S7) The Shoulder Flashcards
1
Q
There are two types of muscles of the shoulder. Identify and describe them
A
- Extrinsic muscles originate from the torso and attach to the bones of the shoulder (clavicle, scapula or humerus)
- Intrinsic muscles originate from the scapula and/or clavicle and attach to the humerus
2
Q
Identify the 6 intrinsic muscles of the shoulder
A
- Deltoid
- Teres major
- Supraspinatus
- Infraspinatus
- Subscapularis
- Teres minor
3
Q
Describe the structure and function of the deltoid muscle
A
- Structure: consists of anterior, middle and posterior parts
- Action: shoulder flexion (anterior fibres), shoulder extension (posterior fibres), abduction 15-90o (middle fibres)
4
Q
State the origin and attachment of the deltoid muscle
A
- Origin: scapula and clavicle
- Attachment: deltoid tuberosity on lateral surface of the humerus
5
Q
What innervates the deltoid muscle?
A
Axillary nerve
6
Q
Describe the structure and function of the teres major muscle
A
- Structure: forms inferior border of the quadrangular space
- Function: adduction, medial rotation
7
Q
State the origin and attachment of the teres major muscle
A
- Origin: posterior surface of the inferior angle of the scapula
- Attachment: intertubercular groove of the humerus
8
Q
What innervates the teres major muscle?
A
Lower subscapular nerve
9
Q
What are the rotator cuff muscles and what do they do?
A
- The rotator cuff muscles are a group of four muscles that originate from the scapula and attach to the humeral head
- Collectively, the resting tone of these muscles acts to ‘pull’ the humeral head into the glenoid fossa stabilising the glenohumeral joint
10
Q
Identify the 4 rotator cuff muscles
A
11
Q
State the function of supraspinatus muscle
A
Abducts the arm 0-15° and assists deltoid for 15-90°
12
Q
State the origin and attachment of the supraspinatus muscle
A
- Origin: supraspinous fossa of the scapula
- Attachment: greater tubercle of the humerus
13
Q
What innervates the supraspinatus muscle?
A
Suprascapular nerve
14
Q
State the function of the infraspinatus muscle
A
Lateral rotation
15
Q
State the origin and attachment of the infraspinatus muscle
A
- Origin: infraspinous fossa of the scapula
- Attachment: greater tubercle of the humerus
16
Q
What innervates the infraspinatus muscle?
A
Suprascapular nerve
17
Q
State the function of the subscapularis muscle
A
Medial rotation
18
Q
State the origin and attachment of the subscapularis muscle
A
- Origin: subscapular fossa on the costal surface of the scapula
- Attachment: lesser tubercle of the humerus
19
Q
What innervates the subscapularis muscle?
A
Upper and lower subscapular nerves
20
Q
State the function of the teres minor muscle
A
Lateral rotation
21
Q
State the origin and attachment of the teres minor muscle
A
- Origin: posterior surface of the scapula
- Attachment: greater tubercle of the humerus
22
Q
What innervates the teres minor muscle?
A
Axillary nerve
23
Q
Where extrinsic muscles of the shoulder found?
A
Extrinsic muscles of the shoulder are located in the back aka. superficial back muscles
24
Q
Which two muscles are in the superficial layer of the shoulder?
A
- Trapezius
- Latissimus Dorsi
25
Describe the structure and function of the trapezius muscle
- **Structure:** broad, flat and triangular muscle, most superficial of all the back muscles
**- Function:** elevate rotates scapula during abduction (upper fibres), retract scapula (middle fibres), pull scapula inferiorly (lower fibres)
26
State the origin and attachment of the trapezius muscle
- **Origin**: skull, nuchal ligament and the spinous processes of C7-T12
- **Attachment**: clavicle, acromion and the scapula spine
27
What innervates the trapezius muscle?
Accessory nerve
28
Describe the function of the lattismus dorsi
- Extension
- Adduction
- Medial rotation
29
State the origin and attachment of the lattismus dorsi
- **Origin**: spinous processes of T6-T12, iliac crest, thoracolumbar fascia and the inferior three ribs
- **Attachment**: intertubercular sulcus of the humerus
30
What innervates the lattismus dorsi?
Thoracodorsal nerve
31
Which three muscles are in the deep layer of the shoulder?
- Levator Scapulae
- Rhomboid major
- Rhomboid minor
32
Describe the structure and function of the levator scapulae
- **Structure:** small strap-like muscle
**- Function:** elevates the scapula
33
State the origin and attachment of the levator scapulae
- **Origin**: transverse processes of the C1-C4 vertebrae
- **Attachment**: medial border of the scapula
34
What innervates the levator scapulae?
Dorsal scapular nerve
35
State the function of the rhomboid major
Retracts and rotates the scapula
36
State the origin and attachment of the rhomboid major
- **Origin**: spinous processes of T2-T5 vertebrae
- **Attachment**: medial border of the scapula
37
What innervates the rhomboid major?
Dorsal scapular nerve
38
State the function of the rhomboid minor
Retracts and rotates the scapula
39
State the origin and attachment of the rhomboid minor
- **Origin**: spinous processes of C7-T1 vertebrae
- **Attachment**: medial border of the scapula
40
What innervates the rhomboid minor?
Dorsal scapular nerve
41
Describe the division of the back muscles
The muscles of the back can be divided into three groups – superficial, intermediate and deep:
- **Superficial** – associated with movements of the shoulder
- **Intermediate** – associated with movements of the thoracic cage
- **Deep** – associated with movements of the vertebral column
42
Compare and contrast and describe the development the muscles of the back
- The deep muscles develop embryologically in the back, and are thus described as **intrinsic** muscles
- The superficial and intermediate muscles do not develop in the back, and are classified as **extrinsic** muscles
43
What is the shoulder joint?
- The shoulder joint (glenohumeral joint) is a ball and socket joint between the **scapula** and the **humerus**
- It is the major joint connecting the upper limb to the trunk
- It is one of the most mobile joints in the human body, at the cost of joint stability
44
Describe the formation of the shoulder joint
The shoulder joint is formed by the articulation of the **head** of the humerus with the **glenoid cavity** (or fossa) of the scapula
45
What covers the articulating surfaces of the shoulder joint?
Both the articulating surfaces are covered with **hyaline cartilage**
46
What makes the shoulder joint unstable and which structure tackles this?
- The **head of the humerus** is much larger than the glenoid fossa
- Glenoid fossa is deepened by a fibrocartilage rim, the **glenoid labrum**, to provide more stability
47
Describe the structure, function and location of the joint capsule in the shoulder
- **Structure**: fibrous sheath, lax to permit greater mobility
- **Function**: encloses the structures of the joint
- **Location**: extends from the anatomical neck of the humerus to the border of the glenoid fossa
48
What is a synovial membrane and what does it do?
The **synovial membrane** lines the inner surface of the joint capsule, and produces **synovial fluid** to reduce friction between the articular surfaces
49
What is a bursa?
A **bursa** is a synovial fluid filled sac, which acts as a cushion between tendons and other joint structures and reduces friction
50
Identify and describe the bursae in the shoulder of clinical importance
- **Subacromial** **bursa** is located inferiorly to the deltoid and acromion, and superiorly to the supraspinatus tendon and the joint capsule
**- Subscapular bursa** is located between the subscapularis tendon and the scapula
51
Describe the structure and function of the ligaments in the shoulder joint
- **Structure**: thickenings of the joint capsule
- **Function:** stabilise the bony structures of the shoulder joint
52
Identify the 3 key ligaments in the shoulder joint
- Glenohumeral ligaments (superior, middle and inferior)
- Coracohumeral ligament
- Transverse humeral ligament
53
Describe the location and function of the glenohumeral ligaments of the shoulder
- **Location**: three bands which run with the joint capsule from the glenoid fossa to the anatomical neck of the humerus
- **Function**: stabilise the anterior aspect of the joint
54
Describe the location and function of the coracohumeral ligament of the shoulder
- **Location**: attaches the base of the coracoid process to the greater tubercle of the humerus
- **Function**: supports the superior part of the joint capsule
55
Describe the location and function of the transverse humeral ligament of the shoulder
- **Location**: spans the distance between the two tubercles of the humerus
- **Function**: holds the tendon of the long head of the biceps in the intertubercular groove
56
The other major ligament of the shoulder is the coracoacromial ligament.
Describe its structure, function and location of this ligament
- **Structure**: not a thickening of the joint capsule
- **Function**: overlies the shoulder joint, preventing superior displacement of the humeral head
- **Location**: runs between the acromion and coracoid process of the scapula, forming the coraco-acromial arch
57
Describe the neurovascular supply of the shoulder joint
- Arterial supply via the **anterior** and **posterior circumflex humeral arteries**, and the **suprascapular artery**
- Innervated by the **axillary, suprascapular** and **lateral pectoral nerves**
58
Identify the 6 primary movements of the shoulder joint
- Extension
- Flexion
- Abduction
- Adduction
- Medial Rotation
- Lateral Rotation
59
Identify the muscles involved in the flexion and extension of the shoulder joint
- **Extension** is produced by the posterior deltoid, latissimus dorsi and teres major
**- Flexion** is produced by the biceps brachii, pectoralis major, anterior deltoid and coracobrachialis
60
Identify the muscles involved in the abduction and adduction of the shoulder joint
- **Abduction** is produced by the supraspinatus (0-15o), middle deltoid (15-90o), trapezius and serratus anterior (\>90o)
**- Adduction** is produced by the pectoralis major, latissimus dorsi and teres major
61
Identify the muscles involved in the medial and lateral rotation of the shoulder joint
- **Medial rotation** is produced by the subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid
**- Lateral Rotation** is produced by the infraspinatus and teres minor
62
Identify 3 factors that contribute to the mobility of the shoulder joint
- **Nature** **of joint** (ball and socket joint)
**- Bony surfaces** (shallow glenoid cavity and large humeral head)
- Laxity of the **joint capsule**
63
Identify 3 factors that contribute to the stability of the shoulder joint
- Rotator cuff muscles
- Glenoid labrum
- Ligaments
64
Describe the structure and function of the scapula
- **Structure**: triangular, flat bone, attachment site for 17 muscles
- **Function**: articulates with the humerus at the glenohumeral joint and with the clavicle at the acromioclavicular joint, to connect the upper limb to the trunk
65
Identify the key anatomical features visible on the anterior view (costal surface) of the scapula
66
Identify the key anatomical features visible on the posterior view of the scapula
67
Identify the key anatomical features visible on the lateral view of the scapula
68
Describe the structure and location of the clavicle
- **Structure**: slender bone, medial aspect is convex, lateral aspect is concave
- **Location**: extends between the sternum and the acromion of the scapula
69
The clavicle has three main functions.
Identify them
- **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
70
Divide the clavicle into 3 parts
71
Describe the structure and function of the sternal end of the clavicle
- **Structure**: inferior surface is marked by a rough oval depression for the costoclavicular ligament
- **Function**: contains large facet for articulation with the manubrium of the sternum at the sternoclavicular joint
72
Describe the structure and function of the shaft of the clavicle
- **Structure**: contains a groove for attachment of subclavius
- **Function**: acts a point of origin and attachment for several muscles (deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid)
73
Describe the structure and function of the acromial end of the clavicle
- **Structure**: conoid tubercle attaches conoid ligament (medial part of coracoclavicular ligament), trapezoid line attaches trapezoid ligament (lateral part of coracoclavicular ligament)
- **Function**: contains small facet for articulation with the acromion of the scapula at the acromioclavicular joint
74
What is a traumatic anterior shoulder dislocation?
An **anterior shoulder dislocation** is a clinical condition in which the humeral head is displaced anteriorly in relation to the glenoid fossa
75
Anterior shoulder dislocations account for as many as 95-98% of shoulder dislocations.
Why is this?
**Muscular** and **ligamentous support** anterior to the humeral head is much less robust than the posterior aspect with the rotator cuff and scapula
76
What is a traumatic posterior shoulder dislocation?
An **posterior shoulder dislocation** is a clinical condition in which the humeral head is displaced posteriorly in relation to the glenoid fossa
77
Due to low levels of clinical suspicion and insufficient imaging, posterior shoulder dislocations are often missed.
Identify 2 causes
- Electric shock
- Seizure
78
How many different ways can the acromioclavicular joint be dislocated?
Acromioclavicular joint has six different ways of dislocating
79
The clavicle is the most commonly fractured bone in the body.
How do these fractures occur?
- Falling onto the shoulder
- Falling onto an outstretched hand
80
The most common point of fracture is the junction of the medial 2/3 and lateral 1/3.
Describe the displacement of the different ends of the clavicle
- **Lateral end** is displaced inferiorly by the weight of the arm, and medially by the pectoralis major
- **Medial end** is displaces superiorly by the sternocleidomastoid muscle
81
Describe how clavicle fractures present
- **Suprascapular nerves** may be damaged by the upwards movement of the medial end of clavicle
- Lateral rotators of the upper limb are paralysed so unopposed medial rotation of the upper limb presents as **‘waiters tip’**
82
What is rotator cuff tendonitis?
- **Rotator cuff tendonitis** is the inflammation of the tendons of the rotator cuff muscles, usually occurring secondary to repetitive use of the shoulder joint
- Degenerative changes occur in the subacromial bursa and supraspinatus tendon, increasing friction between the structures of the joint
83
How does rotator cuff tendonitis present?
The characteristic sign of rotator cuff tendonitis is the **painful arc pain** in the middle of abduction, where the affected area comes into contact with the acromion
84
The most common cause of accessory nerve damage is iatrogenic.
Identify medical procedures which might cause trauma to this nerve
- Cervical lymph node biopsy
- Cannulation of the internal jugular vein
85
How can the accessory nerve function be tested?
Trapezius function can be assessed – patient should to **shrug his/her shoulders**
