Block 12 Flashcards
myotomes + dermatomes arise from
somites
myotomes
group of skeletal muscles innervated by a single spinal nerve
Ankle strategy produces mostly
torque
the ankle strategy is used on
surfaces with low resistance to shear forces
which postural strategy shifts COG abt hip joint by flexion/extension?
Hip strategy
Postural strategy used when ankle + hip strategies are inadequate
Stepping strategy
Which muscle in the posterior compartment of the lower leg is important for proprioception?
Plantaris
which position is the talocrural joint most stable in?
dorsiflexion - anterior talus in mortise
Osteopathy is based on the principle tht
the wellbeing of an individual depends on their bones, muscles, ligaments and connective tissue functioning smoothly together
largest neurons within the body
alpha motor neurons (type of LMN)
Increasing plantorflexor activity moves COP
anteriorly
Increasing inverter activity moves COP
laterally
Medial superior olivary nuclei detects differences in
the time tht sounds reach each ears
Lateral superior olivary nuclei detects differences in
sound intensity reaching each ear
Area that the optic nerve enters the retina
Optic disc
has no light detecting cells
Function of the vitreous humour
- hold the layers of the retina in place
- support the lens
- improve vision clarity
- shock absorption
Fibrous layer of eyeball is made up of:
- cornea
- sclera (85%)
Controls the shape of the lens and contributes to aqueous humour formation
Ciliary body
Vascular layer of eyeball is made up of:
- Choroid
- Ciliary body
- Iris
Function of fovea centralis
high vision acuity
Depression on macula
Fovea centralis
Found at centre of retina
Macula
3 main layers of the eye
Fibrous
- cornea
- sclera
Vascular
- iris
- ciliary body
- choroid
Neural
- retina
Conjugate eye movements
eyes moves in the same directions
Disconjugate eye movements
eyes move in opposite directions
Purpose of meridonial fibres in ciliary body
hold lens in place and help it change shape
Structure producing aqueous humour
ciliary body
Appearance of lens when object far away
ciliary muscles are relaxed allowing lens to flatten + appear elongated
Appearance of lens when object close by
ciliary muscles are contracted so lens more rounded
Define cataracts
opacification of the lens due to protein deposition + compaction
Extra-axial lesion
injury occurring within skull but outside of brain
olfactory nerve is derived from
olfactory placode - thickening of ectoderm
passageway in sphenoid bone that allows optic nerve to leave the bony orbit
optic foramen
Fibres forming left optic tract
fibres from L temporal and R nasal retina
Fibres forming R optic tract
fibres from R temporal + L nasal retina
Lateral geniculate nucleus
relay system located in thalamus
Clinical features of oculomotor nerve damage
- Ptosis - drooping of upper eyelid
- Down + out position of eyeball
- Dilated pupil
The only cranial nerve to exit from posterior midbrain
CN IV - trochlear nerve
Largest cranial nerve
CN V- Trigeminal
Ganglion
collection of the neurone cell bodies outside the central nervous system
Nucleus
collection of neurone cell bodies within the central nervous system.
Triad of anaesthesia
Analgesia - pain free
Hypnosis - sleep
Areflexia - loss of reflexes
Axillary nerve damage presents w
- inability to abduct shoulder
- loss of sensation over the deltoid muscle on the upper-arm
e. g. due to shldr dislocation
3 cords of the brachial plexus are named according to
their relationship to the axillary artery
Signs of proximal injury to radial nerve
- inability to extend at the elbow, wrist or fingers
Nerve compressed in carpal tunnel syndrome
Median nerve
Signs of ulnar nerve damage
- inability to flex the wrist + little+ring fingers
- atrophy of hypothenar eminence
- claw hand
Most frequently injured nerve of upper limb
ulnar nerve
Name of the muscle that runs between the 2 gemelli muscles
obturator internus
Which nerve innervates the gluteus medius + gluteus minimus?
Superior gluteal nerve
Which nerve innervates the gluteus maximus?
Inferior gluteal nerve
Which nerve innervates the semimembranosus, semitendinosus and long head of the biceps femoris?
Tibial division of sciatic nerve
Which muscles make up the hamstrings?
Semimembranosus
Semitendinosus
Biceps femoris long head
4 individual muscles that make up the quadriceps femoris
Rectus femoris
Vastus medialis
Vastus lateralis
Vastus intermedius
Nerve that innervates the 4 quadriceps muscles
femoral nerve
Action of the quadriceps muscles
extend the knee joint AND stabilise the patella
Longest muscle in body
Sartorius
muscles that make up the rotator cufff
Subscapularis - aDDuct & rotates arm medially
Supraspinatus - aBDucts arm before deltoid
Most commonly injured
Infrapinatus - Rotates arm laterally
Teres minor - aDDucts & rotates arm laterally
hemiarthroplasty
femoral head replaced with prosthesis
Extracapsular hip fracture
can either be trochanteric or subtrochanteric (the lesser trochanter is the dividing line)
Intracapsular hip fracture
from edge of femoral head to insertion of the capsule of the hip joint
structures passing through the internal acoustic meatus
vestibulocochlear nerve, facial nerve and labyrinthine artery
nerve that innervates the deep flexors of the forearm
Anterior interosseous nerve - branch of median nerve
Specifically:
Flexor pollicis longus
Pronator quadratus
The radial half of flexor digitorum profundus (the lateral two out of the four tendons).
ulnar nerve roots
C8, T1
Hip adductors are found in
medial compartment of thigh:
adductors longus, brevis + magnus
pectineus
gracilis
Most muscles in the medial compartment of the thigh are innervated by
obturator nerve
2 nerves supplying the adductor magnus
adductor part -> obturator nerve
hamstring part -> tibial division of sciatic nerve
Hip abductors
gluteus medius
gluteus minimus
piriformis
tensor fascia latae
Only intracapsular ligament of hip joint
ligament of the head of femur
IMPORTANT - artery to femoral head runs in this ligament
Strongest extracapsular ligament of the hip
iliofemoral ligament
limits hyperextension +lateral rotation
Sensory innervation by the musculocutaneous nerve is to the
lateral half of the anterior forearm, and a small lateral portion of the posterior forearm
Medial rotators of hip
anterior fibres of gluteus medius + minimus
tensor fascia latae
Ligaments attaching the spinal cord to the dura
Denticulate ligaments
Principal nerve supply to flexors of forearm
median nerve
Principal nerve supply to flexors of forearm
median nerve
Borders of the antecubital fossa
medial border - pronator teres
lateral border - brachioradialis
floor - brachialis
Common flexor origin
Medial epicondyle - common flexor origin, all flexor muscles of forearm originate here
Flexor muscle in forearm absent in 10% of ppl
Palmaris longus
Muscles in the superficial layer of the anterior forearm (4)
- pronator teres
- flexor carpi radialis ( inserts on carpals on radial side)
- palmaris longus
- flexor carpi ulnaris
Only flexor found in the intermediate layer of the anterior compartment of the forearm
flexor digitorum superficialis
3 muscles found in the deep compartment of the anterior forearm
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus - pulls radius over ulna
2 nerves innervating the flexor digitorum profundus
lateral part - median nerve
medial part - ulnar nerve
Muscles innervated by the musculocutaneous nerve
coracobrachialis
biceps brachii
brachialis
Define posture
relative position of various parts of the body w respect to one another, the environment and gravity
2 key features of postural systems
- automatic
- help stabilise and maintain body position
2 goals for postural control depending on circumstances:
prepare for a voluntary movement
maintain balance
4 descending tracts controlling posture
vestibulospinal tract
tectospinal tract
pontine reticulospinal
medullary reticulospinal tract
Origin of vestibulospinal tract
vestibular nuclei of medulla
Sensory input of vestibulospinal tract
vestibular labyrinth
Ventromedial tract that helps maintain upright posture
vestibulospinal tract
Origin of tectospinal tract
superior colliculi
Sensory input to tectospinal tract
retina
Function of tectospinal tract
directs head + eyes to move to a particular location in space AND controls posture of head+neck
Function of pontine reticulospinal tract
- enhances antigravity reflexes
- maintains standing posture against gravity
Function of medullary reticulospinal tract
liberates antigravity muscles
Features of decerebrate rigidity
plantarflexion
extension at knee
flexion of fingers
pronation
extension at elbow
adduction of arms
What is decerebrate rigidity/response?
cerebral cortex damaged due to disease or injury can’t send normal tonic inhibition to brainstem ⇒ disinhibition of brainstem significant extensor tone e.g. cerebral malaria
3 structures making up the outer ear:
Pinna/auricle
External acoustic meatus
Tympanic membrane
Functions of pinna
funnels sound into ear canal
aids in vertical localisation of sound
filters sounds - preferentially selects sound in freq. range of human speech
Function of earwax/cerumen
sticks to dust + particles prevents them entering inner ear
Functions of external acoustic meatus
focuses sound energy onto the eardrum
amplifies sound
Collagenous membrane separating the outer ear from the middle ear
Tympanic membrane
Ossicle firmly attached to medial tympanic surface
Malleus
Most depressed part of the tympanic membrane concavity
Umbo
Function of tympanic membrane
- vibrates in resp. to sound pressure waves
- helps transmit sound energy from ear canal to middle ear bones
3 bones of middle ear
malleus
stapes
incus
Function of middle ear
converts kinetic energy of tympanic membrane to hydraulic energy in inner ear via oscillations of the ossicles
How does the stapes help amplify sound?
footplate of stapes 17x smaller than that of eardrum, sound vibrations concentrated onto much smaller area, pressure gain of 20 or more
Function of eustachian tube
connects middle ear cavity to nasopharyx
Function of eustachian tube
- allows pressure equalisation btwn. middle ear + external ear
- prevents damage to tympanic membrane due to lrge external pressure changes
2 main middle ear muscles
Tensor tympani - attaches to malleus
Stapedius - attaches to stapes
How can middle ear muscles dampen sound reaching the inner ear?
contract - reduce ability of ossicles to vibrate
Middle ear muscles contract in response to:
high intensity sounds OR when speaking
Branches of facial nerve entering the middle ear cavity
stapedial nerve - innervates stapedius muscle
chorda tympani - taste sensation to anterior 2/3 of tongue
Innervation to tensor tympani
mandibular part of the trigeminal nerve
Membranous labyrinth is filled with
Endolymph - fluid w a high potassium concentration
2 main parts of labyrinth
Vesitbular system
Cochlea
Location of labyrinth
deep within petrous part of temporal bone
Conductive hearing loss
disorder/damage to the tympanic membrane and/or middle ear ossicles
Examples of causes of sensorineural hearing loss
infection
exposure to loud noises
tumours
ototoxic drugs -> aminoglycosides
Scala media
cochlear duct filled w endolymph
3 sections of the cochlea
scala media
scala vestibuli
scala tympani
Separates scala vestibuli from scala media
Reissner’s membrane
Separates scala media + scala tympani
Basilar membrane
Organ of corti
sensory epithelium on basilar membrane
Function of Otolith organs
detect force of gravity + tilts of the head e.g. linear acceleration
Function of Semicircular canals
sensitive to head rotation e.g. rotational motion AND angular acceleration
Superficial muscles of thenar eminence
Opposens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Superficial muscles of thenar eminence are innervated by
median nerve
Deep muscle of thenar eminence
Adductor pollicis
Nerve innervating the adductor pollicis
ulnar nerve
Frozen shoulder
inflamed shoulder capsule
Clinical signs of frozen shoulder
reduced range of both active and passive movement due to pain
pain on palpation of shoulder
Joint aspiration in gout would show
monosodium urate crystals
Commonly affected joints in Gout
big toe joint
ankle
wrist
knee
Crystals found in Pseudogout
calcium pyrophosphate crystals
Structures running in the spiral groove of the humerus
- radial nerve
- profunda brachii artery
MoA of Pilocarpine
muscarinic receptor agonist
promotes pupil constriction
Signs of LMN disease
decreased tone
decreased reflexes
fasiculations
which gland does the facial nerve run through?
parotid
Wallerian degeneration
axonal degeneration distal to the site of injury
Typically begins 24-36 hours following injury
Artery supplying dura mater that runs foramen spinosum
middle meningeal artery
Muscles inserting on greater trochanter
POGO: Piriformis Obturator internus Gemelli Obturator externus
Damage to the superior gluteal nerve will cause
Trendelenburg gait
paralysis of gluteus medius + minimus
Cutaneous innervation to the lateral foot
Sural nerve
Innervation to the medial aspect of the leg
Saphenous nerve which arises from femoral nerve
Structure attaching periosteum to bone
Sharpey’s fibres
the subclavian vein lies behind…
the medial part of the clavicle
Longest strap muscle in the body
Sartorius
Which structure separates the ulnar artery from the median nerve?
Pronator teres
ACL receives blood supply:
middle genicular artery
Innervation to the short head of the biceps femoris
common peroneal division of the sciatic nerve
What type of joint is the wrist joint?
synovial condyloid joint
Most common type of glaucoma
Primary open-angle glaucoma
Why do symptoms in open-angle glaucoma appear overtime?
because the trabecular meshwork draining system gets clogged slowly time
==> SLOW increase in intraocular P
==> slow damage to optic nerve
(outer rim of nerve damaged first -> loss of peripheral vision, then as it progressively gets worse loss of central vision)
Type of glaucoma where you get sudden build up of pressure due to reduced aqueous humour
CLOSED-ANGLE GLAUCOMA
functions of CSF
protection - cushions brain
buyonancy - reduces net weight of brain; prevents XS pressure on base of brain
chemical stability
cells lining ventricles
Ependymal cells
How many ventricles are there in total?
FOUR:
R+L lateral ventricles
3rd ventricle
4th ventricle
Which ventricles have horns that project into the frontal, temporal + occipital lobes?
R+L lateral ventricles
Foramen/structure that connects lateral ventricles to 3rd ventricle
INTERVENTRICULAR FORAMEN
Foramen of Monro
Ventricles surrounded by the R+L thalamus
THIRD VENTRICLE
Connects the 3rd + 4th ventricles
CEREBRAL Aqueduct
Structure that sits below supraoptic recess
optic chiasm
Structure that sits below the infundibular recess
optic stalk
Relates to CSF absorption
What happens at the subarachnoid cisterns?
CSF bathes brain btwn arachnoid + pia mater
CSF REABSORBED HERE!
Which structure allows CSF fluid to drain into the dural venous sinuses?
Arachnoid granulations which project into the dura mater
How is CSF produced?
choroid plexus surrounded by cuboidal epithelial cells which filter plasma out of the blood to make CSF
Where does the trochlear nerve emerge from?
POSTERIOR SURFACE of brainstem
emerges inferior to the inferior colliculus
Structures making up the bony labyrinth
- cochlea
- vestibule
- 3 semicircular canals
Structures making up the membranous labyrinth
- cochlear ducts
- semicircular ducts
- utricle
- saccule
Central part of bony labyrinth
VESTIBULE
structure separating the vestibule from the middle ear
OVAL WINDOW
The utricle and saccule are located within
the VESTIBULE - central part of bony labyrinth
Modiolus
bony column that the cochlea twists around
What is contained within the semicircular canals?
semi-circular ducts
Effect of excessively loud noise on hair cells of organ corti
can damage them => Sensorineural hearing loss
Structure that holds cochlear duct in place
SPIRAL LAMINA
the joints between ossicles are
SYNOVIAL
Common cause of subarachnoid haemorrhages
BERRY ANEURYSM - aneurysm tht often occurs in Circle of Willis region
Nucleus of the facial nerve
GENICULATE NUCLEUS