L15, Pectoral Girdle: Scapula, Humerus, Radius, Ulna

features of the scapula

paired flat bone

articulates with the humerus and clavicle

only bone that is floating virtually freely in muscle

sites stop posterior aspects of R2-R7

only direct articulation with another bone at acromioclavicular joint

What is the correct orientation for the scapula?

Superior border

• Processes are superior

• Glenoid fossa is lateral

Anterior/ventral surface

• Concave

Posterior/dorsal surface

• Convex

Where is the origin of subscapularis muscle (medial rotation of the arm; one of the rotator cuff muscles)?

subscapular fossa

Where is the attachment for conoid ligament and trapezoid ligament?

coracoid process

Where is the attachment for the conoid ligament and trapezoid ligament?

coracoid process

Where is the origin of serratus anterior muscle on anterior surface (protraction of scapula)?

inferior angle

Where is the origin of deltoideus muscle (abduction, flexion, and extension of the shoulder), insertion of trapezius muscle (rotation, retraction, elevation, and depression of scapula)?

acromion process

Where is the origin of infrapinatus muscle (lateral rotation of the arm; one of the rotator cuff muscle)?

infraspinous fossa

Where is the origin of teres minor muscle (lateral rotation of arm; one of the rotator cuff muscles)?

axillary (lateral) border

Where is the origin of supraspinatus muscle (abduction of the arm; one of the rotator cuff muscles)?

supraspinous fossa

Where is the origin of the teres major muscles on posterior surface (medial rotation and adduction of the arm)?

inferior angle

What is the attachment of the conoid and trapezoid ligaments from clavicle?

coracoid process

What type of joint is the acromioclavicular?

plane joint, diarthroses

joint is between acromial facet of clavicle and acromion process of the scapula.

allows ability to raise arm above the head

Where is the origin of biceps brachii muscle (flexor of arm and forearm)?

supraglenoid tubercle

Where is the origin of triceps brachii muscle (extends forearm, extends, and adducts arm at shoulder)?

infraglenoid tubercle

What attaches around the rim of the glenoid fossa to seal the synovial joint capsule of the glenohumeral joint?

labrum fibrocartilaginous structure

What type of joint is the glenohumeral?

ball and socket joint

allows for multiaxial movement including circumduction

joint is between glenoid fossa of scapula and head of humerus

it is the most mobile joint in the body due to shallowness of gleoid fossa, loose synovial joint capsule, and lacking strong ligaments.

The clavicular facet is apart of what joint?

acromioclavicular joint

What type of ossification does the scapula undergo?

endochondral

What are the osteological variants of the scapula?

bridging of scapular notch, multiple suprascapular foramina, os acromiale

What is the cortex?

Cortical, compact bone

Outer layer of bone

Harder and denser than the bone it encases

In long bones it surrounds the medullary cavity

What is Trabecular bone?

Spongy, cancellous bone

Found at ends of bones and near internal surface of cortex

Characterized by trabeculae (lattice-like network)

Transfers stresses to walls of bone itself

Becomes more vacuous with age

What are the connective tissues (internal and external) assoicated with mature bone?

Periosteum

• Outer covering of bone, a strong fibrous “skin”

• Allows innervation and blood supply

• Contains osteoblasts and osteoclasts

Endosteum

• Cellular membrane lining internal marrow cavities

• Also contains osteoblasts and osteoclasts

Cartilage

• Protects articular surface

What is the Medullary cavity of mature bone?

Found in shafts of many postcranial bones

Enlarges as marrow is laid down and with age

Contains marrow and nutrient arteries

What are the 3 segments of the upper limb?

1. Proximal (upper arm) humerus

2. Intermediate (forearm) radius and ulna

3. Distal (hand) carpals, metacarpals, and phalanges

features of the humerus

paired long bone

articulates with scapula, radius, and ulna

largest and proximal-most bone in upper limb

What is the insertion of subscapularis muscle (medial rotation of shoulder); one of the rotator cuff muscles?

lesser tubercle

What is the insertion of supraspinatus (abduction of the arm), infraspinatus (lateral rotation of the arm), and teres minor (medial rotation and adduction of the arm); all rotator cuff muscles?

greater tubercle

What is the insertion of biceps brachii muscle (flexor of arm and foreaem?

intertubercular groove

What is the insertion of deltoideus muscle (aducts the arm)?

deltoid tuberosity

What reseives coronoid process of ulna during maximum flexion of forearm?

coronoid fossa

What anchors the ulnar collateral ligament?

medial epicondyle

What articulates with the ulna; part of the humeroulnar joint?

trochlea

What receives head of radius during maximum flexion?

radial fossa

What anchors radial collateral ligament of elbow?

lateral epicondyle

What articulates with teh radius; part of the humeroradial joint?

capituilum

What receives the proximal end of the ulna at maximum extension?

olecrannon fossa

What composes the eblow joint?

It is a compound diarthrosis made up of three parts, held together in a single joint capsule.

1. Humeroulnar joint:

   hinge joint

   • Trochlea of humerus

   • Trochlear notch of ulna

2. Humeroradial joint:

   ball-and-socket joint

   • Capitulum of humerus

   • Head of radius

3. Proximal radioulnar

   joint: pivot joint

   • Head of radius

   • Radial notch of ulna

What is the ossification of the humerus?

endochondral ossification

How to side the humerus?

Head is proximal and medial

Olecranon fossa distal and posterior

Medial epicondyle is medial

Greater tubercle and deltoid tuberosity are lateral → on side

features of the radius

paired long bone

lateral of the two bones in forearm

articulates with humerus, ulna, lunate, and scaphoid

it is the shortest of the 3 arm bones

It is part of elbow (humeroradial and proximal radioulnar) and wrist (radiocarpal) joints.

What is part of the middle radioulnar joint and anchors the interosseous ligament (binds diaphyses of radius and ulna)?

interosseous crest

What is part of the radial head that rotates against the radial notch of the ulna to allow for pronation and supination at the proximal radioulnar joint?

articular circumference

What part of the radius is apart of the the humeroradial joint?

articular fovea

What part of the radius is apart of the proximal radioulnar joint?

head

What is the insertion for biceps brachii muscle (flexor of the arm and forearm)?

radial tuberosity

What part of the radius is apart of the middle radioulnar joint; anchor for interosseous ligament (binds diaphyses of radius and ulna)?

interosseous crest

What is the anchor for the extrinsic extensor muscles of the hand (extend the joints of the hand)?

dorsal tubercle

On the distal radius, what is apart of the distal radioulnar joint; travels around the articular circumference of the ulna to allow for pronation and supination?

ulnar notch

On the distal radius end, what is apart of the radiocarpal joint?

carpal articular surface

What kind of joint is the radiocarpal joint?

condyloid joint, diarthroses

joint between carpal articular surface of the radius, scaphoid and lunate, and triquetral (indirect via fibrocartiulage)

this joint allows for felxion, extension, adduction, and abduction

the ulna is NOT involved in this joint

What is Colle’s fracture?

a fracture where the distal radius is bent backwards

What are the ossifcation of the radius?

endochondral

How to side the radius?

Head is proximal

Styloid process is distal

Smooth concave distal surface is anterior

Dorsal tubercle is posterior

Radial tuberosity, interosseous crest, and ulnar notch are medial

styloid process is lateral and points to the side

features of the ulna

paired long bone

medial of the two long bones in forearm

articulates with the humerus, radius, and triquetral

thinnest of the 3X arm bones

apart of the elbow (humeroulnar and proximal radioulnar) joints

On the proximal ulna, what feature is apart of the humeroulnar joint?

trochlear notch

What is the insertion of triceps brachii muscle (extends forearm, extends and adducts arm at shoulder)?

Olecranon process

What is apart of the middle radioulnar joint; anchor for interosseous ligament (binds diaphyses of radius and ulna)?

interosseous crest

What is the origin for supinator muscle (spinates forearm)?

supinator crest

What feature of the distal ulna is apart of the sital radioulnar joint against which the ulnar notch of the radius travels during pronation and supination?

articular circumference

What is the attachment for the ulnar collateral ligament?

styloid process

What three joints connect the bony forearm?

1. Proximal radioulnar joint

   • Head and articular circumference of radius

   • Radial notch of ulna

2. Distal radioulnar joint

   • Ulnar notch of radius

   • Head, articular circumference, and styloid process of ulna

3. Middle radioulnar joint

   • Interosseous crest of radius

   • Interosseous crest of ulna

What does the interosseous ligament do?

bind the diaphyses of the radius and ulna

What is the ossification of the ulna?

endocondral

What is a parry fracture?

a defensive injury resulting from a direct blow to the forearm when it is raised to shield the face

How to side the ulna?

Olecranon process proximal

Ulnar head and styloid process distal

Trochlear notch anterior

Interosseous crest lateral

Radial notch lateral → on side