Axilla and Brachial Plexus Flashcards Preview

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Flashcards in Axilla and Brachial Plexus Deck (46)
1

Axilla

Pyramidal shaped region between arm & chest
Pec. major & minor mm. = Anterior wall
Lat. dorsi, teres major & subscapularis mm. = Posterior wall
Serratus anterior m. = Medial wall
Intertubercular sulcus of humerus = Lateral wall
Skin & Fascia of armpit = base

2

Axilla boundaries

Pectoralis major & minor mm. = Anterior wall
Lat. dorsi, teres major & subscapularis mm. = Posterior wall
Serratus anterior m. = Medial wall
Intertubercular sulcus of humerus = Lateral wall
Skin & Fascia of armpit = base

3

Axilla
Muscles in the lateral wall

include the Coracobrachialis (larger and posterior); & anteromedially = short head of Biceps m.; anterolaterally = Long head of Biceps m.

4

Axilla: Contents

Fat & connective tissue

Axillary v. & lymphatics (outside sheath)

Cutaneous nerves

Axillary sheath – axillary a. & brachial plexus

5

Axillary nodes

in fat; 5 principle groups:
pectoral nodes (anterior): 3-5 nodes near the lateral thoracic v. & inferior border of the pectoralis minor m. – receiving lymph from ant. thoracic wall and most of breast.
subscapular nodes (posterior): 6-7 nodes along subscapular vessels – receiving lymph from the post. thoracic wall and scapular region
humeral nodes (lateral): 4-6 nodes along lateral axilla and around axillary v. – receiving lymph from UL except for the portion along the cephalic v. which drain into the apical axillary and infraclavicular nodes.
central nodes: 3-4 large nodes deep to pectoralis minor
apical nodes: receive lymph from all the other groups of axillary nodes as well as the proximal cephalic v. nodes; forms the subclavian lymphatic trunk and may be joined by the jugular and bronchomediastinal trunks on the Rt side to form the Rt lymphatic jugular duct OR on the left the subclavian trunk most commonly joins the thoracic duct.

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pectoral nodes (anterior)

(anterior): 3-5 nodes near the lateral thoracic v. & inferior border of the pectoralis minor m. – receiving lymph from ant. thoracic wall and most of breast.

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subscapular nodes

(posterior): 6-7 nodes along subscapular vessels – receiving lymph from the post. thoracic wall and scapular region

8

humeral nodes

(lateral): 4-6 nodes along lateral axilla and around axillary v. – receiving lymph from UL except for the portion along the cephalic v. which drain into the apical axillary and infraclavicular nodes.

9

central nodes

3-4 large nodes deep to pectoralis minor

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apical nodes

receive lymph from all the other groups of axillary nodes as well as the proximal cephalic v. nodes; forms the subclavian lymphatic trunk and may be joined by the jugular and bronchomediastinal trunks on the Rt side to for the Rt lymphatic jugular duct OR on the left the subclavian trunk most commonly joins the thoracic duct.

11

Sensory Innervation of UL

Sensory = cutaneous

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Axillary sheath

contains the axillary a., nerves, veins and lymphatics
Location of the sheath is down the medial aspect of the arm

13


Axillary artery

Arises from the subclavian a. at the lateral border of the 1st rib

gives rise to the brachial a. at the inferior border of the teres major m.

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superiorly located branches of the subclavian a.: Suprascapular a. & Dorsal Scapular a. will

anastomose with the more inferiorly found Circumflex scapular arterial branch of the subscapular a from the 3rd part of the Axillary a.

15

deep transverse cervical branch will

anastomose with the dorsal scapular a.

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Axillary Artery: 3 Parts

1st: between 1st rib & pec. minor m.
Gives off Superior thoracic a.

2nd: deep to pec. minor m.
Gives off Thoracoacromial & Lateral Thoracic aa.

3rd: between pec. minor & teres major mm.
Gives off Subscapular, Anterior, & Posterior Circumflex Humeral aa.

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The Brachial Plexus

Composed of ventral rami C5-T1

Provides nerves for all UL mm. except trapezius m. (innervated by CN XI)

8 cervical nn., but only 7 cervical vertebrae

C1-C7 nn. emerge above C1-C7 vertebrae

C8 n. emerges below C7 vertebra

All other spinal nerves emerge below vertebrae of same number

18

Structure of Brachial plexus

Rami (5): emerge in upper neck
Trunks (3): form in lower neck
Divisions (6): split off behind clavicle
Cords (3): form in axillary region
Branches (5): split off in upper arm

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Brachial Plexus: Rami

These are the ventral Rami of spinal nerves C5-T1

20

Brachial Plexus: Trunks

C5 & C6 rami join to form the upper trunk
C7 ramus becomes the middle trunk
C8 and T1 rami join to for the lower trunk

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Brachial Plexus: Cords

The divisions recombine into cords (3) where the lateral cord contains the anterior contributions from the upper and middle trunks (thus contributions from C5-C7); the posterior cord combines all the posterior divisions of all the trunks (thus contributions from C5-T1); and the medial cord is derived from the anterior portion of the lower trunk (thus is contains C8 & T1 contributions).

22

Brachial Plexus: Branches

Read The Darn Cadaver Book

The terminal branches recombine again to give 5 major nerves of the UL.
Musculocutaneous C5, C6, & C7
Median C5-T1
Axillary C5 & C6
Radial C5-T1
Ulnar C8 & 1


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M” – 3 major branches
Brachial plexus


musculocutaneous n.
median n.
ulnar n

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Y - brachial plexus

other 2 major branches (reverse Y)
Radial nerve from posterior cord
and
Axillary n

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Musculocutaneous N. (C5-C7)

Formed from lateral cord
Passes thru coracobrachialis m.
Enters biceps brachii & brachialis mm.
‘Major N.’ of the anterior arm
Innervates coracobrachialis, biceps & ½ of brachialis m.

26

Median N. (C5-T1)

Formed from ½ lateral cord & ½ medial cord
Passes medial to arm mm.
‘Major N.’ of the anterior forearm
Innervates most of the anterior forearm, 3 thenar eminence mm. & 1st 2 lumbricals in hand

27

Ulnar N. (C8-T1)

Formed from medial cord
Runs behind medial epicondyle
‘Major N.’ of the hand
Innervates most of the mm of the hand, FCU m. & ulnar ½ FDP m. in forearm

28

Axillary N. (C5-C6)

Formed from posterior cord
Circles behind humerus in quadrangular space
Innervates deltoid & teres minor mm.

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Radial N. (C5-T1)

Formed from posterior cord
Passes posterior to humerus in radial groove & within triangular interval
“Major N.” of the posterior arm & forearm
Innervates all mm in both regions + ½ of brachialis m.

30

Upper plexus includes

branches from C5-C7

31

Pectoral nn from the

upper and lower trunks

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Lower plexus from the

posterior portion of all 3 trunks.

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Upper Plexus Nerves

Dorsal scapular n,
Long Thoracic n. (C5-C7)
Suprascapular n. (C5-C6)

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Dorsal Scapular n. (C5)

rhomboid & levator scapulae mm.

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Long Thoracic n. (C5-C7)

Serratus anterior m.

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Suprascapular n. (C5-C6)

supraspinatus & infraspinatus mm.

37

Pectoral Nerves

Lateral Pectoral n. (C5-C7)
pectoralis major m.

Medial Pectoral n. (C8-T1)
pectoralis major & minor mm.

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Lateral Pectoral n. (C5-C7)

pectoralis major m.

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Medial Pectoral n. (C8-T1)

pectoralis major & minor mm.

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Lower Plexus Nerves

Upper Subscapular n. (C5-C6)

Thoracodorsal n. (C6-C8)

Lower Subscapular n. (C5-C6)

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Upper Subscapular n. (C5-C6)

subscapularis m.

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Thoracodorsal n. (C6-C8)

latissimus dorsi m.

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Lower Subscapular n. (C5-C6)

subscapularis & teres major mm.

44

Nerve to subclavius m. (C5-C6)
-extra nerves

subclavius m.

45

Medial brachial cutaneous n. (C8-T1)
extra nerves

sensory to medial arm

46

Medial antibrachial cutaneous n. (C8-T1)
extra nerves

sensory to medial forearm