Arm and Elbow Flashcards
1
Q
What are the 5 big terminal branches of the brachial plexus?
A
Musculocutaneous Axillary Median Radial Ulnar
2
Q
What is function of brachial plexus?
A
Gives motor and sensory innervation to upper limb
3
Q
What is the brachial plexus composed of?
A
The ventral rami of the spinal nerves from the spinal cord segments C5 (C5, C6, C7, C8) to T1
4
Q
When spinal nerves exist the spinal canal, how do they leave?
A
Via intervertebral foramen
5
Q
What are dermatomes?
A
Areas of skin that are innervated by a single spinal nerve
6
Q
What do spinal nerves contain?
A
Mixed - motor and sensory information
7
Q
What do anterior rootlets of a spinal nerve contain?
A
Motor information
8
Q
What do posterior/dorsal rootlets contain?
A
Sensory information
9
Q
What do the anterior/ventral rootlets come together to form?
What do the posterior/dorsal rootlets come together to form?
A
An anterior root
A posterior root
10
Q
What do the ventral and dorsal roots join to form?
A
Mixed spinal nerve –> this then exits canal via intervertebral foramen
11
Q
What happens once spinal nerve leaves intervertebral foramen?
A
It splits into an ventral ramus and a posterior ramus that head to the respective sides of the body (these contain both motor and sensory info)
12
Q
Is the ventral or dorsal ramus larger?
A
Anterior
13
Q
What rami form the brachial plexus?
A
Anterior rami of C5, C6, C7, C8 and T1
14
Q
The anterior rami of C5-T1 form the roots of the brachial plexus. Some of these roots come together to form common nerves. Which roots come together?
A
C5 and C6 join to form a common nerve
C7 continues on its on
C8 and T1 join to form a common nerve
15
Q
What is the common spinal nerve of C5 and C6, of C8 and T1, and C7 on its own collectively known as?
A
The trunks of the brachial plexus
Superior trunk: C5 and C6
Middle trunk: C7
Inferior trunk: C8 and T1
16
Q
What do the superior, middle and inferior trunks then divide into?
A
Each trunk divides into an anterior segment and a posterior segment
- The anterior segments of the superior and middle trunks come together
- The anterior trunk of the inferior trunk continues alone
- The posterior segments of all 3 trunks come together
These are called the divisions
17
Q
What do the divsions then turn into?
A
Cords
18
Q
What are the cords of the brachial plexus called? How are they formed?
A
- Lateral –> formed from anterior divsions of superior and middle trunks
- Posterior –> formed from posterior divisions of all 3 trunks
- Medial –> formed from continuation of anterior division of inferior trunk
19
Q
How are the cords named?
A
According to their location to the axillary artery (lateral, posterior, medial)
20
Q
What do the cords then turn into?
A
The 5 terminal branches (formed by the 3 cords)
21
Q
What does the posterior cord give rise to?
A
Posterior cord gives rise to 2 out of 5 terminal branches:
- Axillary nerve –> a smaller branch given off the posterior cord
- The rest of the cord continues as the radial nerve
22
Q
Where does the axillary nerve carry nerve fibres from?
A
C5-C6
23
Q
What does the axillary nerve innervate?
A
Travels posteriorly, behind surgical neck of humerus (where it is vulnerable to fracture), emerge in the posterior pectoral region through the quadrilateral space, innervates deltoid and teres minor
Deltoid and teres minor
Skin on upper lateral arm
24
Q
Where does the radial nerve carry fibres from?
A
C5-T1
25
What does the radial nerve innervate?
Goes into posterior portion of arm to supply:
* Posterior arm (triceps) and forearm muscles
* Skin of the arm and hand
26
What happens to the lateral cord?
Divides into 2 branches
27
What happens to the medial cord?
Divides into 2 branches
28
What forms the terminal median nerve?
One of the divsions from the lateral cord and one of the divisions from the medial cord come together to form the terminal **median nerve**
29
Where does the median nerve carry fibres from?
C5-T1
30
What does the median nerve innervate?
Most atnerior forearm muscles, small muscles of the thumb, skin of the hand
Passes through arm but doesn't innervate any muscles until it reaches the forearm
31
What does the 2nd division of the lateral cord form?
The terminal **musculocutenous nerve**
32
Where does the musculocutaneous nerve carry fibres from?
C5-C7
33
What does the musculocutaenous nerve innervate?
Travels anteriorly --\> Muscles of the anterior arm, skin of the arm
34
What happens to the 2nd division of the medial nerve?
Continues down the arm as the terminal **ulnar nerve**
35
Where does the ulnar nerve carry fibres from?
C8-T1
36
What does the ulnar nerve innervate?
2 anterior forearm muscles, most small muscles of the hand, skin of the hand
37
What is an important nerve landmark of the brachial plexus?
M shape --\> lies anterior to axillary artery
3 legs of M: musculocutenous, median and ulner nerve
38
What are the forearm bones?
The ulna and radius
39
What forms the elbow joint?
The distal humerus articulates with the ulna and radius to form the elbow joint
40
Right humerus, anterior surface image
41
Right humerus, posterior surface image
42
What is this groove? It separates the greater and lesser tubercle
Intertubercular sulcus OR bicipital groove
43
What runs in the intertubercular sulcus?
One of the tendons of the bicep muscle
44
What is the deltoid tuberosity?
Roughened slightly raised area on midpart of anterior humerus where **deltoid** muscle inserts
45
Name this landmark
Medial epicondyle (positioned on side closest to body)
46
Name this landmark
Lateral epicondyle
47
Name these 2 regions
Lateral and medial supracondylar ridge (lateral on the left, medial on the right as closest to the body)
48
Name this region. What is its importance?
Trochlea - important for articulation of the humerus at the elbow joint
49
Name the 3 highlighted landmarks
Blue - coronoid fossa
Left yellow - capitulum
Middle yellow - trochlea
50
Full labelled diagram of right humerus **anterior** surface
51
Where is the radial groove?
A shallow depression that runs diagonally down the **posterior surface** of the humerus, parallel to the deltoid tuberosity.
52
Name the 2 dotted landmarks
1. Anatomical neck
2. Radial groove
53
Clinical importance of radial groove?
Where the radial nerve runs
54
Name the highlighted landmark. Note this is now the **posterior surface** of the humerus
Olecranon fossa
55
Full labelled diagram of **posterior** surface of humerus
56
What 3 bones are involved in the elbow joint?
1. Humerus
2. Ulna
3. Radius
57
What 2 articulations are involved in the elbow joint?
1. Humero-ulnar
2. Humero-radial
58
Describe the humero-ulnar articulation
Between the **trochlea** on the humerus and the **trochlear notch** on the ulnar
59
Where is the trochlea found? Where is the trochlear notch found?
Trochlea - found on the distal end of humerus
Trochlear notch - found on ulna
60
Describe the humero-radial articulation
Between the **capitulum** and **radial head** (orange highlight)
61
Where is the capitulum found? Where is the radial head found?
Capitulum - found on the distal end of the humerus
Radial head - found at the top of the radius bone
62
Is the elbow joint stable?
Yes due to good congruity
63
What does the coronoid fossa articulate with?
Coronoid fossa (found on distal end of humerus) receives coronoid process (found on the ulna) but **only during flexion**
Highlighted in blue
64
Where is the coronoid fossa found?
Distal end of humerus
65
Where is the coronoid process found?
Ulna
66
What does olecranon fit into during **extension?**
Only during extension, olecranon (on the ulna) fits into the olecranon fossa on the humerus
67
Where is the olecranon found?
On the ulna
68
What ligaments is the joint capsule of the elbow reinforced by?
- Reinforced laterally by the **radial collateral** ligament
- Reinforced medially by the **ulnar collateral** ligament
69
The elbow joint capsule is thin and loose anteriorly and posteriorly. What does this allow for?
Allows for flexion and extension
70
What are the movements of the elbow joint?
Flexion and extension only
71
What is pronation? What is supination?
Pronation - turning palm down
Supination - turning palm up
72
Where does pronation and supination happen?
At proximal radioulnar joint --\> it is a pivoting joint between head of radius and the ulnar
73
What are the 2 radioulnar joints?
Proximal and distal
74
Where is the proximal radioulnar joint found? What is it an articulation between?
At the elbow joint
Articulation between the **radial head** and the **radial notch of the ulna**
75
What type of joint is the elbow joint?
A hinge joint
76
What is necessary for a muscle to be able to move a joint?
If that muscle (or its tendon) **crosses** that joint
I.e. only the muscles (and their tendons) that cros the elbow joint can move the elbow
77
Why can some muscles in the arm also move the shoulder?
As they cross the shoulder
78
What are the 2 muscle compartments in the arm?
Anterior and posterior
79
How do muscles in the anterior compartment move the elbow?
They flex (bend) the elbow
80
How do muscles in the posterior compartment move the elbow?
They extend (straighten) the elbow
81
What are the 3 muscles of anterior arm?
1. Bicep
2. Brachialis
3. Coracobrachialis
82
What is the bicep, brachialis and the coracobrachialis innervated by?
The musculocutaneous nerve (C5-C7)
83
How many heads does biceps have?
2 - a short head and a long head
* These converge distally to form a common tendon that attaches onto the radial tuberosity
* Proximally: 2 heads attach separately to scapula
84
Where are the 2 heads of biceps attached to?
The scapula proximally
Short head - attached to the **coracoid process**
Long head - attached to the **supraglenoid tubercle** (just above glenoid fossa)
85
Describe distal attachment of biceps
2 heads converge and attach to the **radial tuberosity**
86
What is movement of the biceps?
Flexes the elbow and shoulder (can move both)
87
Where is the brachialis found?
Lies deep to biceps
88
What are the attachments of the brachialis?
Proximal: humeral shaft (where is originates)
Distal: ulna
89
Movements of brachialis?
Flexes the elbow (cannot move shoulder as doesn't cross shoulder)
90
Attachments of the coracobrachialis?
Attached to the coracoid process (of scapula) and inserts onto the proxima part of the humeral shaft (arm)
91
Movements of coracobrachialis?
Weakly flexes the shoulder (no effect on elbow as doesn't cross elbow joint)
92
What muscle makes up the posterior arm?
Triceps
93
What nerve innervates the triceps?
The radial nerve (C5-T1)
94
How many heads does the triceps have?
3 - all have separate origins but all heads insert via a common tendon onto the olecranon of the ulna
95
Where do all 3 heads of the triceps insert?
All insert via a common tendon onto the **olecranon** of the ulna
96
Movements of the triceps?
Extends the elbow by contracting and pulling on ulna
97
What are the 3 heads of triceps?
1. Long head
2. Lateral head
3. Medial head
98
Where does the long head of triceps originate?
Attaches to the **infraglenoid tubercle** on the scapula - so contributes to shoulder extension
99
Where does the lateral head of the triceps originate?
Attaches proximally to the posterior shaft of the humerus
100
Where does the medial head of the triceps originate?
Attaches to the shaft of the humerus (is found deep to the long and lateral heads)
101
How is the brachial artery formed?
Subclavian artery travels under clavicle and enters axilla --\> becomes axillary artery
Axillary artery continues down arm --\> becomes brachial artery
102
What posterior branch does the brachial artery give rise to?
The deep artery of the arm --\> **profunda brachii**
103
Describe path and function of deep artery of arm
Comes off brachial artery, travels behind humerus and supplies posterior compartment of arm
104
Describe how the axillary vein is formed and its tributaries
- The basilic vein of the arm (a superficial vein on medial aspect of arm) continues **proximally** as the axillary vein
- **Deep veins** of the arm and the **cephalic vein** (another superficial vein) are major tributaries of the axillary vein
105
What 4 of the terminal branches of the brachial plexus are found in the arm?
1. Musculocutaneous; heads into anterior compartment
2. Median; travels through anterior compartment towards forearm
3. Radial; heading behind the humerus into the posterior compartment
4. Ulnar; travels on medial aspect of arm towards forearm
106
Which 3 of the terminal branches of the brachial plexus run close to the humerus? What is the danger of this?
Axillary nerve = surgical neck
Radial nerve = radial groove
Ulnar nerve = medial epicondyle
Fracture of humerus can lead to damage to nerves
107
How can nerve damage in the arm be assessed?
To assess whether there has been any nerve damage you need to know the muscles the nerve innervates and the skin it supplies) and then test the **function of those muscles and sensation** in those regions.
108
What does hitting your 'funny bone' refer to?
Hitting the ulnar nerve (that crosses the elbow)
109
What is at risk during fracture near:
1. surgical neck of humerus?
2. radial shaft?
3. supracondular fracture (just proximal to epicondyles of humerus)?
4. medial epicondyle?
1. Axillary nerve
2. Radial nerve
3. Median nerve, brachial artery
4. Ulnar nerve
110
What is osteomyelitis?
Infection of bone
111
Normal elbow x-ray: AP (from anterior to posterior)
112
Normal elbow xray: lateral
113
Labelled diagram of ulna and radius
114
What has happened here? What nerve is at risk? What would you need to do to assess whether the nerve had been injured?
* Region of break: fracture at the surgical neck
* Nerve at risk: axillary nerve
* Assessment of nerve: Compare feeling of skin on upper lateral arm. Also test function of deltoid by asking patient to adduct arm --\> this may not be possible here as painful for patient
115
Why is axillary nerve at risk in surgical neck fracture?
Axillary nerve comes off the **posterior cord** of the brachial plexus and runs really close to the bone at the surgical neck
Fracture to surgical neck can tear the axillary nerve
116
How can damage to axillary nerve be assessed?
To answer this we need to know 2 things:
1. What the axillary nerve does --\> innervates deltoid and teres minor and the skin over the upper lateral arm
2. What the muscle(s) innervated by this nerve (in this case, deltoid and teres minor) do? --\> deltoid abducts the shoulder beyond 20 degrees, teres minor laterally rotates the shoulder.
Now we can work out a logical way of assessing the function of the nerve:
1. Ask the patient to abduct their arm (if possible)
2. Test the patient’s sensation over the upper lateral arms (both!) and ask the patient if it feels the same on both sides.
117
What hashappened here? What nerve is at risk? What would you need to do to assess whether the nerve had been injured?
* Anterior dislocation of shoulder
* Humeral head moved medially and inferiorly
* Axillary nerve at risk
* Test motor and sensory functions of axillary nerve (note that most patients will not be able to move arm due to fracture so test sensory function instead)
* Do this BEFORE putting joint back into place
118
What has happened here?
What nerve is at risk?
What artery is at risk?
What would you need to do to assess whether the nerve had been injured?
* Comminuted fracture (more than 2 fragments)
* **Radial nerve** at risk
* To test motor function: wrist extension (as innervates all muscles of posterior forearm)
* To test motor function: straighten wrist? straighten fingers?
* To test sensory function: sensation over back of hand near thumb?
119
What has happened here?
What nerve is at risk?
What would you need to do to assess whether the nerve had been injured?
Injury: posterior dislocation of the ulna (elbow dislocation)
Nerve at risk: ulnar nerve behind the medial epicondyle
Assessment: impaired function of the muscles and sensory disturbance in skin innervated by the ulnar n.
* Motor: 2 muscles in forearm, most of muscles of hand
* Sensory: medial forearm, medial wrist, and medial one and one-half digits (on palm surface and dorsal surface)
120
What has happened here?
What nerve is at risk?
What artery is at risk?
What would you need to do to assess whether the nerve had been injured?
Injury: Humeral supracondular fracture (fracture of humerus just above the epicondyles)
At risk: Median nerve and brachial artery
Assessment:
* Median nerve:
* Motor: anterior forearm muscles, some of small muscles of hand (thenar particularly)
* To test: flex wrist, flex fingers (make a fist)
* Sensory: look at diagram (around thumbm, lateral palm)
* Brachial artery:
* Assess capillary refill (measure of time taken for distal capillary bed e.g. finger to regain colour after pressure has been applied)
* Assess colour, pulse, temperature etc
121
What does sublux mean?
To become partially dislocated or displaced
122
What happens during 'pulled elbow' in children?
Radial head subluxes from the annular ligament
123
How is a pulled elbow in children usually caused?
Usually by an upward force on an abducted arm (e.g. by swinging child by arms)
124
What can be palpated during pulled elbow?
The radial head
This is panful and the child will not move their arm
125
Muscles in the forearm have attachments to the medial and lateral epicondyles. What can inflammation at the humeral epicondyles cause?
* Medial epicondylitis = inflammation at the medial epicondyle = **‘golfer’s elbow**
* Lateral epicondylitis = inflammation at the lateral epicondyle = **‘tennis elbow’**
126
Where is pain felt during medial and lateral epicondylitis?
Pain radiates into forearm along the muscles
127
What is treatment for humeral epicondylitis?
Rest and maybe injection of corticosteroids
128
What are bursae?
Fluid-filled sacs located around joints - areas of potential friction, e.g. between a muscle and bone.
129
What is bursitis?
Inflammation of bursae - quite common
130
How does bursitis present?
the bursa swells (may be visible) and is painful when touched
131
What can cause inflammation of the olecranon bursa?
Excessive, repeated pressure and friction over the olecranon can cause inflammation of the olecranon bursa
132
What nerve can a humeral **supracondylar** fracture injure? What would this then impair?
The median nerve
Impaired function of the forearm muscles and sensory disturbance in skin innervated by the median nerve
133
What artery can a humeral supracondylar fracture injure? What would this then potentially cause?
Brachial artery
--\> can lead to ischaemia of the forearm muscles
134
What nerve can posterior dislocation of ulna (i.e. elbow dislocation) damage?
Ulnar nerve
135
What would damage of ulnar nerve lead to?
Impaired function of the muscles and sensory disturbance in skin innervated by the ulnar n.
136
What does the capitulum on the humerus articulate with?
Radial head
137
What other nerves leave the brachial plexus (except the 5 terminal branches)?
- Long thoracic nerve
- Thoracodorsal nerve
138
What is found just below the radial head?
The radial neck - common place of fracture
139
What is found just below the radial neck?
The radial tuberosity - bony protrusion
140
What attaches to the radial tuberosity?
The biceps muscle - tendon comes across elbow joint to insert here
141
What tuberosity is found on the ulna, just lateral to the radial tuberosity?
The ulna tuberosity - less pronounced that the radial tuberosity
142
What is the ulna tuberosity the attachment point of?
Brachialis - sweeps down across elbow joint to insert here --\> works on elbow joint
143
Diagram of proximal radial-ulnar joint. What movement happens here?
Pivoting supination and pronation
144
What are the anterior arm muscles all innervated by?
Musculocutaneous nerve
145
What do the anterior arm muscles move?
The elbow and the shoulder
146
Where does the posterior arm muscle insert?
On the ulna
147
What does the posterior arm muscle move?
Elbow and shoulder
148
What is the triceps (the posterior arm muscle) innervated by?
The radial nerve
149
Describe route of long head of bicep
Travels proximally through intertubercular sulcus, through the capsule of the shoulder joint and comes to insert on the **supraglenoid tubercle** of the scapula
150
What muscle
151
Image of axillary artery
Goes on to form brachial artery
152
Where is the regimental badge area?
Upper lateral arm (where axillary nerve innervates)
153
Where does the radial nerve pass after innervating triceps?
* Into the posterior forearm to innervate the posterior forearm muscles
* Extend wrist
* Extend fingers
154
What area of skin does the radial nerve innervate?
Back of the hand around thumb area
155
Which muscle attaches to the supraglenoid tubercle?
Long head of biceps
156
Which muscle attaches to the infraglenoid tubercle?
Long head of triceps
157
What epicondyle is the capitulum nearest?
Lateral (as articulates with radial head)
158
What muscles attach to coracoid process of scapula?
1. Pec minor
2. Short head of biceps
3. Coracobrachialis
