These pages have been left in this location as a service to the numerous websites around the world which link to this content. The original authors are no longer at the University of Leeds, and the former Centre for Human Biology became the School of Biomedical Sciences which is now part of the Faculty of Biological Sciences.
There follows the text of the overhead transparencies used by Dr Johnson for introductory lectures in anatomy. These cover terminology, bones, joints, segmentation and muscles.
THE ANATOMICAL POSITION
Standing erect Face and eyes forwards Hands at sides, palms forwards Heels together, great toes adjacent
PLANES OF THE BODY
Three, mutually at right angles
Median or sagittal - sagitta, an arrow Divides the body into equal right and left halves Parasagittal divides the body into unequal right and left parts
Coronal (corona, a crown): any vertical plane at right angles to the sagittal: divides the body into anterior and posterior parts
Horizontal (horizon, the horizon): any plane at right angles to the other two: divides the body into superior and inferior parts
Oblique: any other plane
In order to define the planes we needed three pairs of other terms:
1. medial - closer to the midline lateral - father from the midline
2. anterior - nearer the front surface of the body
3. superior - nearer the crown of the head inferior - nearer the soles of the feet
TERMS IN ZOOLOGY AND EMBRYOLOGY
The human system is inappropriate for other mammals where zoological terms are used. These are also used in embryology and comparative anatomy.
1. ventral = anterior
SPECIAL TERMS FOR SPECIAL BITS
In the limbs we need some special terms. These need care: look at the limbs in the anatomical position.
1. proximal - nearer the trunk, the soggy
2. preaxial - the lateral border (thumb or big toe side)
3. flexor - anterior of upper limb, posterior of lower limb
TERMS OF MOVEMENT
1. to flex - to bend or make an angle to extend - to straighten
2. to abduct - to draw away from the median plane
A combination of abduction, adduction, flexion and extension is called circumduction
3. to protrude or protract - move forwards to (retrude) or retract - move backwards
4. to pronate - turn the hand so the palm faces backwards to supinate - turn the hand so the palm faces forwards
5. to medially rotate - to turn a limb around its long axis - so the palm faces inwards to laterally rotate - to turn a limb around its long axis the other way
ODDS AND PIECES OF TURF
1. inside, interior, internal
2. invaginations - bulges into
3. superficial - near the surface
contralateral - other side
Greek to cut up = anatomy
SUBDIVISIONS OF ANATOMY
Embryology - development from egg to adult
Cytology - about cells Histology - about groups of cells, tissues and organs
Neuroanatomy - about nerve cells, and nervous tissues
Gross anatomy - anything you can see and handle without a microscope.
METHODS OF STUDY
Bone vs Bones
Bone - a connective tissue impregnated with minerals
Bones - pieces of the skeleton
That bones are dead
If broken they hurt, bleed and bruise
They metabolise at a fairly rapid rate: turnover inorganic matrix and collagen.
High: in standing still the weight on the hip is about 3x bodyweight
due to muscular pull.
Strength is high due to:-
the material - organic and inorganic extracellular matrix
and to the structure.
Structure of bones
Outer casing of cortical bone acts like a bicycle frame.
Inner trabecular bone is arranged along lines of force. Calcified fibres run out into tendons.
Determined by many factors:
Growth involves remodelling:
Origin of bone
Bone is either:-
preformed in cartilage - replacement or endochondral
Centres of ossification
Destruction of cartilage to make replacement bone
Why two types? History lesson
Classification of bones
Purely for our entertainment - not functional
Long bones:- epiphysis, diaphysis, plywood
Sesamoid bones - tendons turning corners
Surface markings on bones
Joints occur where 2 bones meet
two are called synarthroses (sing. synarthrosis) and have no cavity
TYPES OF JOINT
Synarthrosis bone - solid connective tissue - bone
1. Fibrous connective tissue
sutures bone -
collagenous sutural ligament - bone
synchondrosis bone - hyaline cartilage
rigid bony union
Diarthrosis bone - cavitated connective tissue - bone
Synovial joints bone - articular cartilage - fluid in cavity - articular cartilage - bone
Sutures - in skull
primary synchondroses - named in skull (and unnamed elsewhere)
SYNOVIAL JOINT COMPONENTS
Bone attached to articular cartilage.
Articular cartilage has:
Articular cartilage on each bone is separated by synovial fluid
Synovial fluid - dialysate of plasma secreted by
synovial membrane (specialised connective tissue)
Leakage prevented by fibrous capsule which forms a cuff
INCLUSIONS IN JOINTS
Non-articular bony surface
articular disc or meniscus
labra or lips - cartilage around the edge of an articular margin which may deepen a concavity and add stability
CLASSIFICATION OF SYNOVIAL JOINTS
Two articular surfaces - simple.
2. Degrees of freedom
Moves in one plane (elbow) uniaxial
SHAPES OF JOINT SURFACES
Classification by function
Movements at two bone ends are
made up of:
THE FIT OF JOINTS
Surfaces are spheroids, egg shaped
Because of this there will be a better fit at some positions of the joint than others
range of movement
loose fitting surfaces can spin, roll and slide
LIMITATION OF JOINT MOVEMENT
by using up articular surface
by adjacent soft tissues
by pain and stretch receptors in ligaments and muscles Hilton's law says that joints and muscles share a nerve supply
muscle paralysis affects joints spastic paralysis - movement restricted other paralyses - joints become flails
What is it?
Serial repetition of similar structures along body axis.
Who needs it?
Pro-vertebrates and Vertebrates
What causes segmentation?
Tissues close to the notochord segment.
Mainly mesoderm (middle stuff)
which fills the gap between
The mesoderm nearest notochord forms somites.
Other parts (kidneys, genitalia, blood supply) get involved either because they are near the notochord too, or secondarily
Somites - segmental paired blocks of mesoderm, each side of the notochord
Break up immediately into sclerotome (hard slice) and dermomyotome (skin/muscle slice)
Each dermomyotome splits again into dermatome and myotome
Sclerotome forms axial skeleton - vertebral column
Myotome forms axial muscles (back, rib, body wall, limb muscles, voluntary muscles of genitals, anus) and skin of trunk
Mesoderm more lateral (so further from the notochord) forms unsegmented muscle - smooth muscle around gut, blood vessels etc.
Segmented axial muscles originally moved the vertebrae from side to side (as in fish tail)
To do this they need to be out of step
This is achieved by making a vertebra from: The inferior half of one sclerotome plus the superior half of the one behind
1. Muscles to attach between vertebrae
2. Spinal cord (which is inside vertebrae) to run nerve roots between vertebrae to myotomes and from dermatomes
3. Notochord obliterated within vertebrae but survives between vertebrae as intervertebral disc.
Because of this vertebrae (named and numbered according to where they are i.e. C6, T4, L2, S1) lie immediately below nerve with the same number.
NERVOUS SYSTEM AND SEGMENTATION
Nerve tube (neural tube, brain + spinal cord) is affected by the somites.
Primitively nerves to muscles derived from the myotome are a. segmental - between vertebrae b. ventral in the cord
When dermomyotomes split sensory nerves from skin tend to be dorsal.
Dorsal and ventral roots unite as mixed spinal nerves.
Dermatomes of the skin form a series of bands around the embryo, one to each segment.
Segmental muscles also tend to form groups with common nerve supply
What about muscle that didn't segment but formed smooth muscle of the viscera?
New stuff. Ancestral forms had gut cilia, not muscles. Later forms had a system like this:
The autonomic nervous system:-
To genitalia, heart, glands etc.: - same thing but between the head and tail sections.
Originally only one part received nerves from both sets - the heart. Stimulation of both systems makes the heart beat faster in the Lamprey.
SITUATION IN MAN
Anatomically as already described: Parasympathetic (Gk alongside the sympathetic) outflow in head and tail. Sympathetic outflow between the two.
Functionally now different: most areas (except the limbs) have both sympathetic and parasympathetic supplies.
ACTION OF SYMPATHETIC AND PARASYMPATHETIC
Sympathetic (originally to heart, glands, genitalia) perks thing up - fear and anger, dry mouth, cramped gut, rapid heartbeat, pallor, sweaty palms, goosepimples.
Parasympathetic (originally to the gut, associated with peace, tranquillity, digestion) slows the heart, increases salivation, peristalsis, secretion of stomach juices etc.
Achieved by 2 different neurotransmitters:- sympathetic - norepinephrine parasympathetic - acetylcholene
The head is different because:
a. It is fairly recent (vertebrates, Amphioxus -, lamprey +)
b. The notochord doesn't go that far forward
c. Only a few somites in the tongue and eye muscles
d. Cranial nerves represent dorsal (sensory) and ventral (motor) roots which do not unite
group III, IV, VI, IX
n.b. I and II are both oddballs, associated with nose and eyes.
Types of muscle: Smooth Skeletal and cardiac - both striated
Smooth not under voluntary control
Striated (cardiac) not under voluntary control
Striated (skeletal) under voluntary control
around a viscus (pl. viscera) in so called circular and longitudinal
layers (gut) forming a sphincter to close off a tube (anus)
specialised: only in heart walls histologically distinct
Striated or skeletal:
usually attached to bone
Name from musculus, little mouse
Attachment to bone
Usually attached to skeleton at two bony points (one at each end) which are brought together by muscular contraction
1. tendon. Cords or strips of
collagen fibres (white) - flexible, resists stretch. Integral part of
muscle. Mainly parallel bundles, visible to naked eye
May be circular in cross section, oval or flattened sheet (aponuerosis). Aponeuroses often have plywood-like crossed fibres
Friction reduced by bursae or sheaths
2. fleshy insertion
Muscle joined to bone without visible tendon. Collagen still there as inclusion within muscle.
Fleshy and tendinous insertions have Sharpey's fibres running through - continuous with collagen of bone
ORIGINS AND INSERTIONS
Origin at one end
Classically origin (which moves least on contraction) proximal, insertion distal
Muscles often arise from two, three or four places (bicipital, tricipital, quadricipital) and so has more than one head
In some circumstances origin and insertion get confused, so talk of attachments
FORM OF MUSCLES
Wide functional variation in size and shape. Bundles (fascicles) of muscle fibres (10-60µm diameter, 15-30cm length) arranged in series/parallel for power/range of contraction
Strap muscles. Flat. Short with one set of fibres, long with fibres in series (tendinous insertions between) or wide with fibres in parallel
Fusiform muscles. Spindle shaped classic, three dimensional for more fibres. One or more bellies (digastric), one or more heads.
Unipennate, bipennate, multipennate. Relations are as quill pen barbs to shaft. Unipennate (like multi headed) often unbalanced. Bipennate balanced, multipennate a variation
Spiralised impart twist
Muscle tone. All muscle fibres cycle. At a
given time some will be:
When a muscle contracts tends to approximate ends
This opposed by
If the force exerted exceeds this limb accelerated from rest: lower force will maintain movement
TYPES OF MUSCLE ACTION
Prime mover or agonist (to start movement) Antagonists in opposition (to control or stabilise)
If movement is abolished joint is stable - better to close pack or use gravity
Action of agonist often produces unwanted movement (in wrong direction) opposed by other muscles
With two bones linked by a joint
across which a muscle acts movement is resolved:
Relative size of each varied by moving attachments
Steve Paxton and Terry McAndrew