MSK Anatomy Flashcards
rectus fibers run…
straight
transversus fibers run…
at right angles
oblique fibers run…
at angles to imaginary defined axis
what are the muscles of mastication
four pairs, all innervated by cranial nerve 10
- jaw closure: temporalis and masseter
- grinding: pterygoids
- chewing: buccinator
muscles promoting tongue movements
three extrinsic muscles anchor and move the tongue (all innervated by CN VII/hypoglossal)
- genioglossus
- hyoglossus
- styloglossus
what muscle divides the neck into two triangles (ant and post)
SCM
what are the anterior neck muscles
suprahyoid muscles
infrahyoid muscles
process of swallowing
tongue and buccinator muscles push food back toward pharynx, where muscles in post mouth and pharynx complete swallowing
epiglottis closes over larynx while muscles in walls of pharynx propel food foward to stomach
suprahyoid muscle group actions
four muscles involved in swallowing
- form floor of oral cavity
- anchor tongue
- elevate hyoid bone
- move larynx during swallowing
infrahyoid muscle group actions
four straplike muscles that depress the hyroid bone and larynx during swallowing and speaking
- sternohyoid
- sternothyroid
- omohyroid
- thyrohyoid
what muscles move the head
anterolateral neck muscles
what muscles extend the trunk/maintain posture
intrinsic muscles of the back
muscles of inspiration
diaphragm and external intercostals
- contraction = enlarges rib cage
- diaphragm divides thoracic and abdominal cavities
muscles of expiration
expiration brought on by relaxation of inspiratory muscles (dec rib cage size), as well as contraction of internal intercostals
action of anterior abdominal muscles
- lateral flexion and rotation of trunk
- compression of abdominal viscera
- promote urination, defacation, childbirth, vomiting, coughing, screaming
anterior abdominal wall muscles
four paired muscles; their fasciae and aponeuroses form lateral and anterior abdominal wall
- rectus abdominis
- external obliques
- internal obliques
- transversus abdominis
all innervated by intercostal nerves
muscles of pelvic diaphragm
two paired muscles, both innervated by sacral nerves
- levator ani
- coccygeus
muscles of the urogenital diaphragm
- anterior half of perineum, inf to pelvic floor
- deep transverse perineal muscle
- contains external urethral sphincter (voluntary)
muscles of superficial perineal space
- ischiocavernosus + bulbospongiosus help maintain erection of penis/clitoris
- superficial transverse perineal muscles
where do C1-C7 nerve roots come out in relation to their vertebrae?
ABOVE the vertebrae
where does C8 nerve root come out in relation to their vertebrae?
Above T1
where do T1- coccygeal nerve roots come out in relation to their vertebrae?
BELOW the vertebrae
where does the cervical cord nerve root come out in relation to their vertebrae?
1 above SP
where does the thoracic cord nerve roots come out in relation to their vertebrae?
2 above SP
where does the lumbar cord nerve root come out in relation to their vertebrae?
4 above SP
rootlets location
extend out from dorsal and ventral horns and converge into ROOTS
dorsal and ventral horns location
exit vertebral column and unite to form SPINAL NERVE
spinal nerve splits into…
RAMI
remi innervation
- dorsal ramus innervates deep back muscles and overlying skin
- ventral remus innervates remaining muscles, skin, etc
____ form the brachial plexus
ventral/ant rami
most nerves we encounter are…
ventral rami
at what joint does the upper extremity articulate with the axial skeleton?
sternoclavicular
what are the muscles called that support, propel, and stabilize the pectoral girdle?
axioappendicular muscles
what nerves make up the brachial plexus? where do they innervate?
C5 - shoulder
C6 - elbow
C7 - wrist
C8 - hand
T1 - hand
brachial plexus trunks
C5 + C6 > 1st trunk
C7 > 2nd
C8 + T1 > 3rd
from which nerve roots on the brachial plexus does the long thoracic nerve run from?
C5-C7
from which nerve roots on the brachial plexus does the dorsal scapular nerve run from?
C5
what are the end branches of the brachial plexus? where do they stem from?
- musculocutaneous (C5-C7)
- axillary
- radial (C5-C8, T1)
- median (C5-C8, T1)
- ulnar (C8, T1)
where does the axillary nerve stem from?
off the radial nerve
what are the three trunks of the brachial plexus?
superior
middle
inferior
what is the order of splitting of the brachial plexus?
“Rugby Teams Don’t Cover Bruises”
- 5 roots (C5-T1)
- 3 trunks (sup, mid, inf)
- 2 divisions (each trunk > ant + post)
- 3 cords (lateral, medial, post)
- 5 branches (musculocut, axil, median, radial, ulnar)
branches of the lateral cord of the brachial plexus
Rugby players are:
Long Legged Movers
- lat pectoral n
- lat root of medial n
- musculocutaneous n
branches of the medial cord of the brachial plexus
Rugby Players:
Make Many Moves Using Muscles
- medial brachial cutaneous n
- medial antebrachial cutaneous n
- medial pectoral n
- ulnar n
- medial root of median n
branches of the posterior cord of the brachial plexus
Rugby players are:
ULTRA competitive
- upper subscapular n
- lower subscapular n
- thoracodorsal n
- radial n
- axillary n
what four joints make up the shoulder
- glenohumoral
- sternoclavicular
- acromioclavicular
- scapulothoracic
what is the glenohumoral joint?
ball and socket joint between the head of humerus and the glenoid fossa of the scapula
capsule is thin and loose; lies in folds when arm is adducted, and is taunt when arm is abducted
what part of the glenohumeral capsule is weakest? why?
inf part is weakest bc its not reinforced by rotato cuff mm
what runs through an aperature in the glenohumeral capsule?
long head of biceps
what are the capsular ligaments of the glenohumeral joint? what are their functions?
- glenohumeral: thickening of ant capsule
- coracohumeral: strengthens sup part of capsule
- transverse humeral: holds down tendon
- coracoacromial: limits superior movement
what strengthens the shoulder/AC joint superiorly?
acromioclavicular ligament
where does most of the strenght of the acromioclavicular joint come from?
coracoclavicular ligament
- trapezoid ligament (extends to trapezoid line on inf clavicle)
- conoid ligament (attached to root of coracoid process and conoid tubercle on inf clavicle)
arterial supply of acromioclavicular joint
suprascapular and thoracoacromial arteries
nerve supply of acromioclavicular joint
supraclavicular, lateral pectoral, axillary
main superficial vessels of upper limb
cephalic and basilic
- originate in subcutaneous tissue on dorsum of hand from dorsal venous network
- both lead to axillary v
B > A
C > MC > A
basilic vein path
basilic vein ascends on medial side, pierces brachial fascia, runs superiorly and parallel to brachial atery and drains into axillary v
cephalic vein path
- ascents to ant elbow to communivate with median cubital vein
- cephalic passes b/w deltoid and pec major muscles in deltopectoral groove and enters delto/clavipectoral triange and pierces the costocoracoid membrane to join the axillary v
what is the main vein used in blood draws
median cubital vein
pec major origin
- medial clavicle
- sternum
- upper 6 costal cartilages (2 heads, clavicular and sternocostal)
pec major insertion
bicipital groove (humerus)
pec major nerve
medial and lateral pectoral nerves
pec major action
flex, adduct, medially rotate humerus
what forms the anterior axillary fold?
inferior border of pec major
pec minor origin
ribs 3,4,5
pec minor insertion
coracoid process of scapula (forms a bridge under which the neurovascular bundle travels)
pec minor nerve
medial pectoral n
pec minor action
- protraction, depression, med rotation of scapula
- stabilizes scapula, esp when stretching for something just out of reach
subclavius origin
1st costal cartilage
subclavius insertion
inf groove of clavicle
subclavius nerve
n to subclavius
subclavius action
- depresses and stabilizes scapula
- protects neurovascular bundle if clavicle breaks
serratus anterior action
- holds scapula to chest wall
- protraction and sup rotation of scapula
serratus anterior origin
external surfaces of ribs 1-8
serratus anterior insertion
medial border of scapula
trap origin
- sup nuchal line
- EOP
- nuchal ligament
- spines of C7-T12
trap insertion
- spine of scapula
- acromion
- lateral third of clavicle
serratus anterior innervation
long thoracic nerve
what forms the medial wall of the axilla?
serratus anterior
trap innervation
CN XI (accessory)
what is the posterior triangle
- space between trap, clavicle, and SCM
- brachial plexus and axillary artery pass between ant and middle scalene muscles
accessory nerve location
descends from base of skull, out of post triangle of neck, down side of neck, and deep to trapezeius
lat dorsi origin
- spines of T6-L5
- median crest of sacrum
- iliac crest
lat dorsi insertion
intertubercular groove of humerus
lat dorsi actions
extend, adduct, medially rotate humerus
- chin ups
lat dorsi innervation
thoracodorsal nerve
rhomboid minor origin and insertion
- O: SPs of C7-T1
- I: medial border of scapula, at level of spine
rhomboid major origin and insertion
- O: SPs of T2-T5
- I: medial border of scapula, below level of spine
levator scapulae origin, insertion, and relationship to SCM
- deep to SCM
- O: TPs of C1-4
- I: medial border of scapula, above the spine
levator scap, rhomboid major, rhomboid minor actions
- ALL elevate, retract, and medially rotate the scapula
- LEV SCAP ONLY - unilaterally flexes neck, B/L extends neck
levator scap, rhomboid major, rhomboid minor innervation
dorsal scapular nerve
nerves to muscles of the superficial back and what CN they come off of
- dorsal scapular (CN5)
- suprascapular (CN5,6)
- accessory (CN XI)
- axillary (CN
muscles on the scapula that move the humerus
- deltoid
- supraspinatus
- infraspinatus
- subscapularis
- teres major
- teres minor
- triceps
deltoid origin
CLASPs
- clavicle (lateral 1/3, ant deltoid)
- acromion (intermediate deltoid)
- SPine of scapula (post deltoid)
deltoid insertion
deltoid tuberosity of humerus
deltoid innervation
axillary
deltoid actions
acts on humerus
- flex and extend
- abduct (all 3 parts together)
- medially and laterally rotate
axillary nerve innervation, location, clinical importance
- innervates deltoid and teres minor
- passes through quadrangular space b/w teres and the long head of triceps and humerus
Clinical: quadrilateral space syndrome (QSS) = compression of axillary n and post humeral circumflex artery as they pass through this space
what are the rotator cuff muscles?
SITS (clockwise from top)
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
tendons of all these blend w glenohumeral joint capsule, reinforcing it
supraspinatus origin and insertion
O: supraspinous fossa
I: greater tubercle
supraspinatus action
abduct humerus (with deltoid)
supraspinatus innervation
suprascapular n
infraspinatous origin and insertion
O: infraspinous fossa
I: greater tubercle
infraspinatous action
laterally rotates humerus
infraspinatous innervation
suprascapular n
teres minor origin and insertion
O: lat border scap
I: greater tubercle humerus
teres minor action
laterally rotates humerus
teres minor innervation
axillary nerve
subscapularis origin and insertion
O: subscapular fossa
I: lesser tubercle
subscapularis action
medially rotates humerus
subscapularis innervation
upper and lower subscapular nerves
suprascapular nerve pathway, innervation
- originates from upper trunk of brachial plexus
- passes thru suprascapular foramen > post scapular region
- innervates supraspinatus
- passes thru greater scap (spinoglenoid) notch
- terminates in and innervates infraspinatus
teres major origin and insertion
O: lateral border scap
I: medial intertubercular groove
teres major action
adduct, medially rotate, and extend humerus
teres major innervation
lower subscapular nerve (off axillary nerve)
arteries of upper limb
- subclavian: bw ant and middle scalenes
- axillary: from lat 1st rib > lower teres major
- brachial: from teres major > bifurcation of R + U arteries
- radial
- ulnar
- deep and superficial palmar arches
- digital arteries
location of axillary artery
lateral border of first rib > inf border teres major
axillary artery divisions
divided into three parts relative to pec minor
- 1st: gives rise to sup thoracic artery and is enclosed in the axillary sheath
- 2nd: post to pec minor and gives rise to thoracoacromial and lateral thoracic arteries which pass medial and lateral to the muscle respectively
- 3rd: supscapular (largest branch), and anterior + posterior circumflex humeral arteries
collateral circualtion around scapula
anastomoses from subclavian and axillary arteries
- dorsal scapular a (vertebral scap border)
- suprascap a (supra and infraspinous fossa)
- circumflex scapular a (medial triangular space)
- transverse cervical artery
elbow joint ligaments, arterial supply, and innvervation
- ulnar collateral
- radial collateral
- annular
arterial: anastomasis of arteries around elbow joint
innervation: musculocutaneous, radial, ulnar nerves
ulnar collateral anatomy
triangular shaped, upper and lower bands (ulnar nerve passes bw bands post to medial epicondyle)
“funny bone”
radial collateral ligament anatomy
attached to annular ligament
annular ligament anatomy
sling around head of radius to form proximal radioulnar joint
proximal radioulnar joint
joint type, ligaments
pivot type synovial joint
- annular ligament (permits rotation of head of radius around ulna)
- interosseous membrane (links bones together)
muscles of the arms, innervation rules to live by
- all extensors and supinators: radial n
- all “pronator” names: median nerve
- flexors: musculocutaneous
this means some have 2
MAIN arm flexor
brachialis; the only PURE flexor, produces the most force
brachialis origin and insertion
O: ant surface of distal half of humerus
I: coronoid process/ulnar tuberosity of ulna
brachialis innervation
musculocutanous
(in some people it also includes radial)
brachialis action
flexes forearm in slow and quick movements
steadies arm during extension by slow relaxation
coracobrachialis origin and insertion
O: coracoid process
I: middle 1/3 humerus
coracobrachialis action
flex and adduct arm
stabilizes glenohumeral joint
coracobrachialis innervation
musculocutaneous (pierced by the nerve which then continued as lateral cutaneous nerve of forearm)
triceps origin and insertion
O
- long head: infraglenoid tubercle
- lateral head: post humerus (sup/lat to radial groove)
- medial head: post humerus (inf/med to radial groove)
I: olecranon process of ulna
triceps innervation
radial n
triceps action
extends arm and forearm
stabilizes adducted glenohumeral joint
what muscle helps the tricep extend the forearm and also abducts humerus during forearm pronation?
anconeus m
what nerves would be affected by fractures at different points of the humerus?
ARM
- Axillary: head of humerus
- Radial: mid shaft
- Median: supracondylar
cubital fossa boundaries
- medial: pronator teres
- lateral: brachioradialis
- superior: imaginary line connecting medial and lateral epicondyles of humerus
- floor: brachialis + supinator mm
- roof: brachial and antebrachial fascia w/ bicipital aponeurosis
structures in the cubital fossa
Really Need Beer To Be At My Nicest (lateral to medial)
- radial n
- biceps tendon
- brachial artery
- median nerve
flexor digitorum superficialis anatomy, insertion, innervation, action
intermediate layer
inserts on middle phalanges of 4 fingers
median n
flexes fingers
deep layer of lower arm muscles
- flexor digitorum profundus
- flexor pollicus longus
- pronator quadratus
flexor digitorum profundus insertion and innervation
inserts on distal phalanges
median n to radial half
ulnar n to ulnar half
flexor pollicis longus insertion and innervation
inserts on distal phalanx of thumb
median n
pronator quadratus location and innervation
extends from ulna to radius
prime mover for pronation, reinforces interosseus membrane (keeps radius and ulna together, esp in FOSH injury)
median n
extensor muscles of the forearm (post)
- mm that extend/abduct/adduct hand at the wrist (extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris)
- extend the medial four digits (extensor digitorum, extensor indicis, extensor digiti minimi)
- extend/abduct thumb (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus)
brachioradialis origin, insertion, innervation, and action
origin on lat humerus
inserts on radius
radial n
flexes elbow, maintains half pronated position “beer drinking muscle”
extensors carpi radialis longus and brevis
insertion, innervation, action
insert on MC 2,3
radial n
extends and radially deviates wrist
extensors digitorum and digiti minimi
insertion, innervation, action
insert into extensor expansions over middle and distal phalanges
radial n
extends fingers
extensor carpi ulnaris
insertion, innervation, action
insert on MC 5
radial n
extends wrist and ulnar deviate
posterior forearm muscles and innervation
- supinator
- abductor pollicis longus
- extensor pollicis brevis
- extensor pollicis longus
- extensor indicis
radial n
ulnar nerve location and innervation
- passes post to medial epicondyle > enters forearm between heads of flexor carpi ulnaris > down ulnar side between this and FCU and FDP > becomes superficial at wrist
innervates
- flexor carpi ulnaris
- 1/2 of flexor digitorum profundus
what artery is used to take BP
brachial
superficial palmar arch anatomy
- formed primarily by ulnar artery, as it enters palm through tunnel of guyon
- anastomosis with radial artery
structures in carpal tunnel
- median n
- flexors digitorum superficialis and profundus
- flexor pollicis longus
carpal tunnel syndrome results
- cutaneous senosry loss on median n distribution (thumb, pointer, middle)
- thenar wasting
- weakness of lumbricals 1,2
ulnar n innervation cutaneous
1.5 digits, ulnar side of palm, dorsum of hand
