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Anatomy - Upper limb > L5: Musculo-neuro-vascular systems of pectoral and dorsal regions > Flashcards

L5: Musculo-neuro-vascular systems of pectoral and dorsal regions Flashcards

1
Q

what is a muscle

A

Muscle is a contractile tissue consisting of cells called myocytes
Muscles cross at least one joint; i.e., each end of muscle attached to different bones

“Origin” – Proximal attachment*Usually remains fixed during movement
“Insertion” – Distal attachmentUsually, the part that moves

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2
Q

how do muscles work

A

Skeletal muscle consists of:
-Myocytes (muscle fibres)
-Bundled into fascicles
-Bundled into muscle

Myocytes contract (shorten) when they are activated by nerves (neurons)
Induces contraction of myofibrils with muscle cells via the sliding filament mechanism

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3
Q

myocyte activation

A

Electrical signals (nerve impulse) travels along nerves, towards muscles
1.Electrical signal triggers release of acetylcholine (ACh) neurotransmitter from the end of the nerve cell
2.Neurotransmitter (ACh) travels across neuromuscular junction where it binds to ACh receptor on muscle cell
3.Triggers muscle action potential and muscle contraction

Muscles consist of many myocytes
*Many myocytes contracting together produces strong muscular movement

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4
Q

brachial

A

relating to, or situated in the arm

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5
Q

plexus

A

a network of anastomosing or interlacing blood vessels or nerves

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6
Q

brachial plexus

A

is the system of nerves that emerge lateral to the spinal chord and :
- allow motor nerves send their signals from brain to upper limb muscles
- allow sensory nerves send their signals back to the brain

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7
Q

brachial plexus; intro

A

spinal nerves leave spine through spaces between vertebrae

brachial plexus formed by C5-T1 spinal nerves

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8
Q

brachial plexus- sections

A

Roots - 5 > C5-T1
Trunks - 3 > sup, mid, inf
Divisions - 6 > anterior , posterior
Cords - 3 > lat, medial, post

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9
Q

movements of the scapula

A

elevation + depression
protraction + retraction
upward + downward rotation

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10
Q

scapular movers or stabilisers (6 muscles)

A

muscles that connect the scapula to the axial skeleton

dorsal region [back];
1. trapezius
2. levator scapulae
3. rhomboid minor
4. rhomboid major

pectoral region [front of chest]
5. pectoralis minor
6. serratus anterior

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11
Q

trapezius; origin

A

large diamond shaped superficial muscle of the back
developed in rowers

origin:
-external occipital protuberance
-nuchal ligament
-spinous process of C7-T12 vertebrae

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12
Q

trapezius; insertion

A
  • spine of scapula
  • acromion of scapula
  • lateral 1/3 of clavicle
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13
Q

trapezius; innervation

A

spinal accessory nerve
aka cranial nerve 11

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14
Q

trapezius; actions

A
  • powerful retractor of scapula [rowing]
  • elevates scapula [upper fibres]
  • depresses scapula [lower fibres]
  • upward rotation of scapula [upper fibres]
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15
Q

levator scapular; origin

A

small muscles from neck vertebrae to medial superior scapula. deep to trapezius

origin: transverse processes of C1-4 vertebrae

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16
Q

levator scapular; insertion

A

superior part of medial border of scapula

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17
Q

levator scapular; innervation

A

dorsal scapular nerve [C4-5]

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18
Q

levator scapular; actions

A
  • elevates medial border of scapula
  • downward rotation of scapula
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19
Q

rhomboid minor; origin

A

deep to trapezius, superior to rhomboid major
spinous process of C7-T1
vertebrae

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20
Q

rhomboid minor; insertion

A

medial border of scapula, root of spine

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21
Q

rhomboid minor; innervation

A

dorsal scapular nerve (C4-5)

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22
Q

rhomboid minor; actions

A
  • retracts scapula
  • downward rotation of scapula
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23
Q

rhomboid major; orign

A

deep to trapezius, inferior to rhomboid minor

origin: spinous process of T2-T5 vertebrae

24
Q

rhomboid minor; insertion

A

medial border of scapula (inferior 2/3)

25
Q

rhomboid minor; innervation

A

dorsal scapular nerve (C4-5)

26
Q

rhomboid minor; actions

A
  • retracts scapula
  • downward rotation of scapula
27
Q

dorsal scapular nerve

A

formed from spinal nerve roots C4-5
Passes inferiorly, medial to medial border of scapula
Innervates:
- levator scapula
- rhomboid minor
- rhomboid major

28
Q

pectoralis minor; origin

A

deep to pectoralis major

origin: anterior surface of ribs 3-5

29
Q

pectoralis minor; insertion

A

coracoid process of the scapula

30
Q

pectoralis minor; innervation

A

medial pectoral nerve (C8-T1)

31
Q

pectoralis minor; actions

A

protracts and stabilises scapula by pulling it antero-inferiorly onto posterior thoracic wall

32
Q

medial pectoral nerve

A

arises from medial cord of brachial plexus
formed by contributions from spinal nerve roots C8-T1)
passes inferiorly deep to pectoralis minor providing innervation

33
Q

serratus anterior; origin

A

between scapula and posterior thoracic wall

origin: medial border of scapula, anterior surface

34
Q

pectoralis minor; insertion

A

individual muscle slips that insert into anterolateral surface of ribs 1-8

35
Q

pectoralis minor; innervation

A

long thoracic nerve (C5-7)

36
Q

pectoralis minor; actions

A
  • protracts and stabilises scapula by pulling it anteriorly against the thoracic wall
  • very important in pushing + punching
  • assists with upward rotation of scapula by pulling inferior angle laterally
37
Q

long thoracic nerve

A

formed from spinal nerve roots C5-7
passes inferiorly over the lateral surface of serratus anterior
innervates serratus anterior
nerve protected when limbs at side, but is vulnerable when limbs elevated

38
Q

long thoracic nerve palsy

A

caused by injuries to the long thoracic nerve
trauma, heavy weightlifting repeated throwing
causes paralysis of serratus anterior - lack of protraction
scapular cannot be held firmly against the posterior aspect of the thoracic cage

winging of the scapula
‘‘C5, 6, 7 spread your wings and go to heaven’’

39
Q

muscles that stabilise and/or move the glenohumeral joint and arm

A
  1. pectoralis major
  2. latissimus dorsi
40
Q

pectoralis major; origin

A

large muscle on anterior chest wall - it has 2 heads

origin:
clavicular head: medial 1/2 clavicle
sternocostal head: sternum, upper 6 costal cartilages, aponeurosis of external oblique

41
Q

pectoralis major; insertion

A

lateral lip of bicipital groove

42
Q

pectoralis major; innervation

A

medial pectoral nerve [C8-T1]
lateral pectoral nerve [C5-7]

43
Q

pectoralis major; actions

A
  • flexes shoulder from the extended position
  • adducts and internally rotates humerus
44
Q

medial pectoral nerve

A

arises from medial cord of brachial plexus
formed by contributions from spinal nerve roots C8-T1.
passes inferiorly deep to pectoralis minor providing innervation

45
Q

lateral pectoral nerve

A

arises from lateral cord of brachial plexus
formed by contributions from spinal nerve roots C5-7
descends deep to pectoral muscles and innervates them from posterior

46
Q

latissimus dorsi; origin

A

back muscle, very well developed in rowers

origin:
- spinous process of T6-L5 & S1-2
- thoracolumbar fossa
- inferior ribs
- posterior iliac crest of pelvis
- inferior angle of scapula

47
Q

latissimus dorsi; insertion

A

floor of bicipital groove

48
Q

latissimus dorsi; innervation

A

thoracodorsal nerve C6-8

49
Q

latissimus dorsi; actions

A
  • extends, adducts, medially rotates humerus
  • downward rotation of scapula
50
Q

thoraco-dorsal nerve (C6-8)

A

arises from posterior cord of the brachial plexus
formed by contributions of spinal nerves C6-8
passes inferiorly, between scapula and thorax to reach and innervate latissimus dorsi
upon reaching latissimus dorsi, runs obliquely [inferomedially] along L. Dorsi innervating the whole muscle

51
Q

arterial blood supply to upper limb

A

the axillary artery has 3 parts:
1. proximal to pectoralis minor
2. deep to pectoralis minor
3. distal to pectoralis minor

there are 6 branches of the axillary artery:
1st part: 1 branch
2nd part: 2 branches
3rd part: 3 branches

once the axillary artery passes the inferior border of the teres major muscle, it becomes known as the brachial artery

52
Q

axillary artery [part 1]

A

superior thoracic artery
- passes anteriorly and inferiorly between pectoralis major and minor
- supplies pectoralis major and minor

53
Q

axillary artery [part 2]

A

Thoraco-acromial artery:
- runs over pectoralis minor and divides into 4 branches supplying: clavicle, deltoid, acromion, pectoral muscles

Lateral thoracic artery:
- descends along lower border of pectoralis minor to supply: serratus anterior, both pectoral muscles, N.B. in female provides additional branches to breast

54
Q

axillary artery [part 3]

A

Anterior circumflex humeral artery:
- passes anteriorly around surgical neck of humerus anastomosing with posterior circumflex humeral artery

Posterior circumflex humeral artery:
- passes posteriorly around surgical neck of humerus anastomosing with anterior circumflex humeral artery

Subscapular artery:
- largest branch of axillary nerve
- divides into: circumflex scapular artery & thoracodorsal artery

55
Q

anastomosis:

A

Anastomosis: a cross-connection between adjacent channels, tubes, fibres, or other parts of a network

56
Q

Arterial Supply Around the Scapula: Anastomosis

A

Terminal branches from Subclavian artery supply medial and superior scapula.
Terminal branches from axillary artery supply inferior and lateral scapula
These terminal branches anastomose together to provide complete coverage of the scapula

57
Q

veins of pectoral and dorsal region

A

Axillary Vein drains venous blood proximally toward the heart.
It is formed at the lower border of teres major by the union of the brachial vein and basilic vein.
It runs superomedially, anteromedial to axillary artery, until it crosses the lateral border of the first rib where it becomes the subclavian vein.
The axillary vein receives tributaries that correspond to branches of the axillary artery.
Proximally, the axillary vein also receives the cephalic vein

Anatomy - Upper limb (10 decks)

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