Mod 1: Anatomy Flashcards
Kyphosis
primary curvature
thoracic and sacral
Lordosis
secondary curvature
cervical and lumbar
Where does sc end in adult?
L2
What spinal cord segments correspond to…
cervical and lumbar enlargements?
Cervical: C4-T1
Lumbar: L2-S3
How many spinal nerves are there?
How many at each level?
31 total 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Epidural sac contains
fat and veins – post vertebral venous plexus (outside the dura mater)
Clincal significance of vertebral venous plexuses
valveless, so blood can flow sup or inf depending on BP gradients
serve as routes for metastasis of cancer from pelvis –> vertebrae, vert canal, cranial cavity
Where do lumbar punctures occur?
below conus medullaris
no possibility of piercing spinal cord
Functions of upper and lower limbs
Upper: mobility and manipulation (not wt bearing)
–sternoclavicular joint is only attachment (ant)
Lower: stability and locomotion (wt bearing)
–pelvic girdle connects to ant skeleton ant (vert column) and post (sacrum)
Similarities of upper and lower limb
segmented
connected to axial skeleton via girdles
developmental homologies (similar development)
dermatomes
fascial compartments that ensheathe limbs and subdivide them into muscular compartments
Homologous elements in upper and lower limbs
scapula -- hip humerus -- femur RADIUS -- TIBIA ULNA -- FIBULA carpals -- tarsals metacarpals -- metatarsals phalanges -- phalanges
Developmental rotations of upper and lower limbs
Week 5
–upper and lower limbs protrude from body wall and face laterally (upper first, lower second)
Week 6
–upper and lower bend at elbow and knee (palms and soles face trunk)
Week 7
–elbows rotate caudally to face post
–knees rotate cranially to face ant
What joint connects upper limb to axial skeleton?
sternoclavicular
Mvmts of forearm bones vs leg bones
Radius and ulna: pronate and supinate
leg bones: fixed
Supination vs pronation
supine: palm up
pronate: palm down
Functions of clavicle
suspend scapula and upper extremity from axial skeleton
protect large nerve trunks and vessels passing from neck to axilla
transmit sudden impacts from upper extremity to axial skeleton
Scapula located over what ribs?
T2-T7
Fossae of scapula
Ant or post?
Ant: subscapular
Post: supraspinous and infraspinous
Why use CT scan for trauma of shoulder girdle, pelvic girdle, and skull?
scapula difficult to interpret on film
Most frequent bone broken in newborns?
How frequent in kids, adults?
Why?
Clavicle
Kids: 7% (top 5)
adults: 3% (top 10)
Why:
small, strut-like
only bone connecting upper limb to axial skeleton
first bone to ossify (5th week) – more mineralization so more stiff
How do Clavicular fractures present?
Why do they occur in middle of bone?
- medial segment of clavicle sup
- upper limb depressed, adducted, medially rotated (sagging shoulder)
Middle of bone b/c ends anchored by strong ligaments
Are medial or lateral rotators larger?
medial are larger
Joint that is only connection b/w axial skeleton and upper limb
sternoclavicular
Sternoclavicular articular surfaces covered in…
Acromioclavicular…
Tough or loose?
Sternoclavicular: fibrocartilage and intra-articular disc
–tough
Acromioclavicular: fibrocartilage
–loose
Glenoid labrum
fibrocartilaginous rim attached around the margin of the glenoid cavity
deepens glenoid fossa
Capsule of glenohumeral joint pierced by what tendon?
long head of biceps
what forms a protective structure limiting sup displacement in glenohumeral joint
coracoacromial arch
Shoulder separation vs dislocation
joint involved, cause, presentation
Separation
–dislocation of acromioclavicular joint
–direct, forceful impact on shoulder or fall on outstretched arm
–prominence on shoulder (clavicle extends above acromion)
Dislocation
–dislocation of glenohumeral joint
–lat rotation of humerus
–humerus dislocated ant to make intact AC joint more prominent
What muscle forms medial wall of axilla?
serratus ant
What are the scapular arterial anastamoses?
Dorsal scapular (from thyrocervical trunk)
Suprascapular (from subclavian)
Circumflex scapular (from subscapular)
Intercostal (from thoracic aorta)
Brachial plexus arises from what roots?
VENTRAL rami of C5-T1
If brachial plexus starts at C4 or ends at T2, what are these called?
Prefixed or postfixed
Ventral roots carry what kind of nerve?
Dorsal roots?
Ventral: motor
Dorsal: sensory
come together to form mixed spinal nerve –> dorsal and ventral rami (ventral rami are brachial plexus)
What part of the brachial plexus passes under the clavicle?
What parts are supraclavicular?
Infraclavicular?
divisions
supra: roots and trunks
infra: cords and terminal branches
Anterior divisions innnervate…
Flexors (ant compartment of fore limb)
Posterior divisions innervate
Extensors (post compartment of fore limb)
Cords are named based on their relationship to what structure?
axillary a
lateral, post, medial cords
Which is more lateral in the body?
Med or lat pec nerve?
Medial pec nerve is more lateral than lateral pec nerve (flipped b/c named according to origin)
Musculocutaneous innervates Axillary Radial Median Ulnar
Musculocutaneous: ant compartment of arm Axillary: deltoid and teres minor Radial: post compartments of arm and forearm Median: ant compartment of forearm Ulnar: ant compartment of forearm
Dermatomes for thumb and fingers
Thumb: C6
index and middle: C7
ring and pinky: C8
Upper brachial plexus injury
Lower
Upper: Erb-Duchenne palsy (waiter’s tip hand)
Lower: Klumpke paralysis
Path of long head of triceps brachii in axillary region
passes ant to teres major
passes post to teres minor
medial to axillary n and post to circumflex humoral a
Retromammary space
space behind breast and in front of pec major
What lymph vessels run with great saphenous v?
Small spahenous v?
Great: sup inguinal nodes, deep inguinal nodes, or external iliac nodes
Small: popliteal nodes, deep lymph vessels
Cloquet’s node
most sup of the deep inguinal nodes or most inf of the ext iliac nodes (sampled to test for metastasis of cancer from lower limb to more proximal regions)
What hip bone do these attach to?
Gluteal
Post compartment of thigh
Med compartment of thing
Gluteal: ilium
Post compartment of thing: ischium
Med compartment of thigh: pubis
What are attachments for ligaments to make notches into foramina?
sacrospinous (ischial spine) – lesser scientic foramen
sacrotuberous (ischial tubercle) – greater sciatic foramen
Obturator formed by what bones?
ischium and pubis
covered by obturator membrane (obturator nav run through here)
Ligaments that reinforce hip joint
iliofemoral
pubofemoral
ischiofemoral
When is hip joint dislocation most likely to occur?
flexed
abducted
externally rotated
(prevent by iliofemoral ligament)
How does hip dislocation present?
Hip fracture?
Dislocation: shorter and internally rotated
Fracture: shorter and externally rotated
3 types of hip fracture
subcapital (intracapsular) – most complications
trochanteric
subtrochanteric
Sesamoids
ossifications in tendons near a joint (always one at the metacarpo-phalangeal joint of thumb) (can occur in other places too)
Only extensor of the leg
quads femoris
Largest and most powerful muscle in body
quads femoris
Muscles of ant compartment of leg
iliopsoas pectineus sartorius quads femoris --rectus femoris --vastus lateralis --vastus medialis --vastus intermedius
Longest muscle in human body
sartorius
Locations of thigh muscle compartments in relation to intermuscular septa
Ant: b/w lat and med
Med: b/w post and med
Muscles of med compartment of leg
adductor longus adductor brevis adductor magnus gracilis obturator externus
What is the most ant of the adductor muscles in the thigh?
adductor longus
What is the largest adductor muscle?
Adductor magnus (made of 2 muscles)
Which muscle of post compartment has half of its length made up by a cord-like tendon?
Which one has a broad, flat tendon of distal attachment?
Long cord-like tendon: semitendinosus
Broad, flat tendon: semimembranosus
What is the only muscle in the body innervated by the common fibular nerve?
SHORT HEAD of biceps femoris
Muscles of post compartment of leg
semitendinosus
semimembranosus
biceps femoris (long head and short head)
**short head is NOT in the hamstrings
Muscles of pes anserinus
sartorius
gracilis
semitendonosus
Nerves supplying compartments of thigh (with exceptions)
Ant: femoral n (exception: psoas major innervated by ventral rami of L1-L3)
Med: obturator n (exception: ischiocondylar/hamstring portion of adductor magnus innervated by tibial portion of sciatic n)
Post: sciatic n, tibial div (exception: short head of biceps femoris innervated by sciatic n, common fibular div)
How many nerve fibers can be innervated by a single axon?
one or many
Motor unit
single nerve fiber and all the muscle fibers that it innervates
–all muscle fibers contract at once (on or off)
Difference b/w fine control and course mvmts
Fine: fewer muscle fibers per axon
Courser: more muscle fibers per axon
Henneman’s size principle
inc force by recruiting additional motor units
Describe structure of NMJ
- -myelinated motor nerves pass through perimysium giving off several terminal nerve axons
- -axons lose myelin and become dilated at presynaptic button (site of innervation)
- -primary and secondary synaptic clefts
- -axons covered by thin layer of Schwann cells at motor end plate
- -axon terminal has mito and synaptic vesicles with acetylcholine
Primary synaptic cleft
dilated nerve endings sit in trough of muscle fiber
Secondary synaptic cleft
deep junctional fods of sarcolemma – this is the motor unit end plate
–junctional folds have acetylcholine receptors
What NT at NMJ?
acetylcholine
T-tubules
invaginations of sarcolemma into fiber
encircle A and I bands in regular order
carry depolarization signal into fiber
Sarcoplasmic reticulum
branching network in skeletal and smooth muscle
surrounds each myofibril
terminal cisternae bracket T-tubules
regulates Ca flow
Passively releases Ca to filaments, initiating contraction and transports Ca back to cisternae ending contraction
Triad
Diad
Triad: skeletal muscle –T tubule and 2 sarcoplasmic terminal cisternae
depolarization of T tubules transmitted to SR at triads
Diad: cardiac muscle – one T tubule w/ 2 SR cisternae (diads located at Z lines)
When muscle contracts, each …shortens, but the … remain the same length
sarcomeres, Z bands, and I bands shorten, but actin and myosin (A bands) remain the same length
–thin filaments slide past thick filaments – overlap
Concentric vs eccentric contraction
Concentric: sarcomeres shorten
Eccentric: sarcomeres lengthen
**actin and myosin do not change length in either
Sliding filament theory
cross-bridging of actin and myosin slide thin filaments past thick ones (I bands shorten)
Golgi tendon organs
encapsulated bundles of Type I collagen in tendons near muscle fiber insertions
Recieves sensory info (NOT motor)
contraction of muscle compresses collagen
golgi tendon organs sense change in tension – relays info to CNS on muslce tension to help coordinate muscle contraction
Muscle spindles
encapsulated proprioceptors
CT space containing fluid and intrafusal fibers
sensory neurons penetrate capsule to detect changes in lenght and relay info to SC
Reflex pathways initiated
–bag and chain fibers
–sensory and gamma motor nerves
Cardiac muscle derived from what germ layer?
Smooth muscle?
Cardiac: splanchnic mesoderm (lateral plate) surrounding the heart tube
Smooth: splanchnic (gut), neural crest cells (eye m), local mesoderm (vascular)
Difference b/w fusion of skeletal vs cardiac muscle
vs smooth
Skeletal: syncytial
Cardiac: fuse to form complex junctions at ends
–chain like arrays that can bifurcate and join other arrays (results in “wringing out of the heart ventricles)
Smooth: fusiform cells w/ single nuclei