Anatomy Pratical 1

Question 1

what are the two parts of the skull

Answer 1

• cranial bones

- facial bones

Question 2

what are the bones of the cranium

Answer 2

frontal bone, parietal bone, occipital bone, temporal bone, sphenoid bone, ethmoid bone

Question 3

what are the bones of the facial bones

Answer 3

mandible, maxilla, zygomatic bone, nasal bone, lacrimal bone, palatine bone, vomer

Question 4

describe the structure of the temporal bone

Answer 4

The thicker part of the bone (the petrous part) houses the middle and inner ear. On the external surface identify the external auditory (acoustic) meatus and internally identify a small foramen (hole), the internal auditory meatus, through which 2 cranial nerves pass (the nerve of hearing and balance, the vestibulocochlear nerve CNVIII, and the facial nerve CNVII).

Identify the bar like zygomatic process of the temporal bone that forms part of the zygomatic arch – the cheek bone.

The mastoid process is an anchoring site for some neck muscles. The needle like styloid process (often broken off) is an attachment for tongue and pharynx muscles.

Question 5

describe the structure of sphenoid bone

Answer 5

The sphenoid bones is a butterfly shaped bone. It is a key bone of the cranium because it articulates with all other cranial bones.
It is made up of the central body, the greater wings and the lesser wings and 4 pterygoid plates.

Hold the sphenoid bone next to a skull so you can orientate its position in the cranium.

There are a number of important foramina (foramen = hole or opening) in the sphenoid bone. These include the superior orbital fissure, the optic canals, the foramen rotundum, foramen ovale and foramen spinosum.

Question 6

describe the structure of peterion

Answer 6

The pterion (temple) is an important clinical landmark because it marks the position of the anterior branches of the middle meningeal artery. The pterion marks the union of the frontal, parietal temporal and sphenoid bones and the skull is thinnest at this point. Lying in the skull periosteum is a groove in which runs the middle meningeal artery, which supplies the dura and the bone. This artery grooves the bone of the skull and is often implicated in intracranial haemorrhage.

Question 7

describe the structure of the ethmoid

Answer 7

The ethmoid bone is very delicate and serves like a sieve through which air can pass.
On the superior surface of the ethmoid bone is the cribiform plate where the olfactory bulbs of the olfactory nerve (the special sensory nerve of smell, CN I) sit.

Question 8

what do the air sinuses do

Answer 8

These lighten the skull and enhance the resonance of the voice

Question 9

How many vertebrae are in the spine

Answer 9

There are 33 vertebrae in the spine

Question 10

Describe the structure of vertebrae (typical)

Answer 10

The body
The vertebral arch forms a vertebral foramen through which the spinal cord passes
The transverse and spinous process is an attachment for the muscles of the back

Question 11

describe C1

Answer 11

CI The Atlas articulates with occipital condyles of the skull

Question 12

describe C2

Answer 12

C2 The Axis. More similar to a typical vertebra but has a dens process which acts like a pivot, and allows the atlas to pivot around the horizontal axis (

Question 13

what does the sacrum articulate with

Answer 13

Laterally the sacrum articulates with the 2 hip bones to form the sacroiliac joints. The vertebral canal continues inside the sacrum

Question 14

where do the sacral spinal nerves go through

Answer 14

The anterior and posterior sacral foramina transmit the anterior and the posterior rami of the sacral spinal nerves

Question 15

Describe the structure of spinal nerves

Answer 15

A spinal nerve is only short, dividing almost immediately after emerging from intervertebral foramen, it divides into a small dorsal ramus and a larger ventral ramus.
Each ramus is mixed. The spinal nerve rami and their branches supply the entire somatic region of the body (voluntary muscles and skin).

Question 16

what is a dermatome

Answer 16

The area of skin innervated by the cutaneous branches of a single spinal nerve is called a dermatome

Question 17

what are the 2 functional subdivisions of PNS

Answer 17

• sensory afferent

- motor efferent

Question 18

what does the sensory division do

Answer 18

The sensory (or afferent) division, that conveys impulses from sensory receptors to the CNS. Sensory fibres conveying impulses from the skin, joints and muscles are called somatic afferents (soma=body) and those transmitting impulses from the visceral organs are called visceral afferents.

Question 19

what does the motor division do

Answer 19

The motor (or efferent) division of the PNS transmits signals to effector organs

Question 20

what are the divisions of the motor system

Answer 20

somatic and autonomic

Question 21

what are the divisions of the autonomic system

Answer 21

(The enteric nervous system that controls gut function)
The parasympathetic nervous system, which is involved in rest, relaxation and recuperation
The sympathetic nervous system, which is the bodies alarm warning system for danger and stress

Question 22

what is the parasympathetic nervous system outflow

Answer 22

Cranio-sacral outflow. The axons synapse in ganglia close to the target organ

Question 23

what is the cranial outflow

Answer 23

Oculomotor nerve (III)
Facial Nerve (VII)
Glossopharyngeal nerve (IX)
Vagus Nerve (X)

Question 24

what is the sacral outflow

Answer 24

S2-S4

Question 25

where does the sympathetic outflow arise from

Answer 25

T1-L2

Question 26

how is the sympathetic trunk connected to the spinal nerves

Answer 26

by grey and white rami

Question 27

what do white rami do

Answer 27

they contain the axons of the pregangliionic sympathetic fibre
- after leaving the cord via the ventral root preganglionic sympathetic fibres pass through white rami communicates to enter the adjoining sympathetic trunk

Question 28

describe what happens in the sympathetic trunk

Answer 28

1. Synapse in the same chain ganglion from the spinal segment that they arise (paravertebral synapse)
2. Ascend or descend in the chain to synapse with postganglionic neurons higher or lower in the chain (paravertebral synapse)
3. Pass through the trunk to synapse in prevertebral ganglia along the abdominal aorta (e.g. splanchnic nerves)

Question 29

what do the grey rami do

Answer 29

• once the synaptic contact has been established in the sympathetic trunk grey rami exit the sympathetic trunk and form postganglionic neurones

Question 30

how long is the adult spinal cord

Answer 30

18 inches long

- extends from the oramen magnum to the level of the L2 vertebra

Question 31

what grows faster the spinal cord or vertical column

Answer 31

This is not so at birth where it extends much lower but because the vertebral column grows faster than the cord it leaves the cord positioned progressively higher up in the spinal canal

Question 32

what does the spaniel cord form at its end

Answer 32

• at its end the spinal cord tapers off and forms the conus medullar is (L2)
• Then beyond this point it forms the caudal equina

Question 33

what is the spinal cord surrounded by

Answer 33

meninges

• tough, outer layer (dura mater)
• delicate, middle layer (arachnoid mater)
• inner layer firmly attached to the surface of the spinal cord (pia mater).

Question 34

describe the structure of the arachnoid layer

Answer 34

avascular

• has thin processes or trabecular that extend toward the spinal cord
• These trabeculae cross the subarachnoid space and become continuous with the pia matter

Question 35

what is the hilum terminals

Answer 35

the filum terminale is an extension of the pia mater that is attached to the coccygeal segments, whose function is to suspend the cord in CSF

Question 36

describe the structure of the Pia

Answer 36

• thin
• cellular and very delicate
• difficult to identify as a discrete membrane except as the denticulate ligaments along the sides of the spinal cord.

Question 37

what do the denticulate ligaments do

Answer 37

The denticulate ligaments span the space between the surface of the cord and the dura and have an important protective mechanical function in relation to the cord.