Appendicular Skeleton: Upper Limb

Question 1

How many bones are in the Upper limb? What the the 3 divisions?

Answer 1

30 bones

Divides into:

• -arm (upper arm/brachium): humerus
• -forearm (antebrachium): radius and ulna
• -hand (includes wrist): 27 bones (carpals, metacarpals, phalanges)

Question 2

Humerus

Answer 2

Largest and longest bone of upper limb
Head articulates w/ scapula at glenoid cavity
Distal end articles w/ radius and ulna (elbow)
Greater and lesser tubercles are sites of attachment; deltoid tuberosity is attachment for deltoid muscle

Question 3

Where does the humerus most frequently fracture?

Answer 3

at the surgical neck

Question 4

Fractures of the Humerus

Answer 4

Commonly occur in 2 places:

• -surgical neck
• -midshaft spiral fractures

Nerves pass along bone and can be damaged by these 2 fractures. MAY lead to permanent upper limb dysfunction

Question 5

Distal Humerus and Elbow (anterior view)

Answer 5

Ulna and Radius articulate w/ humerus
Ulna is main forearm bone contributing to elbow
Trochlea of humerus articulates w/ trochlear notch of ulna. Trochlear notch fits over trochlea to create a hinge
Coronoid fossa receives coronoid process when forearm bends

Question 6

Distal Humerus and Elbow (posterior view)

Answer 6

Olecranon fossa of humerus receives olecranon process of ulna when forearm extends
Lateral and medial epicondyles on humerus are attachment site for forearm muscles

Question 7

Distal Humerus/Articulations

Answer 7

Capitulum of distal humerus articulates w/ head of radius
Radial head ALSO articulates w/ radial notch of ulna (proximal radioulnar joint) to form a pivot joint
Elbow can bend or forearm can twist