Functional anatomy and biomechanics (Upper Extremity) Flashcards
1
Q
Humerus
A
- proximal end of humerus is approximately half a spheroid
- articular surface is coveredby hyaline cartilage
- head is retroverted 20-30 degrees
- longitudinal axis of head is 135 degrees from axos of neck
2
Q
Scapula
A
- large, flat triangular bone
- sits over 2nd-7th ribs
- three angles
- orientation of glenoid fossa places true abduction at 30 degrees anterior to frontal plane
3
Q
Shoulder biomechanics: GHJ arthro/osteo-kinematics
A
- occurs in opposite direction
- with shoulder elevation of humerus, head of humerus moves in an inferior direction because of convex moving on concave
- rolling/gliding occurs during elevation of the humerus, so that the instantaneous center of rotation varies considerably during the complete range
- at approx 75 degrees of elevation, ER occurs, preventing compression of great tubercle against acromion
4
Q
Shouder biomechanics: Scapulothoracic and glenohumeral rhythm
A
- ratio of movement of the GH with the scapulothoracic joint
- with 180 deg ABD, there is a 2:1 ratio of movement between the two joints
- first 30-60 degrees of elevation occurs mainly in the GHJ
- 120 degrees of movement occurs at GHJ
- 60 degrees of movement at scapulothoracic joint
5
Q
Requirements of full elevation
A
- scapular stabilization
- inferior glide of humerus
- ER of humerus
- rotation of the clavicle at SC joint
- scapular abduction and lateral rotation of AC joint
- straightening of thoracic kyphosis
6
Q
Humeroulnar joint
A
- distal end humerus (trochlea) articulates with proximal end of ulna
- trochlea and trochlear notch face anteriorlyat a 45 degree angle, allowing space between ulna and humerus during flexion
7
Q
Humeroradial joint
A
- distal end humerus (capitulum) articulates with concave over facet of proximal radius
8
Q
Proximal radioulnar joint
A
- radial head is ovoid and cone shaped
- medil radius articulates with radial notch (of ulna)
9
Q
Distal radioulnar joint
A
- convex ulna articulates with concave radius (opposite to proximal articulation)
10
Q
Elbow ligaments
A
- UCL
- RCL
- Annular
- Quadrate
- Distal radioulnar
11
Q
Annular ligament
A
- osteofibrous ring attached to medial ulna and encircles radial head
- cone shaped, inner surface is lined with fibrocartilage
- protects radial head, especially in semiflexion, where it is unstable
- taut in extremes of pronation and supination
12
Q
Quadrate ligament
A
- extends from radial notch (una) to the neck of radius
- reinforces inferior joint capsule, maintains radial head in opposition to ulna, limits amount of spin in supination and pronation
13
Q
Elbow biomechanics
A
- ulna pronates slightly with extension. Ulna supinates slightly with flexion
- proximal ulna glides medially during extension and laterally during flexion
- flexion/extension of elbow is accompanied by screw-home mechanism with conjunct rotation ofulna. Ulna externally rotates (or supinates) during elbow flexion and internally rotates (or pronates) during
14
Q
Wrist and hand osteology
A
- radius is bioconcave relative to carpals
- ulna is convex at its distal end relative to the triquetrum
15
Q
Radiocarpal joint
A
- convex scaphoid and lunate articulate with concave radius
16
Q
Midcarpal joint
A
- articulation between four proximal and four distal carpal bones is known as midcarpal joint
- functional rather than anatomical joint
- middle and lateral pillars
17
Q
Carpometacarpal joint (CMC)
A
- first CMC (thumb) is a saddle articulation with trapezium being convex in medial/lateral direction and concave in anterior/posterior direction
- first metacarpal is opposite in shape to trapezium
- second through fifth CMC joints are essentially flat between bases of matacarpals and distal row of carpals
18
Q
Metacarpalphalangeal (MCP) joints
A
- consists of convex metacarpals with concave proximalm phalanges
19
Q
Extensor hood
A
- fibrous mechanism on the dorsum of each finger that is a fibrous expansion of the extensor digitorum tendon
- purpose is to assist with extension of the PIP and DIP joints
20
Q
Wrist and hand region nerves
A
- ulnar innervates hypothenar region (palmarly and dorsally), fifth digit, and medial half of fourth digit
- median nerve innervates reminder of palmar surface not innervated by ulnar nerve and dorsal portions of second, third, and lateral half of fourth digit from DIP to tip of finger
- radial nerve innervates remainder of dorsum not innervated b ulnar or median nerves
21
Q
Wrist flexion biomechanics
A
- proximal aspect of scaphoid/lunate glide dorsally relative to radius
22
Q
Wrist extension biomechanics
A
- proximal aspect of scahpoid/lunate glie ventrally relative to radius
23
Q
Wrist radial deviation biomechanics
A
- proximal row glides ulnarly
- proximal surface of scaphoid rotates palmarly
24
Q
Wrist ulnar deviation biomechanics
A
- proximal row glides radially as a unit