45. Fascia, efferent vessels, cutaneous innervation and myotomes of upper limb Flashcards
Discuss the principles of fascial layers in the upper limb
Deep to the skin is
1) subcutaneous tissue (superficial fascia) that contains fat, and
2) deep fascia that compartmentalises and invests the muscles.
If no structure (no muscle, tendon, or bursa) intervenes between the skin and the bone, the deep fascia is usually attached to bone.
Discuss the principles of fascial layers in the upper limb
Deep to the skin is
1) subcutaneous tissue (superficial fascia) that contains fat, and
2) deep fascia that compartmentalises and invests the muscles.
If no structure (no muscle, tendon, or bursa) intervenes between the skin and the bone, the deep fascia is usually attached to bone.
Fascia of the pectoral region include
- Pectoral fascia which invests the pectoralis major and is continuous inferiorly with the fascia of the anterior abdominal wall.
- Axillary fascia is formed from lateral border of the pectoralis major. Deep to the pectoral fascia and the pectoralis major is another fascial layer the clavipectoral fascia.
- The clavipectoral fascia desends from the clavicle, enclosing the subclavius and then the pectoralis minor, becoming continuous inferiorly with the axillary fascia.
Where is the costocoracoid membrane located and what is it’s significance?
The costocoracoid membrane is part of the clavipectoral fascia and is located between the pectoralis minor and the subclavius. It is pierced by the lateral pectoral nerve which primarily supplies the pectoralis major.
What forms the suspensory ligament of the axilla and what is it’s role?
The suspensory ligament is part of the clavipectoral fascia inferior to the pectoralis minor and it supports the axillary fascia and pulls it and the skin inferior to it upwards during abduction of the arm, thus forming the axillary fossa.
What is the fascia that covers the scapulohumeral muscles and where does it descend from?
The deltoid fascia descends over the superficial surface of the deltoid from the clavicle, acromion and scapular spine
What three (3) structures are created by the septa that penetrate between the fascicles (bundles) of muscles that originate from the deltoid fascia and what is achieved by their attachments to overlying fascia?
The three structures are the osseofibrous subscapular, supraspinous and infraspinous compartments. By attaching to the overlying fascia it allows the muscle to have greater bulk than would be the case if only bony attachments occurred.
What is significant about the supraspinous and infraspinous fascia that overlie the supraspinatus and infraspinatus muscles?
The are both so dense at the posterior aspect of the scapula that they must be removed during dissection to view the muscles
Describe key aspects of the brachial fascia
- The brachial fascia is a sheath of deep fascia that encloses the arm like a snug sleeve deep to the skin and subcutaneous tissue.
- It is continuous superiorly with the deltoid, pectoral, axillary and infraspinous fascial
- Inferiorly it is attached to the epicondyles of the humerus and the olectranon of the ulna and is continuous with the antebrachial fascia, the deep fascia of the forearm.
The upper arm is divided by two intermuscular septa, where are they located and what do they divide?
- The intermuscular septa of the upper arm are identified as the medial and lateral intermuscular septa. The extend from the deep surface of the brachial fascia to the central shaft, and medial and lateral supraepicondylar riges of the humerus.
- These intermuscular septa divide the arm into anterior (flexor) and posterior (extensor) fascial compartments, with each containing muscles serving similar functions and sharing common innervation.
TEST YOURSELF Fig. 6.13 p. 688
TEST YOURSELF Fig. 6.13 p. 688
How are fascial compartments organised in the forearm?
Similar to the upper arm, the fascial comparments are surrounded by the antebrachial fascia and are separated by the interosseous membrane connecting the radius and ulna.
The distal ends of the antebrachial fascia forms what?
The distal end of the antebrachial fascia forms the palmar carpal ligament anteriorly, which is continuous with the extensor retinaculum posteriorly which retains the extensor tendons in position.
What sits immediately distal and at a deeper level to the palmar carpal ligament and what is its function?
Immediately distal and at a deeper level to the palmar carpal ligament and continuous with the antebrachial fascia is the flexor retinaculum (transverse carpal ligament).
Where are the points of attachment for the flexor retinaculum (transverse carpal ligament)?
It extends between the anterior prominences of the outer carpal bones and convert the anterior concavity of the carpus into the carpal tunnel, through which the flexor tendons and median nerve pass.
Discuss the anatomy of the palmar fascia.
- The palmar fascia is an extension of the deep fascia of the upper limb that extends beyond the extensor and flexor retinacula and is teathered to the skin by innumerable minute, strong skin ligaments to stop sliding movement of the skin.
- Its central part is a thick, tendious triangular structure, the palmar aponeurosis that overlies the central compartment of the palm. Its apex is located proximally and is continuous with the tendon of the Palmaris longus (when present)
- The base forms four distinct thickenings that radiate to the bases of the fingers and become continuous with the fibrous tendon sheaths of the digits.
- The base of the palmar aponeurosis is formed by the superficial transverse metacarpal ligament.
TEST YOURSELF Fig. 6.14 p.688
TEST YOURSELF Fig. 6.14 p.688
What are the superficial veins of the upper limb?
The cephalic (lateral) and basilic (medial) veins that originate in the subcutaneous tissue on the dorsum of the hand from the dorsal venous network
What is the function of the perforating veins?
They form communications between the superficial and deep veins
Describe the cephalic vein.
- It ascends in the subcutaneous tissue from the lateral aspect of the dorsal venous network, proceeding along the lateral border of the writ and the anterolateral surface of the proximal forearm and arm.
- Anterior to the elbow it communicates with the median cubital vein which passes obliquely across the anterior aspect of the elbow in the cubital fossa and joins the basilic vein.
Describe the basilic vein
- It ascends in the subcutaneous tissue from the medial end of the dorsal venous network along the medial side of the forearm and the inferior part of the arm.
- Near the junction of the middle and inferior thirds of the arm, it passes deeply piercing the brachial facia and running superiorly parallel to the brachial artery and the medial cutaneous nerve of the forarm to the axilla, where it merges with the accompanying veins of the axillary artery to form the axillary vein.
Describe the median antebrachial vein (median vein of the forearm).
- It is highly variable.
- It begins at the base of the dorsum of the thumb and curves around the lateral side of the wrist, and ascends in the middle of the anterior aspect of the forearm between the cephalic and the basilic vein
- It sometimes divides into a median basilica vein and joins the basilica vein or a median cephalic vein, which joins the cephalic vein.
List the key differences between the superficial and deep veins of the upper limb.
- Deep veins lie internal to the deep fascial
- Deep veins usually occur as paired (continually interanastomosing) accompanying veins that travel with, and bear the same name as the major arteries of the limb.
TEST YOURSELF fig 6.15 p.690
TEST YOURSELF fig 6.15 p. 690
List the deep veins of the forearm from the deep palmar arch
- The ulnar and radial veins
- The anterior interoseous vein and posterior interoseous veins
- The radial and ulnar recurrent veins (at the level of the elbow)
- The collateral veins of the elbow joint
- The brachial veins and deep brachial vein which anastomose with the basilic vein
TEST YOURSELF fig 6.16 p. 691
TEST YOURSELF fig 6.16 p. 691
Where do the superficial lymphatic vessels of the upper limb arise from?
Superficial lymphatic vessels arise from lymphatic plexuses in the skin of the fingers, palm, and dorsum of the hand to ascend mostly with the superficial veins, such as the cephalic and basilic veins.
Discuss the key points of the cubital lymph nodes.
- Some vessels accompanying the basiclic vein enter the cubital lymph nodes, located proximal to the medial epicondyle and medial to the basilic vein.
- Efferent vessels from these lymph nodes ascend in the arm and terminate in the humeral (lateral) axillary lymph nodes.
Where do most superficial lymphatic vessels of the upper limbs travel?
Most superficial lymphatic vessels of the upper limb accompany the cephalic vein and cross the proximal part of the arm and the anterior aspect of the shoulder to enter the apical axillary lymph nodes, however some may previously enter the more superficial deltopectoral lymph nodes.
What is the course of the lymphatic vessels and where possible draw comparison with the superficial vessels
Deep lymphatic vessels are less numerous than superficial vessels and accompany the major deep veins in the upper limb (radial, ulnar and brachial) to terminate in the humeral axillary lymph nodes. In fact there are very few deep lymph nodes occurring along their course.
What structures do deep lymphatic vessels drain?
They drain lymph from the joint capsules, periosteum, tendons, nerves, and muscles
Where are the axillary lymph nodes drained?
The axillary lymph nodes are drained by the subclavian lymphatic trunk.
TEST YOURSELF fig 6.17 p.692
TEST YOURSELF fig 6.17 p. 692
TEST YOURSELF fig 6.18 p.693
TEST YOURSELF fig 6.18 p.693
Identify the dermatome regions associated with these spinal segments • C3, C4 • C5 • C6 • C7 • C8 • T1 • T2
- C3,C4 – Region at the base of the neck, extending laterally over the shoulder
- C5 – Lateral aspect of the arm (i.e. superior aspect of the abducted arm)
- C6 – Lateral forearm and thumb
- C7 – Middle and ring fingers and centre of posterior aspect of the forearm
- C8 – Little finger, medial side of hand and forearm (i.e. inferior aspect of abducted arm)
- T1 – Medial aspect of forearm and inferior arm
- T2 – medial aspect of uperior arm and skin of axilla
The pain sensation experienced with myocardial ischaemia may be felt radiating down the medial side of the left arm, what dermatome is this?
• T1 & T2
Where are the nerves of the upper limb derived from?
The brachial plexus, a major nerve network formed by the anterior rami of the C5-T1 pinal nerves.
Where are the nerves of the shoulder derived from.
The cervical plexus, a nerve network consisting of a series of nerve loops formed between adjacent anterior rami of the first four cervical nerves.
Where is the cervical plexus located?
The cervical plexus lies deep to the sternocleidomastoid muscle on the anterolateral aspect of the neck.
TEST YOURSELF fig 6.19 p.696
TEST YOURSELF fig 6.19 p. 696
Why are there no anterior cutaneous nerves of the arm and forearm?
Because this pattern corresponds to that of the cords of the brachial plexus
Where do the supraclavicular nerves originate, what is their contributing spinal nerve and describe their course and distribution
- The supraclavicular nerves originate from the cervical plexus and their contributing spinal nerves are C3 & C4.
- They pass anterior to the clavicle, immediately deep to the platyma, and supply skin over the clavicle and superiolateral aspects of pectoralis major
Where does the superior lateral cutaneous nerve of the arm originate, what is it’s contributing spinal nerve and describe it’s course and distribution
- The superior lateral cutaneous nerve of the arm is the terminal branch of the axillary nerve and its contributing spinal nerve is C5 & C6
- It emerge from beneath the posterior margin of the deltoid and supplies skin over the lower part of this muscle, and on the lateral side of the midarm
Where does the inferior lateral cutaneous nerve of the arm originate, what is it’s contributing spinal nerve and describe it’s course and distribution
- The inferior lateral cutaneous nerve originates from the radial nerve (or posterior cutaneous nerve of the arm), from C5 & C6.
- It perforates the lateral head of the tricep, passing clos to the cephalic vein to supply skin over the inferolateral aspect of the arm
Where does the posterior cutaneous nerve of the arm originate, what is it’s contributing spinal nerve and describe it’s course and distribution
- The posterior cutaneous nerve of the arm has it’s source in the radial nerve (in the axilla) and it’s contributing spinal nerves are C5-C8
- It crosses posterior to and communicates with the intercostobrachial nerve and supplies skin on the posterior arm as far as the olecranon
Where does the posterior cutaneous nerve of the forearm originate, what is it’s contributing spinal nerve and describe it’s course and distribution
- The posterior cutaneous nerve of the forearm also has it’s source with the radial nerve (with the inferior lateral cutaneous nerve of the arm) and its contributing spinal nerve is C5 – C8
- It perforates the lateral head of the triceps descends laterally in the arm, then rungs along and supplies the posterior forearm to the wrist
Where does the lateral cutaneous nerve of the forearm originate, what is it’s contributing spinal nerve and describe it’s course and distribution
- The lateral cutaneous nerve of the forearm originates from the musclocutaneous nerve (terminal branch) and it’s contributing spinal nerves are C6&C7
- It emerge lateral to the biceps tendon deep to the cephalic vein, supplying the skin of anterolateral forearm to the wrist.
