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MSK > Session 2 > Flashcards

Session 2 Flashcards

1
Q

Name & identify the structures that form the shoulder joint (bones, ligaments, rotator cuff) LO

  1. The shoulder joint (? joint) is a ball and socket joint between the ?. It is the major joint connecting the ?
  2. The shoulder joint is formed by the articulation of the ? of the humerus with the ? (or fossa) of the scapula. This gives rise to the alternate name for the shoulder joint – the glenohumeral joint.
  3. Both the articulating surfaces are covered with ? – which is typical for a ? type joint.
  4. The head of the humerus is much larger than the glenoid fossa, giving the joint inherent instability. To reduce the disproportion in surfaces…
A
  1. glenohumeral, scapula & the humerus, upper limb to the trunk.
  2. head, glenoid cavity
  3. hyaline cartilage, synovial
  4. the glenoid fossa is deepened by a fibrocartilage rim, called the glenoid labrum.
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2
Q
  1. The joint capsule is a ?
  2. It extends from the ?
  3. Function?
  4. How does the shoulder joint reduce friction?
A
  1. fibrous sheath which encloses the structures of the joint.
  2. anatomical neck of the humerus to the border of the glenoid fossa.
  3. The joint capsule is lax, permitting greater mobility (particularly abduction).
  4. The synovial membrane lines the inner surface of the joint capsule, and produces synovial fluid to reduce friction between the articular surfaces.

To reduce friction in the shoulder joint, several synovial bursae are present. A bursa is a synovial fluid filled sac, which acts as a cushion between tendons and other joint structures. The bursae that are important clinically are:

Subacromial – Located inferiorly to the deltoid and acromion, and superiorly to the supraspinatus tendon and the joint capsule. It supports the deltoid and supraspinatus muscles. Inflammation of this bursa is the cause of several shoulder problems.

Subscapular – Located between the subscapularis tendon and the scapula. It reduces wear and tear on the tendon during movement at the shoulder joint.

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3
Q
  1. In the shoulder joint, the ligaments play a key role in stabilising the bony structures. The majority of the ligaments are thickenings of the joint capsule:
  2. The other major ligament is the coracoacromial ligament. Unlike the others, it is not a thickening of the joint capsule. It runs between the acromion & coracoid process of the scapula, forming the coraco-acromial arch. This structure overlies the shoulder joint, preventing?
A
  1. Glenohumeral ligaments (superior, middle and inferior) – Consists of three bands, which runs with the joint capsule from the glenoid fossa to the anatomical neck of the humerus. They act to stabilise the anterior aspect of the joint.

Coroacohumeral ligament – Attaches the base of the coracoid process to the greater tubercle of the humerus. It supports the superior part of the joint capsule.

Transverse humeral ligament – Spans the distance between the two tubercles of the humerus. It holds the tendon of the long head of the biceps in the intertubercular groove

  1. Superior displacement of the humeral head.
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4
Q

Neurovascular supply of the glenohumeral joint

A
  • anterior & posterior circumflex humeral arteries, & suprascapular artery. - Branches from these arteries form an anastomotic network around the joint.
  • axillary, suprascapular & lateral pectoral nerves. These nerves are derived from roots C5 and C6 of the brachial plexus. Thus, an upper brachial plexus injury (Erb’s palsy) will affect shoulder joint function.
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5
Q

As a ball & socket synovial joint, there is a wide range of movement permitted: name the movements & the muscles that permit these movements (6)

A

 Identify the muscles that produce the main movements of the shoulder and state their actions LO

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6
Q

Describe the factors that contribute to the mobility & stability of the shoulder joint LO

  1. Factors that contribute to mobility:
  2. Factors that contribute to stability:
A
  1. Type of joint – It is a ball and socket joint.

Bony surfaces – Shallow glenoid cavity and large humeral head – there is a 1:4 disproportion in surfaces. A commonly used analogy is the golf ball and tee.

Laxity of the joint capsule.

  1. Rotator cuff muscles – These muscles surround the shoulder joint, attaching to the tubercles of the humerus, whilst also fusing with the joint capsule. The resting tone of these muscles act to ‘pull’ the humeral head into the glenoid cavity.

Glenoid labrum: This is a fibrocartilaginous ridge surrounding the glenoid cavity. It deepens the cavity, reducing the risk of dislocation.

Ligaments – The ligaments act to reinforce the joint capsule, and forms the coraco-acromial arch.

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7
Q

Dislocation of the Shoulder Joint

  1. Clinically, dislocations at the shoulder are described by where the ?
  2. What type of dislocations are more prevalent? 3. Superior movement of the humeral head is prevented by the ?
  3. An anterior dislocation is usually caused by ?
  4. Tearing of the joint capsule is associated with an increased risk of ?.
  5. The axillary nerve runs in close proximity to the shoulder joint, and can be damaged in the dislocation. Injury to the axillary nerve causes paralysis of the deltoid, and loss of sensation over regimental badge area. A dislocation can also stretch the radial nerve, as it is tightly bound in the ?.
  6. What is the regimental badge area?
A
  1. humeral head lies in relation to the infraglenoid tubercle
  2. Anterior dislocations are the most prevalent, although posterior dislocations can sometimes occur.
  3. coraco-acromial arch.
  4. excessive extension & lateral rotation of the humerus. The humeral head is forced anteriorly & inferiorly – into the weakest part of the joint capsule.
  5. future dislocations
  6. radial groove
  7. The axillary nerve also carries sensory information from the shoulder joint, as well as the skin covering the inferior region of the deltoid muscle - the “regimental badge” area (which is innervated by the superior lateral cutaneous nerve branch of the axillary nerve).
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8
Q

Understand the common conditions & injuries affecting the shoulder joint & their consequences on joint integrity & function: LO

List the common shoulder conditions

A
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9
Q
  1. Why do patients with an anterior dislocation have a square looking shoulder?
  2. Complication of anterior dislocation
  3. Causes
A

The Glenohumeral joint is poorly supported inferiorly so when the arm is abducted trauma

forces the humerus inferiorly & pectoralis major pulls the humerus medially, forcing the humeral head anterior to the scapula – anterior dislocation. Patient ends up with a square

looking shoulder because the deltoid & humeral head normally gives a rounded shoulder

which has now moved.

  1. This injury could also damage the axillary nerve.

If the Axillary nerve is injured (for example in Glenohumeral

dislocation due to the close proximity) then you get paralysis of the deltoid muscle so you cannot abduct your arm past 15°. You will also get lack of sensation in the

regimental badge area which branches of the Axillary nerve

supply (this can be tested clinically).

  1. Sports, falls particularly when upper extremity is in 90° abduction and external rotation
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10
Q
  1. How do patients with a posterior dislocation present?
  2. How does this effect joint function LO
  3. Causes
  4. Complications
A
  1. Typically the arm is held in internal rotation and adduction.
  2. The most significant finding on examination is a limited range of active and passive external rotation of the effected arm as the head of the humerus is caught to the glenoid rim
  3. In adults, convulsive disorders are the most common cause. Electrocution is a classic but uncommon cause of posterior shoulder dislocation. In both situations, bilateral dislocations are not infrequent.

Occasionally, they can be the result of strength imbalance within the rotator cuff muscles.

  1. Osteonecrosis of the humeral head

Acute re-dislocation

Recurrent posterior shoulder instability

Joint stiffness and functional incapacity

Post-traumatic osteoarthritis

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11
Q

ACJ DISLOCATION

  1. The Acromioclavicular Joint is usually injured by a ?
  2. A simple joint with six different ways of dislocating:

(coracoclavicular ligaments are important)

3.

A
  1. direct fall onto the point of the shoulder. The shoulder blade (scapula) is forced downwards & the clavicle (collarbone) appears prominent.
  2. The degree of damage to the joint is classified by the joint displacement and injury to the ligaments which support the AC joint (pic)
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12
Q

FRACTURES

  1. 80% of cases undisplaced

20% are displaced:

  • some need fixing
  • some need joint replacement

Why?

A
  1. Anterior head s broken of and stripped of soft tissue

It is also displaced fracture

Piece of dead bone in AXILLARY will not unite due to no blood supply

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13
Q

Humeral neck fracture

  1. Mechanism of injury:

Complications:

A
    • Usually after a fall on to an outstretched hand from standing height.
      - Can also occur during seizures or electric shock when fracture may be associated with a posterior shoulder dislocation.
      - Can also result from a direct blow.

Neurovascular injury:

Axillary nerve damage is most common. Suprascapular, radial & musculocutaneous nerves can also be affected. Axillary artery injury may (rarely) occur (look for expanding mass over the proximal shoulder girdle). The brachial artery is also rarely injured.

Avascular necrosis of the humeral head: this is more common in complex fractures with multiple fragments where interruption to the blood supply is more likely and in fractures of the surgical neck. It causes pain & stiffness in the shoulder. Shoulder arthroplasty may eventually be needed or may be the initial treatment of choice in the fracture management. The development of intramedullary nails and minimally invasive locking plates provides greater ability to fix more complex fractures with less risk to the blood supply.

Malunion.

Associated glenohumeral dislocation.

Associated rotator cuff injury.

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14
Q

Shoulder impingement syndrome

  1. The tendon & muscle run through a narrow space at the top of the shoulder called the ? In shoulder impingement syndrome, the ?
  2. The subacromial space is naturally quite narrow, especially when the arm is raised. Anything that further narrows this space can cause the tendon to become trapped.

Possible causes include:

  1. Treatment
  2. Patients present with?
  3. Test?
  4. Risk factor for shoulder impingement syndrome.
A
  1. subacromial space,

tendon becomes trapped in this space & repeatedly scrapes against the bone above, causing pain that tends to be worse when you raise your arm over your head.

  1. • Bursitis,
  • Tendinopathy (e.g.a build-up of calcium deposits within the rotator cuff tendon/swelling or thickening of the rotator cuff tendon – which may result from an injury or general overuse of the shoulder)
  • Dynamic impingement
  1. • Steroid & physio

• Surgical decompression

  1. Low painful arc -> Pain when abducting to 90 degrees

Further abduction alleviates pain

Tender over tuberosity

  1. Hawkins test +ve
  2. Overhead activity of the shoulder, especially repeated activity, e.g. painting, lifting, swimming, tennis, & other overhead sports. Other risk factors include bone and joint abnormalities.
  3. Overhead activity of the shoulder, especially repeated activity, e.g. painting, lifting, swimming, tennis, & other overhead sports. Other risk factors include bone and joint abnormalities.
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15
Q

Calcification supraspinatus tendonitis

  1. Calcific tendonitis, refers to the deposition of
  2. Common locations

3.

A
  1. Calcium hydroxyapatite
  2. Supraspinatus tendon (80% of cases): critical zone - Most Common

Infraspinatus tendon (15% of cases): lower 1/3

Subscapularis tendon (5%of cases): pre-insertional fibers

  • Subacromial Impingement if large
  • If bursts – acute calcific tendinitis
  • 2 day history
  • Rapidly progressive pain
  • 10/10 severity
  • Resolves 1 to 2 weeks
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16
Q

Rotator cuff tears

  1. A rotator cuff tear is?
  2. Symptoms of partial & full rotator cuff tears
  3. What diagnostic tests do you do & what are the results
  4. Progressive functional loss with size of tear
  5. Treatment
  6. Rotator cuff arthropathy (shoulder arthritis in setting of rotator cuff dysfunction) is defined as a combination of
  7. Usually occurs in the ? Where the?
  8. Symptoms
  9. Physical examination
  10. Treatment
A
  1. A tear of your shoulder’s rotator cuff tendons.
  2. Partial rotator cuff tear may only present with mild shoulder pain, clicking during shoulder elevation & mild shoulder weakness lifting your hand above shoulder height or reaching behind your back.
  3. Partial rotator cuff tear may only present with mild shoulder pain, clicking during shoulder elevation and mild shoulder weakness lifting your hand above shoulder height or reaching behind your back.
  4. Partial: mild shoulder pain, clicking during shoulder elevation & mild shoulder weakness lifting your hand above shoulder height (abduction) or reaching behind your back.

Impingement signs

Full thickness: severe shoulder pain & an inability to lift your elbow away from your body. (Abduction) However, in some cases the rotator cuff tear is so severe that a significant number of your pain fibres are also torn, which can make them less painful but very weak.

  1. • Supraspinatus test weak
  • Infraspinatus weak & ER lag
  • Subscapularis push off & belly press weak

ultrasound scan

  1. Open repair, augmentation with

allograft

Autograft: donor is the recipient (most successful)

Homograft: donor is a different human (may be rejected as ‘foreign’)

Heterograft: donor is of a different species (least successful, though calf bone loses antigenicity with refrigeration)

    • massive chronic rotator cuff tear
      - glenohumeral cartilage destruction
      - subchondral osteoporosis
      - humeral head collapse
  2. Elderly
  • Cuff not repairable
  • Glenohumeral arthritis
  • Acromial erosion +/- fracture

8.pain & subjective weakness

9.

  1. Reverse anatomy shoulder replacement
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17
Q
  1. Osteoporosis is a ?
  2. What is the patient at risk of & why ?
  3. Osteoporosis associated with aging results from ?
  4. Describe the radiological changes LO
  5. Histological changes

occurring in osteoporosis. LO

  1. List the most common risk factors for osteoporosis.
  2. Explain the importance of osteoporosis as a risk factor for fractures in the elderly.
  3. Primary osteoporosis (type 1 and 2) is by far the most common form of

osteoporosis.

Type 1 occurs in ?

Type 1 is due to an ?

Type 2 occurs in ?

Type 2 generally occurs ?

A
  1. Metabolic bone disease in which mineralized bone

is decreased in mass & no longer provides adequate mechanical support.

  1. Loss of mass within the trabecular bone is particularly relevant to increased susceptibility to fracture.

Because enhanced bone resorption relative to formation.

  1. incomplete filling of osteoclast resorption bays (pic)
  2. (Compression) is fractures
  3. highly attenuated (thin) bony trabeculae
  4. Genetic: Peak bone mass is higher in blacks than in whites or asians

Insufficient calcium intake: recommended value for postmenopausal women is 800 mg/day.

Insufficient calcium absorption and Vitamin D: decreased renal activation of Vitamin D with age may be a factor in populations without Vitamin D supplementation or with the elderly confined indoors.

Exercise: immobilization of bone (prolonged bed rest or application of a cast) leads to accelerated bone loss. Physical activity is needed to maintain bone mass.

Cigarette smoking in women has been correlated with increased incidence of osteoporosis.

  1. Bone mass peaks between 25 – 35 years. It begins to decline in the 5th or 6th decade.

In the USA 1.2 million fractures annually (most are #s of the vertebral bodies and hip) Complications of hip fracture are fatal in 12-20% of cases.

15% of people have a hip fracture by the age of 80. 25% have a hip fracture by the age of 90.

  • women at higher risk

Amongst whites, women have 2X the risk of hip fracture as men. Amongst whites, women have 8X the risk of vertebral fractures as men.

  1. T2: postmenopausal women, increase in osteoclast no, a result of oestrogen withdrawal.

T2: elderly persons of both sexes (senile osteoporosis).

after age 70 & reflects attenuated osteoblast function.

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18
Q

Osteoarthritis

  1. What is osteoarthritis
  2. The most common symptoms are ?
  3. Treatment includes?
A
  1. Joint disease that results from breakdown of joint cartilage & underlying bone
  2. joint pain and stiffness. Initially, symptoms may occur only following exercise, but over time may become constant. Other symptoms may include joint swelling, decreased range of motion, and when the back is affected weakness or numbness of the arms and legs.

symptoms come on over years!

  1. exercise, efforts to decrease joint stress, support groups, and pain medications.[2][6] Efforts to decrease joint stress include resting and the use of a cane. Weight loss may help in those who are overweight. Pain medications may include paracetamol (acetaminophen) as well as NSAIDs such as naproxen or ibuprofen.[2] Long-term opioid use is generally discouraged due to lack of information on benefits as well as risks of addiction and other side effects.[2][6] If pain interferes with normal life despite other treatments, joint replacement surgery may help.[3] An artificial joint typically lasts 10 to 15 years.[7]
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19
Q

ACROMIOCLAVICULAR OSTEOARTHRITIS

  1. What is it?
  2. Symptoms?
  3. Causes?
  4. Tests & results
  5. Non surgical treatment
  6. If osteoarthritis symptoms are severe and activity modification and nonoperative treatments do not succeed, surgery may provide relief. Surgeries to relieve osteoarthritis of the shoulder’s acromioclavicular joint include:
A

1.

  1. Majority are asymptomatic, High painful arc, Joint tender (sign)

3.

  1. Scarf test +ve

Xray/US scan/MRI

  1. NSAIDs

Injection – diagnosis/treatment (Injections. Steroid injections are normally used for treatment of severe pain from acromioclavicular osteoarthritis. The goal of steroid injections is to reduce swelling and thereby alleviate shoulder stiffness and pain.)

  1. AC joint arthroscopy to remove loose pieces of damaged cartilage

AC joint osteotomy to shave off osteophytes and reduce friction between bones

Resection of the distal clavicle, sometimes called distal clavicle excision, to remove a small portion of the end of the clavicle, thereby eliminating friction between the clavicle and scapula. Eventually, scar tissue bridges the gap between the two bones. This surgery can be done with an arthroscope and seems to provide pain relief to most people suffering from moderate-to-severe acromioclavicular arthritis,13,14 however, there have been no large studies comparing the efficacy of surgical and non-surgical treatments.

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20
Q

GLENOHUMERAL OSTEOARTHRITIS

  1. Shoulder osteoarthritis is a degenerative joint disease that involves two primary processes:
  2. Symptoms
  3. Treatments
  4. Tests to make diagnoses
  5. What shows up on the X-ray
  6. How can injections be diagnostic?
A
    • The cartilage in the joints breaks down
      - Abnormal bony growths, called osteophytes or bone spurs, develop in the joint
  2. Progressive pain & stiffness over years, Crepitus (Feeling a crunching or hearing a popping sound when rotating the shoulder may be a sign that cartilage has worn away and is not protecting the bones from friction.)
  3. Analgesia & exercises, Steroid injections, Eventually joint replacement

• Hemi/TSR/Short stem/Surface

  1. Injection of a local anesthetic, X-ray , MRI
  2. X-rays can show if there is a loss of joint space in the glenohumeral joint. A loss of joint space indicates a loss of cartilage. An x-ray can also show bone spurs and other malformations of the humeral head, a sign that the bones have tried to compensate for cartilage loss with extra bone growth. (BUT MAY NOT BE THE CASE)
  3. Injecting a local anesthetic such as lidocaine directly into the glenohumeral joint is one of the most effective ways to test for arthritis.5 If the pain is temporarily relieved after the injection, then a diagnosis of shoulder arthritis is confirmed. If the pain persists, another shoulder problem, such as a rotator cuff injury, is a more likely cause of the patient’s symptoms.
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21
Q

Clinical Relevance: Rotator Cuff Tendonitis

Rotator cuff tendonitis refers to inflammation of the tendons of the rotator cuff muscles. This usually occurs secondary to repetitive use of the shoulder joint.

The muscle most commonly affected is the supraspinatus. During abduction, it ‘rubs’ against the coraco-acromial arch. Over time, this causes inflammation and degenerative changes in the tendon itself.

Conservative treatment of rotator cuff tendonitis involves rest, analgesia, and physiotherapy. In more severe cases, steroid injections & surgery can be considered.

A
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22
Q

Common shoulder problems not in LO

A
  • FROZEN SHOULDER Adhesive Capsulitis
  • Long Head of Biceps Rupture

• Popeye muscle

  • CLAVICLE FRACTURES

-

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23
Q

Clavicle fractures

Numerous ways to fracture your clavicle. Some need fixing but

controversial about risks and

benefits. Clinical trials needed

  • Nonop v Op meta-analysis.
  • Xin-Hua Wang et al Aug 2015
  • Non union – 14% v 1.7%
  • Malunion – 20% v 1.8%
  • Advised against fix all policy
A

SURGERY HAS RISKS

• K wires migrate – spine, chest, heart

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24
Q
A

FROZEN SHOULDER Adhesive Capsulitis
Pain - severe, progressive, nocturnal, jerk pain, Progressive stiffness follows Resolves after 2 or 3 years
Distension arthrography Manipulation under anaesthesia Surgical release

X rays normal
Gradually pan goes away
Gradually more stiff
Women 40-60
Normally triggered by other disease injury

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25
Q
  1. Name & identify the bones of the pectoral girdle & upper limb LO
  2. Function
  3. Joints i forms
A
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26
Q

Identify important landmarks on these bones e.g. condyles, tuberosities, fossae grooves LO

A
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27
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A
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28
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29
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30
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31
Q
A
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32
Q

Identify the above bones & their features on plain X-rays & be able to describe in simple terms the anatomical location of fractures of these bones e.g. mid-shaft fracture of humerus LO

A
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33
Q

Identify the important surface anatomy of the bones in the shoulder region and in the upper limb. LO

A
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34
Q

What is in the anterior aspect of the arm?

A

Muscles:

coracobrachialis

short and long head of biceps

brachialis

brachioradialis

pronator teres

Nerves:

musculocutaneous nerve

median nerve

ulnar nerve

Arteries:

brachial artery

profunda brachii (deep brachial)

Veins: cephalic, basilic & median cubital veins

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35
Q

Origin, insertion, innervation, movement

coracobrachialis

A

Originates from the coracoid process of the scapula. The muscle passes through the axilla, and attaches the medial side of the humeral shaft, at the level of the deltoid tubercle.

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36
Q

Short & long head of biceps

A
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37
Q

Clinical significance of rupture of he biceps tendon

A
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38
Q
A
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39
Q

brachialis

A
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40
Q

brachioradialis

A
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41
Q
A
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42
Q

Origin, insertion, nerve suppl for pronator teres

A
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43
Q

There are three muscles located in the anterior compartment of the upper arm – ?

They are all innervated by the ? A good memory aid for this is BBC – biceps, brachialis, coracobrachialis.

Arterial supply to the anterior compartment of the upper arm is via muscular branches of the ?

The posterior compartment of the upper arm contains the triceps brachii muscle, which has three heads. The ? head lies deeper than the other two, which cover it.

Arterial supply to the posterior compartment of the upper arm is via the ?

A

biceps brachii, coracobrachialis and brachialis

musculocutaneous n

brachial artery

medial

profunda brachii artery

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44
Q

cephalic, basilic and median cubital veins

A
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45
Q

Posterior aspect / dorsum:

On a prosection, you should be able to recognise the following structures:

  1. Muscles:
  2. Nerves:
  3. Blood Vessels:
A
    • trapezius
      - latissimus dorsi
      - serratus anterior
      - levator scapulae
      - rhomboids
      - deltoid
      - teres major
      - the rotator cuff muscles (subscapularis, supraspinatus, infraspinatus and teres minor)
      - long, lateral and medial heads of triceps
  2. accessory nerve (supplying trapezius) axillary nerve (supplying deltoid) radial nerve
  3. posterior circumflex humeral vessels (accompanying the axillary)
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46
Q
A
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47
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48
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49
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50
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51
Q
  1. The arterial supply to the upper limb begins in the chest as the subclavian artery. The ? subclavian artery arises from the brachiocephalic trunk, while the ? subclavian branches directly off the arch of aorta.
  2. When are they called the axillary arteries?
  3. The axillary artery passes through the ?, just underneath the ?, enclosed in the ?
  4. Where does the axillary artery first branch of & into what branches?
  5. When does the axillary artery become the brachial artery?
A
  1. right, left
  2. cross the lateral edge of the 1st rib
  3. axilla, pectoralis minor muscle, axillary sheath
  4. Humeral surgical neck:
    - posterior & anterior circumflex humeral arteries arise (circle posteriorly around the humerus to supply the shoulder region)
    - subscapular artery (Largest branch)
  5. lower border of the teres major
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52
Q

Clinical relevance of the axillary artery

A
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53
Q
  1. The brachial artery is the main source of blood for the ?
  2. Immediately distal to the teres major, the brachial artery gives rise to the ?
  3. Where does this branch travel? What muscles does it supply?
  4. The brachial artery descends down the arm immediately ? to the median nerve.
  5. When does it bifurcate? What does it bifurcate into?
A
  1. arm
  2. profunda brachii – the deep artery of the arm
  3. posterior surface of the humerus, running in the radial groove. It supplies structures in the posterior aspect of the arm (e.g the triceps brachii, & terminates by contributing to a network of vessels at the elbow joint.
  4. posterior
  5. As it crosses the cubital fossa, underneath the brachialis muscle, the brachial artery terminates by bifurcating into the radial and ulnar arteries.
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54
Q
A
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55
Q
A
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56
Q

Clinical significance of the brachial artery?

A
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57
Q

In the forearm

  1. The radial artery supplies the ? aspect of the forearm & the ulnar artery supplies the ? aspect. The two arteries anastomose in the hand, by forming two arches, the ?
A
  1. posterior, anterior, superficial palmar arch, & the deep palmar arch.
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58
Q
A
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59
Q

In the Hand

  1. The hand has a very good blood supply, with many ? arteries, allowing the hand to be perfused when ?. A good majority of these arteries are superficial, allowing for heat loss when needed. In the hand, the ulnar & radial arteries interconnect to form two arches, from which branches to the digits emerge.
  2. Radial artery supplies what in the hand?
  3. Ulnar artery supplies what in the hand?
  4. How does the ulnar artery move into the hand? And how does it branch?
  5. From the superficial palmar arch, ? arise, supplying the digits. The superficial palmar arch then anastamoses with a branch of the radial artery. 6. The superficial palmar arch is found anteriorly to the ? in the hand, ? to the palmar aponeurosis.
A
  1. anastomosing, grasping or applying pressure
  2. contributes mainly to supply of the thumb and the lateral side of the index finger
  3. contributes mainly to the supply of the rest of the digits, and the medial side of the index finger
  4. anteriorly to the flexor retinaculum, & laterally to the ulnar nerve. In the hand, it divides into two branches, the superficial palmar arch, and the deep palmar branch.
  5. common palmar digital arteries
  6. flexor tendons, deep
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60
Q
  1. How does the radial artery enter the hand?
A
  1. dorsally, crossing the floor of the anatomical snuffbox.

It turns medially & moves between the heads of the adductor pollicis. The radial artery then anastamoses with the deep palmar branch of the ulnar artery, forming the deep palmar arch, which gives rise to five arteries supplying the digits.

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61
Q
  1. The major superficial veins of the upper limb are the ?
  2. As their name suggests, they are located within the ? of the upper limb.
  3. The basilic vein originates from the ? venous network of the hand. It ascends the ? aspect of the upper limb.
  4. Where does the brachial artery combine to form the axillary vein?
  5. The cephalic vein arises from the ? venous network of the hand. It ascends the ? aspect of the upper limb, passing ? at the elbow.
  6. At the shoulder, the cephalic vein travels between the ? muscles (known as the ?), & enters the axilla region via the clavipectoral triangle.
  7. Within the axilla, the cephalic vein terminates by joining the axillary vein. At the elbow, the cephalic & basilic veins are connected by the ?
A
  1. cephalic & basilic veins.
  2. subcutaneous tissue
  3. dorsal, medial, at the border of the teres major, the vein moves deep into the arm.
  4. dorsal, antero-lateral, anteriorly
  5. deltoid & pectoralis major, deltopectoral groove
  6. median cubital vein
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62
Q

The deep veins

  1. The deep veins of the upper limb are situated underneath the ?
  2. They are paired veins that accompany and lie either side of an artery. The brachial veins are the largest in size, & are situated either side of the brachial artery. The pulsations of the brachial artery assists the venous return. Veins that are structured in this way are known as ?
  3. Perforating veins run between the deep & superficial veins of the upper limb, connecting the two systems.
A
  1. deep fascia
  2. vena comitantes
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63
Q

Where would you place an IV

A

Where would you place an IV

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64
Q

The anatomical arrangement & function of the axillary lymph nodes & their clinical relevance

  1. The majority of the upper lymph nodes are located in the axilla. They can be divided anatomically into 5 groups: LO
A
  1. Pectoral (anterior) – - 3-5 nodes
    - medial wall of the axilla.
    - lymph anterior thoracic wall, including most of the breast.

Subscapular (posterior) –

  • 6-7 nodes
  • posterior axillary fold & subscapular blood vessels.
  • lymph posterior thoracic wall & scapular region.

Humeral (lateral) –

  • 4-6 nodes
  • lateral wall of the axilla, posterior to the axillary vein.
  • lymph drained from the upper limb.

Central –

  • 3-4 large nodes,
  • base of the axilla (deep to pectoralis minor, close to the 2nd part of the axillary artery).
  • lymph via efferent vessels from the pectoral, subscapular & humeral axillary lymph node groups.

Apical –

  • apex of the axilla, close to the axillary vein & 1st part of the axillary artery.
  • lymph from efferent vessels of the central axillary lymph nodes, therefore from all axillary lymph node groups. The apical axillary nodes also receive lymph from those lymphatic vessels accompanying the cephalic vein.
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66
Q
  1. Efferent vessels from the apical axillary nodes travel through the ?, before converging to form the ? The right subclavian trunk continues to form the ?, and enters the right venous angle (junction of internal jugular & subclavian veins) directly. The left subclavian trunk drains directly into the ?
A
  1. cervico-axillary canal, subclavian lymphatic trunk, right lymphatic duct, thoracic duct.
67
Q

Clinical Relevance:

A
  • Enlargement of Axillary Lymph Nodes
  • Axillary Lymph Node Dissection
68
Q

Enlargement of these lymph nodes can have a no of either infectious/ malignant causes:

A
  • Infection of the upper limb, resulting in lymphangitis (inflammation of lymphatic vessels, with tender, enlarged lymph nodes). The humeral group of lymph nodes is usually affected first, and red, warm & tender streaks are visible in the skin of the upper limb.
  • Infections of the pectoral region & breast.
  • Metastasis of breast cancers.
69
Q

Axillary Lymph Node Dissection

  1. Removal & analysis of the axillary lymph nodes is often a vital tool for the ? of breast cancers.
  2. Interruption of lymphatic drainage from the upper limb can however result in ?
  3. During this procedure there is also a risk of ?
A
  1. staging
  2. lymphoedema, a condition whereby accumulated lymph in the subcutaneous tissue leads to painful swelling of the upper limb.
  3. Damage to either of the long thoracic nerve (potentially causing a winged scapula deformity), or the thoracodorsal nerve.
70
Q

Origin, insertion, innervation, movement

  • trapezius
A

ORIGIN: Descending: the external occipital protuberance, ligamentum nuchae & spinous process of the C1-C7 vertebrae; Transverse: the aponeurosis of the spinous processes at the T1-T4 vertebrae; Ascending: the spinous processes of the T5-T12 vertebrae.

INSERTION: Descending: the lateral one-third of the clavicle; Transverse: the medial side of the acromion; Ascending: the upper crest & tubercle of the scapular spine.

ACTION: Retraction, superior rotation, elevation & depression of the scapula.

NERVE SUPPLY: Accessory nerve (CN XI), C3-C4.

ARTERIAL SUPPLY: Transverse cervical artery.

71
Q

How do you test the accessory nerve

72
Q

I- latissimus dorsi

A

ORIGIN: Inferior angle of the scapula; the 9th-12th ribs; the spinous processes of T7-T12 vertebrae; the thoracolumbar fascia; the posterior one-third of the iliac crest.

INSERTION: Crest of the lesser tuberosity of the humerus and the intertubercular groove.

ACTION: Extension, adduction and internal rotation of the arm; aids in respiration.

NERVE SUPPLY: Thoracodorsal nerve

ARTERIAL SUPPLY: Thoracodorsal artery.

73
Q

serratus anterior

A

serratus anterior

74
Q

What happens if the thoracic nerve is damaged?

75
Q
  • levator scapulae

(Atlas C1 & Axis C2)

A

Origin: transverse C1-C4 vertebrae

Insert: medial border of the scapula.

Innervation: Dorsal scapular nerve

Actions: Elevates the scapula.

76
Q
  • rhomboids

Spinous

A

Rhomboid minor is situated superiorly to the major

Rhomboid Major

Origin: spinous processes of T2-T5 vertebrae.

Insertion: medial border of the scapula, between the scapula spine and inferior angle.

Innervation: Dorsal scapular nerve

Actions: Retracts & rotates the scapula.

Rhomboid Minor

Origin: C7-T1

Insert: medial border of the scapula, at the level of the spine of scapula.

Innervation: Dorsal scapular nerve

Actions: Retracts & rotates the scapula.

77
Q
  • deltoid
78
Q

teres major

A

The teres major forms the inferior border of the quadrangular space – the ‘gap’ that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapula region.

Origin: from the posterior surface of the inferior angle of the scapula. It attaches to the intertubercular groove of the humerus.

Innervation: Lower subscapular nerve.

Actions: Adducts at the shoulder and medially rotates the arm.

79
Q

Subscapularis

A

Origin: subscapular fossa

Insertion: lesser tubercle of the humerus.

Innervation: Upper & lower subscapular nerves.

Actions: Medially rotates the arm.

80
Q
  • Long, lateral & medial heads of triceps
A

Origin:

Long head - infraglenoid tubercle

Lateral head – the humerus, superior to the radial grove. Medial head – the humerus, inferior to the radial groove.

Insertion: (distally heads converge onto one tendon and insert into the) olecranon of the ulna.

Function: Extension of the arm at the elbow/ extension of the elbow joint to extend the forearm

Innervation:

Radial nerve. A tap on the triceps tendon tests spinal segment C7.

81
Q

Name & identify the bones of the pectoral girdle

& the upper limb on an articulated & disarticulated skeleton. Identify important landmarks on these bones e.g. condyles, tuberosities, fossae & grooves.

  1. The anterior surface of the scapula is termed ‘?’, this is because it is the side facing the ribcage.
  2. This side of the scapula is relatively unremarkable, with a concave depression over most of its surface, called the ?. The subscapularis muscle, one of the rotator cuff muscles, originates from this side.
  3. Originating from the superolateral surface of the costal scapula the ?. It is a hook-like projection, which lies just underneath the clavicle. The ? muscles originates from this projection.
A
  1. costal
  2. subscapular fossa
  3. coracoid process, pectoralis minor inserts here, while the coracobrachialis & biceps brachii
83
Q

Lateral Surface

The lateral surface of the scapula faces the humerus. It is the site of the glenohumeral joint, and of various muscle attachments.

Bony landmarks

A

Glenoid fossa – A shallow cavity, which articulates with the humerus to form the glenohumeral joint. The superior part of the lateral border is very important clinically, as it articulates with the humerus to make up the shoulder joint, or glenohumeral joint.

Supraglenoid tubercle – A roughening immediately superior to the glenoid fossa, this is the place of attachment of the long head of the biceps brachii.

Infraglenoid tubercle – A roughening immediately inferior to the glenoid fossa, this is the place of attachment of the long head of the triceps brachii.

84
Q

Posterior Surface

The posterior surface of the scapula faces outwards. It is a site of attachment for the majority of the rotator cuff muscles of the shoulder.

Bony landmarks:

A

Spine – The most prominent feature of the posterior scapula. It runs transversely across the scapula, dividing the surface into two.

Infraspinous fossa – The area below the spine of the scapula, it displays a convex shape. The infraspinatus muscle originates from this area.

Supraspinous fossa – The area above the spine of the scapula, it is much smaller that the infraspinous fossa, and is more convex in shape. The supraspinatus muscle originates from this area.

Acromion – projection of the spine that arches over the glenohumeral joint and articulates with the clavicle.

85
Q

Fractures of the scapula are relatively ?, & if they do occur, it is an indication of ? They are frequently seen in high speed road collisions, crushing injuries, or sports injuries.

The fractured scapula does not require much intervention, as the tone of the surrounding muscles holds the pieces in place for healing to occur.

A

uncommon, severe chest trauma,

86
Q

The clavicle (collarbone) extends between the sternum & the acromion of the scapula.

It is classed as a long bone, and can be palpated along its length. In thin individuals, it is visible under the skin. The clavicle has three main functions:

A
  • Attaches the upper limb to the trunk.
  • Protects the underlying neurovascular structures supplying the upper limb.
  • Transmits force from the upper limb to the axial skeleton.
87
Q

Shape?

A

The clavicle is a slender bone with an ‘S’ shape. Facing forward, the medial aspect is convex, and the lateral aspect concave. It can be divided into a sternal end, a shaft & an acromial end.

88
Q

Sternal (medial) End

  1. The sternal end contains a ? – for articulation with the manubrium of the sternum at the sternoclavicular joint. The inferior surface of the sternal end is marked by a rough oval depression for the ? (a ligament of the SC joint).
  2. Shaft

The shaft of the clavicle acts a point of origin & attachment for several muscles – ?

  1. Acromial (lateral) End

The acromial end houses a ? for articulation with the acromion of the scapula at the acromioclavicular joint. It also serves as an attachment point for two ligaments:

A
  1. large facet, costoclavicular ligament
  2. deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid & sternohyoid
  3. small facet

Conoid tubercle – attachment point of the conoid ligament, the medial part of the coracoclavicular ligament.

Trapezoid line – attachment point of the trapezoid ligament, the lateral part of the coracoclavicular ligament.

The coracoclavicular ligament is a very strong structure, effectively suspending the weight of the upper limb from the clavicle.

89
Q

Clinical Relevance: Fracture of the Clavicle

  1. A function of the clavicle is to transmit forces from the upper limb to the axial skeleton. Thus, the clavicle is ?
  2. Fractures commonly result from a ?
  3. The most common point of fracture is ?
  4. After fracture, the lateral end of the clavicle is displaced ? Why?
  5. The medial end is pulled ? Why?
  6. The ? nerves (medial, intermedial and lateral) may be damaged by the upwards movement of the medial part of the fracture. These nerves innervate the ? rotators of the upper limb at the shoulder – so damage results in ?
A
  1. the most commonly fractured bone in the body
  2. fall onto the shoulder, or onto an outstretched hand.
  3. the medial 2/3 & lateral 1/3
  4. inferiorly by the weight of the arm, & medially, by the pectoralis major.
  5. superiorly, by the sternocleidomastoid muscle.
  6. suprascapular, lateral, unopposed medial rotation of the upper limb – the ‘waiters tip’ position.
90
Q
  1. The head of the humerus is connected to the greater & lesser tubercles by the ? which is short in width & nondescript.
  2. The greater tubercle is located laterally on the humerus. It has an anterior & posterior face. The greater tubercle serves as attachment site for three of the rotator cuff muscles –
  3. The lesser tubercle is much smaller, and more medially located on the bone. It only has an anterior face. It is a place of attachment for the last rotator cuff muscle – ?.
  4. Separating the two tubercles is a deep depression, called the intertubercular sulcus, or groove. The tendon of the long head of biceps brachii runs through this groove. The edges of the intertubercular sulcus are known as lips. Tendons of the ? attach to the lips of the intertubercular sulcus.

5.

A
  1. anatomical neck,
  2. supraspinatus, infraspinatus & teres minor.
  3. subscapularis
  4. pectoralis major, teres major & latissimus dorsi

5.

91
Q
  1. The shaft of the humerus contains some important bony landmarks such as the ? & is the site of attachment for various muscles.
  2. On the lateral side of the humeral shaft is a roughened surface where the deltoid muscle attaches. This is known is as the deltoid tuberosity.

The radial groove is ? that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity.

  1. The ? lie in this groove. The following muscles attach to the humerus along its shaft:
A
  1. Deltoid tuberosity & radial groove
  2. shallow depression
  3. radial nerve and profunda brachii artery

Anteriorly: Coracobrachialis, deltoid, brachialis, brachioradialis

Posteriorly: Medial and lateral heads of the triceps

92
Q

What can happen if you get a mid shaft fracture?

I.e. What can be damaged &a what is the effect on the patient/presentation

93
Q

Distal region

  1. The lateral & medial borders of the humerus form medial & lateral supraepicondylar ridges. The lateral supraepicondylar ridge is more roughened, as it is the site of attachment for many of the ? muscles in the ? forearm.
  2. Immediately distal to the supraepicondylar ridges are the lateral & medial epicondyles – projections of bone. Both can be palpated at the elbow (the ? more so, as it is much larger).
  3. The ? passes into the forearm along the posterior side of the medial epicondyle, & can also be palpated there.
  4. Distally, the ? is located medially, & extends onto the posterior of the bone. Lateral to the trochlea is the ?, which articulates with the radius.
  5. Also found on the distal portion of the humerus are three depressions, known as the ?They accommodate the forearm bones during movement at the elbow.
A
  1. extensor, posterior
  2. medial
  3. ulnar nerve
  4. trochlea, capitulum
  5. coronoid, radial and olecranon fossae
94
Q

Articulations

  1. The proximal region of the humerus articulates with the scapula to form the ? joint (shoulder joint). The distal part of the humerus articulates with the ulna and radius at the ? joint, at the trochlea & capitulum respectively. Here, the bone adopts a flattened, almost 2-D shape.
A
  1. glenohumeral, elbow
95
Q

What fractures are common in the distal humerus, causes & effects

A

Supracondylar fracture of the humerus, Falling on a flexed elbow. It is a transverse fracture, spanning between the two epicondyles

Direct damage, or swelling can cause interference to the blood supply of the forearm from the brachial artery. The resulting ischaemia can cause Volkmann’s ischaemic contracture – uncontrolled flexion of the hand, as flexor muscles become fibrotic & short. There also can be damage to the median, ulnar / radial nerves.

Medial epicondyle fracture could damage the ulnar nerve, a deformity known as ulnar claw is the result. There will be a loss of sensation over the medial 1 and 1/2 fingers of the hand, on both the dorsal and palmar surfaces.

96
Q

Identify the above bones & their features on plain X-rays & be able to describe in simple terms the anatomical location of fractures of these bones e.g. mid-shaft fracture of humerus

97
Q

What is this image showing?

A

Clavicular fracture

98
Q

Why is the medial 2/3 superior & the lateral 1/3 inferiorly/medially?

A

The most common point of fracture is the junction of the medial 2/3 and lateral 1/3. After fracture, the lateral end of the clavicle is displaced inferiorly by the weight of the arm, & medially, by the pectoralis major. The medial end is pulled superiorly, by the sternocleidomastoid muscle.

99
Q

Clavicular fracture & brachial plexus injury

Most likely to damage ?

A

trunks or divisions

100
Q

How do we assess for brachial plexus injury?

A

Sensation & movement

101
Q

Assessing brachial plexus injury: Movement

103
Q

complications of clavicular fracture

A

The suprascapular nerves (medial, intermedial and lateral) may be damaged by the upwards movement of the medial part of the fracture. These nerves innervate the lateral rotators of the upper limb at the shoulder – so damage results in unopposed medial rotation of the upper limb – the ‘waiters tip’ position.

104
Q

Other complications of clavicular fracture

105
Q

Case study B: Mid-shaft humeral fracture

What major muscles does the radial nerve supply?

106
Q

How might a patient present

A

Assessment of pulses

107
Q

Assessment of pulses

108
Q

Dislocated shoulder

What provides stability of the shoulder joint

A
  • Glenohumeral ligaments
  • Coroacohumeral ligament
  • Transverse humeral ligament
  • coracoacromial ligament = coraco-acromial arch

glenoid labrum.

109
Q

Complications of humeral head dislocation

110
Q
  1. Clinically, dislocations at the shoulder are described by where the humeral head lies in relation to the ? Anterior dislocations are the most prevalent, although posterior dislocations can sometimes occur. Superior movement of the humeral head is prevented by the ?
  2. Cause of anterior dislocation?
  3. The humeral head is forced anteriorly & inferiorly – into the weakest part of the joint capsule. ? is associated with an increased risk of future dislocations.
A
  1. infraglenoid tubercle, coraco-acromial arch
  2. excessive extension & lateral rotation of the humerus.
  3. Tearing of the joint capsule
  4. The axillary nerve runs in close proximity to the shoulder joint, & can be damaged in the dislocation. Injury to the axillary nerve causes paralysis of the deltoid, and loss of sensation over regimental badge area. A dislocation can also stretch the radial nerve, as it is tightly bound in the radial groove.
111
Q

How does a patient with a posterior dislocation present

112
Q

Shoulder Girdle

  1. Consists of the ?
  2. Connect the arm to the axial
    skeleton. Joints:
A
  1. clavicle & the

scapula

  1. Sternoclavicular Joint (SCJ)

Acromioclavicular Joint (ACJ)

Scapulothoracic Joint

Glenohumeral Joint (Shoulder Joint)

115
Q

Identify the above bones & their features on plain X-rays & be able to describe in simple terms the anatomical location of fractures of these bones e.g. mid-shaft fracture of humerus

117
Q
A

Supraspinatus - Suprascapular N.

Infraspinatus - Suprascapular N.

Teres Minor - Axillary N.

Subscapularis - Upper & Lower Subscapular N

118
Q

Space between the acromion and

head of humerus is around 1-1.5cm. Within this space:

A
  • Subacromial Bursa
  • Rotator Cuff Tendons
  • Capsule
  • Long Head of Biceps
119
Q

State Muscles needed for abduction

120
Q

Adduction

121
Q

Flexion

122
Q

Extension

123
Q

Internal rotation

124
Q

External rotation

126
Q

Space between the acromion and

head of humerus is around 1-1.5cm. Within this space:

A
  • Subacromial Bursa
  • Rotator Cuff Tendons
  • Capsule
  • Long Head of Biceps
129
Q

Glenohumeral Stability

  • Static Stabilisers:
  • Dynamic Stabilisers:
A
  • Articular Congruency / Anatomy - Glenoid Labrum - Capsule - Glenohumeral Ligaments - Extra-capsular Ligaments - Negative Intra-articular pressure
  • Rotator Cuff Muscles
  • Biceps Brachii
  • Muscles Crossing the Shoulder
130
Q

Describe the structure & organisation of skeletal muscle LO

  1. Arrangements of muscle fibres:
A
  1. Parallel (most common), Pennate & circular
131
Q

Parallels

  1. Fibres run parallel to ?
  2. Most ? type
  3. Three main categories: give examples & descriptions of the shape of the parallel muscle types
A
  1. force generating axis
  2. common

3.

132
Q

Pennate muscles

  1. How do you know if it is a pennate muscle? 2. Three different types: give examples & descriptions of the shape of the pennate muscle types
A
  1. One or more aponeuroses run through muscle body from tendon.

Fascicles attach to aponeuroses at an angle (pennation angle)

133
Q

Circular muscles

  1. Act as ? to adjust opening
  2. ? fibres
  3. Attach to ?
A
  1. sphincters
  2. Concentric
  3. skin, ligaments &

fascia rather than bone

134
Q

Fascia

A

sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs

135
Q

Aponeuroses

A

layers of flat broad tendons

136
Q

tendon is a

A

tough band of fibrous connective tissue

137
Q

Four types of tissue

A

Muscular, epithelial. Nervous, connective

138
Q

7 types of connective tissue

A

Cartilage

Haematopoietic

Adipose

Lymph

Blood

Bone

140
Q

Origin & Insertion

  1. Origin (3)
  2. Insertion (5)
A
  1. Bone, typically proximal, which has greater mass & is more stable during contraction than the muscle’s insertion.
  2. • Structure the muscle attaches to

• Tends to be moved by

contraction

  • Tends to be distal
  • May be bone, tendon or

connective tissue (usually tendon

to bone).

• Greater motion than origin during contraction.

141
Q

Compartments

  1. Limbs divided into compartments delineated

by ?

  1. Trauma in one compartment could cause

internal bleeding which exerts pressure on ?

  1. Can give rise to compartment syndrome. Explain what this is. (6)
  2. Treatment
A
  1. fascia
  2. blood vessels & nerves
  3. • Deep constant poorly localised Pain
  • Aggravated by passive stretch of muscle group
  • Paresthesia (altered sensation e.g., “pins & needles”)
  • Compartment may feel tense and firm.
  • Swollen shiny skin, sometimes with obvious bruising.
  • Prolonged capillary refill time.
  1. fasciotomy

Subsequently covered by skin graft

142
Q

Describe roles of muscles in movement & the types of contraction they undergo

  1. Agonists:

Antagonists: Synergists:

Neutralisers:

Fixators:

A
  1. Agonists:

Prime movers (main muscles responsible for a particular movement)

• Antagonists:

Oppose prime movers

Synergists:

Assist prime movers (acting alone they cannot perform the movement but their angle of pull assists)

• Neutralisers:

Prevent the unwanted actions that an agonist can perform

• Fixators:

Act to hold a body part immobile whilst another body part is moving.

143
Q
  1. Contraction types:
A

Isotonic contraction

constant tension, variable muscle length - the muscle changes length & moves the load:

  • Concentric – muscle shortens e.g. lifting a load with the arm
  • Eccentric - muscle exerts a force while being extended

e.g. walking downhill. In excess can cause delayed-onset muscle soreness

Isometric contraction

Constant length (mm), variable tension e.g. hand grip

144
Q

Describe the three types of levers

145
Q

Rigor mortis

A

If ATP is depleted, myosin heads cannot detach. Usually commences ~3 hrs post mortem, reaching maximum stiffness ~12 hrs & gradually dissipating ~72 hrs. Can be used to estimate the time of death.

146
Q

skeletal muscle ultrastructure

147
Q

The motor unit

(An α−motor neurone & the muscle fibres it innervates)

  1. Each individual muscle fibre innervated by ? motor neuron
  2. A single motor neuron, however, can innervate ?
  3. The muscle fibres that make up a motor unit are all of the ?, so each motor unit is fast/ slow contracting.
A
  1. one
  2. many muscle fibres
  3. same contractile type
148
Q

Muscle fibre types

  1. Histochemical staining for ? in human deltoid muscle
  2. 3 main fibre types:
A
  1. myosin ATPase
  2. • Slow Type I
  • Fast Type IIA
  • Fast Type IIX
  • Several intermediate

types (e.g. IIC = MHC IIa > MHC I)

Based on Myosin heavy chain (MHC) expression

149
Q

Explain the mechanism for muscle contraction LO

150
Q
  1. Define a motor unit LO
  2. Explain the basis of muscle tone in relation to causes of hypotonia LO

Each skeletal muscle is supplied by a number of motor neurons which stimulate the muscle fibres to contract. The type of motor neurons innervating skeletal muscle fibres are called ? neurons & the cell bodies of these neurons are either located in the ?

  1. The axons of α-motor neurons leave the central nervous system & form part of a peripheral nerve, to supply the muscle fibres of a skeletal muscle. The connection between the individual muscle fibres and the α-motor neuron is via the neuromuscular junction. The neurotransmitter ? is released from vesicles into the synapse and activates nicotinic acetylcholine receptors on the muscle surface.
  2. Any single muscle fibre is innervated by only one α-motor neuron, but each α-motor neuron can innervate a number of different muscle fibres. The number of muscle fibres in a motor unit varies between different muscles and depends on the function of the muscle. Muscles that perform precise fine movements, such as inferior rectus which moves the eyeball have around ten muscle fibres in each unit motor unit whereas powerful muscles, where fine control is less important, such as gastrocnemius may have several thousand muscle fibres in each motor unit. Thus fine control means?
A
  1. an α-motor neuron and the group of individual muscle fibres that it innervates.
  2. α-motor, ventral horn of the spinal cord, for muscles of the limbs and trunk, or in the motor nuclei of the brainstem for the muscles of the head and face
  3. acetylcholine
  4. Fewer muscle fibres in a motor unit
151
Q
  1. Intrafusal muscle fibres facilitate ?
  2. Innervated by
  3. γ Motor neurone keeps fibres ?
  4. Function of type Ia sensory neurones
  5. Function of Type II sensory neurones
  6. Spindle walled off from rest of muscle by?
  7. Patients with large-fibre sensory neuropathy:
A
  1. proprioception, sense of position of self and movement.
  2. two sensory & one motor axons
  3. taught
  4. relay rate of

change in muscle length back to CNS

  1. position sense
  2. collagen sheath
  3. are able to perform accurate movements while watching the affected limb, but in the absence of vision small movements are grossly inaccurate.
152
Q

Controlling Muscle Force

  1. What is the size principle?
  2. What is the Rate Code?
  3. The ? varies between muscles depending on their function. The contractile force produced by a muscle depends on two factors: ?
  4. The size principle simply means that ?

In general this means that motor units with slow type I fibres are recruited first followed by those containing mostly fast IIa fibres and then those containing fast IIX fibres.

  1. The Rate code refers to the ?
  2. Consecutive AP in a repetitive train result in ? giving a slightly larger ? with each contraction.
  3. Eventually a limit is reached where no further force can be produced termed tetany.
A
  1. Small motor neurons recruited before large. In general this means motor units with mostly fibre types: Slow type I → Fast IIa → Fast IIx
  2. More action potentials = more force

Subsequent action potential produce summation (up to a limit).

Limit = Tetanus

  1. number of muscle fibres per motor unit and the proportion of the different fibre types, the size principle & the rate code.
  2. small motor neurons are recruited before large ones.
  3. frequency at which the muscle fibres are stimulated by their α-motor neuron.
  4. summation, force
153
Q

Muscle tone

  1. What is muscle tone?
  2. Baseline tone due to:
  3. Control of muscle tone via ?
A
  1. Healthy muscles never fully relaxed.

Retain amount of tension & stiffness

(muscle tone).

  1. • Motor neuron activity

• Muscle elasticity

  1. motor control centres in the brain
154
Q
  1. Hypotonia:
  2. Most common in ?
  3. Examples:
  4. Causes
  5. All muscle has some degree of baseline tone (degree of tension) due to the ? LO
  6. Skeletal muscle tone is controlled by motor control centres in the brainstem. The locus ?, which contains noradrenergic cells, projects ascending axons to spinal motor neurons, where it facilitates muscle tone. Muscle tone is lost in REM sleep when the locus coeruleus cells shut off. A lack of skeletal muscle tone is known as hypotonia. This could result from damage to the motor cortex or cerebellum or spinal cord. Alternatively there could be degeneration of the muscle itself (myopathy).
A
  1. elasticity of the muscle tissue and low levels of motor neuron activity.
  2. coeruleus

R.E.M.: a kind of sleep that occurs at intervals during the night and is characterized by rapid eye movements, more dreaming and bodily movement, and faster pulse and breathing.

155
Q

• Action potential opens voltage

gated Ca2+ channels and triggers

vesicle fusions and acetylcholine

release. • ? channels open.

Na+ flows into the muscle cell. • Ach rapidly broken down in

synaptic cleft by the enzyme

acetylcholinesterase • Depolarization opens voltage-

gated Na+ channels in the

muscle cell. • Muscle action potential

generated

A

Nicotinic Ach

156
Q

Briefly explain excitation-contraction coupling in muscles

159
Q
  1. Demonstrated
    underlying cause was a
  2. Disease subsequently shown to be caused by ?
  3. Channel forms a?
A
  1. Reduction of the skeletal muscle

Cl- conductance.

  1. mutation in the skeletal muscle Cl- channel.
  2. homodimer

Gene: Chromosome: 7 Size: 40kb Exons: 22 Amino acids: 988

160
Q
  1. Sources of ATP in muscle:
  2. Advantage of using glycolysis
  3. Fast type II muscle fibres use what as an ATP source?
  4. Disadvantage of using glycolysis under anaerobic conditions
  5. Slow muscle fibres
A
  1. • Short term stores of ATP in muscle fibre
  • Creatine Phosphate
  • Glycolysis
  • Oxidative phosphorylation
  1. Anaerobic/aerobic thus does not require a constant blood supply
  2. Anaerobic glycolysis (jump, sprint)
  3. lactate -> cramps -> fatigues -> inefficient
  4. Aerobic glycolysis , oxidative phosphorylation & beta oxidation

Adipose provides fatty acids (TAG)

MSK (7 decks)

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