Axilla and Brachial Plexus Flashcards
The arterial supply, venous drainage, lymphatic drainage and nerve supply of the upper limb all pass through the:
axilla
The lymph nodes of the axilla receive drainage from:
- back
- neck
- upper limb
- anterior chest wall (including the breast)
The shoulder girdle consists of:
- scapula and clavicle
- no joint connection to the back; only muscle
Muscles that connect the shoulder girdle to the back:
- levator scapulae
- trapezius
- rhomboids
- latissimus dorsi
What is the only joint connecting the should girdle/upper limb to the axial skeleton?
sternoclavicular joint
Label:
- left: head of humerus
- right: glenoid fossa
Label:
glenohumeral joint
- between head of humerus and glenoid fossa of the scapula.
The four walls of the axilla:
- posterior (back)
- lateral (side)
- anterior (front)
- medial (bottom)
Composition of the Lateral Wall of the axilla:
Humerus (bicipital groove)
- where the anterior and posterior walls converge
Composition of the Anterior Wall of the axilla:
- Pectoralis Major
- Pectoralis Minor
Composition of the Medial Wall of the axilla:
- Serratus Anterior
Composition of the Posterior Wall of the axilla:
- Subcapularis
- Teres major
- Latissimus Dorsi
Axillary Arteries Diagram:
Label:
Three cords of the brachial plexus run through the axilla and surround the axillary artery. What are the three cords?
- lateral
- medial
- posterior
Axillary sheath:
- connective tissue that surrounds the axillary artery and brachial plexus cords.
- axillary vein is not contained in the axillary sheath.
An aneurysm of the axillary artery can cause:
- compression of the brachial plexus cords due to their containment in the axillary sheath.
A nerve plexus is:
- a network of nerve fibers that arise from multiple sources, intermingle, and then give rise to nerves that contain nerve fibers from these multiple sources.
The multiple sources of nerve fibers in the brachial plexus are:
- anterior rami of C5, C6, C7, C8, and T1
The lateral and medial cords of the brachial plexus contain only _______ nerve fibers.
- anterior division
The posterior cord of the brachial plexus contains only _________ nerve fibers.
- posterior division
What terminal nerves of the brachial plexus contain only anterior division fibers?
- musculocutaneous, median, and ulnar nerves
What terminal nerves of the brachial plexus contain only posterior division fibers?
- radial and axillary nerves
What are the collateral nerves of the brachial plexus?
- long thoracic nerve
- dorsal scapular and suprascapular nerves
- three subscapular nerves (from posterior cord)
- lateral and medial pectoral nerves (from lateral and medial cords)
The three subscapular nerves of the brachial plexus innervate:
- muscles that form the posterior wall of the axilla
The lateral and medial pectoral nerves of the brachial plexus innervate:
- muscles that form the anterior wall of the axilla
The long thoracic nerve of the brachial plexus innervates:
- muscle on the medial wall of the axilla.
The dorsal scapular and suprascapular nerves of the brachial plexus innervate:
muscles of the shoulder girdle.
The musculocutaneous nerve of the brachial plexus innervates:
- all muscles of anterior arm.
The median nerve of the brachial plexus innervates:
- most muscles of anterior forearm (except 1.5)
- remaining muscles innervated by ulnar nerve
The ulnar nerve of the brachial plexus innervates:
- most muscles of anterior hand (except 5)
- remaining muscles innervated by median nerve
The radial nerve of the brachial plexus innervates:
- all muscles of posterior arm and forearm.
The axillary nerve of the brachial plexus innervates:
- only two muscles: deltoid and teres minor.
The collateral nerves of the brachial plexus innervate:
- proximal muscles of shoulder and axillary walls
Segmental innervation of the muscles of the upper limb has what kind of gradient?
- “proximo-distal gradient”
- more proximal muscles innervated by higher spinal cord segments.
- more distal muscles innervated by lower spinal cord segments.
The median nerve contains nerve fibers from C6 to T1, and innervates the anterior muscles of the forearm. What is the segmental innervation?
- proximal forearm: C6 and C7
- distal forearm: C7 and C8
- hand muscles: C8 and T1
In general, higher spinal cord segments provide sensory innervation to the ______ side of the upper limb.
lateral side
In general, lower spinal cord segments provide sensory innervation to the ______ side of the upper limb.
medial side
In general, pre-plexus nerve injuries (i.e. SUPRACLAVICULAR) will result in:
- dermatomal sensory losses and segmental muscular weakness.
In general, post-plexus nerve injuries (i.e. INFRACLAVICULAR) will result in:
- cutaneous nerve sensory losses and muscle paralysis related to specific terminal/collateral nerves.
The long thoracic nerve (LTN) innervates what muscle?
- serratus anterior muscle.
- injury leads to “winged-scapula”.
The thoracodorsal nerve predecesor and innervation:
- arises from posterior cord of the brachial plexus
- innervates latissimus dorsi (attaches to humeral head)
- injury results in deficits in arm movement
Label dermatomes:
Label dermatomes:
Label nerves:
