The Musculoskeletal System (Revision) Flashcards
Functions of Skeleton
Support
- Provides structural integrity to the body
Mobility
- Facilitates movement, has lightweight structure
Hematopoiesis
- Produces blood cells within the bone marrow
Mineral Storage
- Eg calcium and magnesium for bodily functions
Fat Storage
- Houses fat in the bone marrow
Types of Bones
Long Bones
- Shape: Tubular
- e.g. femur, humerus
- Function: Levers for movement; support body weight
Short Bones
- Shape: Cube-like, equal length and width
- e.g., carpals, tarsals
- Function: Provide support and stability, but limited movement
Flat Bones
- Shape: Thin and flat
- e.g., sternum, ribs
- Function: Protect underlying organs, has muscle attachment sites
Irregular Bones
- Shape: Non-uniform
- e.g., vertebrae
- Function: Support and protect, has varied movements
Sesamoid Bones
- Shape: Small and round, embedded in tendons
- e.g., patella
- Function: Protect tendons, enhance leverage
Pneumatic Bones
- Features: Contain air spaces
- e.g., certain skull bones
- Function: Reduce weight of the skull, assist in voice resonance
Sutural Bones:
- Shape: Small, irregularly shaped
- found between skull bones
- Function: skull stability
Joints
Where two bones meet
Fibrous Joints
- Dense connective tissue
- Little to no movement (Synarthrosis)
Cartilaginous Joints
- Connected by cartilage
- Limited movement (Amphiarthrosis)
Synovial Joints
- Freely movable type (Diarthrosis)
- Includes articular capsule, articular cartilage, and synovial fluid
Types of Synovial Joints
- Hinge Joints: Angular movement in one direction and one plane (e.g., elbow, ankle, knee)
- Pivot Joints: Rotation in one axis (e.g., C1/2 joint, proximal radioulnar joint)
- Ball-and-Socket Joints: Angular movement in all directions and pivot (e.g., shoulder, hip).
- Condylar Joints: Angular movement in two directions (e.g., wrist).
- Saddle Joints: Flexible movement (e.g., carpo-metacarpal in thumb).
- Plane Joints: Gliding movements (e.g., intercarpal joints).
Cartilage
Hyaline Cartilage
- Features: Has collagen fibers
- Location: Found at the ends of long bones, in the ribcage, and in the trachea
- Function: Provides a smooth surface for joint movement, supports the respiratory structures
Fibrocartilage
- Features: Dense, many collagen fibers, tough and resilient
- Location: Intervertebral discs, pubic symphysis
- Function: Tensile strength, absorbs compressive forces
Elastic Cartilage
- Features: High density of elastic fibers, flexible and resilient
- Location: Outer ear (auricle), epiglottis
- Function: Maintains shape while allowing flexibility
Muscle Contraction
Isometric Contraction
- Definition: Muscle fibers generate force without changing length
- Example: Holding a weight steady
Isotonic Contraction
- Definition: Muscle fibers change length while contracting
- Types:
- Concentric: Muscle shortens (e.g., lifting a weight)
- Eccentric: Muscle lengthens (e.g., lowering a weight)
Pectoral Girdle
Functions
- Connects the upper limb to the axial skeleton
- Stabilizes the head and its movements
Components
- Clavicle
-
Scapula: The shoulder blade
- Acromial Process: Articulates with the lateral end of the clavicle to form the acromioclavicular joint
- Medial end of scapula articulates with manubrium to form sternoclavicular joint
Bones of the Upper Limbs
Humerus
- Proximal: head, neck, greater and lesser tubercles
- Distal
- Condyle: Smooth surface for articulation
- Trochlea and Capitulum: Distal ends that articulate to forearm bones
- Epicondyles: Rough areas for muscle attachment
Forearm Bones
- Radius: Thumb side (lateral)
- Ulna: Little finger side (medial)
- Interosseous Membrane: Connects and stabilizes the radius and ulna
Joints of the Upper Limbs
Glenohumeral Joint
- Ball-and-socket joint
- Wide range of motion
Elbow Joint
- Humeroulnar and humeroradial joints
- Flexion and extension
Radioulnar Joint
- Pronation and supination of the forearm
Wrist and Hand Anatomy
Wrist (Radiocarpal) Joint
- Condyloid joint
- Biaxial movements
Carpal Bones
- Proximal Row: Scaphoid, Lunate, Triquetrum, Pisiform
- Distal Row: Trapezium, Trapezoid, Capitate, Hamate
Metacarpal Bones
- Five bones
Phalanges
- Each finger has three phalanges
- Except the thumb, which has two
Brachial Plexus
Innervate the upper limb
Roots
- Anterior rami of spinal nerves C5-T1
Trunks
- Formed from the roots:
- Upper Trunk: C5 and C6
- Middle Trunk: C7
- Lower Trunk: C8 and T1
Divisions
- Each trunk splits into anterior and posterior divisions
- Six divisions
Cords
- The divisions reorganize into three cords
- Lateral Cord: From the anterior divisions of the upper and middle trunks
- Posterior Cord: From all posterior divisions.
- Medial Cord: From the anterior division of the lower trunk
Branches
- Musculocutaneous Nerve: anterior compartment of the arm
- Axillary Nerve: deltoid and teres minor
- Radial Nerve: posterior compartment of the arm and forearm
- Median Nerve: most of the flexors in the forearm, some hand muscles
- Ulnar Nerve: intrinsic hand muscles, some flexors of the forearm
Muscles of the Upper Limb
Classified based on function
Agonist (Prime Mover)
- Main muscle for a specific movement
- Via concentric contraction
Antagonist
- Opposes the action of another muscle
Synergist
- Assists the agonist
Fixator
- Stabilizes the proximal parts during movement
Muscles that move the arm
Deltoid
- Major abductor of the arm
Pectoralis Major & Latissimus dorsi
- Medial rotation
- Flexion, and adduction of the humerus
Rotator Cuff Muscles
- Stabilize the shoulder joint
Subscapularis
- Medial rotation of humerus
Supraspinatus
- Initiates arm abduction
Infraspinatus & Teres Minor
- Lateral rotation of the shoulder joint
Major Wrist and Finger Flexors
Flexor Digitorum Superficialis (FDS)
- Flexes the middle phalanges of the fingers
Flexor Digitorum Profundus (FDP)
- Flexes the distal phalanges of the fingers
Flexor Pollicis Longus (FPL)
- Flexes the thumb
Flexor Carpi Radialis (FCR)
- Flexes and abducts the hand at the wrist
Flexor Carpi Ulnaris (FCU)
- Flexes and adducts the hand at the wrist
Major Wrist and Finger Extensors
Extensor Digitorum
- Extends the fingers
Extensor Pollicis Longus and Brevis
- Extend the thumb
Extensor Carpi Radialis Longus and Brevis
- Extend and abduct the wrist
Extensor Carpi Ulnaris
- Extends and adducts the wrist
Major Muscles Controlling Thumb Movement
Abductor Pollicis Brevis
- Abducts the thumb
Flexor Pollicis Brevis
- Flexes the thumb
Opponens Pollicis
- Allows opposition of the thumb
