Upper limb: Anatomy, Biomechanics, Neural Control Flashcards
Arm Movement
Free movement limb, large degree of freedom. Comparable musculature to the legs.
Hand Movement. What is it capable of? (4)
The hand has 27 bones, 18 joints, 39 intrinsic and extrinsic muscles.
The hand is capable of simultaneous movement in a large number of muscles; grasping objects; handle delicate objects; involved in complex movements with multiple digits (fine degree of movement).
What bones are in the arm?
Trunk: Clavicle, Scapula
Arm: Humerus, radius/ulna
Hand: Carpals (8), Metacarpals (5), Phalanges (14)
Nervous Control of the arm
Brachial plexus, arises from cervical vertebrae C4-T1. Nerves off brachial plexus to arm.
What are the sensory and motor nerve innervations of the arm? (4)
- Radial Nerve: mainly extensors (elbow, wrist, and fingers)
- Median Nerve: pronators and flexors of wrist, flexors of hand and fingers on radial side, abducts hand
- Ulnar Nerve: flexors of hand on ulnar side, adducts hand
- Musculocutaneous: flexors of elbow, extension and adduction of shoulder
How many muscles are needed to move the shoulder? (6)
Internal Rotation - 5
Flexion - 4
Extension - 4
Adduction - 4
External Rotation - 3
Abduction - 2
How many muscles are needed to move the elbow? (4)
Flexion - 4
Extension - 2
Pronation (forearm) - 2
Supination (forearm) - 2
How many muscles are needed to move the wrist/hand? (4)
Wrist extension - 8
Wrist flexion - 5
Wrist Abduction - 3
Wrist Adduction - 2
How many muscles are needed to move the fingers? (5)
Digit Flexion - 6
Digit Extension - 6
Digit Abduction - 4
Digit Adduction - 2
Digit Opposition - 2
Shoulder range of motion
Shoulder has extensive range of motion (180° AB and flexion, 60° hyperextension, 75° AD, 90° internal/external rotation, 135° horizontal flexion, 45° horizontal extension)
In order of strength: Adduction - Extension - Flexion - Abduction - Rotation.
Elbow range of motion
Elbow itself can only flex and extend (145° active flexion, 160° passive flexion).
For forearm (70° pronation, 85° supination)
Wrist and hand range of motion
Wrist has various ranges of motion. So does carpometacarpal joint (thumb), metacarpophalangeal joints (1st knuckle), interphalangeal joints (2nd and 3rd knuckles)
Examples of hand movements being used in communication? (2)
ASL, Diving signals
Two types of grips?
Power - stability and force development; uses all the fingers and palm; (cylindrical, spherical, hook)
Precision - uses thumb and index finger for dexterity and fine control; (pinch, tripod, lumbrical)
Basic cerebral cortical brain structure
Motor cortical areas are anterior to central sulcus.
Proprioceptive cortical areas located posterior to central sulcus.
Layers of cerebral cortex
Composed of 6 layers. Depending on where, thickness of areas can vary due to function of area.
Ex. Primary Motor Cortex: Layers V and VI are thick;
Primary Occipital Cortex: Layer IV is thick
Motor cortical brain structures (3)
- Primary motor cortex: sends commands to muscles
- Premotor cortex: guidance of movement and control of trunk and proximal limb muscles
- Supplementary motor area: planning of motor actions
What is the motor homunculus?
Topographic model carried down through motor system.
Funny dude with big hands and big lips.
What is stereognosis?
Ability of recognition of objects from touches (aka haptic perception of touch gnosis). Requires input from sensory and motor systems (skin - feedback)
Uses tactile info (texture, size, spatial properties, temperature)
What is the corticospinal tract?
Axons from upper motor neurons (pyramidal/Betz cells) descend down spinal cord on lower motor (alpha) neurons in spinal cord
Lower motor neuron axons leave cord via ventral root into spinal nerve and go innervate muscle fibers
What is a motor unit?
MU: single, smallest controllable muscular unit. Consists of a single alpha motor neuron, its neuromuscular junction and the muscle fibers it innervates (3-2000)
What is the primary somatic sensory area responsible for? (3)
- Interpreting specific positions of parts of the body
- Interpreting the amount of force being placed on any point
- The shape and textures of materials being manipulated
What is the sensory homunculus?
Sensory cortex organization (somatosensory map)
Another dude with big lips and big hands.
What are the ascending pathways? (2)
Bring sensory information from the periphery up to the somatosensory cortex.
- Dorsal Column-Medial Leminscal pathway: touch, pressure, and proprioception
- Spinothalamic pathway: pain and temperature
