Question 1 – Basal Ganglia
Write short notes on the anatomy of the basal ganglia.
Marks are allocated under the following headings: overview and function, components, location and relations, connections, and arterial supply.
OVERVIEW AND FUNCTION
– group of subcortical nuclei that provides a feedback mechanism to the cerebral cortex, modulating and refining cortical activation. Primarily, its function is related to motor refinement.
COMPONENTS & LOCATION & RELATIONS
1. Caudate nucleus
– paired deep subcortical structure with head, body, tail
– forms lateral wall of the lateral ventricles
2. Globus pallidus (interna & externa)
– Globus pallidus externa – lateral (external)
– Globus pallidus interna – medial (internal)
– separated from each other by the medial/internal medullary lamina
– laterally: putamen
– medially: genu of the internal capsule
– anteriorly: anterior limb of internal capsule
– posteriorly: posterior limb of internal capsule
3. Putamen
– round structure base of forebrain, most lateral of the basal ganglia on axial section
– forms lateral aspect of the lentiform nucleus
– concave inner surface is lateral to globus pallidus externa
– separated by GPe by lateral mddullary lamina
– separates internal capsule medially from external capsule
– laterally: external capsule – white matter fibres, claustrum – thin bundle of grey matter, insular cortex, circular sulcus
– posteriorly: optic radiation
– medially: anterior horn of lateral ventricle, thalamus, interthalamic adhesion, fornix
– anteriorly: anterior limb of internal capsul
4. Subthalamic nucleus
– long nucleus located in the midbrain
5. Substantia nigra (pars compacta and pars reticulata)
CONNECTIONS
– Putamen is connected to substantia nigra and globus pallidus
– The striatopallidal pathway is an inhibitory connection between the striatum and both segments of the globus pallidus.
– The striatonigral pathway is an inhibitory connection between the striatum and the SNr.
– The globus pallidus external segment makes an inhibitory connection to the subthalamic nucleus.
– The subthalamic nucleus makes excitatory connections onto both segments of the globus pallidus and the SNr.
– The nigrostriatal pathway makes a synapse onto striatal neurons.
ARTERIAL SUPPLY
– predominantly the lenticulostriate arteries (medial and lateral branches, from MCA) provides supply to striatum and lenticular nucleus
– head of caudate nucleus also supplied by medial striate artery (of Heubner), a branch of the anterior cerebral artery (variable origin: A1, ACom or A2)
– substantia nigra and subthalamic nucleus – posterior structures hence receive branches from posterior cerebral and posterior communicating arteries
Question 2 – Dural venous sinus
Write short notes on the anatomy of the dural venous sinuses, excluding the cavernous sinuses.
Marks are allocated under the following headings: overview, course, tributaries and drainage of each named dural venous sinus, and variants.
OVERVIEW
– lie between the periosteal and meningeal layers of the dura mater
– 11 venous sinuses in total
– receives blood from cerebral veins and CSF from subarachnoid space via arachnoid granulations
COURSE
1. Superior and inferior sagittal sinus
– Superior: runs between foramen caecum to the internal occipital protuberance
– Inferior: resides in the double-folder free-border of the falx cerebri, dorsal to corpus callosum. Joins great cerebral vein (of Galen) at the intersection of falx cerebri and tentorium cerebelli to form the straight sinus
2. Straight sinus
– lies within the posterior end of flax cerebri, in middle of tentorium cerebelli
3. Sphenoparetal sinus
– runs along free border of lesser wing of sphenoid bone
– drains into the cavernous sinus
4. Petrosal sinus
– Superior: run along petrous part of temporal bone, in base of tentorium cerebelli, terminates in sigmoid sinus
– Inferior – exit the cavernous sinus and terminates in sigmoid sinus or internal jugular bulb
5. Sigmoid sinus
– An extension of the transverse sinus as it leaves the tentorium cerebelli
TRIBUTARIES
1. Superior sagittal sinus
– superior cerebral veins
– scalp veins
– parietal emissary and diploic veins
2. Inferior sagittal sinus
Veins draining:
– the limbic lobe (cingulate gyrus)
– medial frontoparietal lobe
– genu of the corpus callosum
– deep cerebral veins
3. Straight sinus
– superior cerebellar veins
4. Transverse sinus
– inferior cerebral and inferior cerebellar veins
– superior petrosal sinus
– anastomotic veins (inferior anastomotic vein (of Labbe))
– diploic veins
5. Superior petrosal sinus
– cerebellar, inferior cerebral, tympanic veins
DRAINAGE
Eventually, drain into internal jugular vein via a dilated portion known as the jugular bulb:
1. Superior sagittal sinus drains into right transverse sinus
2. Inferior sagittal sinus drains into straight sinus
3. Straight sinus drains into left transverse sinus
4. Transverse sinus (left and right) drain into sigmoid sinus
5. Sigmoid sinus drains into internal jugular vein
VARIANTS
– hypoplasia of the middle part of the superior sagittal sinus
– duplication of the rostral superior sagittal sinus
– unilateral hypoplastic rostral superior sagittal sinus
– complete or bilateral hypoplastic rostral superior sagittal sinus
Question 3 – External carotid artery
Write short notes on the anatomy of the external carotid artery.
Marks are allocated under the following headings: origin and course, branches and structures supplied, relations, and variants.
ORIGIN
– arises at bifurcation of common carotid, at level of upper border of thyroid cartilage or level of C4, within the carotid triangle
COURSE
– it ascends curving anteriorly and superiorly in the space behind the mandibular rami
– terminates as maxillary artery (large) and superficial temporal artery within the parotid gland
RELATIONS
– covered by the skin, superficial fascia, Platysma, deep fascia, and anterior margin of the Sternocleidomastoid muscle;
– it is crossed by the hypoglossal nerve, digastric and stylohyoid muscles
– superiorly/distally, within the substance of the parotid gland, it lies deep to the facial nerve and the junction of the temporal and maxillary veins.
Medial:
– hyoid, wall of pharynx, pharynx, superior laryngeal nerve, part of parotid gland
Posterior:
– superior laryngeal nerve
– IJV
– separated from ICA by styloglossus, stylophayrngeus, glossopharyngeal nerve, pharyngeal branch of vagus, part of parotid
BRANCHES & STRUCTURES SUPPLIED
– Superior thyroid: thyroid and larynx
– Ascending pharyngeal: pharynx
– Lingual: sublingual gland, tongue, gingiva and oral mucosa
– Facial: skin and muscles of face, palatine tonsils, soft palate, pterygoid/mylohyoid/digastric muscles, submandibular gland
– Occipital: back of scalp, sternocleidomastoid, deep muscles in back and neck
– Posterior auricular: scalp and ear
– Maxillary:
1st part (posterior to lateral pterygoid muscle)
– deep auricular
– anterior tympanic
– middle meningeal
– inferior alveolar
– accessory meningeal
2nd part (within the lateral ptyergoid muscle)
– masseteric
– pterygoid
– deep temporal (anterior and posterior)
– buccinator
3rd part (anterior to lateral pterygoid muscle)
– sphenopalatine
– descending palatine (greater and lesser)
– infraorbital
– posterior superior alveolar
– middle superior alveolar
– pharyngeal
– anterior superior alveolar
– artery of pterygoid canal
– Superificial temporal: scalp
VARIANTS
– anomalous bifurcation of the common carotid artery – commonly cricoid cartilage (C5 level) or hyoid bone (C2 level)
– linguofacial trunk
– lingothyrofacial trunk
– lingothyroid trunk
Question 4 – Lymph nodes of the neck
Write short notes on the anatomy of the lymph nodes of the neck.
Marks are allocated under the following headings: overview and general classification, level based landmarks and drainage.
OVERVIEW
The lymphatic system drains tissue fluid, plasma proteins and other cellular debris back into bloodstream
GENERAL CLASSIFICATION & DRAINAGE
Superficial and deep
Occipital (1-3 nodes)
– located in the back of the head at the lateral border of the trapezius muscle
– drains occipital area of the scalp.
Posterior auricular (2 nodes)
– located posterior to the ear and lie on the insertion of the sternocleidomastoid muscle into the mastoid process.
– drain posterior neck, upper ear and the back of the external auditory meatus (the ear canal).
Pre-auricular (1-3 nodes)
– located anterior to the auricle of the ear
– drains superficial areas of the face and temporal region
Parotid
– located superficially to the parotid gland.
– drain nose, the nasal cavity, the external acoustic meatus, the tympanic cavity and the lateral borders of the orbit.
– lymph nodes deep to the parotid gland drain the nasal cavities and the nasopharynx.
Submental
– located superficially to the mylohoid muscle
– drain central lower lip, the floor of the mouth and the apex of the tongue.
Submandibular (3-6 nodes)
– located below the mandible in the submandibular triangle
– drain lymph from the cheeks, the lateral aspects of the nose, upper lip, lateral parts of the lower lip, gums and the anterior tongue.
– receive lymph from the submental and facial lymph nodes.
Facial
– maxillary/infraorbital, buccinator and supramandibular lymph nodes.
– drain the mucous membranes of the nose and cheek, eyelids and conjunctiva.
Superficial Cervical
– anterior nodes lie close to the anterior jugular vein
– drain superficial surfaces of the anterior neck
– posterior lateral nodes lie close to the external jugular vein
– drain collect lymph from superficial surfaces of the neck.
Deep Lymph Nodes
– receive all of the lymph from the head and neck, directly or indirectly via the superficial lymph nodes.
– organised into a vertical chain, located within close proximity to the internal jugular vein within the carotid sheath.
– The efferent vessels from the deep cervical lymph nodes converge to form the jugular lymphatic trunks.
– The nodes can be divided into superior and inferior deep cervical lymph nodes.
LEVEL BASED LANDMARKS
Level 1
– Ia (submental): anteromedial between anterior bellies of both digastrics
– Ib (submandibular): posterolateral to anterior belly of digastric
Level II
– upper internal jugular (deep cervical) chain
– level IIa: inseparable from or anterior to the posterior edge of the internal jugular vein; includes jugulodigastric nodal group
– level IIb: posterior to and separable by a fat plane from the internal jugular vein
Level III
– middle internal jugular (deep cervical) chain
Level IV: lower internal jugular (deep cervical) chain
Level V: posterior triangle
– level Va: superior half, superior to inferior border of the cricoid cartilage (posterior to levels II and III); includes spinal accessory nodes
– level Vb: inferior half, inferior to inferior border of the cricoid cartilage (posterior to level IV); includes lateral supraclavicular nodes
Level VI: central (anterior) compartment
– includes anterior jugular, pretracheal, paratracheal, prelaryngeal/precricoid (Delphian), and perithyroidal nodes
Question 5 – Axis (C2 vertebra)
Write short notes on the anatomy of the axis (C2 vertebra).
Marks are allocated under the following headings: overview, parts and connections, relations, blood supply, and variants.
OVERVIEW
The second cervical vertebra, atypical due to unique features. It is important in the rotation of the head, around the dens at the atlanto-axial joint.
PARTS AND CONNECTIONS
– dens: odontoid (tooth-like) process conical in shape, projects superiorly from body. Anterior articular facet articulates with the anterior arch of C1 (median atlanto-axial joint). Posteriorly facet articulates with transverse ligament of atlas. Connected to occipital bone via apical ligament (attached to apex) and alar ligament (below apex)
– body
– lateral masses: bears weight of skull
– transverse process with transverse foramen: transmits the vertebral artery bilaterally
– superior articular facet: articulate with inferior articular surface of C1 (atlas)
– inferior articular facet: articulates with superior articular surface of C3 (zygapophysial joint)
– pedicle: short and thick
– lamina: thick and rounded
– spinous process: bifid, large
– vertebral canal: circular
RELATIONS
– Superior: C1 vertebra, C2 nerve roots, spinal radicular vessels
– Inferior: C3 vertebra, C3 nerve roots, spinal radicular vessels
– Within spinal canal: dura, arachnoid, pia, cervical cord, nerve rootlets, spinal arteries and intervertebral venous plexus
– Anterior: anterior atlantoaxial membrane, anterior longitudinal ligament, Longus coli, longus capitis, danger space, prevertebral space, pharynx
– Posterior: posterior atalantoaxial membrane, posterior longitudinal liagemnt, splenius capitis, semispinaliscapitis, ligamentum nuchae on tips of spinous processes, suboccipital triangle (obliquus capitus superior, obliquus capitus inferior, rectus capital posterior major).
– Lateral: vertebral artery and vein (within transverse foramen of C1 – C7, C7 usually only contains vein), levator scapulae, sympathetic chain
BLOOD SUPPLY
– Nutrient vessels from ascending cervical artery branch of thyrocervical trunk
– Spinal branches of vertebral artery
VENOUS DRAINAGE
External vertebral venous plexus (anterior and posterior)
– anastomoses with the internal venous plexus via communicating veins
– drains vertically to vertebral veins, which courses posteriorr (on right)/ anterior (on left) to the subclavian artery to drain into brachiocephalic artery
– drains deep cervical vein
Interior vertebral plexi (anterior and posterior)
– both are located in epidural space
– anastomoses with external vertebral plexi
– anterior drains basivertebral vein and intervertebral vein
VARIANTS
– Odontoid hypoplasia/aplasia (rare)
– Bifid spinous process
– Os odontoideum
– Persistent os terminale
– Bicornuate odontoid
– Basilar invagination (upward displacement of tip above foramen magnum)
– Os avis
– Absent dens
– Anteverted dens
Question 6 – Arterial Supply of Spinal Cord
Write short notes on the anatomy of the arterial supply of the spinal cord.
Marks are allocated under the following headings: overview, origin, course and termination, branches or tributaries, vascular territories supplied, and variants.
OVERVIEW
Formed by different vessels with extensive collateral supply and drainage
ORIGIN
– Predominantly supplied by three longitudinal arteries: single anterior spinal artery, paired posterior spinal artery.
– Reinforced by radicular or segmental medullary arteries which enter the vertebral canal via the intervertebral foramina and divide into anterior and posterior branches with variable anastomoses with the spinal arteries.
Anterior spinal artery formed by branches of the vertebral artery before they unite to form the basilary artery
– Supplies anterior two-thirds of the spinal cord
Paired posterior spinal artery arise mostly from PICA (sometimes vertebral artery)
– Supplies the posterior one-third of the spinal cord
COURSE & TERMINATION
– Anterior spinal artery arises from two small branches, arising bilaterally near the termination of the vertebral artery. The branches descends along the anterior aspect of the medulla oblongata, uniting at the foramen magnum to form a single trunk. The anterior spinal artery travels in the anterior median fissure, terminating as a slender twig on the filum terminale (S1 – S2)
– Posterior spinal artery descends posterior to the medulla, passing in front of the posterior roots of the spinal nerves. It is reinforced by segmental and radicular branches. It terminates around the point of the cauda equina
BRANCHES
The anterior and posterior spinal arteries are connected by pial anastomoses termed arterial vasocorona.
Radicular and segmental arteries contributing to supply include:
PICA, vertebral arteries, ascending cervical arteries, deep cervical arteries, posterior intercostal arteries, lumbar arteries, lateral sacral arteries. The dominant segmental artery of the lumbosacral cord segments is the artery of Adamkiewics, arising on the left sides between T9 and L2.
VARIANTS
– Variable origin of artery of Adamkiewicz: arises on the right side, arising from lumbar arteries at level of L1 – L2, intercostal arteries T5 – T8
– Duplicate anterior spinal arteries
– Single-origin anterior spinal artery from unilateral vertebral artery
– Single or duplicate anterior spinal arteries arising off vascular arcade between vertebral arteries
– Posterior spinal arteries arising from vertebral artery (25%) or PICA (75%)
Question 7 – Thoracic Diaphragm
Write short notes on the anatomy of the thoracic diaphragm.
Marks are allocated under the following headings: overview, attachments, openings, relations,
neurovascular supply, actions and variants.
OVERVIEW
Broad musculotendinous sheet shaped as upward-curved double domes attached at its circumference to the internal wall of the torso, at the inferior thoracic aperture. It separates the thoracic and abdominal cavities, and alters the volume of the thoracic cavity in inspiration and expiration by contracting and relaxing.
ATTACHMENTS
-Peripherally: lumbar vertebrae, costal cartilage of ribs 7 – 10 (attaches to ribs 11 – 12 directly), xiphoid process of the sternum
– lateral arcuate ligament from tip of rib 12 to transverse process of L1
– medial arcuate ligament from transverse process of L1 to anterior surface of vertebral bodies as left and right crura (tendinous attachment that blends with anterior longitudinal ligament)
– Right crus – vertebral bodies L1-3
– Left crus – vertebral bodies L1-2
– medial fibres of left and right crura meet in the midline to form median arcuate ligament
OPENINGS
T8 – Caval hiatus through the central tendon: transmits the inferior vena cava and right phrenic nerve
T10 – Oesophageal hiatus left of the midline: transmits the oseophagus, anterior and posterior vagal trunks, oesophageal branch of left gastric artery and vein
T12 – Aortic hiatus midline between the crura: transmits the abdominal aorta, thoracic duct and azygos vein
RELATIONS
NEUROVASCULAR SUPPLY
Blood supply:
– superior phrenic arteries – branch of thoracic aorta
– inferior phrenic artery – paired, 1st branch of abdominal aorta at level of T12
– musculophrenic artery and pericardiacophrenic – paired, branches of internal thoracic artery (from subclavian artery)
– intercostal and subcostal arteries
Innervation:
Phrenic nerve – formed within the cervical plexus
– cervical roots C3, C4, C5
– descends from neck, penetrating the diaphragm and supplying it from the abdominal surface
ACTIONS
Contraction – occurs during inspiration, increase thoracic volume
Relaxation – occurs during expiration, decreases thoracic volume
VARIANTS
– Eventration of the diaphragm
– congenital diaphragmatic hernia (Bochdalek and Morgagni types)
– muscle slips
– scalloped or serrated appearance: due to individual muscle slips
– dromedary diaphragm (hump)
– accessory diaphragm
– connection with transversus abdominis muscle
– sternal portion of the diaphragm may be absent
– extension of muscle fibres onto the quadratus lumborum muscle
– hemiazygos vein may run through the aortic hiatus
– azygos vein may run through the right crus
Question 8 – Brachiocephalic Veins
Write short notes on the anatomy of the brachiocephalic veins.
Marks are allocated under the following headings: overview, course, relations and tributaries, and
variants.
OVERVIEW
Paired veins of the superior mediastinum that drains the upper limbs, head and neck. It is formed by the confluence of the internal jugular and subclavian veins (termed the venous angle), posterior to the sternoclavicular joint.
COURSE
The left and right brachiocephalic vein course toward the midline and unite at the inferior border of the 1st right costal cartilage to form the superior vena cava, which eventually empties into the right atrium
The left brachiocephalic vein courses obliquely downwards and medially. The right brachiocephalic vein has a shorter more vertical course.
RELATIONS
Posteriorly: subclavian artery, (left) common carotid, (right) brachiocephalic trunk), left internal thoracic artery, left vagus, left phrenic nerve.
Anteriorly: thymus gland, sternohyoid and sternothyroid muscles.
Inferiorly: aortic arch (to left brachiocephalic vein)
TRIBUTARIES
Right brachiocephalic vein
– right vertebral vein
– inferior thyroid vein
– right internal thoracic vein
– right superior intercostal vein
Left brachiocephalic vein
– left vertebral vein
– inferior thyroid vein
– left internal thoracic vein
– supreme intercostal vein
– thymic veins
– pericardiophrenic veins
VARIANTS
– retroaortic left brachiocephalic vein
Question 9 – Head of the Pancreas
Write short notes on the anatomy of the head of the pancreas.
Marks are allocated under the following headings: overview, position and relations, ducts, vascular supply and lymphatic drainage, development and variants.
OVERVIEW
The pancreas is an oblong-shaped, elongated organ with exocrine (digestive) and endocrine (hormonal) functions.
POSITION
The pancreas is located deep within the epigastrium at the level of the transpyloric plane (level of L1)
The head is located in the retroperitoneal cavity, to the right to the midline and the tail (intraperitoneal cavity) extends to the left hypochondrium.
RELATIONS
Anterior: transverse colon, stomach
Posterior: Splenic vein, SMA and SMV, abdominal aorta, IVC, left renal artery and vein, origin of portal vein behind neck, portal triad
Superior: epiploic foramen
Medially: neck of the pancreas
Inferiorly: uncinate process
DUCTS
– Main pancreatic duct (of Wirsung): joins the pancreas to the common bile duct, supplies pancreatic juice
– Accessory pancreatic duct (of Santorini): drains into the main pancreatic
– Common bile duct: formed by the union of the common hepatic duct and cystic duct. It is later joined by the pancreatic duct to form the ampulla of Vater.
VASCULAR SUPPLY
– Gastroduodenal artery (branch of common hepatic artery)
– Anterior and posterior branch of superior pancreaticoduodenal artery (branch of gastroduodenal)
– Inferior pancreaticoduodenal artery (branch of superior mesenteric artery)
– Greater pancreatic artery (branch of splenic)
– Dorsal pancreatic artery (branch of splenic)
– Inferior pancreatic artery (branch of splenic artery)
LYMPHATIC DRAINAGE
– Lymphatic vessels follow arterial supply
– Empty into pancreaticosplenal nodes and pyloric nodes, which in turn drain into the superior mesenteric and coeliac lymph nodes
DEVELOPMENT
– forms from a dorsal and ventral pancreatic bud that arise from the duodenal part of the foregut
– the dorsal bud forms the neck body and tail
– the ventral bud forms the head and uncinate process
VARIANTS
Pancreas
Pancreas divisum (Most common variant)
Annular pancreas
Meandering main pancreatic duct
Ansa pancreatica (rare)
Anomalous pancreaticobiliary junction
Pancreatic Duct
Double accessory pancreatic duct (Santorini)
Double main pancreatic duct (Wirsung)
Anastomosis between ducts
Crossing or double-crossing of ducts
No communication between ducts
Toruosity of ducts
Absence of accessory pancreatic duct
Question 10 – Levator Ani
Write short notes on the anatomy of the levator ani.
Marks are allocated under the following headings: overview (with its parts), attachments, actions, apertures (with their contents), and neurovascular supply.
OVERVIEW
The levator ani is a broad, thin muscle group situated on either side of the pelvis. It is formed by three paired muscles; pubococcygeus, iliococcygeus and puborectalis. It is the largest component of the pelvic floor.
ATTACHMENTS & ACTIONS
Puborectalis
– Originates from both sides of the body of the pubis, and passes posteriorly to encircle the rectum and form a U-shaped sling around the anorectal junction
– Tonic contraction bends the canal anteriorly and forms a 90-degree anorectal angle at the anorectal junction to maintain faecal continence
Pubococcygeus
Main component of levator ani
– Originates from the body of pubis, lateral to the origin of the puborectalis muscle
– The fibres course around margin of urogenital hiatus posteriorly to attach to the tendinous centre of the perineum, anococcygeal body and coccyx.
Iliococcygeus
– Originates from the inner surface of the ischial spine and along tendinous arch (a thickened band of fascia covering the inner aspect of obturator internus muscle)
– Posteriorly attaches to iliococcygeus of the opposite side in the midline to form anococcygeal raphe extending from anal aperture to coccyx.
APERTURES
Urogenital hiatus – U-shaped defect anteriorly in levator ani, allowing passage of urethra (and vagina in females)
Rectal hiatus – centrally positioned defect allowing passage of anal canal
NEUROVASCULAR SUPPLY
Blood supply
– Inferior gluteal artery
– Inferior vesical
– Pudendal
Innervation
– Innervated by nerve to levator ani, branches from ventral ramus of S4
– Also contributions from inferior rectal branch of pudendal nerve (S2-4)
Question 11 – Lumbar Plexus
Write short notes on the anatomy of the lumbar plexus.
Marks are allocated under the following headings: overview, origin, branches, and course and relations of branches and variations.
OVERVIEW
A network of nerves supplying the skin and musculature of the lower limb. Located in the lumbar region, within the substance of psoas major muscle, anterior to transverse process of lumbar vertebrae
ORIGIN
Anterior rami of spinal nerves L1 – L4 (with contributions from T12) form the lumbar plexus. At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina, then divide into anterior and posterior fibres.
BRANCHES, COURSE & RELATIONS
Iliohypogastric nerve
– Spinal roots: T12 – L1
– Runs to the iliac crest, across the quadratus lumborum muscle of the posterior abdominal wall. It then perforates the transversus abdominis and divides into its terminal branches.
– Motor: internal oblique and transversus abdominis
– Sensory: posterolateral gluteal skin
Ilioinguinal nerve
– Spinal roots: L1
– Follows the same anatomical course as the larger iliohypogastric nerve. After innervating the muscles of the anterior abdominal wall, it passes through the superficial inguinal ring to innervate the skin of the genitalia and middle thigh.
– Motor: internal oblique and transversus abdominis
– Sensory: skin on the superior anteromedial thigh. In males, skin over the root of the penis and anterior scrotum. In females, skin over mons pubis and labia majora.
Genital branch of genitofemoral nerve
– Spinal roots: L1 – L2
– After leaving the psoas major muscle, the genitofemoral nerve quickly divides into a genital branch, and a femoral branch.
– Motor: The genital branch innervates the cremasteric muscle.
– Sensory: skin of the anterior scrotum (in males) or the skin over mons pubis and labia majora (in females). The femoral branch innervates the skin on the upper anterior thigh.
Lateral Cutaneous nerve of the thigh
– Spinal roots L2 – L3
– Enters the thigh at the lateral aspect of the inguinal ligament, where it provides cutaneous innervation to the skin there
– Motor: None
– Sensory: Anterior and lateral aspect of thigh down to knee
Obturator Nerve
– Spinal roots: L2 – L4
– Motor: Muscles of the medial thigh – the obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis.
Sensory: Skin over the medial thigh.
Femoral Nerve (largest branch)
– Spinal roots: L2 – L4
– Travels inferiorly through the psoas major muscle, branching to the iliacus and pectineus muscles prior to entering the thigh. Then passes underneath the inguinal ligament to enter the femoral triangle lateral to the femoral artery and vein. The nerve is not enclosed within the femoral sheath. Approximately 4cm below the inguinal ligament, the femoral nerve divides into anterior and posterior divisions
– Anterior: Anterior cutaneous branches, branch to sartorius, branch to pectineus
– Posterior: Saphenous nerve, branches to quadriceps femoris
– Terminal branch: saphenous nerve. Travels through the adductor canal (accompanied by the femoral artery and vein) and exits prior to the adductor hiatus. The saphenous nerve innervates the medial aspect of the leg and the foot.
VARIATIONS
– absent iliohypogastric nerve (~20%)
– early branching (within psoas muscle) of the genitofemoral nerve (~20%)
– accessory obturator nerve (~10%)
– lateral femoral cutaneous nerve arising as a branch of the femoral nerve
Question 12 – Acromioclavicular and Sternoclavicular Joints
Write short notes on the anatomy of the acromioclavicular and sternoclavicular joints.
Marks are allocated under the following headings: articulations, type of joint and internal structures, ligaments, and movements.
ACROMIOCLAVICULAR JOINT
TYPE OF JOINT
– Plane synovial joint (lined by hyaline cartilage, enclosed by synovial membrane lined fibrous capsule)
ARTICULATIONS
– Medial tip of acromion of scapula
– Lateral tip of clavicle
INTERNAL STRUCTURES
LIGAMENTS
– Acromioclavicular ligament – superior surfaces of acromion and clavicle
– Coracoclavicular ligament, accessory ligament, between coracoid process of scapula and clavicle, consists of:
– Conoid ligament – conoid tubercle to coracoid process
– Trapezoid ligament – trapezoid line to coracoid process
STERNOCLAVICULAR JOINT
TYPE OF JOINT
– Synovial saddle joint (lined by hyaline cartilage, enclosed by synovial membrane lined fibrous capsule)
ARTICULATIONS
– Medial end of clavicle – convex
– Clavicular notch of manubrium of sternum – concave
– Small part of first costal cartilage
INTERNAL STRUCTURES
LIGAMENTS
– Interclavicular ligament – between medial ends of clavicles, over the suprasternal notch of manubrium
– Anterior and posterior sternoclavicular ligaments
– Costoclavicular ligament – lateral to joint, links inferior surface of proximal clavicle and first costal cartilage
Question 13 – Axilla
Write short notes on the anatomy of the axilla.
Marks are allocated under the following headings: overview, boundaries, contents, and axillary lymph node groups.
OVERVIEW
Passage way for neurovascular and muscular structures entering and exiting upper limb
BOUNDARIES
Anterior wall
– Pectoralis major and pectoralis minor
– Clavipectoral fascia
– Subclavius muscle
Posterior wall
– Latissimus dorsi
– Subscapularis
– Teres major
– Proximal part of long head of triceps
Medial wall
– Ribs and intercostal spaces
– Upper part of serratus anterior
Lateral wall
– Floor of bicipital (interbercular) groove of humerus
– Tendon of long head of biceps
Tendon of latissimusdorsi
Apex (axillary inlet)
– Posterior border of clavicle
– Superior border of scapula
– Lateral border of first rib
Lower limit of axilla is the level of the 4th rib.
CONTENTS
Axillary sheath, extension of prevertebral fascia
Axillary artery
– Has three parts divided in relation to the pectoralis minor:
– First part: medial to pectoralis minor, branches: superior thoracic artery
– Second part: posterior to pectoralis minor, branches: thoracoacromial, lateral thoracic
– Third part: lateral to the pectoralis minor, branches: anterior and posterior circumflex humeral artery, subscapular artery
– Only the medial and posterior parts pass through the axilla
Axillary vein
Inferior trunk, and all divisions of brachial plexus
Long thoracic nerve
Lymphatics
Muscles:
– Proximal short head of biceps brachii
– Proximal coracobrachialis
Arteries:
o Axillary artery and branches:
First part: Superior thoracic a.
Second part: Thoracoacromial a., lateral thoracic a.
Third part: Anterior and posterior circumflex humeral a., subscapular a.
• Veins:
o Axillary vein and tributaries:
Thoracoacromial v
Subscapular v.
Anterior and posterior circumflex humeral v.
Brachial v.
Profundabrachii v.
• Brachial plexus, divisions, cords, nerves
• Lymphatics
o Axillary lymph nodes (anterior, posterior, lateral, central and apical)
o Efferent lymph trunks
• Axillary process of mammary gland
LYMPH NODE GROUPS
-Pectoral (anterior) – located in the medial wall of the axilla, receive lymph primarily from the anterior thoracic wall and breast.
-Subscapular (posterior) – located along the posterior axillary fold and subscapular blood vessels. They receive lymph from the posterior thoracic wall and scapular region.
– Humeral (lateral) – located in the lateral wall of the axilla, posterior to the axillary vein. They receive most of the lymph drained from the upper limb.
– Central – located near the base of the axilla (deep to pectoralis minor, close to the 2nd part of the axillary artery), receive lymph via efferent vessels from the pectoral, subscapular and humeral axillary lymph node groups.
– Apical – Located in the apex of the axilla, close to the axillary vein and 1st part of the axillary artery, receive lymph from efferent vessels of the central axillary lymph nodes, therefore from all axillary lymph node groups.
Question 14 – Ankle
Write short notes on the anatomy of the ankle (talocrural) joint.
Marks are allocated under the following headings: overview (type and articular surface), capsule/ligaments, synovium, muscles/mobility/stability, and relations/neurovascular supply.
OVERVIEW
A synovial hinge joint located in the lower limb, formed by the tibia, fibula and talus. It permits dorsiflexion and plantar flexion of the foot.
The tibia and fibula are bound by tibiofibular ligaments and form a bracket-shaped socket known as a mortise, which is covered in hyaline cartilage. The body of talus fits within the mortise joint.
CAPSULE/LIGAMENTS
Medial collateral (deltoid) ligament
– 4 part triangular shaped ligament attached above from medial malleolus and fans out with a broad base attached to medial surfaces of navicular and talus
– Tibionavicular part: attaches to tuberosity of navicular and calcaneonavicular (spring ligament)
– Tibiocalcaneal part (central): attaches to sustentaculum tali of calcaneus
– Posterior tibiotalar part: attaches to medial side and medial tubercle of talus
– Anterior tibiotalar part: attaches deep to tibionavicular part of medial ligament
Lateral ligament
– 3 separate ligaments
– Anterior talofibular ligament: lateral malleolus to lateral surface of talus
– Posterior talofibular ligament: malleolar fossa of lateral malleolus to posterior process of talus
– Calcaneofibular: lateral malleolus to posterior tubercle of calcaneus
SYNOVIUM
– Synovial membrane attaches to margins of articular surfaces
– Fibrous membrane covers synovial membrane attached to adjacent bone
MUSCLES
Plantarflexion – muscles in the posterior compartment of the leg (gastrocnemius, soleus, plantaris and posterior tibialis).
Dorsiflexion – muscles in the anterior compartment of the leg (tibialis anterior, extensor hallucis longus and extensor digitorum longus).
RELATIONS
Posteromedial: tarsal tunnel posterior to medial malleolus (tendons of tibialis posterior, flexor digitorum longus, flexor hallucis longus, posterior tibial artery, tibial nerve), flexor retinaculum
Anterior: tendons of extensor digitorum longus, extensor hallucis longus, tibialis anterior
Posterior: achilles tendon
Lateral: tendons of fibularis longus and brevis, fibular retinuluca
NEUROVASCULAR SUPPLY
Nerve:
– Tibial nerve (branch of sciatic nerve)
– Deep fibular
Arterialy supply:
– Anterior and posterior tibial arteries
– Fibular artery
Question 15 – Tibial Nerve
Write short notes on the anatomy of the tibial nerve.
Marks are allocated under the following headings: origin, course and relations, termination, and branches and supply
ORIGIN
– Branch of sciatic nerve in posterior compartment of thigh, at apex of popliteal fossa where sciatic nerve bifurcates into tibial nerve and common fibular nerve
– Nerve roots: L4-S3
COURSE & RELATIONS
– Descends through popliteal fossa, lateral to popliteal vessels and medial to common fibular nerve. Between semitendinosus and semimembranosus (medial) and biceps femoris (lateral).
– Enters posterior compartment of leg between medial and lateral heads of gastrocnemius, descends vertically on surface of popliteus, crossing it’s oblique fibres
– Enters deep compartment through the tendinous arch of soleus muscle, between heads of soleus
– Descends vertically on surface of tibialis posterior, associated with posterior tibial vessels, courses medially
– Enters foot through tarsal tunnel, behind medial malleolus, between tendons of flexor digitorum longus and flexor hallucis longus
TERMINATION
– Bifurcates with posterior tibial artery, between medial malleolus and heel into medial and lateral plantar nerves
BRANCHES & SUPPLY
Leg
– Branches to posterior compartment of leg (gastrocnemius, soleus, plantaris, popliteus, flexor hallucis longus, flexor digitorum longus and tibialis posterior)
Sural nerve
– Originates in popliteal fossa
– Descends superficial to gastrocnemius
– Penetrates deep fascia mid leg
– Joined by communicating branch from common fibular nerve
– Passes down around lateral malleolus to foot
– Supplies posterolateral surface of leg and lateral side of foot and little toe
Middle calcaneal nerve – distal branch, supplies medial and inferior surface of heel
Foot:
Medial plantar nerve:
– Passes anteriorly, deep to abductor hallucis brevis
– Gives sensory digital branch to medial side of great toe
– Gives 3 common plantar digital nerves on plantar surface of flexor digitorum brevis supplying adjacent surfaces of the medial 3.5 toes
– Supplies abductor hallucis, flexor hallucis brevis, flexor digitorum brevis and first lumbricals
Lateral plantar nerve:
– Passes anterolaterally across the sole between flexor digitorum brevis (superficially) and quadratus plantae (deep), supplying both
– Gives superficial branch to skin and intrinsic muscle of lateral 1.5 toes
– Deep branch accompanies lateral plantar artery deep to long flexor tendons and adductor hallucis muscle and supplies remaining intrinsic muscles of the foot (except extensor digitorum brevis and first dorsal interossei and the four above)