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Borders of Axilla
- Inferior: skin and fat
- Superior: space between 1st rib and clavicle
- Anterior: pectoralis major and minor
- Posterior: subscapularis, teres major, latissimus dorsi
- Medial: serratus anterior
- Lateral: humerus
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Contents of Axilla
- Axillary artery and vein
- Cords of brachial plexus surround artery
- Axillary sheath (axillary artery, vein, and brachial plexus cords)
- Lymph nodes
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Brachial Plexus
- Rules of 5:
- -5 spinal roots:
- -trunks emerge between anterior and middle scalenes
- -C5 is highest
- -5 segments: Roots, Trunks, Divisions, Cords, Branches
- -5 terminal branches: Musculocutaneous, Axillary, Radial, Median, Ulnar
- Roots and trunks are supraclavicular
- Divisions are retroclavicular
- Cords and terminal branches are infraclavicular
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Terminal branch supply (general)
- Musculocutaneous (C5–C7): anterior arm (in general) – pierces coracobrachialis m.
- Axillary (C5–C6): Deltoids, teres minor
- Median (C5-T1): Majority of anterior forearm and thenar eminence (bulge below thumb)
- Ulnar (C7-T1): a couple of muscles in medial forearm; medial muscles of hand
- Radial (C5-T1): posterior brachium and posterio forearm muscles
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Dorsal Scapular n.
- C4–C5
- Comes off roots of brachial plexus
- Innervates: rhomboids, levator scapulae
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Long Thoracic n.
- C5–C7
- comes off roots
- Innervates: serratus anterior
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Suprascapular n.
- C5–C6
- Comes off superior trunk
- Innervates: supraspinatus, infraspinatus
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Lateral Pectoral n.
- C5–C7
- Comes off lateral cord
- Innervates: pectoralis major - clavicular head
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Medial Pectoral n.
- C8–T1
- Comes off medial cord
- Innervates: pectoralis minor, pectoralis major - sternoclavicular head
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Medial Antebrachial cutaneous
- C8–T1
- Comes off medial cord
- Innervates: skin of medial forearm
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Medial Brachial Cutaneous
- C8–T1
- Comes off medial cors
- Innervates: skin of medial arm
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Thoracodorsal n.
- C6–C8
- Comes off posterior cord
- Innervates: Latissimus dorsi
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Upper subscapular n.
- C5–C7
- Comes off posterior cord
- Innervates: subscapularis
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Lower subscapular n.
- C5–C6
- Comes off posterior cord
- Innervates: subscapularis, teres major
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Dermatomes
- C2: back of head
- C3: upper neck
- C4: lower neck and shoulders
- C5: over deltoid region
- C6: thumb
- C7: middle finger
- C8: pinky finger
- T1: medial antebrachium
- T2: upper medial brachium
- T4: nipple line
- T10: umbilical
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Peripheral Innervation
- Axillary: Deltoid region (lower)
- Medial Brachial Cutaneous: Upper medial brachium
- Medial Antebrachial Cutaneous: Medial antebrachium
- Ulnar: lateral hand and 1.5 digits
- Supraclavicular: top of shoulder
- Radial: Posterior brachium, posterior lateral 2/3 of hand but not finger tips
- Median: palmar lateral 2/3 of hand
- Musculocutaneous: lateral antebrachium
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Clavicular orientation
lateral end 20 degrees posterior and 15 degrees superior to medial end
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Scapular Plane
35 degrees anterior off frontal plane
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Sternoclavicular Joint
- Only bone-to-bone connection of UE to axillary skeleton
- Saddle Joint
- Convex superior to inferior
- Concave anterior to posterior
- Articular disk – allows clavicle to spin
- Ligaments: anterior and posterior sternoclavicular; interclavicular; costoclavicular
- Movements: elevation; depression; forward and backward for protraction and retraction; posterior rotation/spin of 30 degrees
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Acromioclavicular Joint
- Plane joint
- Usually, line of joint is posteromedial about 30 degrees
- Ligaments: coracoacromial; coracoclavicular – conoid; trapezoid
- Movements: internal (scapular protraction) and external (scapular retraction) rotation; upward and downward rotation; tilting forward and backward
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Scapulothoracic Joint
- Not a true joint - plane
- several bursas lie between scapula and thorax
- Motions: protraction, retraction, anterior and posterior tilting, upward and downward rotation
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Glenohumeral Joint
- Ball and Socket
- Motions: sliding, gliding, rolling
- Rotator cuff interval: space between subscapularis and supraspinatus
- Ligaments: Superior (prevents: ADDuctions, inferior translation, posterior translation), middle (ER at 45 degrees, ABduction, anterior translation) inferior (ER – anterior band – and IR – posterior band) above 45 degrees, ABduction, )
- GH ligs;
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Scapulohumeral Rhythm
For every 3 degrees of humeral elevation, there is 1 degree of scapular motion (scapulothoracic joint) and 2 degrees of humerus on the scapula (GH joint)
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Suprascapular Artery
- Comes off thyrocervical trunk off subclavian artery
- Goes under clavicle, above scapula, and through suprascapular notch (below superior transverse scapular ligament)
- Supplies: supraspinatus, infraspinatus
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Superior Thoracic a.
- Branch off of 1st part of axillary artery
- Supplies: intercostals; superior part of serratus anterior; overlying pectoral muscles
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Thoracoacromial a.
- Divides into 4 major arteries: acromial, clavicular, pectoral, deltoid
- 1st branch off 2nd part of axillary a.
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Lateral Thoracic a.
- 2nd branch off 2nd part of axillary a.
- Supplies: pectoral, serratus anterior, and intercostal muscles
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Subscapular a.
- Largest branch off the 3rd part of the axillary artery
- Divides into circumflex scapular artery; thoracodorsal artery
- Circumflex scapular: anastomoses with spurascapular to supply scapula area
- Thoracodorsal: supplies latissimus dorsi
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Anterior and Posterior Humeral Circumflex aa.
- Branch(es) off 3rd part of axillary artery opposite subscapular a.
- Sometime have common turnk
- Posterior passes through quadrangular space
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