Anatomy Of Shoulder and Brachial Plexus Flashcards
What is the functional consideration of the upper limb and how does this affect the bone structure?
- Mobility and ability to perform fine motor skills and grasp.
- Weight bearing is not a consideration
- Allows bones to be lighter and less robust
What 4 regions can the upper limb be separated into?
- Shoulder
- Arm
- Forearm
- Hand
What does the emphasis on mobility of the UL compromise and how?
- Stability compromised
- Limited fixation to axial skeleton
How is the UL fixated to the axial skeleton?
- Ant. = sternoclavicular joint
- Post = muscles to vertebral column
What does the clavicle connect?
-Upper limb to trunk
What do the sternal and acromial ends of the clavicle articulate with?
- Sternal: with manubrium at the sternoclavicular joint (SC)
- Acromial: with the acromion of the scapula at the acromioclavicular joint (AC).
What are the shapes of the parts of the clavicle?
- Medial 2/3rds concave ant.
- Lateral 1/3rd flattened and concave ant.
What function can the clavicle act out?
Acts as a strut
Can transmit weight
What is the internal structure of the clavicle?
No medullary cavity, trabecular with a shell of compact bone.
What shape is the scapula?
Large flat triangular bone
Where around would you find the scapula in terms of ribs?
Overlaps ribs 2-7
Name the different parts of the scapula?
- Acromion
- Coracoid
- Glenoid
- Medial border
- Spine
What is the spine of the scapula?
Sharp ridge, divides bone into supraspinous and infraspinous fossa.
What and where are the acromion processes of scapula?
Are lateral and high point
Articulate with clavicle
What and where is the glenoid cavity of scapula?
Lateral, inferior to acromion
Articulates with humerus
What and where are the coracoid processes of scapula?
- Lateral and anterior
- Muscles attatch here
What is the medial border of the spine?
Place for attatchment of muscles
What joins the scapula with the axial skeleton?
No joint
So held in place by muscles
What muscles hold the scapula in place?
- Trapezius
- Rhomboids
- Levator scapulae
- Serratus anterior
- Pectoralis minor
What movments may the muscles surrounding the scapula generate?
- Protraction/retraction
- Lat rotation/ med rotation
- Elevation/ depression
What are the joints of the pectoral girdle?
- Sternoclavicular
- Acromioclavicular
What type of joint is the sternoclavicular joint?
Synovial, acts as ball and socket joint
What makes up the sternoclavicular joint?
-Notch of manubrium and medial clavicle
What strengthens the SC joint to prevent dislocation, name and explain what they do/where they are?
Ligaments
Sternoclavicular ligament = capsule thicked ant. and post.
Interclavicular ligament = at med. end of clavicle
Costoclavicular ligament = from 1st rib to clavicle
What type of joint is the AC joint?
Gliding, synovial
Where is the AC joint?
Lateral clavicle -acromion
What ligaments strengthen the AC joint?
- Coracoclavicular
- Acromioclavicular
- Coracoacromial
What is the shoulder joint?
Glenohumeral joint
What does the glenohumeral joint join?
Head of humerus and glenoid cavity of scapula.
What type of joint is the glenohumeral joint?
Synovial, multiaxial ball and socket
Why does the shoulder joint have limited stability and what can help provide this?
- Poor bony fit, loose capsule and ligaments.
- Stability can be provided by rotator cuff muscles
What is the axilla and what does it do and how?
Is a pyrmaidal space that helps communicate between UL and neck.
It does this through, BP, lymph nodes and axillary vessels.
What are the landmarks of the axilla and how and where do they appear?
- Apex; passageway between neck and axilla, points up and medially
- Floor; upward arching skin sheet
- Ant. wall; pectoral muscles
- Post. wall; subscapularis, teres major and lat. dorsi
- Med. wall; chest wall and serratus ant.
- Lat. wall; humerus and muscles
What is the brachial plexus?
A major network of nerves supplying upper limb.
What nerves make up the brachial plexus?
-Ventral Rami of C5-T1 spinal nerve roots.
Minor contribution from C4 and T2.
What does the brachial plexus do?
Provides sensory, motor and sympathetic nerve supply to pectoral girdle and upper limb (except trapezius).
Where does the brachial plexus extend?
-Extends inferiorly and laterally through neck/axilla into arm.
Why does the brachial plexus have a complex re-routing system?
-Provides a back up mechanism
Describe the organisation of the brachial plexus?
- Roots (5)
- Trunks (3)
- Divisions (6)
- Cords (3)
- Branches
What are the 5 BP roots, where do they emerge and then unite to form?
- Ventral rami of C5-T1
- Emerge between scalene anterior and medial muscles.
- Unite to form 3 trunks
How can the 3 trunks of BP be named, where are they located and what do they divide into?
- Upper - C5 + C6
- Middle C7
- Lower C8 + T1
- Located in neck, each trunk divides into divisions.
How can the divisions of the BP be categorised and what areas do they supply, what do they then form and how?
- Can be anterior or posterior
- Anterior = supply flexor muscles and skin of front of UL.
- Posterior supply the extensors and skin on back of UL.
- Pass deep to middle 1/3 clavicle into apex of axilla and regroup to form cords.
What are the cords of the BP, how are they named, and what makes each of them up?
- Names according to position to axillary artery.
- Lat. cord= ant. divisions of sup. and middle trunks
- Med. Cord= ant. division of inf. trunk
- Post. cord= uniting post. divisions of all 3 trunks.
What are the terminal branches coming from each of the Cords of the BP?
- Lat cord = musculocutaneous, median
- Med. cord = median, ulnar
- Post cord = radial, axillary
What are the other main supraclavicular branches of the BP?
- Dorsal scapular
- Long thoracic
- Suprascapular
What are the other main infraclavicular branches of BP?
- Medial and lateral pectoral
- Upper and lower subscapular
- Thoracodorsal
What may happen as a result of injury to BP?
- Affect movement and sensory.
- Paralysis and anaesthesia
What may cause injury to BP?
- Disease
- Stretching
- Compression damage
Describe crutch palsy and potential effects?
- After prolonged use of crutches
- Commonly affects radial nerve
What may happen as a result of radial nerve damage and what may be another cause of it?
- Drop wrist
- cant extend hand
- May be caused by intramuscular deltoid injections
What happens in carpal tunnel syndrome?
- Median nerve damage
- Numbness, tingling and pain in palm and fingers.
What parts can the humerus be put into (shoulder part)?
- Head
- Neck
- Greater tubercule
- Deltoid tuberosity
- Lesser tubercule
- Intertubercule groove
What parts can humerus be put into (elbow part)?
- Areas that articulate with forearm :
- Laterally, radius joins with capitolum
- Medially, ulna joins with trochlea
- Med and lateral epicondyles are sites for muscle attatchment
What do the rotator cuff muscles do and what are they?
- Join scapula to humerus
- Teres minor
- Infraspinatus
- Supraspinatus
- Subscapularis
What do muscles lying closer to shoulder do and name them?
- Smaller mechanical effect
- Stabilise joints
- Act as ligaments
- Long head biceps
- Triceps brachi
- Rotator cuff
What do muscles attatching a distance from the shoulder do and name them?
- Have considerable mechanical effect
- Deltoid
- Teres major
- Short head biceps brachi
