Anatomy of the Head, Neck and Spine Flashcards
How many bones make up the skull?
- 22
- 8 cranial bones and 14 facial bones
What is in the neurocranium?
- the brain
What is the facial skeleton also called?
- the viscerocranium
State the bones of the cranium.
- unpaired bones: frontal, occipital, sphenoid, ethmoid
- paired bones: parietal (x2), temporal (x2)
State the bones of the cranium.
- unpaired bones: vomer, mandible
- paired bones: maxilla (x2), zygoma (x2), nasal (x2), lacrimal (x2), inferior conchae (x2), palatine (x2)
What are sutures?
- fibrous joints permitting little or no movement
- in an infant they are not completely fused -> fusion doesn’t happen until some months after birth
What are fontanels?
- soft spots on the top of a babies head -> have an anterior and posterior fontanelle
At what ages do the fontanelle close/fuse?
- anterior fontanel = closes between 18-24 months of age
- posterior fontanel = closes during the first 2-3 months
What bones are teeth inserted into?
- maxilla and mandible
What are the nasal conchae?
- sticking out bits of bone in the nasal cavity that are covered by mucous membrane -> help warm air as it is breathed in by humidifying it
What movements are allowed at the temporomandibular joint?
- opening your mouth wide
- sliding jaw forwards/backwards
- moving jaw side to side
What is the lambda?
- the point at which the sagittal and lambdoid suture meet
Where does the medulla and spinal cord exit the cranial cavity?
- foramen magnum
Which skull bones are involved in the joint between the first vertebra and the skull?
- the occipital condyles -> sit on top of C1
Which joint allows the nodding?
- joint between the skull (condyles) and the first next vertebra -> the yes joint
Which joint allows shaking of the head?
- the joint between the first and second vertebra -> the no joint
What is housed within the anterior cranial fossa?
- the frontal lobe
What is housed within the middle cranial fossa?
- the temporal lobe
What is housed within the posterior cranial fossa?
- cerebellum and indirectly the occipital lobe
Describe the path of the internal carotid artery.
- first enters the skull through the carotid canal in the petrous part of the temporal bone -> then passes through the foramen lacerum, to enter the middle cranial fossa
What are the 3 layers of the meninges?
- dura mater
- arachnoid mater
- pia mater
How does the epidural space differs in the brain and spinal cord?
- brain = lack of epidural space
- vertebral column = large epidural space -> can beu sed for spinal anaesthia and block as well as lumbar puncture
Describe the dura mater around the brain.
- the dura is composed of two layers, largely stuck together over the surface of the brain -> outer layer = periosteal dura and inner layer = meningeal dura
- fused over most of the surface, except in certain places (inner layer peels away to create structures filled with blood -> the sinuses
What happens to the dura mater as it emerges from the foramen magnum?
- as the meningeal layer of dura emerges from the foramen magnum, the layer closest to the skull (periosteum) is lost at the foramen magnum (it fuses with the outside of the skull) -> the inner (meningeal) layer continues down the vertebral column surrounding the spinal cord -> hence, there is a large space between the dura and the bone in the vertebral column
Where does the inner layer of the dura peel away from the outer?
- down the longitudinal fissure
- towards the back, to form a shelf between the cerebellum and the occipital lobe
What are the points of the dural folds?
- help stop movement of the brain
- provide spaces in which blood can drain back to the venous system
What is the sagittal sinus?
- blood filled cavity/sinus whihc runs from front to back
- many great veins drain into the venous system by it
- there is a penetration of the arachnoid mater into the sinus to allow CSF to be rebasorbed
What is the major donwnside of dural folds?
- any swelling can cause parts of the brain to pushed down and through which can cause damage to the brain sitting close to it
What is tonsillar herniation, also state its consequence?
a type of cerebral herniation characterised by the inferior descent of the cerebellar tonsils below the foramen magnum which affects the medulla and lower brainstem -> cardiorespiratory failure
What is uncal herniation, also state its consequences?
- a subtype of transtentorial downward brain herniation, usually related to cerebral mass effect increasing the intracranial pressure -> affects the midbrain -> causes unconsciousness
What is the main blood supply to the meninges?
- middle meningeal artery
What is the major consequence of a pterion fracture?
- the middle meningeal artery runs past the pterion (very soft spot of the brain) -> fracture results in a large epidural bleed
What are the functions of the vertebral column?
o support and protection of the spinal cord
- vertebra hold the body weight
- transmit forces
- supports the head and upper limbs (and aid movements)
o movement
- upper limbs and ribs (extrinsic muscles)
- postural control and movement (intrinsic muscles)
Define primary curvature.
- curvatures that are in the direction that you’d expect in the foetal position -> their concave side is facing anteriorly
Define secondary curvature.
- curvatures are in the opposite direction that you’d expect in the foetal position -> their concavity facing posteriorly
Which vertebral sections have primary curvature?
- thoracic
- sarcal
Which vertebral sections have a secondary curvature?
- cervical
- lumbar
What is excessive kyphosis?
- excessive thoracic curvature
- elderly people tend to have a pronounced kyphosis
- in exaggerated kyphosis, the thoracic organs are squeezed
What is excessive lordosis?
- big curvature in the lower back, in the lumbar spine
What is scoliosis?
- laterally curvatures of the spine
- cause severe pain and aesthetic problems
- organs of the thorax and abdomen can become compressed with really severe angles of curvature
When is scoliosis most common?
- not uncommon -> especially to a slight degree
- most common in females around puberty
What part of the vertebra is the major weight bearing section?
- the vertebral body
What movements are permitted by the articular processes?
- with articular facets of vertebrae that are vertical -> is difficult to turn the vertebrae sideways -> able to move these vertebrae forwards and backwards if the facets when in the sagittal plane
- with articular facets that are horizontally located -> can be rotated sideways
Describe the structure of the intervertebral discs.
- water-filled structures with cartilage/collagen rings around them, with some gel in the middle
What is the function of the intervertebral discs?
- helps transmit forces
- helps with allowing flexibility between vertebrae
What happens over time?
- discs lose water and become dehydrated -> happens throughout the day and as you get older
- if the gaps betwen vertebrae get smaller, nerves can get impinged -> this is degenerative disc disease
What is the shape of the vertebral bodies of thoracic vertebra?
- heart-shaped
What is the shape of the vertebral bodies of lumbar vertebra?
- kidney shaped as well as being much bigger
Where does soinal anaesthesia or lumbar puncture occur?
- below the level of L2 there is no spinal cord -> just a bundle of nerves (the caudal equina)
What are prolapsed intervertebral discs?
- disc can rupture and the contents of the disc can emerge into the space occupied by the nerves or the spinal cord -> causes severe pain and paraesthesia due to nerve compression
- disc contents will take the path of least resistance -> will herniate through ready made holes for nerves trying to emerge
Which regions are most likely to suffer from a prolapsed intervertebral disc?
- all regions can be affected, however slipped discs (prolapse) are more likely to happen down the spine -> because more weight being transmitted by the disc
What movements of the spine can occur?
- extension and flexion
- lateral flexion
- rotation
What muscles are classified as sheet muscles?
- oblique muscles
- rectus addominus
- transversus abdominus
What is the function of the sheet muscles?
- aid flexion of the spine
- help with increasing abdominal pressure -> expulsion, coughing, sneezing, breathing etc
- oblique muscles also aid lateral flexion and rotation
What are the roles of the erector spinae muscles?
- straighten the spine
What is the role of the sternocleidomastoid?
- on the front of the neck -> help turn the head
Describe the range of motion of the regions of the spine?
- cervical spine is flexible in extension, rotation and lateral flexion
- thoracolumbar spine is slightly less versatile due to the presence of ribs
Describe the path of the vertebral meninges.
- dura mater and arachnoid mater travel further down the vertebral column than the spinal cord whereas the pia mater is adherent to the spinal cord -> ends essentially surrounding the spinal cord at L2
- a small filament extends down from the base of the spinal cord - know as the filum terminale -> proceeds downward from the apex of the conus medullaris
- pia mater also has a pair of denticulate ligaments, attaching it to the arachnoid and dura mater
- arachnoid and dura extend past L2 down to S2 – this forms the subarachnoid space (for CSF)
What is the difference between epidural and spinal anaesthesia?
- epidural = around the dura
- spinal = inside the subarachnoid space
What is spondylolysis?
- stress fracture of pars interarticularis (part of a vertebra located between the inferior and superior articular processes of the facet joint)
What is sciatica?
- a prolapsed disc that traps a nevre that supplies the feet and legs
What is spondylolisthesis?
- forward displacement of vertebra
What is spondylitis?
- inflammation of vertebrae
What are the functions of the neck?
- structural -> support and move head (inside prevertebral fascia)
- visceral functions (inside or associated with pretracheal fascia)
- conduit for blood vessels and nerves (inside or associated with carotid sheaths)
What are the 4 compartments of the neck?
- the vertebral compartment
- the visceral compartment
- two vascular compartments
What is contained within the vertebral compartment of the neck?
- cervical vertebrae and associated postural muscles
What is contained within the visceral compartment of the neck?
- thyroid
- parathyroid glands
- trachea
- oesophagus
What surrounds the visceral compartment?
- deep fascia called the pretracheal fascia
What is contained within the vascular compartments of the neck?
- internal jugular vein
- carotid artery
- vagus nerve
What are the strap muscles?
- muscles attached to the hyoid bone (free-moving bone)
- are concerned with elevation, depression of the larynx during swallowing and opening of the mandible
- are in an area of vulnerability -> some of the big vessels ascending and descending through the head and neck can be damaged by trauma
What lies at the C2 levels?
- superior cervical ganglion
What lies at the C3 levels?
- body of the hyoid
What lies at the C4 levels?
- upper border of the thyroid cartilage
- bifuraction of common carotid artery
What lies at the C6 levels?
- cricoid cartilage
- middle cervical ganglion
What lies at the C7 levels?
- inferior cervical ganglion
What nerve supplis the sternocleidomastoid and the trapezius?
- spianl accessory nerve
What are the borders of the anterior triangle of the neck?
- superior = inferior border of the mandible
- laterally = anterior border of the sternocleidomastoid
- medially = sagittal line of the neck
What are the borders of the posterior triangle of the neck?
- anterior = posterior border of the sternocleidomastoid
- posterior = anterior border of the trapezius muscle
- inferior = middle 1/3 of the clavicle
What lies within the anterior triangle of the neck?
o mainly muscles
- platysma -> sheet muscle slung underneath the chin to the clavicles
- mylohyoid
- digastric
- infrahyoid (strap) muscles
o carotid arteries (goes in through the carotid canal)
o internal jugular veins (emerges through skull via jugular foramen along with CN IX, X and XI)
What lies within the posterior triangle of the neck?
o blood vessels
- external jugular vein
- subclavian artery
- subclavian vein
o nevres
- trunks of the brachial plexus
- phrenic nerve
- vagus nerve
- spinal accessory nerve
What is can the external jugular artery be used for?
- functionality of the right side of the heart -> is the main drainage vessel of the face
- stands out when someone is angry or holding their breath
Describe lymph nodes in the neck.
- should not be able to palpate lymph nodes in healthy people
- to palpate lymph nodes, you use your hands standing behind the patient.
- lymph nodes in the neck can receive lymph from structures in the chest and abdomen means that metastases are feasible
- the vocal cords are an area which has no lymphatic drainage
What are the sections of the pharynx?
- nasopharynx -> posterior to the nasal cavity
- oropharynx -> posterior to the tongue -> contains lymphoid tissue
- laryngopharynx -> after the epiglottis
What is the sensory input into the pharynx?
- sensory IX and X supply to the pharyngeal plexus
What is the motor input into the pharynx?
- largely due to X innervation but a small supply from XI too
Describe the process of swallowing.
- oral preparatory phase -> food and liquid chewed to form a bolus -> is a voluntary task
- oral transit phase -> bolus propelled to back of mouth, palate seals entrance to nasal cavity -> is a voluntary task
- pharyngeal phase I -> triggered when bolus reaches faucial arch, palate stays elevated, tongue retracts, to push bolus to pharynx -> is a reflex control
- pharyngeal phase II -> bolus propelled through pharynx -> reflex -> the airway is closed during this by the epiglottis, vocal cords & arytenoid action
- oesophageal phase -> oesophagus opens, airway closed, breath held -> bolus propelled through oesophagus -> a reflex -> respiration then resumes with an exhalation, to clear any food particles from airway entrance
Name the 3 pairs of salivary glands.
- parotid
- submandibular
- sublingual
What is prodcued in the parotid glands?
- mainly thin, serous salvia -> is the biggest gland
What is produced in the submandibular glands?
- mainly serous
What is produced in the sublingual glands?
- mainly mucous
What is the nervous supply to the parotid glands?
- parasympathetic fibres of CN IX
What is the nervous supply to the submandibular glands?
- innervation from CN VII -> facial nerve parasympathetic fibres
What is the nervous supply to the sublingual glands?
- innervation from CN VII -> facial nerve parasympathetic fibres
Name the muscles of the tongue.
- styloglossus -> helps to RETRACT the tongue
- hyoglossus
- genioglossus -> from the tongue to the mandible -> contraction protudes the tongue
- intrinsic muscles
What nerve supplies the motor component to the tongue?
- CN XII -> hypoglossal
State a test for the hypoglossal nerve.
- ask the patient to stick his or her tongue out -> when this happens, the genioglossus contracts on either side
- If there is deviation of the tongue, there is a dysfunction of the hypoglossal in the SAME side of the direction of deviation (tongue deviates towards lesional side)
What is the lingual nerve?
- a nerve which has mixed cranial nerve components
- supplies the tongue with touch sensation and taste perception
What nerve supplies the sensation and taste to the anterior 2/3 of the tongue?
- normal sensation is the trigeminal nerve (V3)
- taste fibres are from the facial nerve
What nerve supplies the sensation and taste to the posterior 1/3 of the tongue?
- both sensation and taste fibres are carried in the glossopharyngeal nerves
- is a very little innervation from the vagus
Where is taste percevied?
- taste fibres go back to the nucleus solitaries in the brainstem
What are the muscles of mastication?
- massaeter -> superficial
- temporalis -> superficial
- lateral pterygoid -> deep
- medial pterygoid -> deep
- buccinator muscle -> deep
What muscles are supplied by the mandibular division of the trigeminal nerve?
- masseter
- temporalis
- lateral pterygoid
- medial pterygoid
Where does the masseter attach?
- from the zygomatic arch to lateral surface of ramus and angle of mandible
Where does the temporalis attach?
- from the temporal fossa to the coronoid process of the mandible
Where does the lateral pterygoid attach?
- the sphenoid/lateral pterygoid plate of the neck of the mandible
Where does the medial pterygoid attach?
- lateral pterygoid plate/maxilla/palate to the angle of mandible
What nerve supplis the buccinator muscle?
- the facial nerve -> CN VII
What is the role of the masseter?
- elevates the mandible and allows forced closure of mouth
What does the masseter do?
- elevates the mandible to allow forced closure of the mouth
What does the temporalis do?
- elevates and retracts the mandible