MBBS NAIJA

Perculiarities of the Muscles of facial expression

The perculiarities of muscles of facial expression are:
(i) They are subcutaneous
(ii) They bring about different facial expression(iii) They have small motor unit
(iv) Embryologically, they are derieved from mesenchyme of second pharyngeal arch and are supplied by facial nerve.
(v) They are inserted into the skin
(vi) Functionally, they are regulators of three openings in the face (Palpebral fissure, nostrils and Oral fissures)

Perculiarities of the Muscles of facial expression The perculiarities of muscles of facial expression are:(i) They are subcutaneous(ii) They bring about different facial expression(iii) They have small motor ...

Parts of a typical vertebra and Their functions

Every vertebra has a body (vertebral body), which consists of a large anterior middle portion called the centrum (vertebral centrum, plural centra) and a posterior vertebral arch, also called a neural arch.

Parts of a typical vertebra and Their functions Every vertebra has a body (vertebral body), which consists of a large anterior middle portion called the centrum (vertebral centrum, plural centra) and a pos...

Structures that passes through Optic Canal or optic foramen

Optic nerve
Opthalmic artery
The optic foramen is the entry point to the optic canal, which leads from the middle cranial fossa to the apex of the orbit. The optic canal is directed forward, laterally, and somewhat downward and conducts the optic nerve, the ophthalmic artery, and sympathetic fibers from the carotid plexus.

Structures that passes through Optic Canal or optic foramen Optic nerveOpthalmic arteryThe optic foramen is the entry point to the optic canal, which leads from the middle cranial fossa to the apex of the orbit. The o...

Cause of Opthalmoplegia // Lesion to 3rd, 4th, 6th cranial nerve

Opthalmoplegia is due to lesion of 3rd, 4th and 6th cranial nerveWhat is ophthalmoplegia? Ophthalmoplegia is the paralysis or weakness of the eye muscles. It can affect one or more of the six muscles that hold the eye in place and control its movement.

Cause of Opthalmoplegia // Lesion to 3rd, 4th, 6th cranial nerve Opthalmoplegia is due to lesion of 3rd, 4th and 6th cranial nerveWhat is ophthalmoplegia? Ophthalmoplegia is the paralysis or weakness of the eye muscles. I...

Anatomy of the Obelion // Between two parietal foramina

It is a point on the sagittal suture between two parietal foraminaThe term obelion is applied to that point of the sagittal suture which is on a level with the parietal foramina

Anatomy of the Obelion // Between two parietal foramina It is a point on the sagittal suture between two parietal foraminaThe term obelion is applied to that point of the sagittal suture which is on a level with t...

Nerve to Stylohyoid and its innervation to the stylohyoid muscle

Nerve to stylohyoid gives motor supply to stylohyoid muscleStylohyoid receives innervation from the stylohyoid branch of the facial nerve (Cranial nerve 7). The branch arises right after the facial nerve passes the mastoid process of temporal bone to enter the middle part of the muscle.

Nerve to Stylohyoid and its innervation to the stylohyoid muscle Nerve to stylohyoid gives motor supply to stylohyoid muscleStylohyoid receives innervation from the stylohyoid branch of the facial nerve (Cranial nerve 7). ...

Nerve to stapedius and its supply to Stapedius muscle

They stabilize the stapedius and prevent it from over-vibrationStapedius is the most important muscle in the body and nerve to stapedius is the most important nerve.Stapedius causes vibration so that sound can be heardFailure of function of stapedius result in hyperacusis

Nerve to stapedius and its supply to Stapedius muscle They stabilize the stapedius and prevent it from over-vibrationStapedius is the most important muscle in the body and nerve to stapedius is the most importan...

Anatomy of the Nasion // Bridge of the nose

It is a median elevation between the internasal and frontonasal sutureThe nasion (also known as bridge of the nose) is the midline bony depression between the eyes where the frontal and two nasal bones meet, just below the glabella.

Anatomy of the Nasion // Bridge of the nose It is a median elevation between the internasal and frontonasal sutureThe nasion (also known as bridge of the nose) is the midline bony depression between th...

Nasal meatuses and the structures that open in them // Inferior meatus, Middle meatus and Superior

Inferior Turbinate: Located between the inferior co**ha and the floor of the nasal cavity.Middle Turbinate: Positioned between the inferior and middle co**ha.Superior Turbinate: Found between the middle and superior co**ha.The space between these turbinates is called the meatus

Openings into the Nasal Cavity:The nose plays a crucial role in draining various structures. As a result, several openings connect to the nasal cavity: Paranasal Sinuses: The frontal, maxillary, and anterior ethmoidal sinuses open into the middle meatus. The semilunar hiatus, a crescent-shaped groove on the lateral walls of the nasal cavity, marks the location of this opening. Nasolacrimal Duct: This duct drains tears from the eye and opens into the inferior meatus.Auditory (Eustachian) Tube: It opens into the nasopharynx at the level of the inferior meatus, allowing the middle ear to equalize with atmospheric air pressure.

Posterior ethmoidal air sinus opens into superior meatus

Nasal meatuses and the structures that open in them // Inferior meatus, Middle meatus and Superior Inferior Turbinate: Located between the inferior co**ha and the floor of the nasal cavity.Middle Turbinate: Positioned between the inferior and middle co**ha...

Damage to the ipsilateral motor cortex leading to weakness of risorius muscle of contralateral side

This is an upper motor neuron lesion of facial nerve, also known as supranuclear lesion of facial nerve.There is no weakness in the corrugator supercilli, because this part of the face receives innervation from the nuclear fibres, arising from corticonuclear fibers of both sides of cerebral hemisphere.Therefore, only the lower half of the face in the region of left risorius is paralyzed

Damage to the ipsilateral motor cortex leading to weakness of risorius muscle of contralateral side This is an upper motor neuron lesion of facial nerve, also known as supranuclear lesion of facial nerve.There is no weakness in the corrugator supercilli, be...

Cause of Mydriasis // Dilated and fixed pupil

Mydriasis (dilated and fixed pupil) is due to affectation of occulomotor Nerve Mydriasis refers to the dilation of the pupil, which normally occurs in response to low amounts of light in the environment. In some cases, prolonged mydriasis occurs when an individual's pupil remains dilated regardless of the amount of light in the environment.

Cause of Mydriasis // Dilated and fixed pupil Mydriasis (dilated and fixed pupil) is due to affectation of occulomotor Nerve Mydriasis refers to the dilation of the pupil, which normally occurs in respon...

Anatomy of the Modiolus and Mnemonics to remember muscles that form the Modiolus

It is defined as a point of insertion of facial muscles It has a cart-wheel shapeIt is 10mm - 20mm lateral to the angle of the mouth

The modiolus is formed by 9 muscles
1. Orbicularis oris
2. Buccinator
3. Risorius
4. Levator anguli oris
5. Depressor Anguli oris
6. Zygomatic major
7. Platysma
8. Levator labii superioris
9. Depressor labii inferioris

Anatomy of the Modiolus and Mnemonics to remember muscles that form the Modiolus It is defined as a point of insertion of facial muscles It has a cart-wheel shapeIt is 10mm - 20mm lateral to the angle of the mouthThe modiolus is formed by...

Mnemonics to remember structures pierced during Cisterna Puncture or Cisternal puncture

(i) Skin(ii) Superficial fascia(iii) Deep fascia / investing layer of fascia colli(iv) Ligamentum nuchae(v) Posterior atlanto-occipital membrane(vi) Dura mater(vii) Arachnoid matter(viii) Subarachnoid space

Mnemonics to remember structures pierced during Cisterna Puncture or Cisternal puncture (i) Skin(ii) Superficial fascia(iii) Deep fascia / investing layer of fascia colli(iv) Ligamentum nuchae(v) Posterior atlanto-occipital membrane(vi) Dura mat...

Mnemonics to remember structures pierced during Lumbar Puncture

(i) Skin
(ii) Superficial fascia
(iii) Deep fascia
(iv) Supraspinous ligament
(v) Interspinous ligament
(vi) Ligamentum flavum
(vii) Duramater
(viii) Arachnoid matter
(ix) Subarachnoid space

Mnemonics to remember structures pierced during Lumbar Puncture (i) Skin(ii) Superficial fascia(iii) Deep fascia(iv) Supraspinous ligament(v) Interspinous ligament(vi) Ligamentum flavum(vii) Duramater(viii) Arachnoid matt...

Comparison and Differences between the Male sacrum and female sacrum

The body of the first sacral vertebra is larger in male than in femaleThe width of the first sacral vertebra is less than the ala of the sacrum in female and wider in maleThe sacrum is often wider in proportion to length in female than in male

The anterior surface of the female sacrum is flat superiorly and curve forward inferiorly, whereas that of the male is uniformly concaveThe auricular surface of the sacrum occupies two vertebrae in female and two and a half vertebra in male

Comparison and Differences between the Male sacrum and female sacrum The body of the first sacral vertebra is larger in male than in femaleThe width of the first sacral vertebra is less than the ala of the sacrum in female and...

Anatomy of the Ligamentum Flavum

It passes between the laminae of adjacent vertebrae on each side.
It forms the posterior part of the vertebral canal
It extends from the posterior surface of the lamina above to the anterior surface of the lamina belowIt helps to maintain the normal curvature of the vertebral column

Anatomy of the Ligamentum Flavum It passes between the laminae of adjacent vertebrae on each side.It forms the posterior part of the vertebral canalIt extends from the posterior surface of t...

Anatomy of the Lambda // Meeting point of the Sagittal suture and Lambdoid suture

It is the meeting point between sagittal suture and lamdoid sutureIt is a site of membranous gap in foetus known as POSTERIOR FONTANELLE, which closes at 2 - 3 months of age.Lambda is the point where the sagittal suture, running along the midline, and the lambdoid suture, running sideways, come together.

Anatomy of the Lambda // Meeting point of the Sagittal suture and Lambdoid suture It is the meeting point between sagittal suture and lamdoid sutureIt is a site of membranous gap in foetus known as POSTERIOR FONTANELLE, which closes at 2 -...

Anatom of the interspinous ligament

It passes between the spinous process of adjacent vertebraeIt extend from the base to the apex of the spinous process of the adjacent vertebraeIt blends with ligamentum flavum anteriorly and supraspinous ligament posteriorly on both sides

Anatom of the interspinous ligament It passes between the spinous process of adjacent vertebraeIt extend from the base to the apex of the spinous process of the adjacent vertebraeIt blends with...

Effects of Fracture of the Jugular Foramen

Fracture through jugular foramen will result in lesion of nucleus ambiguus. The nucleus ambiguus gives origin to glossopharyngeal nerve, vagus nerve and cranial accessory nerve.The effects are ipsilateral paralysis of most muscles of:

(a) SOFT PALATE due to affectation of vagus nerve that supplies it
(b) PHARYNX due to affectation of glossopharyngeal nerve, vagus nerve and cranial accessory nerve.
(c) LARYNX due to affectation of the vagus and cranial accessory nerve
(d) There would be loss of CAROTID SINUS REFLEX, due to the affectation of glossopharyngeal nerve that supplies carotid sinus and carotid body.

Effects of Fracture of the Jugular Foramen Fracture through jugular foramen will result in lesion of nucleus ambiguus. The nucleus ambiguus gives origin to glossopharyngeal nerve, vagus nerve and cran...

Boundaries of the intervertebral foramen and Structures that pass through intervertebral foramen

ABOVE: Pedicle of adjacent vertebra
BELOW: Pedicle of adjacent vertebra
IN FRONT: Part of vertebral body and intervertebra disc
BEHIND: Articular processes and joint between

The foramen allows for the passage of the spinal nerve root, dorsal root ganglion, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses, recurrent meningeal (sinu-vertebral) nerves, and transforaminal ligaments.

Boundaries of the intervertebral foramen and Structures that pass through intervertebral foramen ABOVE: Pedicle of adjacent vertebraBELOW: Pedicle of adjacent vertebraIN FRONT: Part of vertebral body and intervertebra discBEHIND: Articular processes and ...

Anatomy of the Inion // Highest point on external occipital proturberance

This is the highest point on the external occipital proturberanceNear the middle of the squamous part of occipital bone is the external occipital protuberance, the highest point of which is referred to as the inion.

Anatomy of the Inion // Highest point on external occipital proturberance This is the highest point on the external occipital proturberanceNear the middle of the squamous part of occipital bone is the external occipital protuberanc...

Anatomy of the Intertransverse ligaments of the vertebral column

It joins the transverse process of the adjacent vertebra The Intertransverse ligaments run all the way up and down the spine.

Anatomy of the Intertransverse ligaments of the vertebral column It joins the transverse process of the adjacent vertebra The Intertransverse ligaments run all the way up and down the spine. ...

Anatomy, Histology and Histophysiology of the Thymus gland

The thymus is a primary lymphoid organ located in the mediastinum.It consists of two lobes connected by an isthmus.Blood supply to the thymus comes from the internal thoracic artery and the superior and inferior thyroid arteries.The thymus extends from the level of the inferior poles of the thyroid gland above to the fourth costal cartilage.It sits anterior to the great vessels of the heart and deep to the sternum.The two distinct lobes are connected in the midline by an isthmus.

The thymus is encapsulated and divided into lobules.Each lobule has three regions:Subcapsular cortical region: Located just beneath the capsule.
Cortical region: Contains thymic epithelial cells and lymphoid cells.
Medullary region: Found centrally within each lobule.
The thymic epithelial cells play a crucial role in the maturation and development of lymphoid cells that migrate into the thymus during intrauterine angiogenesis.

The thymus serves as the initial site of T cell immune maturation.T cells gain their name because they mature in the thymus, while B cells mature in the bone marrow.Positive and negative selection processes occur in the thymus, ensuring that only functional T cells survive.It’s where hemopoietic precursor
cells mature into T cells via these selection processes.

Anatomy, Histology and Histophysiology of the Thymus gland The thymus is a primary lymphoid organ located in the mediastinum.It consists of two lobes connected by an isthmus.Blood supply to the thymus comes from the ...

Anatomy of the Glabella Point // between two supercilliary arches

The glabella is a median elevation between two superciliary arches. Glabella is present just above the nasion- an intersection of internasal and frontonasal suture. The skin covering the glabella is known as glabellar skin, which is also the source of redundant thick skin commonly used for reconstruction of the upper nasal dorsum and medial canthal area.

Anatomy of the Glabella Point // between two supercilliary arches The glabella is a median elevation between two superciliary arches. Glabella is present just above the nasion- an intersection of internasal and frontonasal ...

Ganglia of the facial nerve ( Geniculate, Pterygopalatine, Submandibular ganglion )

There are 3 ganglia of facial nerve
(a) GENICULATE GANGLION
- it is a false ganglion- It has no cell bodies
(b) PTERYGOPALATINE GANGLION
- It gives fibers that supplies the lacrimal gland
(c) SUBMANDIBULAR GANGLION

Ganglia of the facial nerve ( Geniculate, Pterygopalatine, Submandibular ganglion ) There are 3 ganglia of facial nerve(a) GENICULATE GANGLION- it is a false ganglion- It has no cell bodies(b) PTERYGOPALATINE GANGLION- It gives fibers that s...

Structures that pass through Foramen Rotundum

Maxillary nerve
The foramen rotundum is a circular hole in the sphenoid bone of the skull. It connects the middle cranial fossa and the pterygopalatine fossa.

Structures that pass through Foramen Rotundum Maxillary nerveThe foramen rotundum is a circular hole in the sphenoid bone of the skull. It connects the middle cranial fossa and the pterygopalatine fossa....

Mnemonics to remember structures that pass through foramen Ovale

Mandibular branch of trigeminal nerve
Accessory meningeal artery
Lesser petrosal nerve
Emissary vein

Mnemonics to remember structures that pass through foramen Ovale Mandibular branch of trigeminal nerveAccessory meningeal arteryLesser petrosal nerveEmissary vein

Structures that pass through the Foramen lacerum

Internal carotid artery and its accompanying sympathetic plexus crosses the roofNerve to pterygoid canal passes via the anterior wallThe foramen lacerum (lacerated or torn foramen) is an irregular foramen located in the middle cranial fossa, posteromedial to the foramen ovale.

Structures that pass through the Foramen lacerum Internal carotid artery and its accompanying sympathetic plexus crosses the roofNerve to pterygoid canal passes via the anterior wallThe foramen lacerum (lac...

Symptoms, Features and Presentations of Bell's palsy

Loss of horizontal wrinkles on the forehead, due to paralysis of frontal belly of occipitofrontalis Loss of facial assymetry, due to unoppose action of muscles of the opposite side Widening of the palpebral fissure, due to paralysis of orbicularis oris

Drolling of saliva from the angle of the mouth, due to paralysis of orbicularis oris Sagging of angle of the mouth, due to paralysis of zygomaticus major

Symptoms, Features and Presentations of Bell's palsy Loss of horizontal wrinkles on the forehead, due to paralysis of frontal belly of occipitofrontalis Loss of facial assymetry, due to unoppose action of muscl...

The Digastric branch of facial nerve Gives innervation to posterior belly of digastric muscle

The Digastric branch supplies the posterior belly of digastric muscleThe digastric branch of facial nerve provides motor innervation to the posterior belly of the digastric muscle. It branches from the facial nerve (CN VII) near to the stylomastoid foramen as the CN VII exits the facial canal (it thus branches proximal to the parotid plexus of facial nerve).

The Digastric branch of facial nerve Gives innervation to posterior belly of digastric muscle The Digastric branch supplies the posterior belly of digastric muscleThe digastric branch of facial nerve provides motor innervation to the posterior belly o...