pectoral girdle, elbow and shoulder Flashcards
pectoral girdle attachment
- attachment to axial
- only 1 p.o.a to the axial skeleton at the sternoclavicular joint- medial end of the clavicle articulates w manubrium of the sternum
- scapula doesn’t directly attach to the axial skeleton via joint but connects to back of the thorax by muscles- allows 4 large range of movement
- ligs provide stability and support to joints in pec girds
what is pec gird
clavicle n scapula
clavicle
- long bone
- lies horizontally between scapula n sternum
- 2 joint- ACJ (acromioclavular joint) and SCJ (sternoclaviculr joint)
- articulates medially with the sternum at SCJ
- articulates laterally with acromion at ACJ
- serves as muscular attachment point
- one of the most fractured bones in body
scapula
- large, triangular flat bone that connects the trunk to the upper limb
- the posterior bone of pectoral girdle sitting across the back of the thoracic cage, superiorly
- major features= spine, coracoid process, acromion process and glenoid cavity
- got 3 borders n angles (it triangle): superior, medial n lateral and superior, inferior and lateral
- 3 fossas= supraspinous, infraspinous, subscapular
- has a suprascapular notch
acromion process
a continuation of the scapula spine which passes laterally over the shoulder (Glenohumeral) joint
- ACROMION: of the scapula extends from the scapular spine to articulate with the clavicle to form the Acromio-clavicular joint
spine of scapula
oblique ridge of bone that passes across the upper posterior part of the scapula
coracoid process
small hook-like structure which points laterally forward, on the edge of the superior anterior portion of the scapula
- for muscle attachments
glenoid cavity
- a very shallow articular surface that articulates with the humeral head
sternoclavicular joint
- where pec girdle joins to the axial skeleton
- Strong synovial saddle joint
- Contains a fibrocartilaginous articular disc
- Robust ligamentous and muscular support
-sternoclavicular ligament= reinforces the joint capsule and prevents forward/ backward movement - costoclavicular ligament= connects the clavicle to the first rib and prevent elevation of clavicle
- interclavicular ligament= runs along top of sternum, connects the 2 clavicle to prervnt excessive downward movement
Acromioclavicular joint
Small synovial plane joint
Allows scapula and clavicle to move together during arm movement
Strong ligamentous support
Can have a small fibrocartilaginous disc
Relatively prone to injury
- acromioclavicular ligament: keeps joint capsule together and connects acromion n clavicle together
- coracoclavicular ligament: connect coracoid process to the clavicle to prevent displacement
labrum of the shoulder
labrum: fibrous cartilage and deepens the socket and provides additional stability = different movement allowed
glenohumeral joint
- synovial joint of the shoulder has a fibrous articular capsule that completely encloses the joint and extends from the glenoid cavity to the neck of the humerus
- on surface, joint is lined with synovial membrane= provide synovial fluid= lubricates joint and reduce friction
- it has 5 ligaments, a glenoid labrum, and four bursae (act as cushions) to alleviate friction
humerus
- largest and longest bone in upper limb
- articulates with scapula at glenohumeral joint + radius and ulna at the elbow joint
major features of humerus
head:
- rounded part at the proximal end
- fits into the glenoid fossa of scapula
anatomical neck:
- separates the head of the humerus from the greater and lesser tubercles
tubercles (greater and lesser):
- greater is more lateral and larger
intertubercular groove:
- dep groove between tubercles
- houses the tendon of long head of bicep brachii, provides poa for major muscle groups of shoulder
surgical neck:
- site of fractures that require surgery
shaft:
- cylindrical at proximal end but becomes more triangular as it flattens and broadens at the distal end
- contains a central medullary cavity filled with bone marrow
deltoid tuberosity:
- attachment for deltoid muscles
- on posterior side there is radial groove that contain the radial nerve
distal end of humerus
capitulum:
- rounded notch that articulates with radius at the elbow joint
trochlea:
- articulates with the ulna allowing for flexion and extension of elbow
median and lateral epicondyle:
- bony protrusions
- attachment point for muscles n ligaments
olecranon fossa:
- deep indentation on posterior aspect that accommodates the olecranon (bony prominence of the ulna when elbow is extended)
coronoid fossa:
- small indentation on anterior aspect that receives the coronoid process of the ulna during flexion
- large depression on back of humerus