Appendicular Skeleton- Upper Extremities Flashcards
What is the pectoral girdle?
- Articulates with the trunk and supports the upper limbs
- Consists of the right and left clavicles and the right and left scapulae
- Attachment site for many muscles that move the upper limbs
How does the pectoral girdle promote upper limb mobility?
- Because the scapula isn’t directly attached to the axial skeleton, it moves freely across the posterior surface of the thorax, permitting the arm to move with it
- The shallow cavity of the shoulder joint permits a wide range of movement of the upper limb
What are the clavicles?
- Commonly known as collarbones
- S-shaped bones that extend between the manubrium of the sternum and the acromion of the scapula
- The only direct connection between the pectoral girdle and the axial skeleton
What is the sternal end of the clavicle?
- The medial end which is roughly pyramidal in shape
- Articulates with the manubrium of the sternum
- Forms the sternoclavicular joint
What is the acromial end of the clavicle?
- The lateral end which is broad and flattened
- Articulates with the acromion of the scapula
- Forms the acromioclavicular joint
What is the conoid tubercle of the clavicle?
- A rough tuberosity on the inferior surface of the clavicle
- The attachment site for the coracoclavicular ligament
What is the costal tuberosity of the clavicle?
- A rough tuberosity on the inferior surface of the clavicle
- More inferior than the conoid tubercle and located on the sternal end of the clavicle
- Attachment of the shoulders costoclavicular ligament
What are the scapulae?
- Broad, flat, triangular bones that you can palpate by moving your shoulders
- Several large projections extend from the scapula and provide surface area for muscle and ligament attachments
What is the spine of the scapula?
- A ridge of bone on the posterior aspect
What is the acromion of the scapula?
- Continuous projection from the spine
- A larger, flattened, posterior process that forms the bony tip of the shoulder
- Articulates with the acromial end of the clavicle
What is the coracoid process of the scapula?
- Is a smaller more anterior projection of the shoulder
What is the superior border of the scapula?
- The horizontal edge of the scapula
- Superior to the spine of the scapula
What is the medial border of the scapula?
- The edge of the scapula that is closest to the vertebrae
What is the lateral border of the scapula?
- The edge of the scapula that is closest to the axilla (armpit)
What is the suprascapular notch?
- In some people, this is the suprascapular foramen
- In the superior border
- Provides a passage for the suprascapular nerve
What is the superior/inferior/lateral angles of the scapula?
- The pointed part of the scapula between the superior and medial borders (superior angle)
- The pointed part between the superior and lateral borders (inferior angle)
- Composed primarily of the cup-shaped, shallow glenoid cavity which articulates with the humerus bone of the arm (lateral angle)
What are the supraglenoid and infraglenoid tubercles of the scapula?
- Near the superior edge of the glenoid cavity (supra)
- Near the inferior edge of the glenoid cavity (infra)
What are the subscapular fossa? (scapula)
- The broad, relatively smooth, anterior surface of the scapula
- Slightly concave and relatively featureless
- Large muscle called the subscapularis overlies this fossa
What are the supraspinous/infraspinous fossa? (scapula)
- The spine divides the posterior surface of the scapula into 2 shallow depressions
- Depression superior to the spine (supra)
- Depression inferior to the spine (infra)
- The supraspinatus and infraspinatus muscles respectively attach to these fossae
What bones make up the upper limbs?
- Each upper limb contains 30 bones
- Brachium (arm), antebrachium (forearm), and the hand make up the upper limb
What is the humerus?
- The longest and largest upper limb bone
- Proximal end has a hemispherical head that articulates with the glenoid cavity of the scapula
- Adjacent to the head are 2 tubercles
What is the greater tubercle of the humerus?
- Adjacent to the head of the humerus
- Positioned more laterally
- Helps form the rounded contour of the shoulder
What is the lesser tubercle of the humerus?
- Adjacent to the head of the humerus
- Smaller and located more anteromedially
What is the intertubercular sulcus of the humerus?
- Between the 2 tubercles
- A depression that contains the tendon of the long head of the biceps brachii muscle
What is the anatomical neck of the humerus?
- Between the tubercles and the head of the humerus
- Almost indistinct groove that marks the location of the former epiphyseal plate
What is the surgical neck of the humerus?
- The narrowing bone that is immediately distal to the tubercles at the transition from the head to the shaft
- Called the surgical neck because it is a common fracture site on the humerus
What is the shaft of the humerus?
- The lengthy middle section of the humerus
What is the deltoid tuberosity of the humerus?
- Rough protrusion of bone
- Extends along the lateral surface of the shaft
- Takes up about half of the length of the humerus
- Deltoid muscle of the shoulder attaches to this tuberosity
What is the radial groove of the humerus?
- Located adjacent to the deltoid tuberosity
- Where the radial nerve and some blood vessels travel
What bones form the elbow joint?
- The humerus, radius and ulna
What are the medial and lateral epicondyles? (humerus)
- Are the bony side projections on the distal humerus
- Provide surfaces for muscle attachment
- Can be palpated under the skin
- Travelling posterior to the medial epicondyle is the ulnar nerve which supplies many intrinsic hand muscles
What are the capitulum of the humerus?
- On the distal end of the humerus
- Two smooth, curved surfaces for the articulation with the bones of the forearm
- Located laterally and articulate with the head of the radius
What are the trochlea of the humerus?
- Located medially and articulates with the trochlear notch of the ulna
- Pulley-shaped
What are the radial/coronoid/olecranon fossa? (humerus)
- All on the distal end of the humerus
- Anterolaterally placed radial fossa accommodates the head of the radius
- Anteromedially placed coronoid fossa accommodates the coronoid process of the ulna when the elbow is flexed
- Posteriorly placed olecranon fossa accommodates the olecranon of the ulna when the elbow is extended
What bones make up the forearm?
- The radius and ulna
- In anatomical position, these bones are parallel, with the radius lateral and the ulna medial
What is the head of the radius?
- On the proximal end of the radius
- Distinctive disc-shaped head
- Articulates with the capitulum of the humerus
What is the neck of the radius?
- Narrow bone that separates the radial head from the radial tuberosity (attachment site for the biceps brachii muscle)
What is the shaft of the radius?
- Curves slightly
- Leads to a wide distal end
What is the styloid process of the radius?
- Laterally placed on the distal end of the radius
- Is a bony projection that can be palpated on the lateral side of the wrist, just proximal to the thumb
What is the ulnar notch of the radius?
- On the distal medial surface of the radius
- Where the medial surface of the radius articulates with the distal end of the ulna
What is the ulna?
- The longer, medially placed bone of the forearm
What is the trochlear notch of the ulna?
- At the proximal end of the ulna
- C-shaped notch that interlocks with the trochlea of the humerus
What is the olecranon of the ulna?
- On the posterosuperior aspect of the trochlear notch
- Prominent projection that articulates with the olecranon fossa of the humerus and forms the posterior bump of the elbow
What is the coronoid process of the ulna?
- The inferior lip of the trochlear notch
- Articulates with the humerus at the coronoid fossa
What is the radial notch of the ulna?
- Lateral to the coronoid process
- Smooth and curved notch that accommodates with the head of the radius
- Helps form the proximal radioulnar joint
What is the tuberosity of ulna?
- Also at the proximal end of the ulna
What is the head of the ulna?
- At the distal end of the ulna
- Where the shaft narrows and terminates
- Has a poster medial styloid process (may be palpated on the medial side of the wrist)
What are interosseous borders?
- Both the radius and ulna exhibit these borders
- They face each other
- Ulna’s border projects laterally, whereas the radius’ border projects medially
What is the interosseous membrane?
- These borders are connected by an interosseous membrane, composed of dense regular connective tissue (interosseous ligament)
- The membrane keeps the ulna and radius at a fixed distance apart from each other
- Provides a pivot of rotation for the forearm
What are the bones that form the wrist and hand?
- Carpals, metacarpals and phalanges
What are carpals?
- Small, short bones that form the wrist
- Arranged roughly in 2 rows (one proximal and one distal) of 4 bones each
- Allow for the multiple movements possible at the wrist
What are the proximal carpal bones?
- Listed from lateral to medial : scaphoid, lunate, triquetrum and pisiform
What are the distal carpal bones?
- Listed from lateral to medial: most lateral being the trapezium, followed by the trapezoid, capitate and hamate
What are metacarpals?
- The bones in the palm of the hand
- 5 metacarpal bones articulate with the distal carpal bones
- Support the palm
- Roman numerals I-V denote the metacarpal bones, with metacarpal ‘I’ located at the base of the thumb, and metacarpal ‘V’ at the base of the pinky finger
What are the phalanges?
- The bones of the digits (also known as phalanx)
- 3 phalanges in in each of the 2-5 fingers
- 2 phalanges in the thumb (pollex)
- Total of 14 phalanges per hand
What is the proximal phalanx?
- Articulates with the head of a metacarpal
What is the distal phalanx?
- The bone at the very tip of the finger
What is the middle phalanx?
- Lies between the proximal and distal phalanges
- Not found in the thumb
