Upper Limb Flashcards
Discuss the various vascular bed adaptations required to maintain adequate flow to skeletal muscle and skin.
Functional
The main method of adapting blood flow to the muscles and skin is via vasodilation/ vasoconstriction. Vasculature is richly innervated by sympathetic constriction fibres. Metabolic control can also override nervous control,
Structural adaptations: different types of muscle fibre
- 1: red fibres, slow adaptive, slow oxidative, slow twitch: fatigue resistant fibres)
- 2a: red fibres: fast oxidative, large levels of myoglobin, found in postural muscles
- 2x/b: white fibres: phasic, fast glycolytic, fast twitch B or fatigueing fibres, low myoglobin
Describe the innervation of the Musculotaneous nerve.
C5-7
- Flexion of shoulder- biceps brachi and corachobrachialis
- Flexion of elbow and supination of forearm and hand: biceps brachi
- Flexor of elbow: Brachialis
- Cutaneous sensation to lateral surface of forearm
Describe the innervation of the Axillary nerve.
C5-C6
- Lateral rotation of the arm- Teres minor
- Abduction of the arm- Deltoid
Cutaneous sensation to inferior lateral shoulder
Describe the innervation of the median nerve
C5-T1
- Pronation of the forearm and hand- pronator teres and pronator quadratus
- Flexion of the wrist, hands, phalynx:
flexor carpi muscles, flexor digitorium muscles
- Flexor thumb muscles (flexor pollicus longus)
- Thenar muscles (Abductor pollicus brevis, opponans pollicus and flexor policus brevis
- flexion of metacarpal pharyngeal joints: lateral lummbricals
Cutaneous sensation in lateral 2/3 of palm, thumb, index finger and dorsal tips of same fingers.
Describe the innervation of the Radial nerve.
C5-T1
Extends elbow- triceps brachii, anconeous
Flexes elbow: brachialis and brachioradialis
Extends and abducts wrist: externsor carpi radialis and brevis
Supination of forearm: supinator
Extension of fingers: extensor digitorium, digiti minimi, indices
Extension and adduction of wrist: extensor carpi ulnaris
Abduction of thumb: abductor pollicus longus, brevis
- Cutaneous sensation to posterior surface of arm and forearm, lateral 2/3 of dorsum of hand.
Describe the joints of the Pectoral gurdle.
Sternoclavicular joint
- synovial, like ball and socket
- strengthened by ligaments: anterior and posteriorly (sternoclavicular ligaments), interclavicular ligament, costoclavicular ligament from 1st rib to clavicle
Actomioclavicular joint
- gliding synovial joint
- Strengthened by ligaments: Coraclavicular, anterioclavicular, corocoaromial. Will function normally even when dislocated
Describe different types of muscle action
Agonistic- contracts to create the desired action
Synergistic- acts to support agonist.
Anagonistic- apposes action of agonist
Describe different types of muscle action
Agonistic- contracts to create the desired action
Synergistic- acts to support agonist.
Antagonistic- apposes action of agonist
Summarise the different types of joint.
Fibrous
- immovable fixed joints, held together by fibrous CT that develops during childhood
Cartilaginous
- Slightly moveable joints, slight movement: example vertibral column, intervertibral discs
Synovial
- Freely movable, 6 kinds: ball and socket, hinge joint, pivot joint, gliding plane joint, saddle joint, condyloid joint. Movement can by uniaxial, biaxial and multiaxial.
Summarise the cells present in synovial joints
Synoviocytes
Type A- macrophage like, bone marrow derived, remove debris, contribute to fluid
Type B- fibroblast like, abundant in rough ER, producer of synovial fluid
Describe the embryological origins of the the skeletal system.
All skeletal development is derived from mesenchyme differentiation: loosely organised connective tissue, mesoderm or neural crest cells. Paraxial mesoderm forms the axial skeleton: verabrae, ribs and occipital portion of cranial base. Lateral plate mesoderm forms the appendicular skeleton (exception= clavical which is is neural crest cells)
Skull is more complicated – some bones derived from undivided head paraxial
mesoderm and some from neural crests cells.
The paraxial mesoderm forms paired blocks of cells known as somites. These develop at a rate of ~3 a day from roughly day 20. Cranial- Caudal direction. 42-44 form (4 occipital, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and ~3 coccygeal). Remains undivided in the head region (somitomeres)
Describe the embryological origins of the musculature and discuss the research methods used to determine this.
Skeletal- Paraxial mesoderm
Cardiac- lateral plate
Smooth: lateral plate with exceptions of the iris anc ciliary muscles (neural crest), vascular and arrector pili (local mesoderm).
Somitomeres- muscles of the face and eyes,
Somites- laryngeal muscles, tongue muscles, trunk muscles
Splanchnic mesoderm- smooth muscles of the gut and cardiac muscle
Give an account of skeletal ossification and discuss the differences between intramembranous and endochondral ossification.
There are 2 different processes of ossification:
Endochondral: Mesenchyme tissue> cartilage model> bone. Occurs in axial and appendicular skeleton. wk 6: cartilage models of long bones forms and wk 8= ossification begins. Primary centres of ossification in all long bones by wk 12. Epiphyseal plates are still visible at birth but secondary growth plates are formed soon after
Intramembranous: Mesenchyme> bone. Occurs in the skull regions and clavicle.
Give an account of muscle differentiation with a focus on skeletal muscle.
Determined by transcription factors.
- skeletal muscle controlled by myogenin
- cardiac by myocyte enhancer factor 2
- Smooth muscle by serum response factor
Myotome differentiates to form 2 componants (dorsal epimere and ventral hypomere).
Epimere forms back muscles and hypomere forms muscles of the thoracic and abdominal walls, limbs
qual chick grafting- adding somatic mesoderm from a different chick.
Describe basic skeletal muscle development in terms of myotome and dermatome diffferenciation.
Somites divide into ventral (scleratome) which forms vertibral column and dorsolateral part which forms the dermomyotome (dermatome (skin) and myotome (skeletal muscles).
