory to the skin of the lower eyelid, maxilla, ala of nose, upper lip
Lower posterior nasal cavity
Maxilla & maxillary sinus
Floor of the nasal cavity/palate
Maxillary teeth & associated soft tissues
What does CNV3 supply with sensory
Skin over the mandible and temporomandibular joint
Middle cranial fossa
Mandible
Anterior 2/3rds of the tongue - not taste
Floor of the mouth
Buccal mucosa
Mandibular teeth
Which muscles are given their motor supply by CNV3
3 closing jaw muscles - masseter, temporalis and medial pterygoid
Jaw opening muscle - lateral pterygoid
Tensor veli palatini and tensor tymapni
How do you test the trigeminal nerve
Get patient to close eyes and gently brush skin with cotton wool - each area
Compare sides
Palpate the strength of jaw contraction and get them to open jaw against resistance
Which nerves are responsible for the corneal reflex
afferent is trigeminal, efferent is the facial nerve
Describe the path of the facial nerve
Leaves brain at pontomedullary junction
Passes into the internal acoustic meatus and then out of the stylomastoid foramen (through the middle ear)
Most somatic motor axons pass into the parotid gland then into 6 branches that supply the muscles of facial expression
At which point does the facial nerve give off the chorda tympani
When it passes through the middle ear
The chorda tympani will then travel through the posterior wall of the tympanic cavity
What is the function of the chorda tympani
It conveys parasympathetic fibres to the sublingual and submandibular glands and taste to the anterior 2/3 of tongue
Describe the difference in symptoms of facial nerve damage depending on the location
If the facial nerve is damaged below the tympanic cavity it is just facial muscles affected – Bell’s Palsy
If the cavity is affected you also lose taste and get dry mouth
If above the ear the stapedius is affected and noises become much louder
How do you test the facial nerve
Test the muscles of facial expression
raise eyebrows, close eyes tight, smile, puff out cheeks and hold air
Describe the path of the glossopharyngeal nerve
Leaves brain at the medulla
Travels in the posterior fossa then passes through the jugular foramen
Descends towards the pharynx and mouth
What is the function of the glossopharyngeal nerve
Special sensory - taste o posterior 1/3
Sensory - pharynx, tonsils, eustachian tube and middle ear
Motor - stylopharygeus
Visceral afferent - carotid sinus baroreceptors and carotid body chemoreceptors
Parasympathetic - secretion from parotids
What are the functions of the vagus nerve
Sensory
Motor
Visceral afferent
Parasympathetic
Describe the path of the vagus nerve
Leaves brain at medulla
Passes directly towards the jugular foramen in the posterior fossa then passes through
In the neck it runs within the carotid sheath
In chest they run posterior to lung root before passing through the diaphragm
Describe the positions of the recurrent laryngeal nerves
Left recurrent laryngeal nerve curves under arch of the aorta
Right recurrent laryngeal curves under the right subclavian artery
How do you test the vagus nerve
Ask them to say ahhhhh - uvula should lift straight up
Ask them to swallow a small amount of water - watch movement and for spluttering
Listen to their speech
what are SOL’s
Space occupying lesions
Abnormal tissue taking up space in the skull
What is the Munro-Kellie hypothesis
Within the skull there is blood, CSF and brain tissue
If one factor increases, the other 2 must decrease to maintain ICP
What are the layers of the scalp
Skin Connective tissue - tough Aponeurosis Loose connective tissue Pericranium
Why does the scalp bleed so much
Big network of blood vessels in the connective tissue layer
Additionally the CT layer is tough so practically holds the artery open instead of it helping in constrict
List the bones of the skull
Frontal Parietal - L&R Temporal - L&R Sphenoid Occipital
Joined at the sutures
What is the pterion
Pterion is the meeting point of the frontal, parietal, temp and sphenoid and is usually the thinnest part of the skull
What is the major risk of a fracture at the pterion
The middle mengingeal artery runs right underneath it
Fracture can rupture the artery and cause a brain haemorrhage
What are the meninges
Layers of protective tissue around the brain and spinal cord
Dura mater - tough
Arachnoid mater- spidery and thin
Pia mater - very thin
Where is the CSF found
Subarachnoid space
What is meningitis
Infection of the meninges
Pain associated with meningitis is due to stretching of the dura
Which nerve supplies the dura
Trigeminal
Only layer with sensory nerve supply
What is the tentorium cerebelli
Sheet of dura mater “tenting” over the cerebellum
Attaches to the temporal bones
Central gap for pituitary stalk to pass through
What is the falx cerebri
Midline structure of dura mater that separates the hemispheres
What does the falx cerebri attach to
Crista galli of the ethmoid bone anteriorly
Internal aspect of the sagittal suture
Internal occipital protruberance posteriorly
Describe the venous drainage of the brain
Cerebral veins drain blood from the brain itself which then passes it into the dural venous sinuses
These are found between the periosteal layer and meningeal layer
Describe the arterial supply to the brain
Vertebral artery passes through transverse foramina from C6 upwards
They join to form the basilar artery
Internal carotid goes up into the cranial cavity and then joins the circle of willis with the basilar artery to become the main blood supply to the brain
List the areas supplied by the cerebral arteries
Anterior - medial aspect of the hemisphere
Middle - lateral aspect of associated hemisphere
Posterior - posterior aspect
How do you access the subarachnoid space
Can be accessed via lumbar puncture at L3/4 or L4/5 IV disc levels to obtain a sample of CSF
Where does the subarachnoid space close
Around the level of S2
Where is CSF produced
Choroid plexus in the lateral and 3rd ventricles
Modified pia mater
What causes hydrocephalus
excessive production, obstruction to flow or inadequate reabsorption of CSF leads to an increased volume
Leads to an enlarged head in children
How can you treat hydrocephalus
Ventricular peritoneal shunt
Shunt is put into the ventricles and fluid is redirected to the peritoneal cavity where CSF can be reabsorbed
If a vessel is found in the subarachnoid space - what must it be
A branch from the circle of willis
What is a extradural haemorrhage
Occurs between the bone and dura
Due to ruptured meningeal artery
Often the middle due to pterion injury
What is a subdural haemorrhage
Occurs between the dura and arachnoid and separates them
Due to torn cerebral veins
Common after falls in the elderly
What is a subarachnoid haemorrhage
Bleed into the CSF from the subarachnoid space
Due to ruptured aneurysm in the circle of willis - berry aneurysm
May be congenital
What is transcalvarial herniation
Occurs after a blow to the head
Brain can herniate out gap in the bone
What is cingulate herniation
Brain pushes across the falx cerebri
What is uncal herniation
Part of the temporal lobe herniates down and under the tentorium cerebelli
This is very tough dura and so this can lacerate the temporal lobe
Disc prolapse tends to affect the nerve root from the vertebral level above - true or false
False
It affects the lower nerve root
e.g. in a L4/5 prolapse it is L5 that is affected
This is because most discs prolapse backwards and the upper nerve hugs the pedicles and misses the disc, whereas it catches the lower nerve as it leave the cord
If a patient presents with UMN signs, their issue has to be above L1/2 - true or false
True
This is because it has to be in the spinal cord and it ends at that level
If the issue is below L1/2 they will have LMN signs
