Flashcards in MSK non-clinical Deck (138):
What is another name for a coronal section?
What is another name for a transverse section?
What makes up the axial skeleton?
What makes up the appendicular skeleton?
Name two dorsal body cavities
Name 3 ventral body cavities
Is the top of the foot dorsal or ventral?
Is the non-palmar surface of the hand dorsal or ventral?
If someone is lying in a supine position, how are they lying?
Lying face up
If someone is lying in a prone position, how are they lying?
Lying face down
What is a special movement of the shoulder joint?
Describe the movement of the radius during pronation
The radius in the anatomical position is lateral to the ulnar at both the elbow and the wrist. During pronation the distal part of the radius crosses the ulnar superiorly to become medial at the wrist
List the movements that the shoulder can make
List the movements of the elbow and forearm
List the movements of the hand
Ulnar deviation (adduction)
Radial deviation (abduction)
Describe flexion and extension of the wrist
Flexion is when you decrease the angle between the palmar surface of your hand and anterior forearm. Extension is when you increase that angle
List the movements of the fingers
Flexion and extension at metocarpalpharyngeal (MCP)
Flexion and extension at interpharngeal joints (PIP) and (DIP)
List the movements of the thumb
Palmar abduction-adduction (same plane)
Flexion-extension-radial abduction (same plane)
List the movements of the hip
List the movements of the knee
List the movements of the ankle
Inversion - plantar surface faces inwards (more common)
Eversion - plantar surface faces outwards
Which Rami (division of the spinal nerve) forms the brachial plexus?
What does the posterior Rami of the spinal nerves innervate at the levels (C5-T1)?
Local structures - does not form part of the brachial plexus
Where in the brachial plexus does the nerves leave the neck and enter the axilla?
What are the cords named in relation to?
Named due to their relation with the axillary artery
What is the apex border of the axillary region?
Lateral border of the first rib
Superior border of the scapula
What is the lateral border of the axillary region?
Intertubecular groove of the humerus
What is the medial border of the axillary region?
Serratus anterior and the thoracic wall (including costal muscles)
What is the anterior border of the axillary region?
Pectoralis major and minor
What is the posterior border of the axillary region?
What are the contents of the axilla?
Axillary lymph nodes
Tendons of muscles attaching to the scapula: biceps brachii and coracobrachialis
What would you observe if a patient had damage to their long thoracic nerve and pushed their arms against a wall?
Winging of the scapula due to paralysis of the serratus anterior muscles - these muscles no longer hold the scapula against the ribcage whilst their upper limbs reach anteriorly
What are the embryological derivates of the musculoskeletal system?
Somites and lateral plate mesoderm
What type of mesoderm do somites develop from?
In which direction does the development of somites progress?
Cranially to caudally
Where on the body wall do limb buds develop
Ventro-lateral body wall
Which limb bud appears first?
Upper limb - lower limb lags ~2 days behind
When during development do the limb buds appear?
Towards end of fourth week.
Describe the composition of the limb bud when it first appears
Core of proliferating mesenchymal cells with an ectoderm covering
What anatomical axes is the head of the embryo?
What anatomical axes is the tail of the embryo?
What is the anterior axis called in the embryo?
What is the posterior axis called in the embryo?
What mesoderm does the limb buds develop from?
Somatic layer of lateral plate mesoderm
What is the remnant of the notochord?
The nucleus pulposus - it becomes marooned by axial skeleton formation
What does the lateral plate mesoderm (somatic mesoderm) contribute to the limbs?
What does the somite mesoderm - which moves into the limb buds - contribute to the limbs?
How does the limb bud elongate?
Proliferation of the mesenchyme core
What is the apical ectodermal ridge (AER)?
Thickended ectoderm at the apex of the limb bud. It exerts an influence on the underlying mesenchyme and is responsible for elongation of the limb bud - is a group of organising cells.
What are the three degree of assymmetry of the limb buds?
1. proximal-distal axis: shoulder to fingertips
2. Dorsal-ventral axis: e.g. no hairy palms
3. Anterior-posterior axis: side to side (left and right hands are always mirror images of each other)
What is the role of the AER (apical ectodermal ridge) in limb bud development?
1. Critical for limb bud outgrowth
2. Orchestrates limb development proximal to distal
3. Final stage is appearance of paddles
4. Then AER regresses
How is the proximal to distal axis generated?
1. AER exerts a diffusion-limited inductive influence on the immediately underlying mesenchyme so it remains undiffferentiated and continues dividing and elongating the limb bud.
2. Proximal mesenchyme (free of the inductive influence of the AER) begins to differentiate into constitutive tissues
3. Finally AER induces development of the digits within the hand/foot plates
How is dorsoventral patterning of the limb bud achieved?
Ectoderm exerts dorsalising and ventralising influences over the mesenchymal core.
What marks the boundary between the developing dorsal and ventral limb ectoderm?
What does ZPA stand for?
Zone of polarising activity. It is a signalling centre located at the posterior base of the limb bud.
How is the anterior-posterior axis of the limbs determined?
By the ZPA which controls both the anterior-posterior patterning and maintains the AER.
What controls the anterior-posterior axial specification?
What controls the dorsal-ventral axial specification?
What controls the proximal-distal axial specification?
In the developing hand and foot plates, digital rays develop. What are they?
Mesenchyme condensations within plates that go on to form the cartilaginous models of the digital bones.
What happens between the digital rays in the hand and foot plates?
Apoptosis of the tissue between the digits progressively sculpts the interdigital sapces
Where does maintenance/ regression of the AER occur in the digital hand and foot plates?
It is maintained over the tips of the digital rays, so it can continue extending the digits, and breaks up between them
Which limb is more affected by limb defects?
What causes limb defects?
These are usually rare hereditary disease but teratogen-induced defects have been described.
What type of ossification occurs to the cartilage formed in the digital rays?
When does fusion of the ilium, ischium and pubis occur? What is the name of the cartilage found between these three bones?
At the end of puberty. Triradiate cartilage.
How does the musculature of the limbs develop?
Myogenic precursors migrate into the limbs from somites bringing with them the nerves that innervate them. These coalesce into 2 common muscle masses around the newly formed skeleton:
1. Ventral= flexor compartment
2. Dorsal= extensor compartment
Individual muscles then split from the common masses.
Why is the flexor compartment of the upper limb in the adult anterior wherease the flexor compartment in the lower limb is posterior?
The upper and lower limb extend ventrally at first but as they elongate they rotate:
1. Upper limb rotates laterally
2. Lower limb rotates medially
The upper limb develops opposite which spinal segments?
Caudal cervical spinal segments
The lower limb develops opposite which spinal segments?
Lumbar and sacral spinal segments
What happens if spinal nerves do not enter the limb buds early in their development?
Without innervation development stalls.
Why do the anterior divisions of the brachial plexus supply the anterior compartment of the upper limb and the posterior divisions of the brachial plexus the posterior compartments of the upper limb?
Muscle are compartimentalised and nerves grow into these common masses
What is a dermatome?
An area of skin supplied by a single spinal nerve.
What is a myotome?
A muscle/group of muscle supplied by a single spinal nerve.
What is meant by the preaxial and postaxial border?
Preaxial - thumb and big toe side of the limb
Postaxial - little finger and toe side of the limb
What is the ventral axial line?
An axial line is the line between two adjacent dermatomes that are not represented by immediately adjacent spinal levels e.g. C5 and T1. At axial lines, adjacent dermatomes do not overlap.
What is the role of osteocytes?
Maintain bone tissue
What are osteogenic cells?
What is the initial template of intramembranous ossification?
What is the initial template of endochondral ossification?
List the functions of the skeleton
4. Mineral and growth factor storage -Ca2+, phosphate, IGF, TGF, BMP
What is haematopoesis?
The formation of blood cellular components.
Where does haematopoesis occur in children?
Marrow within cavities of long bones e.g. femur and tibia.
Where does haematopoesis occur in adults?
Marrow within cavities. Mainly in pelvis, cranium, vertebrae and sternum.
What are the 6 classifications of bone shape? Provide an example of each.
1. Flat bone e.g. frontal bone
2. Short bone e.g. carpal
3. Sesamoid bone e.g. patella
4. Sutural bone
5. Irregular bone e.g. vertebrae
6. Long bone e.g. femur
What is the function of flat bones?
Curved - protect organs
What is notable about short bones?
They are equal in length and width
What is a sesamoid bone?
A bone embedded within a tendon or muscle
Where is a sutural bone found?
Within a cranial suture
What is notable about long bones? What is their function?
They are longer than they are wide. Muscles act on them as rigid levers.
What is periosteum?
a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.
What is endosteum?
A thin vascular membrane of connective tissue that lines the surface of the bony tissue that forms the medullary cavity of long bones.
What is the difference between red and yellow bone marrow?
Red consists mainly of hematopoietic tissue, and yellow is mainly fat cells. Red blood cells, platelets, and most white blood cells arise in red marrow. Both types of bone marrow contain numerous blood vessels and capillaries. At birth, all bone marrow is red. With age, more and more of it is converted to the yellow type.
What is the structure of short, flat and sesamoid bones?
1. Consist mainly of spongy bone with a thin layer of periosteum-covered compact bone on the outside
2. No epiphyses or diaphysis
3. Contain bone marrow between the trabeculae
What is notable about the blood supply of epiphyseal growth plates?
The metaphysis is supplied by metaphyseal arteries , before epiphyseal fusion, which DO NOT cross the growth plates in children. These arteries enter metaphysis at site of capsule attachment.
Which blood vessels supply the epiphysis (long bones)?
Which blood vessels supply the periosteum adn outer 1/3 of cortex (long bones)?
How does the nutrient artery/ medullary artery enter the medullary cavity in long bones?
Through the diaphysis via the nutrient foramen.
What happens to the epiphyseal and metaphyseal arteries after epiphyseal fusion?
What is the role of the fibrous capsule of synovial joints?
It stabilises the joint, permitting movement but resisting dislocation.
Describe the fibrous capsule of synovial joints.
It consists of longitudinal and interlacing collagen bundles. It completely encloses the joint except where it is interrupted by synovial protrusions (e.g. obturator externus bursa at posterior aspect of the hip joint).
What is the role of the synovial membrane of synovial joints?
Produces and maintains the synovial fluid.
Describe the synovial membrane of synovial joints.
Thin highly-vacularised membrane that lines the capsule covering the exposed osseous surfaces, tendon sheaths and bursae. It does not cover the articular cartilage of intra-articular discs/mensici.
What are bursa?
They are sacs lined with synovial membrane and filled with synovial fluid - that is communicating or non-communicating with the joint cavity.
What is the function of bursa?
They are located at tissue sites where tendons or muscles pass over bony prominences near joints, such as the knee. The function of a bursa is to facilitate movement and reduce friction between moving parts.
What is a tendon sheath?
An elongated bursa that wraps itself around a tendon
What is the composition of synovial fluid?
Hyaluronic acid, lubricin, proteinase, collagenase
What is the function of synovial fluid?
Reduces friction, shock absorption, nutrient and waste transportation.
How much synovial fluid is there in a large joint e.g. the knee?
What is the function of articular fat pads?
adipose tissue pads that protect the articular cartilage, as seen in the infrapatellar fat pad in the knee
What is the function of menisci?
1. Transfer load.
2. Stabilise joint by balancing load during changes to the articulating surfaces during movement.
What is the purpose of the periarticular arterial plexus of synovial joints?
Plexus ensures that when joint is moved all its blood supply is not cut off.
Which parts of the synovial joint have a poor blood supply?
Articular cartilage (avascular), fibrous capsule and ligaments (poor blood supply).
Which part of the synovial joint has a rich blood supply?
What is Hilton's Law regarding the innervation of joints?
The nerves supplying the joint capsule also supply the muscles moving the joint and the skin overlying the insertions of these muscles. Therefore you can work out the nerve supply of the skin and capsule if you know the muscle nerve supply.
What factors affect the stability and range of movement at a joint?
1. Structure/ shape of articulating bones
2. Strength and tension of joint ligaments
3. Arrangement and tone of muscle
4. Apposition of neighbouring soft tissue
5. Hormones e.g. relaxin in pregnancy
What is the shoulder joint capsule attached to?
1. Glenoid labrum and margins of glenoid cavity
2. Anatomical neck of humerus
Why does the capsule of the shoulder joint dip down medially to the surgical neck?
Provides laxity for full adbuction
Why is there a small open in the capsule of the shoulder joint anteriorly?
Where the synovial membrane of the synovial joint communicates with the subscapular bursa.
Where does the tendon of the long head of biceps brachii attach? What is its relation the the synovial membrane of the shoulder joint?
It attaches to the supraglenoid tubercle of the scapula. The tendon passes through the joint cavity where it acquires a tubular sleeve of synovium which surrounds the tendon up to its insertion.
Name three extracapsular shoulder ligaments:
1. Coracoacromial = most important
3. Transverse humeral ligament
What is the purpose of the transverse humeral ligament?
It holds the biceps brachii tendon in place during shoulder movement.
Name three intracapsular shoulder ligaments:
Superior, middle and inferior glenohumeral ligaments (between glenoid labrum and humerus).
What is the function of the glenohumeral ligaments?
Reinforce the capsule anterioly
What forms the coracoacromial arch?
What is the function of the coracoacromial arch?
Prevents upper displacement of the humerus.
What four muscles make up the rotator cuff muscles?
What is the most important factor giving stability to the glenohumeral joint?
Rotator cuff muscles
Where do the dorsal rotator cuff muscles all insert?
Greater tubercle of the humerus
What important anatomical features does the supraspinatous tendon pass through?
Where does the subscapularis muscle insert?
How do the rotator cuff muscles stabilise the glenohumeral joint?
The tendons of these muscles blend together and fuse with the capsule - strengthening it. Tone in the muscles holds the head of the humerus close to the glenoid cavity.
What is found in the space between the acromion and the head of the humerus? When are these structures at risk of damage?
1. Subacromial bursa
2. Rotator cuff tendons
4. Tendon of long head of biceps
During abduction there is a risk of impingement of these soft tissues between the head of the humerus and teh acromion.
What is the function of the subacromial bursa?
1. Facilitates the movement of the supraspinatous tendon under the coraco-acromial arch
2. Facilitates the movement of the deltoid over the capsule and greater tubercle of the humerus.
What does the brachial artery bifurcate into?
The radial and ulnar artery.
Which pair of arteries runs in the very centre of the forearm?
Anterior and posterior interosseous arteries
Which arteries anastamose forming the deep palmar arch of the hand?
Radial and ulnar arteries.