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Medicine year 2 semester 2 > Case 23- anatomy > Flashcards

Case 23- anatomy Flashcards

1
Q

The Brachial plexus roots

A

Formed from the anterior rami of C5-T1
• 7 cervical vertebra
• 8 cervical spinal nerves
• Cervical spinal nerves arise above their corresponding vertebra
• C8 arises between vertebra C7 and T1
• These are the roots of the brachial plexus

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2
Q

Location of the brachial plexus

A

The roots emerge in the neck between the anterior and middle scalene. It starts in the neck and crosses rib 1 to enter the axilla. In the axilla it lies in close relation to the axillary artery.

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3
Q

The Brachial plexus structure

A
  • The roots are from the anterior rami C5-T1
  • The roots merge to form 3 trunks (superior, middle and inferior)
  • Each trunk separates into different divisions (anterior and posterior)
  • The divisions unite to form cords (lateral, posterior, Medial)
  • The terminal branches arise from the cords (Musculocutaneous, Median, Axillary, Radial, Ulnar)
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4
Q

Subdivisions of the Brachial plexus

A

Roots, Trunks, Divisions, Cords and Branches. You can remember it with the mnemonic Rugby Teams Drink Cold beverages

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5
Q

Key landmarks on the Brachial plexus

A
  • M shape
  • Musculocutaneous nerve pierces the Coracobrachialis
  • Median nerve travels with the brachial artery
  • The Radial nerve is a major branch of the posterior cord
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6
Q

The 5 main terminal branches of the brachial plexus are

A
  • Musculo-cutaneous nerve- C5, C6, C7 root
  • Axillary nerve- C5, C6 root
  • Radial nerve- C5, C6, C7, C8, T1 root
  • Median nerve- C5, C6, C7, C8, T1 root
  • Ulnar nerve- C8, T1 root
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7
Q

Brachial plexus- the trunks which form the divisions and cords

A

Superior trunk- Anterior division goes to lateral cord, posterior division goes to the posterior cord
Middle trunk- Anterior division goes to the lateral cord, posterior division goes to the posterior cord
Inferior trunk- Anterior division goes to the medial cord, Posterior division goes to the posterior cord,

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8
Q

Brachial plexus- what branches does the cords go to

A 
Muscutaneous- Lateral cord
Axillary- Posterior cord
Radial- Posterior cord
Median- Lateral and medial cord
Ulnar- Medial cord
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9
Q

Brachial plexus- what roots do the nerves go from

A

The Musculocutaneous and axillary come from the upper roots, the Ulnar from the lower roots. The median and radial emerge from all roots

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10
Q

Branches of the cords

A
  • Lateral pectoral- lateral cord
  • Thoracodorsal- posterior cord
  • Subscapular nerves- posterior cord
  • Medial pectoral- medial cord
  • Medial brachial cutaneous- medial cord
  • Medial antebrachial cutaneous- medial cord
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11
Q

3 main articulations of the shoulder joint

A
  • Sternoclavicular joint- between the sternum and the clavicle
  • Acromioclavicular joint- between the acromion of the scapula and the clavicle
  • Glenohumeral joint- between the head of the humorous and the Glenoid fossa of the scapula
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12
Q

Role of the clavicle

A

The clavicle helps with weight bearing arm increasing the range of movements by holding the arm away from the thorax

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13
Q

All the shoulder joints are mobile

A
  • Allow movements of the scapular which increases the range of movement
  • Mobility of the scapula is essential for free movement of the upper limb, it can move around the rib cage
  • All three articulations are mobile allowing for increased range of movement
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14
Q

Sternoclavicular joint

A

A synovial, saddle joint between the proximal clavicle and manubrium of the sternum. Contains an articular disk which is a shock absorber for forces transmitted through the clavicle from the upper limb. The joint is very strong as it contains lots of ligaments stabilising the joint. A clavicular fracture is more likely than a Sternoclavicular dislocation.

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15
Q

Ligaments in the shoulder joint

A
  • Costoclavicular ligament- links the proximal clavicle to the first rib, helps anchor the clavicle in place
  • Interclavicular ligament- links the ends of the clavicles together
  • Anterior and posterior sternoclavicular ligaments- reinforcements of the joint capsule on the front and the back
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16
Q

Acromioclavicular joint

A
  • Between the medial acromion process of the scapula and the lateral end of the clavicle
  • A small synovial plane joint
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17
Q

Acromioclavicular joint

A
  • Between the medial acromion process of the scapula and the lateral end of the clavicle
  • A small synovial plane joint
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18
Q

Ligaments of the Acromiocavicular joint

A
  • Acromioclavicular ligmanet- reinforcement of the joint capsule, increasing its stability
  • Coracoclavicular ligament- attaches outside the Acromioclavicular joint- between the coracoid process and the clavicle. Still stabilises the Acromioclavicular joint even if it attaches outside it. Very large, is important for weight bearing Has two parts: The anterior trapezoid ligament and the posterior conoid ligament
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19
Q

Glenohumeral joint stability

A
  • Most commonly dislocated joint
  • Why- the head of the humerus is very large and articulates with the smaller, shallow Glenoid fossa. Inherently unstable joint structure
  • They are arranged like this to allow for a wide range of movement
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20
Q

Glenohumeral joint- features to improve joint stability:

A
  • Glenoid labrum- a Fibrocartilaginous collar/ring around the Glenoid fossa. This makes the fossa a little bit deeper, securing the head of the humorous a little bit more
  • Ligaments
  • Bony projection- Coracoid, acromion prevents superior dislocation by forming a cuff
  • Rotator cuff muscles- holds the head of the humerus in the Glenoid fossa
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21
Q

Glenohumeral joint structure

A
  • Synovial ball and socket- multiaxial, allows for a wide range of movement
  • Hyaline cartilage covers the head of the humerus and the surface of the glenoid fossa
  • The Joint capsule of the Glenohumeral joint is loose inferiorly to allow for abduction
22
Q

Ligaments of the Glenohumeral joint

A
  • They are thickenings of the joint capsule
  • Superior, middle and inferior glenohumeral ligaments
  • Coracohumeral ligaments- thickens the joint capsule superiorly, runs between the humorous and Coracoid process.
  • Transverse humeral ligament- holds the tendon of the long head of the bicep brachii in the intertubercular sulcus. Runs over the top of the groove between the greater and lesser tubercules (intertubercular sulcus). Holds the tendon of biceps in this groove
23
Q

Glenohumeral joint structures- Bursae

A
  • Form as the synovial membrane protrudes through the fibrous joint capsule
  • Bags of synovial membrane which cushion the joint and provide lubrication for different movements. They occur:
  • Between tendons and joint capsule i.e. subtendinous bursa of subcapularis. Stops muscles from catching on the joint capsule
  • Between bony protrusions and the joint capsule i.e. the subacromial bursa. Below the bony arch of the acromian and the coricoid process
  • Between the acromion (bony projection) and the skin
  • Close to the tendons of muscles around the joint
  • Allow for smooth movement
24
Q

Shoulder muscles

A
  • Intrinsic/Scapulohumeral muscles- originate on the scapula and insert on the humerus. Includes the Rotator cuff, Teres major and the Deltoid
  • Extrinsic/Axio-appendicular- originate on the trunk (thoracic wall/back) and insert on the scapula/humerus
25
Q

Rotator cuff

A
  • Made of 4 muscles- Supraspinatus, Infraspinatus, Subscapularis, Teres minor
  • Stabilises the glenohumeral joint- the tendons blend with the joint capsule
  • The muscles form a musculotendinous cuff around the glenohumeral joint, re-enforce the joint capsule
  • The tonic contractions pull the head of humorous into the glenoid fossa and holds it securely
26
Q

Where do the muscles of the rotator cuff originate

A

Supraspinatus, Infraspinatus, Teres minor- Originate on the posterior surface of the scapula and inserts on the greater tubercle of the humerus
Subscapularis- originates on the costal/anterior surface scapula and inserts on the lesser tubercle of the humerus. The one anterior rotator cuff muscle

27
Q

Supraspinatus

A
  • Superior to the spine of the capsular
  • Initiates abduction, the first 15 degrees
  • Attaches to the greater tubercle of the humerous
  • Passes underneath the Acromion process
  • Between the surface of the Supraspinous fossa and the Acromion process
  • The Supraspinatus is the most commonly ruptured rotator cuff tendon as there is very little space for it. Any swelling causes impingement by the two parts of the scapula
  • Poor blood supply means that repeated trauma can lead to tears. This will reduce the range of abduction
  • Originates on the posterior scapula and inserts on the greater tubercle, it initiates abduction
28
Q

Teres minor and infraspinatus

A
  • Teres minor and the Infraspinatus appear to blend together but they are functionally and anatomically different
  • Infraspinatus- inferior to the spine of the scapula, originates from the infraspinal fossa
  • Teres minor- lower (more inferior then the infraspinatus) but still originates from the infraspinal fossa
  • All rotator cuff muscles attach to the greater tubercle of the humerus
  • Have roles in external/lateral rotation
  • Both originate on the Posterior scapula and insert on the greater tubercle
29
Q

Subscapularis

A
  • Anterior- lies in the subscapular fossa, runs across to the lesser tubercle
  • Causes internal/medial rotation
  • Originates on the anterior scapula and inserts on the lesser tubercle
30
Q

Teres major

A

Originates on the posterior scapula and inserts on the intertubercular sulcus on the anterior aspect of the humerous. Has roles in internal/medial rotation and adduction

31
Q

Deltoid muscle

A

Originates from the pectoral girdle (Lateral aspects of the Acromion, clavicle, spine of the scapula) and inserts on the humerus at the Deltoid tuberosity. It’s a major abductor (middle fibres) beyond the 15 degrees. Its mainly the fibres in the middle of the muscle which are responsible for abduction. The anterior and posterior fibres are involved in flexion and extension

32
Q

Innervation of the rotator cuff

A
  • Infraspinatus and Supraspinatus- supplied by the Suprascapular nerve
  • Subscapularis and Teres major- supplied by the Subscapular nerve
  • Teres minor- supplied by the Axillary nerve (also supplies the deltoid)
  • All these nerves branch from the brachial plexus
33
Q

Shoulder- Suprascapular nerve

A

Runs through the Suprascapular notch

34
Q

Shoulder- Axillary nerve

A

Goes through the posterior aspect of the scapula through the Quadrangular space (formed from the Teres minor, Teres major, Humorous and part of the tricep muscle). Wraps around the neck of the humorous. It gives of a sensory branch (the lateral cutaneous nerve of the arm) which provides the upper lateral part of the arm

35
Q

Shoulder- Axillary nerve damage

A

Common causes are fracture of the surgical neck of the humerus, anterior dislocation and misuse of crutches. Damage causes failure to abduct beyond 15 degrees, you will see sensory loss over the lateral proximal arm in the ‘badge area.’

36
Q

Shoulder- Extrinsic/Axio-appendicular muscles

A
37
Q

Shoulder- Extrinsic/Axio-appendicular muscles

A
  • Originate on the trunk and insert on the scapula/humerus
  • Superficial back muscles- Trapezius, Latissimus dorsi. Deep to these you have the Levator scapulae and the rhomboid major and minor. Responsible for moving the shoulders
  • Thoracic wall muscles- Pectoralis major and minor, Serratus anterior
38
Q

Trapezius

A
  • Attaches to the medial aspect of the pectoral girdle (Acromion, Clavicle and Spine of the Scapula).
  • The Pectorial girdle is sandwiched between the Trapezius and the deltoid muscle.
  • Split into upper, middle and lower fibres.
  • The upper fibres elevate the scapula, the middle fibres retract the scapula and bring them towards the midline and the lower fibres depress the scapula
39
Q

Levator scapulae

A
  • Elevates the scapula
  • Attaches to the cervical vertebra and the skull and inserts on the superior angle of the scapula.
  • Helps elevate the Scapula with the upper fibres of the Trapezius. It forms the floor of the posterior triangle of the neck
40
Q

Shoulder- abduction

A
  • Abduction is initiated by the Supraspinatus muscle (first 15 degrees)
  • The Deltoid abducts from 15 to 90 degrees
  • Above 90 degrees it requires rotation of the Scapula by the upper fibres of the Trapezius (and a bit of Serratus anterior
41
Q

Muscles involved in upward rotation of the scapula

A
  • Trapezius (upper fibres)
  • Trapezius (lower fibres)
  • Serratus anterior
42
Q

Muscles involved in the downward rotation of the scapula

A
  • Levator scapulae
  • Rhomboids
  • Pectoralis major
  • Latissimus dorsi
  • Pectoralis minor
43
Q

Latissimus dorsi

A
  • A big broad muscle- makes up part of the superficial layer of muscles in your back
  • Originates posteriorly on the lumbar vertebrae, thoraco-lumbar fascia and the iliac crest. Inserts anteriorly on the intertubercular sulcus
  • It extends, adducts and internally/medially rotates. Important when you are lifting your own body weight when climbing
  • ‘Pull up muscle’
44
Q

Rhomboid major and minor

A
  • The superior larger muscle is the Rhomboid major and the inferior smaller one is the Rhomboid minor
  • Acts to retract the Scapula and pull it towards the midline
  • Runs from the vertebra to the medial border of the scapula
45
Q

Innervation of the Extrinsic/Axio-appendicular muscles

A
  • Levator scapulae, Rhomboid minor, Rhomboid major- innervated by the Dorsal scapular nerve, it’s a branch of the brachial plexus
  • Latissimus dorsi- innervated by the Thoracodorsal nerve
  • Trapezius- innervated by the Spinal accessory nerve (CNXI)
46
Q

Pectoralis major

A
  • Fan shaped muscle, attaches to the humorous
  • Is divided into a Clavicular head (attached to the clavicle) and Sternocostal head (attached to the sternum and ribs). Both converge on a single point on the humorous at the intertubercular sulcus
  • Internal (medial) rotation, adduction and flexion
  • Its innervated by the medial and lateral pectoral nerves
47
Q

Muscles which join at the intertubercular groove

A

Pectoralis major, Latissimus dorsi, Teres major. They have a shared insertion point. Pectoralis major is on the lateral side of the groove whilst Teres major is on the medial side of the groove. All these muscles help with internal (medial) rotation and Adduction

48
Q

Pectoralis minor

A
  • Deep to the major
  • Attaches to the coracoid process of the scapula and to the ribs.
  • Helps protract the scapula and keep it stable
  • Accessory muscle in respiration
  • Its innervated by the medial pectoral muscle
49
Q

Serratus anterior

A
  • Runs underneath the Scapula and attaches to the costal surface and medial border of the scapula. Also attaches to the ribs
  • Involved in protraction and rotation of the Scapula
  • It keeps the medial border of the scapula held against the thoracic wall
  • Innervated by the long thoracic nerve
50
Q

Long thoracic nerve damage

A
  • The nerve lies on the superficial surface of the muscle
  • Its vulnerable to stabbing, bullet injuries etc when the arms are elevated
  • The Serratus anterior can no longer hold the medial border of the scapula against the thorax resulting in a winged scapula
  • Abduction above 90 degrees is impacted as rotation of scapula is impaired

Medicine year 2 semester 2 (47 decks)

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