Podcast
Questions and Answers
In most muscles, the origin is typically considered the upper attachment and the insertion is the lower attachment.
In most muscles, the origin is typically considered the upper attachment and the insertion is the lower attachment.
True (A)
A fixator is a muscle that assists the prime mover by producing the opposite of the desired movement.
A fixator is a muscle that assists the prime mover by producing the opposite of the desired movement.
False (B)
Muscles that prevent unwanted movement during an action are referred to as synergists.
Muscles that prevent unwanted movement during an action are referred to as synergists.
True (A)
The insertion of a muscle's tendon is almost always into the epiphysis near a joint.
The insertion of a muscle's tendon is almost always into the epiphysis near a joint.
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Adductor magnus tendon insertion is unique because it is located on the metacarpals.
Adductor magnus tendon insertion is unique because it is located on the metacarpals.
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Muscle action involving bringing attachments closer together is known as isotonic contraction.
Muscle action involving bringing attachments closer together is known as isotonic contraction.
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The upper end of the popliteus is unanimously considered the origin regardless of circumstances.
The upper end of the popliteus is unanimously considered the origin regardless of circumstances.
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Cancellous bone is composed of trabeculae arranged randomly to resist strains and stresses.
Cancellous bone is composed of trabeculae arranged randomly to resist strains and stresses.
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The nerve to a muscle in the limb contains approximately 40% afferent fibers.
The nerve to a muscle in the limb contains approximately 40% afferent fibers.
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Third, fourth, sixth, and seventh cranial nerves supply the ocular and facial muscles with sensory fibers.
Third, fourth, sixth, and seventh cranial nerves supply the ocular and facial muscles with sensory fibers.
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Proprioceptive impulses from the trapezius muscle are conveyed by C3 and C4.
Proprioceptive impulses from the trapezius muscle are conveyed by C3 and C4.
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At birth, the marrow in all bones is red and involved in active haemopoiesis.
At birth, the marrow in all bones is red and involved in active haemopoiesis.
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Proprioceptive impulses from the tongue muscles are conveyed by the trigeminal nerve.
Proprioceptive impulses from the tongue muscles are conveyed by the trigeminal nerve.
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By adulthood, there is a microscopic difference between cancellous and compact bone.
By adulthood, there is a microscopic difference between cancellous and compact bone.
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The spinal part of the accessory nerve contains sensory fibers.
The spinal part of the accessory nerve contains sensory fibers.
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Yellow marrow found in adults has no haemopoietic activity.
Yellow marrow found in adults has no haemopoietic activity.
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Hair follicles continue to develop throughout an individual's lifetime, even after birth.
Hair follicles continue to develop throughout an individual's lifetime, even after birth.
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The skin is more firmly attached to the underlying structures along the flexure lines.
The skin is more firmly attached to the underlying structures along the flexure lines.
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The sympathetic nerve supply affects the contraction of the arrector pili muscle, causing the hair to 'stand on end'.
The sympathetic nerve supply affects the contraction of the arrector pili muscle, causing the hair to 'stand on end'.
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Melanocyte activity in the hair matrix decreases with age, affecting hair color.
Melanocyte activity in the hair matrix decreases with age, affecting hair color.
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Sweat glands are evenly distributed over the skin, including areas like the lips and the tympanic membranes.
Sweat glands are evenly distributed over the skin, including areas like the lips and the tympanic membranes.
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The claw hand deformity is due to the unopposed action of both the extensors and flexor digitorum profundus.
The claw hand deformity is due to the unopposed action of both the extensors and flexor digitorum profundus.
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Wasting of interossei muscles results in a guttering appearance on the dorsum of the hand.
Wasting of interossei muscles results in a guttering appearance on the dorsum of the hand.
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There is always significant sensory loss on the ulnar side of the hand after an ulnar nerve injury.
There is always significant sensory loss on the ulnar side of the hand after an ulnar nerve injury.
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The median nerve can be exposed by incision along the medial border of the biceps.
The median nerve can be exposed by incision along the medial border of the biceps.
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To test the action of the ulnar nerve, abduction of the index finger by the first dorsal interosseous is examined.
To test the action of the ulnar nerve, abduction of the index finger by the first dorsal interosseous is examined.
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Surgical relief of compression in the carpal tunnel is achieved by transversely incising the flexor retinaculum.
Surgical relief of compression in the carpal tunnel is achieved by transversely incising the flexor retinaculum.
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Flexor pollicis longus and finger flexors are tested by asking the patient to pinch together the pads of the thumb and index finger.
Flexor pollicis longus and finger flexors are tested by asking the patient to pinch together the pads of the thumb and index finger.
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The ulnar nerve can be exposed in the upper arm along the lateral border of biceps.
The ulnar nerve can be exposed in the upper arm along the lateral border of biceps.
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A high lesion of the peripheral nerves affects the ulnar half of flexor digitorum profundus in flexing the distal interphalangeal joint of the little finger.
A high lesion of the peripheral nerves affects the ulnar half of flexor digitorum profundus in flexing the distal interphalangeal joint of the little finger.
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Study Notes
Skin Structure and Function
- Skin adheres to underlying structures variably; more firmly on palms/soles for improved grip.
- Creases are flexure lines over joints, consistent placements. Skin is thinner at flexure lines.
- Skin contains millions of sweat glands, absent on lips, penis tip, and eardrums.
Hair Structure and Growth
- Hair's hard keratin structure originates from the hair matrix (epidermal cells at follicle base).
- Hair cells lose nuclei, forming the hard keratin hair shaft.
- Melanocytes within the hair matrix deposit pigment in the hair.
- Hair color varies based on pigment mixtures.
- Hair follicle growth periods differ across sites; scalp follicles have protracted growth periods.
- An arrector pili muscle, smooth muscle with sympathetic innervation, attaches to each follicle base.
- When contracting, the muscle can squeeze adjacent sebaceous glands.
Muscle Structure and Function
- Muscle attachment sites (origin and insertion) move closer during isotonic contraction.
- Prime movers produce desired movements; antagonists relax to control movement.
- Fixators stabilize a muscle's origin enabling movement at insertion.
- Synergists prevent unwanted movements; relevant in complex movements.
Bone Structure and Function
- Fleshy muscle origins have no visible effect on bone structure.
- Cancellous bone consists of a trabecular spongework, resisting local strains.
- Bone alteration causes trabecular rearrangement.
- Bone molding arises from osteoclast/osteoblast action; but the control mechanism is unknown.
- Cancellous and compact bone appear microscopically identical, differing in overall structure.
- Marrow fills bone cavities in long bones and cancellous interstices.
- Red marrow is present at birth, active in hematopoiesis, but atrophies with age. Yellow marrow (fatty) replaces it.
Nerve Supply and Proprioception
- Muscles of the body wall/limbs contain about 40% afferent fibers.
- These fibers innervate muscle spindles and provide proprioceptive input vital for coordinated muscle contraction.
- Ocular/facial muscles are innervated by cranial nerves without sensory fibers.
- Proprioceptive impulses derive from local branches of trigeminal nerve.
- Neck/shoulder/tongue muscles have proprioceptive innervation from spinal nerves.
- Sensory pathways underlie voluntary movement coordination.
Upper Limb Anatomy (Specific details from the passage)
- Median nerve exposure – incision at biceps medial border.
- Ulnar nerve exposure – incision along biceps medial border.
- Carpal tunnel decompression – longitudinal incision of flexor retinaculum on ulnar side to avoid damaging recurrent branches.
- Flexor digitorum profundus – its ulnar half flexes distal interphalangeal joints, testing is important.
- Ulnar nerve damage symptoms – guttering between metacarpals and sensory loss in hand; testing is important.
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Description
Test your knowledge on the structures and functions of skin, hair, and muscle. This quiz covers key concepts like skin adherence, hair growth, and muscle contraction mechanisms. Explore how these systems work together to support the body’s functions.
