Axial Skeleton Osteology
How many vertebrae are in each region of the spine?
Cervical spine: 7 vertebrae (C1–C7)
Thoracic spine: 12 vertebrae (T1–T12)
Lumbar spine: 5 vertebrae (L1–L5)
Sacrum: 5 fused vertebrae (S1–S5)
Coccyx: 3-4 semi-fused bones
What is the name of the large opening at the base of the skull?
Foramen Magnum
What are two functions of the thoracic cage?
Protects vital organs, assists in respiration by increasing and decreasing in volume
Define Affinity and Efficacy
Affinity: How well a drug binds to a receptor
Efficacy: How well a drug, once bound to a receptor, ellicits a response
What is the fastest way to adminster a medicine?
Intravenous injection
What type of bones are the neurocranium and viscerocranium primarily made of?
Flat bones and Irregular bones
Name three main anatomical features found on a typical vertebra.
Any three of the following:
Vertebral body, Spinous process, Transverse processes, Vertebral foramen, Superior or inferior articular processes, Pedicles or laminae
Why are lumbar vertebrae larger and more robust than cervical vertebrae?
To withstand greater compressive forces
Define EC50.
The concentration of an agonist at which it creates 50% of its maximal response
What is Bioavailability?
The fraction of dose of
an administered drug that reaches the
systemic circulation and is therefore
potentially able to elicit a pharmacological
effect.
What type of joints connect the ribs to the costal cartilage and the costal cartilage (on ribs 2-7) to the sternum.
Synchondroses and synovial joints (plane)
What bones make up the neurocranium?
Frontal bone
Parietal bones
Temporal bones
Occipital bone
Sphenoid bone
Ethmoid bone
Which ribs are the floating ribs?
a) Ribs 8 to 10
b) Ribs 1 and 2
c) Ribs 11 and 12
d) Ribs 1 to 7
c) Ribs 11 and 12
Two drugs bind to the same receptor, but Drug A produces a greater maximum cellular response than Drug B, even when both occupy all available receptors. What pharmacodynamic property differs between these drugs?
Efficacy (intrinsic activity).
An oral drug is 80% absorbed from the gut. The liver then removes 75% of the absorbed drug before it reaches the systemic circulation. What is its oral bioavailability?
a) 0.05
b) 0.20
c) 0.25
d) 0.60
b) 0.20
A patient has a fracture affecting a thoracic vertebra. Imaging reveals damage to the structures that normally articulate with the head and tubercle of a typical rib. Which vertebral features are most likely affected?
A. Transverse foramina and bifid spinous process
B. Costal facets and demi-facets
C. Large kidney-shaped vertebral body and triangular vertebral foramen
D. Anterior and posterior arches and lateral masses
B - Costal facets and demi-facets.
Costal facets on the transverse processes articulate with rib tubercles, while demi-facets on vertebral bodies help articulate with rib heads (typically ribs 2–9).
Which of the following statements about specialised cervical vertebrae is correct?
A. The atlas (C1) has a vertebral body and provides a pivot for the axis.
B. The axis (C2) articulates with the occipital condyles and has no intervertebral disc.
C. The atlas (C1) has no vertebral body and articulates with the occipital condyles.
D. C7 has a bifid spinous process and is the only cervical vertebra with transverse foramina.
C - The atlas (C1) has no vertebral body and articulates with the occipital condyles.
- C1 supports the skull at the atlanto-occipital joint, allowing nodding movements.
What is the purpose of a costal groove?
To protect the intercostal vein, artery and nerve
What is the difference between an agonist and an antagonist in terms of their effects on a receptor?
An agonist binds to and stimulates a receptor to produce a response, while an antagonist binds to the receptor but does not produce a response and blocks the action of agonists.
A patient presents after an aspirin overdose. Aspirin is a weak acid. Which change to the urine most increases aspirin excretion, and why?
d) Alkalinise: aspirin ionised, less reabsorbed
Which feature is characteristic of a typical thoracic vertebra?
a) Transverse foramina
b) Costal facets for articulation with ribs
c) Absence of a vertebral body
d) A dens projecting superiorly
b) costal facets for articulation with ribs
How does efficacy of an antagonist differ from those of an agonist?
An agonist has efficacy and stimulates a response, whereas an antagonist has zero efficacy and does not stimulate a response.