In the development of vertebrates, the pharyngeal arches are primordia for a multitude of structures. In the human embryo (where the vasculature of the pharyngeal arches is also known as the aortic arches), they develop during the fourth week as a series of mesodermal outpouchings on both sides of the developing pharynx. In fish, the branchial arches support the gills.
- Between the ectoderm Branchial clefts and endoderm pharyngeal pouches
- They eventually develop into the face, jaw, pharynx
- 6 pairs
- Nerve supply from cranial nerve, splanchnic mesoderm – so structurally same as skeletal muscle(voluntary) but usually covered by mucosa or near a mucocutaneous junction. Involved in superficial reflexes and glandular secretion
Tension Lines in Skin
- Relaxed skin tension lines(Kraissl) – cuts parallel cause less scarring. Langer is cleavage lines in cadaver.
Types of cartilage
- Hyaline – most common, weakest, has perichondrium – ribs, nose, larynx, trachea. Is a precursor of bone.
- Fibro- strongest, no perichondrium – intervertebral discs, joint capsules, ligaments.
- Elastic – maintains shape, has perichondrium- external ear, epiglottis and larynx.
Muscle form types (unipennate, bipennate etc.) and examples.
- Form is determined by arrangement of muscle fibres – parallel, unipennate(tib posterior), bipennate(rectus femoris), multipennate(deltoid). Parallel ones shorten more.
Types of joints (and examples).
- Fibrous – solid and no joint cavity- bones bridged by fibres eg cranial sutures, syndesmosis, gomphosis
- Cartilagenous – solid and No joint cavity. primary cartilagenous are two bones bridged by hyaline cartilage(epiphyseal plates of long bones), secondary cartilagenous are always in midline – bone-hyaline cartilage- fibrocartilage -H-B eg intervertebral discs, pubic symphysis, manubriosternal angle. – allow little bit of movement.
- Synovial – joint cavity lined by synovial membrane, articular surfaces covered in hyaline cartilage – eg knee, elbow made for movement.
- Plane (facet joint)
- Uni axial, bi axial and multi axial
- Simple/compound/complex(joint cavity subdivided into multiple compartments- sternoclavicular joint)
- The nerve supplying a muscle that extends across or acts at a joint also innervates that joint
Stability of joints
- Bony – congruity of articular surfaces
- Ligamentous – fibrous capsule(intrinsic), collaterals, cruciates, accessory(AC joint)
- Muscular – popliteus, rotator cuff – more important in more mobile joints.
- Other – fibrocatilage, menisci, labrum
- Maximal stability is at the close packed position
Dermatomes / axial lines.
- Overlap for adjacent dermatomes that are consecutive have significant overlap – pain and temp more than touch
- So adjacent dermatomes that aren’t conseq don’t overlap and cutaneous nerve branches don’t cross axial lines.
- Hip flexion: L2,3
- Hip extension: L4,5, S1 (4 muscles, like triceps)
- Hip abduction: L4, 5, S1 (absolutely same as ext)
- Hip adduction: L2,3,4 (add one)
- Knee flexion: L5, S1 (turn point)
- Knee extension: Kick L2,3,4
- Ankle dorsiflexion: Toe high L4,5
- Ankle plantar flexion: S1,2 tippy toe
- Inversion: toe inside L4,5
- Eversion: weird one L5, S1
- Great toe ext: toe high plus one L4,5,S1
- Shoulder abduction: C4,5,6 chicken tonight
- Elbow flexion: C5,6 pick up sticks
- Elbow extension: C7, 8 put em straight
- Wrist flexion: 6,7,8 get on your bike
- Wrist extension: short triceps 6,7
- Finger abduction: C8, T1 muscles of hand
- Finger adduction: T1
- Thumb abduction: T1
- Knee: knee ext: L2,3,4
- Ankle: plantar flexion: S1,2
- Plantar: 5 tippy toes: L5, S1,2
- Triceps: 7,8
- Biceps: 5,6
- Supinator: 5,6
- Finger: 8
Organisation of autonomic nervous system.
- Central/peripheral. Somatic/visceral. Sympathetic/parasympathetic/enteric
- Thoracolumbar outflow T1- L2 – control smooth muscle tone of arterioles. Sympathetic trunk and gnaglion where visceral efferents synapse.
- Dilate pupils and bronchioles, adrenaline, ejaculation
- Craniosacral outflow – CN III, VII, IX, X and S2-4
- Bradycardia, salivation, lacrimation, accomodation, miosis, erection
Organisation of a spinal nerve.
- 31 pairs of spinal nerves.
- Posterior nerve roots are purely sensory and anterior are purely motor. Dorsal root ganglion houses the nerve body of the afferent.
- Spinal nerve is once the ant and post nerve roots join –> after spinal nerve you can split to ant and posterior rami.
- Artery – endothelium, intima, media, adventitia
- Elastic then muscular arteries. Arterioles have the largest wall thickness to lumen ratio. Greatest BP drop occurs over arterioles.
- Capillaries – single layer endothelium with basement membrane.
- Accompany veins, usually have a blind start. Are in the dermis. Drain to atleast one LN before draining into vein
- Ant thorax, skin of glans penis and clitoris drain direct to deep LN
- Watersheds- vertical and horizontal.
- R lymphatic duct and Thoracic duct – origin of R and L brachicephalic veins.
- Are separators eg investing fascia, retinaculum, septa. Made of collagen fibres. Deep is dense, superficial is loose.
- Deep – nonelastic and gives attachment site for muscles. Eg palmar and plantar aponeurosis.
- No deep fascia in face and other areas that expand a lot.
- Mobile fascial planes are two sheets parallel to each other- give path of least resistance. Vessels and liquid may course along it. Vessels do not pierce it cos it can get kinked with movement. Vessels/nerves pierce fixed fascia.